Freshwater Mollusk Biology and Conservation 20:33–58, 2017
Ó Freshwater Mollusk Conservation Society 2017
REGULAR ARTICLE
A REVISED LIST OF THE FRESHWATER MUSSELS
(MOLLUSCA: BIVALVIA: UNIONIDA) OF THE
UNITED STATES AND CANADA
James D. Williams1*, Arthur E. Bogan2, Robert S. Butler3,4, Kevin S. Cummings5,
Jeffrey T. Garner6, John L. Harris7, Nathan A. Johnson8,
and G. Thomas Watters9
1
Florida Museum of Natural History, Museum Road and Newell Drive, Gainesville, FL 32611 USA
North Carolina Museum of Natural Sciences, MSC 1626, Raleigh, NC 27699 USA
3
U.S. Fish and Wildlife Service, 212 Mills Gap Road, Asheville, NC 28803 USA
4
Retired.
5
Illinois Natural History Survey, 607 East Peabody Drive, Champaign, IL 61820 USA
6
Alabama Division of Wildlife and Freshwater Fisheries, 350 County Road 275, Florence, AL 35633
USA
7
Department of Biological Sciences, Arkansas State University, State University, AR 71753 USA
8
U.S. Geological Survey, Wetland and Aquatic Research Center, 7920 NW 71st Street, Gainesville,
FL 32653 USA
9
Museum of Biological Diversity, The Ohio State University, 1315 Kinnear Road, Columbus, OH
43212 USA
2
ABSTRACT
We present a revised list of freshwater mussels (order Unionida, families Margaritiferidae and
Unionidae) of the United States and Canada, incorporating changes in nomenclature and systematic
taxonomy since publication of the most recent checklist in 1998. We recognize a total of 298 species in
55 genera in the families Margaritiferidae (one genus, five species) and Unionidae (54 genera, 293
species). We propose one change in the Margaritiferidae: the placement of the formerly monotypic
genus Cumberlandia in the synonymy of Margaritifera. In the Unionidae, we recognize three new
genera, elevate four genera from synonymy, and place three previously recognized genera in synonymy.
We recognize for the first time two species (one native and one nonindigenous) in the Asian genus
Sinanodonta as occurring in North America. We recognize four new species and one subspecies and
elevate 21 species from synonymy. We elevate 10 subspecies to species status and no longer recognize
four subspecies. We change common names for five taxa, correct spelling for eight species, and correct
the date of publication of original descriptions for four species.
KEY WORDS: Unionidae, Margaritiferidae, taxonomy, systematics, nomenclature, mussel scientific names,
mussel common names
INTRODUCTION
During the past 50 yr, there has been considerable interest
in freshwater mussels (order Unionida) in the United States
*Corresponding Author: fishwilliams@gmail.com
and Canada. Much of this interest was brought about by
passage of the U.S. Endangered Species Acts of 1966, 1969,
and 1973 and the Canadian Species at Risk Act of 2002. These
legislative actions and the environmental movement that
accompanied them focused conservation attention on all
animals and plants, as well as their habitats. This in turn led
33
34
WILLIAMS ET AL.
to assessment of species conservation status and the
development of faunal lists for many states and provinces.
The task of developing species lists was difficult for most
invertebrates, including mussels, because so little attention had
been given to the study of their biology, ecology, and
systematics. In 1970, only six U.S. states had recent lists or
books covering their mussel fauna. The first modern attempt to
provide a comprehensive list of freshwater mussels of North
America was published by Burch (1973, 1975).
The first comprehensive list of freshwater mussels of the
United States and Canada was compiled in Turgeon et al.
(1988) and revised a decade later (Turgeon et al. 1998).
Williams et al. (1993) was another important resource during
this period; although mainly an assessment of species
conservation status, this paper also provided a comprehensive
and widely used species list similar to those of Turgeon et al.
(1988, 1998). These lists standardized and provided taxonomic
stability to mussel common and scientific names to an extent
that was previously unavailable. However, systematic taxonomy of mussels was poorly known at that time, and
classifications at all taxonomic levels were based largely on
concepts from the early 1900s.
Since publication of Turgeon et al. (1988, 1998) and
Williams et al. (1993), many studies have refined our
understanding of mussel systematic taxonomy. Several major
publications have addressed systematic relationships within
the class Bivalvia, including the order Unionida (Bieler et al.
2010; Carter et al. 2011; Bolotov et al. 2016; Araujo et al.
2017; Combosch et al. 2017). Major studies specific to the
Unionida include Graf and Ó Foighil (2000), Hoeh et al.
(2001, 2002, 2009), Roe and Hoeh (2003), Campbell et al.
(2005), Walker et al. (2006), Graf and Cummings (2007,
2017), Cummings and Graf (2010), and Campbell and
Lydeard (2012a, 2012b). In addition, many studies have
examined systematic relationships at lower taxonomic levels
(e.g., Serb et al. 2003; Jones et al. 2006; Lane et al. 2016).
Together, this body of work depicts a view of mussel
taxonomy that differs substantially from that of previous lists
of the North American fauna.
We present a revised classification and list of the
freshwater mussels of the United States and Canada (Tables
1 and 2). The primary purpose of this revision is to provide in
a single resource a comprehensive list and taxonomic
classification that reflects recent refinement of mussel
systematics.
METHODS
We used as a starting point the list of Turgeon et al. (1998).
We revised this list and its taxonomic classification based on a
review of peer-reviewed mussel taxonomic and nomenclatural
literature produced since 1998, unpublished research by the
authors, and discussions with other experts on mussel
systematics. We also corrected the spelling of specific epithets
and publication dates of original descriptions based on the
International Code of Zoological Nomenclature (http://www.
iczn.org/iczn/index.jsp). Species mentioned in the text, but not
included in Table 2, have author and date of publication
following the name. Author and date of publication for all
other species are given in Table 2.
Mussel common names follow Turgeon et al. (1998) with
minor exceptions, but they are capitalized as is now the
practice for many other animal groups (e.g., birds, reptiles,
amphibians, fishes). Capitalization of common names helps
avoid confusion by identifying standardized common names.
For example, reference to a ‘‘fragile papershell’’ could apply to
several thin-shelled species, but the capitalized ‘‘Fragile
Papershell’’ is unambiguously recognized as the common
name for Leptodea fragilis. We note and explain other
instances where we changed common names from those of
Turgeon et al. (1998) or where recognition of previously
unrecognized species necessitated creation of a new common
name.
We provide a rationale for and discussion of all taxonomic
changes in the following accounts for each family and genus
and in Table 2. There is a degree of uncertainty and
subjectivity in our revised list that is unavoidable given our
still imperfect understanding of mussel systematics. We
attempted to reconcile divergent views regarding mussel
systematics based on our assessment of the strength of
evidence for these views. In cases where evidence did not
allow reconciliation, we attempted to provide a plausible
conclusion based on our professional judgment and experience; these conclusions were based on consensus among the
authors to the extent possible.
Subspecies is a taxonomic category applied to populations
that are morphologically distinct and geographically separated
but that exhibit intergradation in contact zones (Mayr et al.
1953; Gilbert 1961). We evaluated morphological and
molecular evidence relating to the status of subspecies
recognized by Turgeon et al. (1998) and subsequent workers
(Jones and Neves 2010). In most cases, recent evidence did not
support recognition of subspecies but supported either
subsuming subspecies under the nominal species or elevating
subspecies to species status; we discuss this evidence for each
case. However, strong evidence with which to evaluate their
status was lacking for several, mostly extinct, subspecies (see
Epioblasma). The designation of subspecies versus species is
arbitrary and inconsistent for many animal groups (Huang and
Knowles 2016), and this has historically been the case for
mussels (e.g., Ortmann 1918, 1920). For subspecies that
lacked strong evidence for synonymization or elevation, we
recognize all as species to provide more consistent null
hypotheses regarding potential diversity in these groups.
This work has been registered with ZooBank and a copy
has been archived at Zenodo.org.
RESULTS
Freshwater bivalve higher classification continues to
evolve as more data are generated and new techniques are
developed. Fossil and modern bivalve higher classification has
REVISED LIST OF FRESHWATER MUSSELS
Table 1. Higher classification of the Unionoidea present in the United States
and Canada.
CLASS Bivalvia Linnaeus, 1758
INFRACLASS Heteroconchia Hertwig, 1895
COHORT Uniomorphi Gray, 1854 [¼Paleoheterodonta]
ORDER Unionida Gray, 1854
SUPERFAMILY Unionoidea Rafinesque, 1820
MARGARITIFERIDAE Henderson, 1929
Margaritifera Schumacher, 1816
UNIONIDAE Rafinesque, 1820
ANODONTINAE Rafinesque, 1820
Anodontini Rafinesque, 1820
Alasmidonta Say, 1818
Anodonta Lamarck, 1799
Anodontoides Simpson in Baker, 1898
Arcidens Simpson, 1900
Lasmigona Rafinesque, 1831
Pegias Simpson, 1900
Pyganodon Crosse and Fischer, 1894
Simpsonaias Frierson, 1914
Strophitus Rafinesque, 1820
Utterbackia Baker, 1927
Utterbackiana Frierson, 1927
Cristariini Lopes-Lima, Bogan, and Froufe, 2017
Sinanodonta Modell, 1945
GONIDEINAE Ortmann, 1916
Gonideini Ortmann, 1916
Gonidea Conrad, 1857
AMBLEMINAE Rafinesque, 1820
Amblemini Rafinesque, 1820
Amblema Rafinesque, 1820
Lampsilini Ihering, 1901
Actinonaias Crosse and Fischer, 1894
Cyprogenia Agassiz, 1852
Cyrtonaias Crosse and Fischer, 1894
Dromus Simpson, 1900
Ellipsaria Rafinesque, 1820
Epioblasma Rafinesque, 1831
Glebula Conrad, 1853
Hamiota Roe and Hartfield, 2005
Lampsilis Rafinesque, 1820
Lemiox Rafinesque, 1831
Leptodea Rafinesque, 1820
Ligumia Swainson, 1840
Medionidus Simpson, 1900
Obliquaria Rafinesque, 1820
Obovaria Rafinesque, 1819
Plectomerus Conrad, 1853
Potamilus Rafinesque, 1818
Ptychobranchus Simpson, 1900
Toxolasma Rafinesque, 1831
Truncilla Rafinesque, 1819
Venustaconcha Frierson, 1927
Villosa Frierson, 1927
35
Table 1, continued.
Pleurobemini Hannibal, 1912
Elliptio Rafinesque, 1819
Elliptoideus Frierson, 1927
Eurynia Rafinesque, 1820
Fusconaia Simpson, 1900
Hemistena Rafinesque, 1820
Parvaspina Perkins, Gangloff, and Johnson, 2017
Plethobasus Simpson, 1900
Pleurobema Rafinesque, 1819
Pleuronaia Frierson, 1927
Quadrulini Ihering, 1901
Cyclonaias Pilsbry in Ortmann and Walker, 1922
Megalonaias Utterback, 1915
Quadrula Rafinesque, 1820
Theliderma Swainson, 1840
Tritogonia Agassiz, 1852
Uniomerus Conrad, 1853
AMBLEMINAE (incertae sedis)
Disconaias Crosse and Fischer, 1894
Popenaias Frierson, 1927
Reginaia Campbell and Lydeard, 2012
recently been summarized by Carter et al. (2011), with
standardized endings for higher taxa within Bivalvia. Recent
evidence supports the order Unionida as a monophyletic clade
(Combosch et al. 2017). There have been two recent
assessments of the taxonomy for Margaritiferidae (Bolotov
et al. 2016; Araujo et al. 2017). Higher level relationships
within the Unionidae have recently been reviewed by LopesLima et al. (2017). Based on these publications, we provide
our assessment of higher classification of the Unionida and its
position in the class Bivalvia (Table 1).
There is general agreement on the three subfamily
divisions within the Unionidae in North America and seven
subfamilies worldwide, but there remains some uncertainty
regarding classification at lower levels. We adopted a
subfamily-, tribe-, and generic-level classification for the
United States and Canada based on recent phylogenetic
research (Table 1). We recognize the Anodontinae as a
subfamily with two tribes in the United States and Canada. We
recognize the subfamily Gonideinae, containing the genus
Gonidea. We recognize the subfamily Ambleminae as
consisting of four tribes: Amblemini, Lampsilini, Pleurobemini, and Quadrulini. The placement of many genera within
tribes in the Ambleminae is well supported and consistent
among studies, but the placement of others is less certain and
varies among studies (e.g., Plectomerus, Campbell et al.
2005). The Mexican and Central American genera Disconaias
and Popenaias and North American Reginaia lack sufficient
phylogenetic information to be confidently assigned to a
classification, and we placed them in Ambleminae incertae
sedis (Table 1).
Our revised list includes many taxonomic changes at the
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WILLIAMS ET AL.
Table 2. List of Margaritiferidae and Unionidae of the United States and Canada. Currently recognized taxa are bolded. Taxa preceded by an asterisk and not
bolded appeared in Turgeon et al. (1998) but are no longer recognized or reassigned to other genera.
Scientific Name
MARGARITIFERIDAE Henderson, 1929
*Cumberlandia Ortmann, 1912
*Cumberlandia monodonta (Say, 1829)
Margaritifera Schumacher, 1816
Margaritifera falcata (Gould, 1850)
Margaritifera hembeli (Conrad, 1838)
Margaritifera margaritifera (Linnaeus, 1758)
Margaritifera marrianae Johnson, 1983
Margaritifera monodonta (Say, 1829)
UNIONIDAE Rafinesque, 1820
Actinonaias Crosse and Fischer, 1894
Actinonaias ligamentina (Lamarck, 1819)
Actinonaias pectorosa (Conrad, 1834)
Alasmidonta Say, 1818
Alasmidonta arcula (Lea, 1838)
Alasmidonta atropurpurea (Rafinesque, 1831)
Alasmidonta heterodon (Lea, 1829)
Alasmidonta marginata Say, 1818
Alasmidonta mccordi Athearn, 1964
Alasmidonta raveneliana (Lea, 1834)
Alasmidonta robusta Clarke, 1981
Alasmidonta triangulata (Lea, 1858)
Alasmidonta undulata (Say, 1817)
Alasmidonta varicosa (Lamarck, 1819)
Alasmidonta viridis (Rafinesque, 1820)
Alasmidonta wrightiana (Walker, 1901)
Amblema Rafinesque, 1820
Amblema elliottii (Lea, 1856)
Amblema neislerii (Lea, 1858)
Amblema plicata (Say, 1817)
Anodonta Lamarck, 1799
*Anodonta beringiana Middendorff, 1851
Anodonta californiensis Lea, 1852
*Anodonta couperiana Lea, 1840
*Anodonta dejecta Lewis, 1875
*Anodonta heardi Gordon and Hoeh, 1995
*Anodonta implicata Say, 1829
Anodonta kennerlyi Lea, 1860
Anodonta nuttalliana Lea, 1838
Anodonta oregonensis Lea, 1838
*Anodonta suborbiculata Say, 1831
Anodontoides Simpson in Baker, 1898
Anodontoides denigrata (Lea, 1852)
Anodontoides ferussacianus (Lea, 1834)
Anodontoides radiatus (Conrad, 1834)
Arcidens Simpson, 1900
Arcidens confragosus (Say, 1829)
Arcidens wheeleri (Ortmann and Walker, 1912)
*Arkansia Ortmann and Walker, 1912
*Arkansia wheeleri Ortmann and Walker, 1912
Common Name
Changes in Scientific
and Common Names
Spectaclecase
Synonym of Margaritifera
Reassigned to Margaritifera
Western Pearlshell
Louisiana Pearlshell
Eastern Pearlshell
Alabama Pearlshell
Spectaclecase
Reassigned from Cumberlandia
Mucket
Pheasantshell
Altamaha Arcmussel
Cumberland Elktoe
Dwarf Wedgemussel
Elktoe
Coosa Elktoe
Appalachian Elktoe
Carolina Elktoe
Southern Elktoe
Triangle Floater
Brook Floater
Slippershell Mussel
Ochlockonee Arcmussel
Publication date corrected
Coosa Fiveridge
Fat Threeridge
Threeridge
Yukon Floater
California Floater
Barrel Floater
Woebegone Floater
Apalachicola Floater
Alewife Floater
Western Floater
Winged Floater
Oregon Floater
Flat Floater
Cumberland Papershell
Cylindrical Papershell
Rayed Creekshell
Rock Pocketbook
Ouachita Rock Pocketbook
Ouachita Rock Pocketbook
Reassigned to Sinanodonta
Reassigned to Utterbackiana
Synonym of Anodonta californiensis
Reassigned to Utterbackiana
Reassigned to Utterbackiana
Reassigned to Utterbackiana
Elevated from synonymy
Reassigned from Arkansia
Synonym of Arcidens
Reassigned to Arcidens
37
REVISED LIST OF FRESHWATER MUSSELS
Table 2, continued.
Scientific Name
Cyclonaias Pilsbry in Ortmann and Walker, 1922
Cyclonaias archeri (Frierson, 1905)
Cyclonaias asperata (Lea, 1861)
Cyclonaias aurea (Lea, 1859)
Cyclonaias houstonensis (Lea, 1859)
Cyclonaias infucata (Conrad, 1834)
Cyclonaias kieneriana (Lea, 1852)
Cyclonaias kleiniana (Lea, 1852)
Cyclonaias mortoni (Conrad, 1835)
Cyclonaias nodulata (Rafinesque, 1820)
Cyclonaias petrina (Gould, 1855)
Cyclonaias pustulosa (Lea, 1831)
Cyclonaias refulgens (Lea, 1868)
Cyclonaias succissa (Lea, 1852)
Cyclonaias tuberculata (Rafinesque, 1820)
Cyprogenia Agassiz, 1852
Cyprogenia aberti (Conrad, 1850)
Cyprogenia stegaria (Rafinesque, 1820)
Cyrtonaias Crosse and Fischer, 1894
Cyrtonaias tampicoensis (Lea, 1838)
Disconaias Crosse and Fischer, 1894
Disconaias fimbriata (Frierson, 1907)
*Disconaias salinasensis (Simpson, 1908)
Dromus Simpson, 1900
Dromus dromas (Lea, 1834)
Ellipsaria Rafinesque, 1820
Ellipsaria lineolata (Rafinesque, 1820)
Elliptio Rafinesque, 1819
Elliptio ahenea (Lea, 1843)
Elliptio angustata (Lea, 1831)
Elliptio arca (Conrad, 1834)
Elliptio arctata (Conrad, 1834)
*Elliptio buckleyi (Lea, 1843)
Elliptio chipolaensis (Walker, 1905)
Elliptio cistellaeformis (Lea, 1863)
Elliptio complanata (Lightfoot, 1786)
Elliptio congaraea (Lea, 1831)
Elliptio crassidens (Lamarck, 1819)
Elliptio dariensis (Lea, 1842)
*Elliptio dilatata (Rafinesque, 1820)
Elliptio downiei (Lea, 1858)
*Elliptio errans (Lea, 1856)
Elliptio fisheriana (Lea, 1838)
Elliptio folliculata (Lea, 1838)
Elliptio fraterna (Lea, 1852)
Elliptio fumata (Lea, 1857)
*Elliptio hepatica (Lea, 1859)
Elliptio hopetonensis (Lea, 1838)
Elliptio icterina (Conrad, 1834)
Common Name
Tallapoosa Orb
Alabama Orb
Golden Orb
Smooth Pimpleback
Sculptured Pigtoe
Coosa Orb
Florida Mapleleaf
Western Pimpleback
Wartyback
Texas Pimpleback
Pimpleback
Purple Pimpleback
Purple Pigtoe
Purple Wartyback
Changes in Scientific
and Common Names
Elevated from synonymy
Reassigned from Quadrula
Reassigned from Quadrula
Reassigned from Quadrula
Reassigned from Quincuncina
Elevated from synonymy
Elevated from synonymy
Species elevated from subspecies; reassigned
from Quadrula
Reassigned from Quadrula
Reassigned from Quadrula
Reassigned from Quadrula
Reassigned from Quadrula
Reassigned from Fusconaia
Western Fanshell
Fanshell
Tampico Pearlymussel
Fringed Mucket
Salina Mucket
Elevated from synonymy
Synonym of Disconaias fimbriata
Dromedary Pearlymussel
Butterfly
Southern Lance
Carolina Lance
Alabama Spike
Delicate Spike
Florida Shiny Spike
Chipola Slabshell
Box Spike
Eastern Elliptio
Carolina Slabshell
Elephantear
Georgia Elephantear
Spike
Satilla Elephantear
Oval Elliptio
Northern Lance
Pod Lance
Brother Spike
Gulf Slabshell
Brown Elliptio
Altamaha Slabshell
Variable Spike
Synonym of Elliptio jayensis
Reassigned to Eurynia
Synonym of Elliptio icterina; publication date
corrected
Elevated from synonymy
Synonym of Elliptio icterina
WILLIAMS ET AL.
38
Table 2, continued.
Scientific Name
Elliptio jayensis (Lea, 1838)
*Elliptio judithae Clarke, 1986
Elliptio lanceolata (Lea, 1828)
*Elliptio lugubris (Lea, 1834)
Elliptio marsupiobesa Fuller, 1972
Elliptio mcmichaeli Clench and Turner, 1956
Elliptio monroensis (Lea, 1843)
Elliptio nigella (Lea, 1852)
Elliptio occulta (Lea, 1843)
Elliptio producta (Conrad, 1836)
Elliptio pullata (Lea, 1856)
Elliptio purpurella (Lea, 1857)
*Elliptio raveneli (Conrad, 1834)
Elliptio roanokensis (Lea, 1838)
Elliptio shepardiana (Lea, 1834)
Elliptio spinosa (Lea, 1836)
*Elliptio steinstansana Johnson and Clarke, 1983
*Elliptio waccamawensis (Lea, 1863)
*Elliptio waltoni (Wright, 1888)
Elliptoideus Frierson, 1927
Elliptoideus sloatianus (Lea, 1840)
Epioblasma Rafinesque, 1831
Epioblasma ahlstedti Jones and Neves, 2010
Epioblasma arcaeformis (Lea, 1831)
Epioblasma aureola Jones and Neves, 2010
Epioblasma biemarginata (Lea, 1857)
Epioblasma brevidens (Lea, 1831)
Epioblasma capsaeformis (Lea, 1834)
Epioblasma cincinnatiensis (Lea, 1840)
Epioblasma curtisii (Frierson and Utterback, 1916)
Epioblasma flexuosa (Rafinesque, 1820)
Epioblasma florentina (Lea, 1857)
*Epioblasma florentina aureola Jones and Neves, 2010
*Epioblasma florentina curtisii (Frierson and Utterback, 1916)
*Epioblasma florentina florentina (Lea, 1857)
*Epioblasma florentina walkeri (Wilson and Clark, 1914)
Epioblasma gubernaculum (Reeve, 1865)
Epioblasma haysiana (Lea, 1834)
Epioblasma lenior (Lea, 1842)
Epioblasma lewisii (Walker, 1910)
Epioblasma metastriata (Conrad, 1838)
Epioblasma obliquata (Rafinesque, 1820)
*Epioblasma obliquata obliquata (Rafinesque, 1820)
*Epioblasma obliquata perobliqua (Conrad, 1836)
Epioblasma othcaloogensis (Lea, 1857)
Epioblasma penita (Conrad, 1834)
Epioblasma perobliqua (Conrad, 1836)
Epioblasma personata (Say, 1829)
Epioblasma propinqua (Lea, 1857)
Epioblasma rangiana (Lea, 1838)
Common Name
Florida Spike
Plicate Spike
Yellow Lance
Sad Elliptio
Cape Fear Spike
Fluted Elephantear
St. Johns Elephantear
Winged Spike
Hidden Spike
Atlantic Spike
Gulf Spike
Inflated Spike
Carolina Spike
Roanoke Slabshell
Altamaha Lance
Altamaha Spinymussel
Tar River Spinymussel
Waccamaw Spike
Florida Lance
Changes in Scientific
and Common Names
Common name changed from Flat Spike
Synonym of Elliptio roanokensis
Synonym of Elliptio icterina
Elevated from synonymy
Elevated from synonymy
Elevated from synonymy
Synonym of Elliptio icterina
Reassigned to Parvaspina
Synonym of Elliptio congaraea
Synonym of Elliptio ahenea
Purple Bankclimber
Duck River Dartersnapper
Sugarspoon
Golden Riffleshell
Angled Riffleshell
Cumberlandian Combshell
Oyster Mussel
Ohio Riffleshell
Curtis Pearlymussel
Leafshell
Yellow Blossom
Golden Riffleshell
Curtis Pearlymussel
Yellow Blossom
Tan Riffleshell
Green Blossom
Acornshell
Narrow Catspaw
Forkshell
Upland Combshell
Catspaw
Catspaw
White Catspaw
Southern Acornshell
Southern Combshell
White Catspaw
Round Combshell
Tennessee Riffleshell
Northern Riffleshell
Described as new species
Species elevated from subspecies
Elevated from synonymy
Species elevated from subspecies
Described as new subspecies; elevated to
species
Subspecies elevated to species
Nominotypical subspecies not required
Subspecies elevated to species
Species elevated from subspecies
Nominotypical subspecies not required
Subspecies elevated to species
Species elevated from subspecies
Species elevated from subspecies
39
REVISED LIST OF FRESHWATER MUSSELS
Table 2, continued.
Scientific Name
Epioblasma sampsonii (Lea, 1861)
Epioblasma stewardsonii (Lea, 1852)
Epioblasma torulosa (Rafinesque, 1820)
*Epioblasma torulosa gubernaculum (Reeve, 1865)
*Epioblasma torulosa rangiana (Lea, 1838)
*Epioblasma torulosa torulosa (Rafinesque, 1820)
Epioblasma triquetra (Rafinesque, 1820)
Epioblasma turgidula (Lea, 1858)
Epioblasma walkeri (Wilson and Clark, 1914)
Eurynia Rafinesque, 1820
Eurynia dilatata Rafinesque, 1820
Fusconaia Simpson, 1900
*Fusconaia askewi (Marsh, 1896)
*Fusconaia barnesiana (Lea, 1838)
Fusconaia burkei (Walker, 1922)
Fusconaia cerina (Conrad, 1838)
Fusconaia chunii (Lea, 1861)
Fusconaia cor (Conrad, 1834)
Fusconaia cuneolus (Lea, 1840)
*Fusconaia ebena (Lea, 1831)
Fusconaia escambia Clench and Turner, 1956
Fusconaia flava (Rafinesque, 1820)
*Fusconaia lananensis (Frierson, 1901)
Fusconaia masoni (Conrad, 1834)
Fusconaia mitchelli (Simpson, 1895)
Fusconaia ozarkensis (Call, 1887)
Fusconaia subrotunda (Lea, 1831)
*Fusconaia succissa (Lea, 1852)
Glebula Conrad, 1853
Glebula rotundata (Lamarck, 1819)
Gonidea Conrad, 1857
Gonidea angulata (Lea, 1838)
Hamiota Roe and Hartfield, 2005
Hamiota altilis (Conrad, 1834)
Hamiota australis (Simpson, 1900)
Hamiota perovalis (Conrad, 1834)
Hamiota subangulata (Lea, 1840)
Hemistena Rafinesque, 1820
Hemistena lata (Rafinesque, 1820)
Lampsilis Rafinesque, 1820
Lampsilis abrupta (Say, 1831)
*Lampsilis altilis (Conrad, 1834)
*Lampsilis australis Simpson, 1900
Lampsilis binominata Simpson, 1900
Lampsilis bracteata (Gould, 1855)
Lampsilis brittsi Simpson, 1900
Lampsilis cardium Rafinesque, 1820
Lampsilis cariosa (Say,1817)
Lampsilis dolabraeformis (Lea, 1838)
Lampsilis fasciola Rafinesque, 1820
Common Name
Wabash Riffleshell
Cumberland Leafshell
Tubercled Blossom
Green Blossom
Northern Riffleshell
Tubercled Blossom
Snuffbox
Turgid Blossom
Tan Riffleshell
Spike
Texas Pigtoe
Tennessee Pigtoe
Tapered Pigtoe
Gulf Pigtoe
Texas Pigtoe
Shiny Pigtoe
Finerayed Pigtoe
Ebonyshell
Narrow Pigtoe
Wabash Pigtoe
Triangle Pigtoe
Atlantic Pigtoe
False Spike
Ozark Pigtoe
Longsolid
Purple Pigtoe
Changes in Scientific
and Common Names
Subspecies elevated to species
Subspecies elevated to species
Nominotypical subspecies not required
Species elevated from subspecies
Elevated from synonymy
Reassigned from Elliptio
Synonym of Fusconaia chunii
Reassigned to Pleuronaia
Reassigned from Quincuncina
Common name changed from Southern Pigtoe
Elevated from synonymy
Reassigned to Reginaia
Synonym of Fusconaia chunii
Reassigned from Quincuncina
Reassigned to Cyclonaias
Round Pearlshell
Western Ridged Mussel
Finelined Pocketbook
Southern Sandshell
Orangenacre Mucket
Shinyrayed Pocketbook
Described as new genus
Reassigned from Lampsilis
Reassigned from Lampsilis
Reassigned from Lampsilis
Reassigned from Lampsilis
Cracking Pearlymussel
Pink Mucket
Finelined Pocketbook
Southern Sandshell
Lined Pocketbook
Texas Fatmucket
Northern Brokenray
Plain Pocketbook
Yellow Lampmussel
Altamaha Pocketbook
Wavyrayed Lampmussel
Reassigned to Hamiota
Reassigned to Hamiota
Species elevated from subspecies
40
WILLIAMS ET AL.
Table 2, continued.
Scientific Name
Lampsilis floridensis (Lea, 1852)
*Lampsilis fullerkati Johnson, 1984
*Lampsilis haddletoni Athearn, 1964
Lampsilis higginsii (Lea, 1857)
Lampsilis hydiana (Lea, 1838)
Lampsilis ornata (Conrad, 1835)
Lampsilis ovata (Say, 1817)
*Lampsilis perovalis (Conrad, 1834)
Lampsilis powellii (Lea, 1852)
Lampsilis radiata (Gmelin, 1791)
*Lampsilis radiata conspicua (Lea, 1872)
*Lampsilis radiata radiata (Gmelin, 1791)
Lampsilis rafinesqueana Frierson, 1927
Lampsilis reeveiana (Lea, 1852)
*Lampsilis reeveiana brevicula (Call, 1887)
*Lampsilis reeveiana brittsi Simpson, 1900
*Lampsilis reeveiana reeviana (Lea, 1852)
Lampsilis satura (Lea, 1852)
Lampsilis siliquoidea (Barnes, 1823)
Lampsilis splendida (Lea, 1838)
Lampsilis straminea (Conrad, 1834)
*Lampsilis straminea claibornensis (Lea, 1838)
*Lampsilis straminea straminea (Conrad, 1834)
Lampsilis streckeri Frierson, 1927
*Lampsilis subangulata (Lea, 1840)
Lampsilis teres (Rafinesque, 1820)
Lampsilis virescens (Lea, 1858)
Lasmigona Rafinesque, 1831
Lasmigona alabamensis Clarke, 1985
Lasmigona complanata (Barnes, 1823)
*Lasmigona complanata alabamensis Clarke, 1985
*Lasmigona complanata complanata (Barnes, 1823)
Lasmigona compressa (Lea, 1829)
Lasmigona costata (Rafinesque, 1820)
Lasmigona decorata (Lea, 1852)
Lasmigona etowaensis (Conrad, 1849)
Lasmigona holstonia (Lea, 1838)
Lasmigona subviridis (Conrad, 1835)
Lemiox Rafinesque, 1831
Lemiox rimosus (Rafinesque, 1831)
Leptodea Rafinesque, 1820
Leptodea fragilis (Rafinesque, 1820)
Leptodea leptodon (Rafinesque, 1820)
Leptodea ochracea (Say, 1817)
*Lexingtonia Ortmann, 1914
*Lexingtonia dolabelloides (Lea, 1840)
*Lexingtonia subplana (Conrad, 1837)
Ligumia Swainson, 1840
Ligumia nasuta (Say, 1817)
Ligumia recta (Lamarck, 1819)
Ligumia subrostrata (Say, 1831)
Common Name
Changes in Scientific
and Common Names
Florida Sandshell
Waccamaw Fatmucket
Haddleton Lampmussel
Higgins Eye
Louisiana Fatmucket
Southern Pocketbook
Pocketbook
Orangenacre Mucket
Arkansas Fatmucket
Eastern Lampmussel
Carolina Fatmucket
Eastern Lampmussel
Neosho Mucket
Arkansas Brokenray
Ozark Brokenray
Northern Brokenray
Arkansas Brokenray
Sandbank Pocketbook
Fatmucket
Rayed Pink Fatmucket
Rough Fatmucket
Southern Fatmucket
Rough Fatmucket
Speckled Pocketbook
Shinyrayed Pocketbook
Yellow Sandshell
Alabama Lampmussel
Elevated from synonymy
Synonym of Lampsilis radiata
Reassigned to Obovaria
Alabama Heelsplitter
White Heelsplitter
Alabama Heelsplitter
White Heelsplitter
Creek Heelsplitter
Flutedshell
Carolina Heelsplitter
Etowah Heelsplitter
Tennessee Heelsplitter
Green Floater
Species elevated from subspecies
Reassigned to Hamiota
Subspecies no longer recognized
Nominotypical subspecies not required
Subspecies no longer recognized
Subspecies elevated to species
Nominotypical subspecies not required
Subspecies no longer recognized
Nominotypical subspecies not required
Reassigned to Hamiota
Subspecies elevated to species
Nominotypical subspecies not required
Elevated from synonymy
Birdwing Pearlymussel
Fragile Papershell
Scaleshell
Tidewater Mucket
Slabside Pearlymussel
Virginia Pigtoe
Eastern Pondmussel
Black Sandshell
Pondmussel
Synonym of Fusconaia
Reassigned to Pleuronaia
Synonym of Fusconaia masoni
41
REVISED LIST OF FRESHWATER MUSSELS
Table 2, continued.
Scientific Name
Medionidus Simpson, 1900
Medionidus acutissimus (Lea, 1831)
Medionidus conradicus (Lea, 1834)
*Medionidus mcglameriae van der Schalie, 1939
Medionidus parvulus (Lea, 1860)
Medionidus penicillatus (Lea, 1857)
Medionidus simpsonianus Walker, 1905
Medionidus walkeri (Wright, 1897)
Megalonaias Utterback, 1915
Megalonaias nervosa (Rafinesque, 1820)
Obliquaria Rafinesque, 1820
Obliquaria reflexa Rafinesque, 1820
Obovaria Rafinesque, 1819
Obovaria arkansasensis (Lea, 1862)
Obovaria choctawensis (Athearn, 1964)
Obovaria haddletoni (Athearn, 1964)
*Obovaria jacksoniana (Frierson, 1912)
Obovaria olivaria (Rafinesque, 1820)
Obovaria retusa (Lamarck, 1819)
*Obovaria rotulata (Wright, 1899)
Obovaria subrotunda (Rafinesque, 1820)
Obovaria unicolor (Lea, 1845)
Parvaspina Perkins, Gangloff, and Johnson, 2017
Parvaspina collina (Conrad, 1836)
Parvaspina steinstansana (Johnson and Clarke, 1983)
Pegias Simpson, 1900
Pegias fabula (Lea, 1838)
Plectomerus Conrad, 1853
Plectomerus dombeyanus (Valenciennes, 1827)
Plethobasus Simpson, 1900
Plethobasus cicatricosus (Say, 1829)
Plethobasus cooperianus (Lea, 1834)
Plethobasus cyphyus (Rafinesque, 1820)
Pleurobema Rafinesque, 1819
*Pleurobema altum (Conrad, 1854)
Pleurobema athearni Gangloff, Williams, and
Feminella, 2006
*Pleurobema avellanum Simpson, 1900
Pleurobema beadleianum (Lea, 1861)
*Pleurobema bournianum (Lea, 1840)
*Pleurobema chattanoogaense (Lea, 1858)
Pleurobema clava (Lamarck, 1819)
*Pleurobema collina (Conrad, 1836)
Pleurobema cordatum (Rafinesque, 1820)
Pleurobema curtum (Lea, 1859)
Pleurobema decisum (Lea, 1831)
Pleurobema fibuloides (Lea, 1859)
*Pleurobema flavidulum (Lea, 1861)
*Pleurobema furvum (Conrad, 1834)
Pleurobema georgianum (Lea, 1841)
Common Name
Alabama Moccasinshell
Cumberland Moccasinshell
Tombigbee Moccasinshell
Coosa Moccasinshell
Gulf Moccasinshell
Ochlockonee Moccasinshell
Suwannee Moccasinshell
Changes in Scientific
and Common Names
Synonym of Leptodea fragilis
Washboard
Threehorn Wartyback
Southern Hickorynut
Choctaw Bean
Haddleton Lampmussel
Southern Hickorynut
Hickorynut
Ring Pink
Round Ebonyshell
Round Hickorynut
Alabama Hickorynut
James Spinymussel
Tar River Spinymussel
Reassigned from Villosa
Reassigned from Villosa
Reassigned from Lampsilis
Synonym of Obovaria arkansasensis
Reassigned to Reginaia
Described as new genus
Reassigned from Pleurobema;
publication date corrected
Reassigned from Elliptio
Littlewing Pearlymussel
Bankclimber
White Wartyback
Orangefoot Pimpleback
Sheepnose
Highnut
Canoe Creek Clubshell
Considered a nomen dubium
Described as new species
Hazel Pigtoe
Mississippi Pigtoe
Scioto Pigtoe
Painted Clubshell
Clubshell
James Spinymussel
Ohio Pigtoe
Black Clubshell
Southern Clubshell
Kusha Pigtoe
Yellow Pigtoe
Dark Pigtoe
Southern Pigtoe
Synonym of Pleurobema rubellum
Synonym of Pleurobema clava
Synonym of Pleurobema decisum
Reassigned to Parvaspina
Elevated from synonymy
Synonym of Pleurobema perovatum
Synonym of Pleurobema rubellum
42
WILLIAMS ET AL.
Table 2, continued.
Scientific Name
*Pleurobema gibberum (Lea, 1838)
*Pleurobema hagleri (Frierson, 1900)
Pleurobema hanleyianum (Lea, 1852)
Pleurobema hartmanianum (Lea, 1860)
*Pleurobema johannis (Lea, 1859)
Pleurobema marshalli Frierson, 1927
*Pleurobema murrayense (Lea, 1868)
*Pleurobema nucleopsis (Conrad, 1849)
Pleurobema oviforme (Conrad, 1834)
Pleurobema perovatum (Conrad, 1834)
Pleurobema plenum (Lea, 1840)
Pleurobema pyriforme (Lea, 1857)
Pleurobema riddellii (Lea, 1861)
Pleurobema rubellum (Conrad, 1834)
Pleurobema rubrum (Rafinesque, 1820)
Pleurobema sintoxia (Rafinesque, 1820)
Pleurobema stabile (Lea, 1861)
Pleurobema strodeanum (Wright, 1898)
Pleurobema taitianum (Lea, 1834)
*Pleurobema troschelianum (Lea, 1852)
Pleurobema verum (Lea, 1861)
Pleuronaia Frierson, 1927
Pleuronaia barnesiana (Lea, 1838)
Pleuronaia dolabelloides (Lea, 1840)
Pleuronaia gibber (Lea, 1838)
Popenais Frierson, 1927
Popenais popeii (Lea, 1857)
Potamilus Rafinesque, 1818
Potamilus alatus (Say, 1817)
Potamilus amphichaenus (Frierson, 1898)
Potamilus capax (Green, 1832)
Potamilus inflatus (Lea, 1831)
Potamilus metnecktayi Johnson, 1998
Potamilus ohiensis (Rafinesque, 1820)
Potamilus purpuratus (Lamarck, 1819)
Ptychobranchus Simpson, 1900
Ptychobranchus fasciolaris (Rafinesque, 1820)
Ptychobranchus foremanianus (Lea, 1842)
Ptychobranchus greenii (Conrad, 1834)
Ptychobranchus jonesi (van der Schalie, 1934)
Ptychobranchus occidentalis (Conrad, 1836)
*Ptychobranchus subtentum (Say, 1825)
Ptychobranchus subtentus (Say, 1825)
Pyganodon Crosse and Fischer, 1894
Pyganodon cataracta (Say, 1817)
Pyganodon fragilis (Lamarck, 1819)
Pyganodon gibbosa (Say, 1824)
Pyganodon grandis (Say, 1829)
Pyganodon lacustris (Lea, 1857)
Common Name
Cumberland Pigtoe
Brown Pigtoe
Georgia Pigtoe
Cherokee Pigtoe
Alabama Pigtoe
Flat Pigtoe
Coosa Pigtoe
Longnut
Tennessee Clubshell
Ovate Clubshell
Rough Pigtoe
Oval Pigtoe
Louisiana Pigtoe
Warrior Pigtoe
Pyramid Pigtoe
Round Pigtoe
Coosa Pigtoe
Fuzzy Pigtoe
Heavy Pigtoe
Alabama Clubshell
True Pigtoe
Tennessee Pigtoe
Slabside Pearlymussel
Cumberland Pigtoe
Changes in Scientific
and Common Names
Reassigned to Pleuronaia
Synonym of Pleurobema rubellum
Elevated from synonymy
Synonym of Pleurobema perovatum
Synonym of Pleurobema stabile
Synonym of Pleurobema georgianum
Elevated from synonymy
Synonym of Pleurobema georgianum
Elevated from synonymy
Reassigned from Fusconaia
Reassigned from Lexingtonia
Reassigned from Pleurobema; spelling
correction of species name
Texas Hornshell
Pink Heelsplitter
Texas Heelsplitter
Fat Pocketbook
Inflated Heelsplitter
Salina Mucket
Pink Papershell
Bleufer
Common name changed from Alabama
Heelsplitter
Described as new species
Kidneyshell
Rayed Kidneyshell
Triangular Kidneyshell
Southern Kidneyshell
Ouachita Kidneyshell
Fluted Kidneyshell
Fluted Kidneyshell
Incorrect spelling of species name
Spelling correction of species name
Eastern Floater
Newfoundland Floater
Inflated Floater
Giant Floater
Lake Floater
Publication date corrected
Elevated from synonymy
43
REVISED LIST OF FRESHWATER MUSSELS
Table 2, continued.
Scientific Name
Quadrula Rafinesque, 1820
Quadrula apiculata (Say, 1829)
*Quadrula asperata (Lea, 1861)
*Quadrula aurea (Lea, 1859)
Quadrula couchiana (Lea, 1860)
*Quadrula cylindrica cylindrica (Say, 1817)
Common Name
Southern Mapleleaf
Alabama Orb
Golden Orb
Rio Grande Monkeyface
Rabbitsfoot
*Quadrula cylindrica strigillata (Wright, 1898)
Quadrula fragosa (Conrad, 1835)
*Quadrula houstonensis (Lea, 1859)
*Quadrula intermedia (Conrad, 1836)
*Quadrula kieneriana (Lea, 1852)
*Quadrula metanevra (Rafinesque, 1820)
Quadrula nobilis (Conrad, 1854)
*Quadrula nodulata (Rafinesque, 1820)
*Quadrula petrina (Gould, 1855)
*Quadrula pustulosa mortoni (Conrad, 1835)
Rough Rabbitsfoot
Winged Mapleleaf
Smooth Pimpleback
Cumberland Monkeyface
Coosa Orb
Monkeyface
Gulf Mapleleaf
Wartyback
Texas Pimpleback
Western Pimpleback
*Quadrula pustulosa pustulosa (Lea, 1831)
Pimpleback
Quadrula quadrula (Rafinesque, 1820)
*Quadrula refulgens (Lea, 1868)
Quadrula rumphiana (Lea, 1852)
*Quadrula sparsa (Lea, 1841)
*Quadrula stapes (Lea, 1831)
*Quadrula tuberosa (Lea, 1840)
*Quincuncina Ortmann, 1922
*Quincuncina burkei Walker, 1922
*Quincuncina infucata (Conrad, 1834)
*Quincuncina mitchelli (Simpson, 1895)
Reginaia Campbell and Lydeard, 2012
Reginaia apalachicola (Williams and Fradkin, 1999)
Reginaia ebenus (Lea, 1831)
Reginaia rotulata (Wright, 1899)
Simpsonaias Frierson, 1914
Simpsonaias ambigua (Say, 1825)
Sinanodonta Modell, 1945
Sinanodonta beringiana (Middendorff, 1851)
Sinanodonta woodiana (Lea, 1834)
Strophitus Rafinesque, 1820
Strophitus connasaugaensis (Lea, 1858)
Strophitus subvexus (Conrad, 1834)
Strophitus undulatus (Say, 1817)
Theliderma Swainson, 1840
Theliderma cylindrica (Say, 1817)
Theliderma intermedia (Conrad, 1836)
Theliderma metanevra (Rafinesque, 1820)
Theliderma sparsa (Lea, 1841)
Theliderma stapes (Lea, 1831)
Mapleleaf
Purple Pimpleback
Ridged Mapleleaf
Appalachian Monkeyface
Stirrupshell
Rough Rockshell
Tapered Pigtoe
Sculptured Pigtoe
False Spike
Apalachicola Ebonyshell
Ebonyshell
Round Ebonyshell
Changes in Scientific
and Common Names
Reassigned to Cyclonaias
Reassigned to Cyclonaias
Nominotypical subspecies not required;
reassigned to Theliderma
Subspecies no longer recognized
Reassigned to Cyclonaias
Reassigned to Theliderma
Reassigned to Cyclonaias
Reassigned to Theliderma
Elevated from synonymy
Reassigned to Cyclonaias
Reassigned to Cyclonaias
Subspecies elevated to species; reassigned
to Cyclonaias
Nominotypical subspecies not required;
reassigned to Cyclonaias
Reassigned to Cyclonaias
Reassigned to Theliderma
Reassigned to Theliderma
Synonym of Theliderma metanevra
Synonym of Fusconaia
Reassigned to Fusconaia
Reassigned to Cyclonaias
Reassigned to Fusconaia
Described as new genus
Described as new species; reassigned
from Fusconaia
Reassigned from Fusconaia; spelling
correction of species name
Reassigned from Obovaria
Salamander Mussel
Yukon Floater
Chinese Pondmussel
Not previously reported from North America
Reassigned from Anodonta
Introduced and established in New Jersey
Alabama Creekmussel
Southern Creekmussel
Creeper
Rabbitsfoot
Cumberland Monkeyface
Monkeyface
Appalachian Monkeyface
Stirrupshell
Elevated from synonymy
Reassigned from Quadrula
Reassigned from Quadrula
Reassigned from Quadrula
Reassigned from Quadrula
Reassigned from Quadrula
44
WILLIAMS ET AL.
Table 2, continued.
Scientific Name
Toxolasma Rafinesque, 1831
Toxolasma corvunculus (Lea, 1868)
Toxolasma cylindrellus (Lea, 1868)
Toxolasma lividum Rafinesque, 1831
Common Name
Southern Purple Lilliput
Pale Lilliput
Purple Lilliput
*Toxolasma lividus (Rafinesque, 1831)
*Toxolasma mearnsi (Simpson, 1900)
Toxolasma parvum (Barnes, 1823)
*Toxolasma parvus (Barnes, 1823)
Toxolasma paulum (Lea, 1840)
*Toxolasma paulus (Lea, 1840)
Toxolasma pullus (Conrad, 1838)
Toxolasma texasiense (Lea, 1857)
*Toxolasma texasiensis (Lea, 1857)
Tritogonia Agassiz, 1852
Tritogonia verrucosa (Rafinesque, 1820)
Truncilla Rafinesque, 1819
Truncilla cognata (Lea, 1860)
Truncilla donaciformis (Lea, 1828)
Truncilla macrodon (Lea, 1859)
Truncilla truncata Rafinesque, 1820
Uniomerus Conrad, 1853
Uniomerus carolinianus (Bosc, 1801)
Uniomerus columbensis (Lea, 1857)
Uniomerus declivis (Say, 1831)
Uniomerus tetralasmus (Say, 1831)
Utterbackia Baker, 1927
Utterbackia imbecillis (Say, 1829)
Utterbackia peggyae (Johnson, 1965)
Utterbackia peninsularis Bogan and Hoeh, 1995
Utterbackiana Frierson, 1927
Utterbackiana couperiana (Lea, 1840)
Utterbackiana hartfieldorum (Williams, Bogan,
and Garner, 2009)
Utterbackiana heardi (Gordon and Hoeh, 1995)
Utterbackiana implicata (Say, 1829)
Utterbackiana suborbiculata (Say, 1831)
Venustaconcha Frierson, 1927
Venustaconcha ellipsiformis (Conrad, 1836)
Venustaconcha pleasii (Marsh, 1891)
Venustaconcha trabalis (Conrad, 1834)
Purple Lilliput
Western Lilliput
Lilliput
Lilliput
Iridescent Lilliput
Iridescent Lilliput
Savannah Lilliput
Texas Lilliput
Texas Lilliput
Venustaconcha troostensis (Lea, 1834)
Villosa Frierson, 1927
*Villosa amygdala (Lea, 1843)
Villosa amygdalum (Lea, 1843)
*Villosa arkansasensis (Lea, 1862)
*Villosa choctawensis Athearn, 1964
Villosa constricta (Conrad, 1838)
Villosa delumbis (Conrad, 1834)
Villosa fabalis (Lea, 1831)
Cumberland Bean
Changes in Scientific
and Common Names
Spelling correction of species name;
parentheses unnecessary
Incorrect spelling of species name
Synonym of Toxolasma texasiense
Spelling correction of species name
Incorrect spelling of species name
Spelling correction of species name
Incorrect spelling of species name
Spelling correction of species name
Incorrect spelling of species name
Pistolgrip
Mexican Fawnsfoot
Fawnsfoot
Texas Fawnsfoot
Deertoe
Eastern Pondhorn
Apalachicola Pondhorn
Tapered Pondhorn
Pondhorn
Common name changed from Florida Pondhorn
Elevated from synonymy
Paper Pondshell
Florida Floater
Peninsular Floater
Barrel Floater
Cypress Floater
Elevated from synonymy
Reassigned from Anodonta
Described as new species; reassigned from Anodonta
Apalachicola Floater
Alewife Floater
Flat Floater
Reassigned from Anodonta
Reassigned from Anodonta
Reassigned from Anodonta
Ellipse
Bleedingtooth Mussel
Tennessee Bean
Florida Rainbow
Florida Rainbow
Ouachita Creekshell
Choctaw Bean
Notched Rainbow
Eastern Creekshell
Rayed Bean
Reassigned from Villosa; common name changed
from Cumberland Bean
Elevated from synonymy
Incorrect spelling of species name
Spelling correction of species name
Reassigned to Obovaria
Reassigned to Obovaria
45
REVISED LIST OF FRESHWATER MUSSELS
Table 2, continued.
Scientific Name
Villosa iris (Lea, 1829)
Villosa lienosa (Conrad, 1834)
Villosa nebulosa (Conrad, 1834)
Villosa ortmanni (Walker, 1925)
*Villosa perpurpurea (Lea, 1861)
Villosa sima (Lea, 1838)
Villosa taeniata (Conrad, 1834)
*Villosa trabalis (Conrad, 1834)
Villosa umbrans (Lea, 1857)
*Villosa vanuxemensis umbrans (Lea, 1857)
Villosa vanuxemensis (Lea, 1838)
*Villosa vanuxemensis vanuxemensis (Lea, 1838)
Villosa vaughaniana (Lea, 1838)
Villosa vibex (Conrad, 1834)
Villosa villosa (Wright, 1898)
Common Name
Rainbow
Little Spectaclecase
Alabama Rainbow
Kentucky Creekshell
Purple Bean
Caney Fork Rainbow
Painted Creekshell
Cumberland Bean
Coosa Creekshell
Coosa Creekshell
Mountain Creekshell
Mountain Creekshell
Carolina Creekshell
Southern Rainbow
Downy Rainbow
genus, species, and subspecies levels relative to previous lists.
We recognize in total 298 freshwater mussel species from the
United States and Canada. These comprise the families
Margaritiferidae with one genus and five species and Unionidae with 54 genera and 293 species (Table 2). Turgeon et al.
(1998) recognized in total 304 taxa: Margaritiferidae with two
genera and five species and Unionidae with 49 genera, 286
species, and 13 subspecies. We summarize our changes to
Turgeon et al. (1998) as follows. We recognize eight
additional genera, including three recently described (Hamiota, Parvaspina, and Reginaia), four elevated from synonymy
(Eurynia, Pleuronaia, Theliderma, and Utterbackiana), and
one newly reported from North America (Sinanodonta). We
place in synonymy four genera, including one in the
Margaritiferidae (Cumberlandia) and three in the Unionidae
(Arkansia, Lexingtonia, and Quincuncina). We recognize 25
additional species (all Unionidae), including four newly
described species and 21 species elevated from synonymy.
We place in synonymy 29 species and consider Pleurobema
altum a nomen dubium, and we reassigned 41 species to other
genera. We corrected the specific epithet spelling for eight
species, corrected the date of publication for four, and changed
the common names of five. Last, we recognized no subspecies,
elevating 10 subspecies to species status and subsuming four
subspecies into their nominal species (see Methods).
Margaritiferidae Henderson, 1929
Turgeon et al. (1998) recognized two genera in Margaritiferidae, Cumberlandia (one species) and Margaritifera (four
species). On the basis of shell morphology and soft anatomy,
Smith (2001) placed Cumberlandia in Margaritanopsis and
Margaritifera (in part) in Pseudunio, but this classification
was not widely accepted. In a molecular phylogenetic analysis,
Huff et al. (2004) considered Cumberlandia a junior synonym
Changes in Scientific
and Common Names
Synonym of Venustaconcha trabalis
Elevated from synonymy
Reassigned to Venustaconcha
Species elevated from subspecies
Subspecies elevated to species
Nominotypical subspecies not required
of Margaritifera, and this classification was followed by some
subsequent authors (e.g., Graf and Cummings 2007, 2017;
Cummings and Graf 2010), but others continued to recognize
the genus as valid (e.g., Williams et al. 2008; Watters et al.
2009; Haag 2012). A more comprehensive phylogeny of the
Margaritiferidae that included eight of 13 currently recognized
species (three from North America) retained the use of
Cumberlandia (Bolotov et al. 2015). However, based on more
recent evidence (Bolotov et al. 2016; Araujo et al. 2017), we
consider Cumberlandia a junior synonym of Margaritifera.
Cumberlandia Ortmann, 1912.—Turgeon et al. (1998)
recognized one species, Cumberlandia monodonta. We place
Cumberlandia in the synonymy of Margaritifera (see
Margaritiferidae).
Margaritifera Schumacher, 1816.—Turgeon et al. (1998)
recognized four species of Margaritifera. Placement of
Cumberlandia in the synonymy of Margaritifera brings the
number of recognized species to five (see Margaritiferidae).
Unionidae Rafinesque, 1820
Turgeon et al. (1998) recognized 49 genera, 286 species,
and 13 subspecies in Unionidae. We recognize 54 genera, 293
species, and no subspecies. We provide support for and
discussion of these changes in the following assessments of
genera.
Actinonaias Crosse and Fischer, 1894.—Turgeon et al.
(1998) recognized two species, Actinonaias ligamentina and
Actinonaias pectorosa. Molecular analyses (e.g., Campbell et
al. 2005; Zanatta and Murphy 2006) found that the two species
of Actinonaias together did not represent a monophyletic
grouping, but the position of each of these lineages within the
Lampsilini was unresolved. The type locality for Actinonaias
is central Mexico, and 10 recognized species are restricted to
this region (Graf and Cummings 2017), but no species
46
WILLIAMS ET AL.
attributable to Actinonaias occur between Mexico and the
range of ligamentina and pectorosa in the central United
States and southern Canada. No phylogenetic research has
examined relationships among Mexican Actinonaias and
ligamentina and pectorosa, but it is unlikely they are closely
related considering the disjunct distribution and lack of
precedent for such a geographical pattern in other freshwater
taxa (e.g., Miller et al. 2005). Actinonaias ligamentina and
pectorosa require placement in two different genera, but at this
time we retain these two species in the genus Actinonaias
pending the outcome of further phylogenetic research.
Alasmidonta Say, 1818.—Turgeon et al. (1998) recognized
12 species, and recent evidence supports no changes to this
classification.
Amblema Rafinesque, 1820.—Turgeon et al. (1998)
recognized three species, and recent evidence supports no
changes to this classification.
Anodonta Lamarck, 1799.—Turgeon et al. (1998) recognized 10 species. Mock et al. (2004) and Zanatta et al. (2007)
found Anodonta to be polyphyletic, with eastern North
American species forming a monophyletic clade distinct from
the one that includes the type species (Anodonta cygnea,
which occurs in Eurasia) and western North American
Anodonta. Without discussion, Graf and Cummings (2007)
and Cummings and Graf (2010) placed Anodonta couperiana,
A. heardi, and A. suborbiculata in Utterbackia, and A.
implicata in Pyganodon. Because no supporting evidence
was provided, we do not recognize these changes. The next
available genus for the eastern North American clade (A.
couperiana, A. heardi, A. suborbiculata, and A. implicata)
identified as distinct by Mock et al. (2004) is Utterbackiana.
Anodonta hartfieldorum Williams, Bogan, and Garner, 2009,
was described subsequently and also belongs to Utterbackiana
(see Utterbackiana).
In a phylogenetic analysis of western North American
Anodonta, Chong et al. (2008) found A. beringiana to be more
closely related to the Asian species Sinanodonta woodiana
than to North American species. Based on this evidence, we
reassign beringiana to Sinanodonta (see Sinanodonta).
We retain the remaining four western North American
species within Anodonta (A. californiensis, A. kennerlyi, A.
nuttalliana, and A. oregonensis) based on their phylogenetic
affinity to Eurasian Anodonta (Mock et al. 2004; Zanatta et al.
2007; Chong et al. 2008). Anodonta dejecta was recognized by
Turgeon et al. (1998), Graf and Cummings (2007), and
Cummings and Graf (2010). This species is treated as a
synonym of A. californiensis by Bequaert and Miller (1973)
and the Arizona Game and Fish Department (2017). We do not
recognize A. dejecta, which is here placed in synonymy of A.
californiensis.
Anodontoides Simpson in Baker, 1898.—Turgeon et al.
(1998) recognized two species. One additional species,
Anodontoides denigrata, was recognized without discussion
by Neves et al. (1997) and Cicerello and Schuster (2003).
Haag and Cicerello (2016) recognized A. denigrata on the
basis of molecular data showing that upper Cumberland River
drainage populations were distinct from A. ferussacianus
(Bogan and Raley 2013), and we recognize this species for the
same reason. Bogan and Raley (2013) referred to A. denigrata
as A. argenteus (Lea, 1840), for which the type locality is
Stones River, Tennessee. The Stones River is a tributary of the
middle Cumberland River and well downstream of the
putative distribution of A. denigrata and other species
considered endemic to the upper Cumberland River drainage
upstream of the hypothesized original location of Cumberland
Falls (Haag and Cicerello 2016). Until further research
delineates this species’ distribution more precisely, we use
A. denigrata, for which the type locality is in the upper
Cumberland River drainage (Clear Fork, Campbell County,
Tennessee; see Ortmann 1918). Ahlstedt et al. (2016) reported
a possibly distinct Anodontoides species from the Powell
River, Virginia, but further work is needed to determine its
validity and taxonomy.
Arcidens Simpson, 1900.—Turgeon et al. (1998) recognized one species, Arcidens confragosus. Clarke (1981)
considered Arkansia (see Arkansia) a junior synonym of
Arcidens (see also Graf and Cummings 2007), and this
classification was supported by morphological and molecular
data (Inoue et al. 2014). We recognize two species of
Arcidens.
Arkansia Ortmann and Walker, 1912.—Arkansia was
described as a monotypic genus including A. wheeleri, which
was recognized by Turgeon et al. (1998). We place Arkansia
in the synonymy of Arcidens (see Arcidens).
Cyclonaias Pilsbry in Ortmann and Walker, 1922.—
Turgeon et al. (1998) recognized Cyclonaias, which has long
been considered a monotypic genus for C. tuberculata.
Cyclonaias tuberculata has been aligned with the Quadrulini
based on morphological (e.g., Frierson 1927; Modell 1964)
and protein polymorphism data (Davis and Fuller 1981).
Heard and Guckert (1971) placed Cyclonaias in the Pleurobemini based on its ectobranchous brooding (see also Graf and
Cummings 2007). However, it appears that ectobranchy arose
multiple times (Davis and Fuller 1981; Graf 2002; Roe and
Hoeh 2003), meaning that this trait does not necessarily
exclude Cyclonaias from the Quadrulini, and some female C.
tuberculata brood glochidia in all four gills (Frierson 1927).
Recent molecular studies consistently supported inclusion
of Cyclonaias in the Quadrulini, but they further show that it is
a member of a monophyletic clade including Q. pustulosa and
related species (Campbell et al. 2005; Campbell and Lydeard
2012b). Serb et al. (2003) did not support this relationship, but
these results were later attributed to an error in sample labeling
(Campbell and Lydeard 2012b). However, Serb et al. (2003)
as well as Campbell et al. (2005) and Campbell and Lydeard
(2012b) support the monophyly of the Quadrula pustulosa
clade and its distinctiveness from other species of Quadrula
(see Quadrula and Theliderma). In addition to Cyclonaias
tuberculata, the Quadrula pustulosa clade identified by these
studies includes the following species recognized by Turgeon
et al. (1998): Q. asperata, Q. aurea, Q. houstonensis, Q.
nodulata, Q. petrina, Q. pustulosa, and Q. refulgens, as well
REVISED LIST OF FRESHWATER MUSSELS
as Fusconaia succissa and Quincuncina infucata (see
Fusconaia and Quincuncina).
The name Quadrula is not available for the Q. pustulosa
clade because the type species, Q. quadrula, is a member of
another distinct, monophyletic clade (see Quadrula). Graf and
Cummings (2007) elevated the generic name Amphinaias
Crosse and Fischer, 1894, for the Q. pustulosa clade. The type
species for Amphinaias (by original designation) is Unio
couchianus Lea, 1860, which has a quadrate shell and sulcus
(but lacks pustules) similar to the Q. quadrula clade. This
morphology is very different from the rounded, pustulose
shells of the Q. pustulosa clade. Quadrula couchiana is
considered extinct and genetic data are unavailable; however,
we do not consider Amphinaias an available name for the Q.
pustulosa clade because of the strongly divergent morphology
of the type species. Campbell and Lydeard (2012b) proposed
Rotundaria Rafinesque, 1820, as a name for the Q. pustulosa
clade, presuming its availability based on statements in
Valenciennes (1827). However, Valenciennes noted that
Rafinesque had confused two species, one for which he kept
Rafinesque’s name Unio verrucosa and named the other Unio
tuberculosa [sic]. As such, Valenciennes’s statement cannot be
accepted as a subsequent designation of Obliquaria tuberculata Rafinesque, 1820, as the type species of Rotundaria (P.
Bouchet, Muséum National d’Histoire Naturelle, Paris,
personal communication), and Herrmannsen (1848) later
designated Obliquaria subrotunda Rafinesque, 1820, as the
type species of Rotundaria. Rafinesque did not select a type
species for Rotundaria and because more than one species was
included by him in the genus, the type species cannot be fixed
by monotypy. Therefore, Rotundaria is not available for the Q.
pustulosa clade. Frierson (1927) erected the subgenus Bullata
for Q. pustulosa but realized this was preoccupied and created
the replacement name Pustulosa with the same type species.
Thus, Cyclonaias becomes the oldest available name for this
group.
Of the 10 species discussed above as members of
Cyclonaias, three were not recognized by Turgeon et al.
(1998) (C. archeri, C. kieneriana, and C. kleiniana), and one
was considered a subspecies (C. mortoni, as Quadrula
pustulosa mortoni). Graf and Cummings (2007) elevated Q.
archeri from synonymy with Q. asperata, but they provided
no justification for this change. The distinctiveness of C.
archeri was recognized by Williams et al. (2008) based on its
morphology, absence of intergrades, and isolated and
restricted distribution. We recognize C. archeri. The distinctiveness of C. kieneriana was recognized by Williams et al.
(2008) based on shell morphology; however, it was not
supported by molecular data (Serb et al. 2003), but that study
included only one specimen of this putative taxon. We
recognize C. kieneriana until additional information becomes
available (see Williams et al. 2008). Cyclonaias kleiniana was
synonymized under Quincuncina infucata by Clench and
Turner (1956), but molecular studies supported the distinctiveness of these species and their inclusion in Cyclonaias
(Lydeard et al. 2000; Campbell and Lydeard 2012b).
47
Molecular data supported the distinctiveness of C. mortoni
from C. pustulosa (Serb et al. 2003). In summary, we
recognize Cyclonaias as including 14 species: C. tuberculata,
seven species recognized by Turgeon et al. (1998) under
Quadrula, one subspecies recognized by Turgeon et al. (1998)
but now elevated to species status (C. mortoni), two species
recognized by Turgeon et al. (1998) in different genera (C.
infucata and C. succissa), and three species elevated from
synonymy (C. archeri, C. kieneriana, and C. kleiniana).
Cyprogenia Agassiz, 1852.—Turgeon et al. (1998) recognized two species. Subsequent molecular data suggested
cryptic species diversity in the genus (Serb and Barnhart
2008; Grobler et al. 2011). The most recent molecular analysis
of Cyprogenia identified three independent evolutionary
lineages: C. aberti in the Ozark drainages of Arkansas,
Missouri, and Kansas; C. stegaria in the Ohio River Basin;
and a third lineage in the Ouachita River drainage in Arkansas
(Chong et al. 2016). Confusion regarding the type locality of
Unio lamarckianus Lea, 1852, requires resolution to determine
whether that name is available for the Ouachita River drainage
population. We recognize the distinctiveness of this species
but defer including it in our list until a specific epithet can be
designated.
Cyrtonaias Crosse and Fischer, 1894.—Turgeon et al.
(1998) recognized one species, Cyrtonaias tampicoensis, and
recent evidence supports no changes to this classification. Five
other species are recognized, all of which occur in Mexico or
Central America (Graf and Cummings 2017).
Disconaias Crosse and Fischer, 1894.—Turgeon et al.
(1998) recognized one species, Disconaias salinasensis
Simpson in Dall, 1908, which was subsequently placed in
the synonymy of Disconaias fimbriata by Graf and Cummings
(2007). Five other species are recognized, all of which occur in
Mexico (Graf and Cummings 2017). We recognize Disconaias
fimbriata as the only species of the genus occurring in the
United States (Rio Grande drainage).
Dromus Simpson, 1900.—Turgeon et al. (1998) recognized
one species, Dromus dromas, and recent evidence supports no
changes to this classification.
Ellipsaria Rafinesque, 1820.—Turgeon et al. (1998)
recognized one species, Ellipsaria lineolata, and recent
evidence supports no changes to this classification.
Elliptio Rafinesque, 1819.—Turgeon et al. (1998) recognized 36 species, making it the largest unionid genus in the
United States and Canada, but species concepts within this
group remain mostly untested, and their highly variable shell
morphology precludes traditional approaches for species
diagnosis. Recent molecular studies have largely supported
the monophyly of Elliptio with two exceptions (Campbell et
al. 2005; Campbell and Lydeard 2012b; Perkins et al. 2017).
Elliptio dilatata, which is morphologically and anatomically
similar to many Elliptio, is not a member of this group; we
recognize reassignment of this species to Eurynia (Campbell
and Lydeard 2012b). We also recognize reassignment of
Elliptio steinstansana to Parvaspina based on molecular data
(Perkins et al. 2017). It is important to note that phylogenetic
48
WILLIAMS ET AL.
affinities remain unknown for most species that we currently
recognize under Elliptio and some may prove to be members
of other genera (e.g., Eurynia; Elderkin et al. 2008; Campbell
and Lydeard 2012b).
Because of our poor understanding of species diversity
within Elliptio, we largely retain the classification of Turgeon
et al. (1998) with the following exceptions. We stress that this
classification is provisional and meant to provide a stable,
working hypothesis for diversity within the genus. We elevate
from synonymy four species of Elliptio: E. fumata (from E.
complanata), E. occulta and E. pullata (from E. icterina), and
E. purpurella (from E. arctata and E. strigosa); these changes
are based primarily on differences in shell morphology (Brim
Box and Williams 2000; Williams et al. 2008, 2011, 2014).
We place eight species into synonymy. Four Atlantic Slope
species (E. errans, E. hepatica, E. lugubris, and E. raveneli)
were recognized by Turgeon et al. (1998) based on Davis and
Mulvey (1993). The research by Davis and Mulvey (1993)
was confined almost exclusively to the Savannah River
drainage and has no context within the greater Atlantic Coast
region. The validity of these species has not been evaluated
further. We return these species to synonymy following
Johnson (1970) as follows: E. errans is synonymized under E.
complanata; and E. hepatica, E. lugubris, and E. raveneli are
synonymized under E. icterina. We place Elliptio waccamawensis into the synonymy of E. congaraea based on molecular
data (McCartney et al. 2016). We place the following species
into synonymy based on examination of shell type material by
Clarke (1992) and Williams et al. (2011, 2014): E. waltoni
(synonymized under E. ahenea), E. judithae (synonymized
under E. roanokensis), and E. buckleyi (synonymized under E.
jayensis). After these changes, we recognize 30 species of
Elliptio, and it remains the largest unionid genus in the United
States and Canada.
Turgeon et al. (1998) listed the common names Flat Spike
and Florida Shiny Spike for Elliptio jayensis and E. buckleyi,
respectively. We follow the recommendation of Williams et al.
(2014) that the common name of E. jayensis be changed to
Florida Spike because the species is largely endemic to that
state and is neither consistently flat nor shiny.
Elliptoideus Frierson, 1927.—Turgeon et al. (1998)
recognized one species, Elliptoideus sloatianus, and recent
evidence supports no changes to this classification.
Epioblasma Rafinesque, 1831.—Turgeon et al. (1998)
recognized 20 species and five subspecies. Our changes to this
classification involve recognition of two newly described
cryptic species, elevating one species from synonymy, and
elevating subspecies to species status. We recognize Epioblasma ahlstedti Jones and Neves, 2010, a cryptic species
formerly included within E. capsaeformis, and we recognize
and elevate to species status Epioblasma aureola Jones and
Neves, 2010, formerly identified as E. florentina walkeri but
described as E. florentina aureola Jones and Neves, 2010.
Epioblasma cincinnatiensis was not recognized by Turgeon et al. (1998), and it has been considered a synonym (e.g.,
Parmalee and Bogan 1998) or a subspecies (e.g., Morrison
1942) of Epioblasma torulosa. Williams et al. (2008) elevated
this species from synonymy based on examination of shell
type material. Watters et al. (2009) also recognized this taxon
but placed it in the synonymy of Epioblasma phillipsii
(Conrad, 1835). However, E. phillipsii is considered a
synonym of Obliquaria reflexa (see Williams et al. 2008).
We follow Williams et al. (2008) in recognizing E.
cincinnatiensis.
Turgeon et al. (1998) recognized eight subspecies of
Epioblasma in three nominal species: florentina (three),
obliquata (two), and torulosa (three). A conclusive assessment
of the taxonomic status of these taxa may be impossible at this
time because half are considered extinct (E. florentina
florentina, E. f. curtisii, E. torulosa torulosa, and E. t.
gubernaculum). Cummings and Berlocher (1990) found no
evidence of intergradation between E. t. torulosa and E. t.
rangiana and both taxa co-occurred at many sites; based on
this evidence, we elevate these subspecies to species status.
Epioblasma aureola and E. walkeri represent morphologically
and genetically distinct sister taxa (Jones and Neves 2010, as
E. florentina aureola and E. florentina walkeri). These taxa
appear to be restricted to two different river systems
(Tennessee and Cumberland, respectively); based on the low
probability of exchange between these populations and their
distinctiveness, we recognize and elevate to full species status
E. aureola and E. walkeri. There is little information with
which to assess the taxonomic status of E. florentina
florentina, E. florentina curtisii, E. obliquata obliquata, E.
obliquata perobliqua, and E. torulosa gubernaculum, but all
have distinctive shell morphology or occupy distinct geographical regions and we recognize all these taxa as distinct
species (see Methods).
We recognize 28 Epioblasma species, making it the second
largest unionid genus in the United States and Canada.
Eurynia Rafinesque, 1820.—Eurynia was not recognized
in Turgeon et al. (1998). Eurynia was elevated from synonymy
by Campbell and Lydeard (2012b) to accommodate Elliptio
dilatata, which consistently falls outside the Elliptio clade in
molecular analyses (see also Perkins et al. 2017). We consider
Eurynia monotypic at this time, but more inclusive molecular
studies may identify other species that belong to this genus,
including some now assigned to Elliptio (Elderkin et al. 2008;
Campbell and Lydeard 2012b).
Fusconaia Simpson, 1900.—Turgeon et al. (1998) recognized 13 species. Several studies showed that the genus
Fusconaia as portrayed by Turgeon et al. (1998) was
polyphyletic (Lydeard et al. 2000; Serb et al. 2003; Campbell
et al. 2005; Campbell and Lydeard 2012a, 2012b; Pfeiffer et
al. 2016). Based on these results, we reassign three species
recognized by Turgeon et al. (1998) to other genera: F.
succissa to Cyclonaias, F. barnesiana to Pleuronaia, and F.
ebenus to Reginaia. Pleuronaia was resurrected to accommodate F. barnesiana, along with two other species in the clade
(Williams et al. 2008; Campbell and Lydeard 2012a, 2012b;
see Pleuronaia). Reginaia was described to accommodate F.
REVISED LIST OF FRESHWATER MUSSELS
ebenus and two other species (Campbell and Lydeard 2012a;
see Reginaia).
These studies also showed that several species assigned to
other genera belonged in Fusconaia. Based on these results,
Quincuncina is a junior synonym of Fusconaia, and we
reassign Q. burkei and Q. mitchelli to Fusconaia (Lydeard et
al. 2000; Serb et al. 2003; Campbell et al. 2005; Pfeiffer et al.
2016; see Cyclonaias, Quadrula, and Quincuncina). Lexingtonia was placed in the synonymy of Fusconaia when its type
species, L. subplana, was determined a junior synonym of
Fusconaia masoni based on molecular data (Bogan et al.
2003).
Fusconaia chunii was not recognized by Turgeon et al.
(1998), but they recognized two other Fusconaia from Texas:
F. askewi and F. lananensis. Subsequent molecular data
showed that all Fusconaia in Texas drainages from the Sabine
River west belonged to a single species (Burlakova et al.
2012). However, Unio chunii Lea, 1861, has priority over
Unio askewi Marsh, 1896, and Quadrula lananensis Frierson,
1901, so we place F. askewi and F. lananensis in the
synonymy of F. chunii.
We adopt the former common name for F. askewi, Texas
Pigtoe, for F. chunii because it is descriptive of the species’
range. Turgeon et al. (1988) listed the common name Gulf
Pigtoe for Fusconaia cerina, but it was changed to Southern
Pigtoe in Turgeon et al. (1998) without comment. However,
Turgeon et al. (1998) also used Southern Pigtoe as the
common name of Pleurobema georgianum. We designate the
common name Gulf Pigtoe for F. cerina.
In summary, we recognize 11 species of Fusconaia,
including eight species recognized by Turgeon et al. (1998)
under Fusconaia, two species recognized by Turgeon et al.
(1998) in other genera, and one species elevated from
synonymy.
Glebula Conrad, 1853.—Turgeon et al. (1998) recognized
one species, Glebula rotundata, and recent evidence supports
no changes to this classification.
Gonidea Conrad, 1857.—Turgeon et al. (1998) recognized
one species, Gonidea angulata, and recent evidence supports
no changes to this classification.
Hamiota Roe and Hartfield, 2005.—Hamiota was described subsequent to Turgeon et al. (1998) to accommodate a
monophyletic clade of four species that produce superconglutinates (Roe et al. 2001). They were previously
recognized under Lampsilis: L. altilis, L. australis, L.
perovalis, and L. subangulata (Roe and Hartfield 2005). We
recognize all four of these species under Hamiota.
Hemistena Rafinesque, 1820.—Turgeon et al. (1998)
recognized one species, Hemistena lata, and recent evidence
supports no changes to this classification.
Lampsilis Rafinesque, 1820.—Turgeon et al. (1998)
recognized 28 species and four subspecies. Molecular data
indicated that Lampsilis, as presented by Turgeon et al. (1998),
is polyphyletic (Graf and Ó Foighil 2000; Campbell et al.
2005). There are likely unrecognized taxa in the genus
Lampsilis (e.g., in Arkansas; Harris et al. 2009). The genus
49
Hamiota was described to accommodate a monophyletic clade
of four species, Lampsilis altilis, L. australis, L. perovalis, and
L. subangulata (Roe and Hartfield 2005), and we recognize
reassignment of these species from Lampsilis to Hamiota. We
also recognize reassignment of Lampsilis haddletoni to
Obovaria (Williams et al. 2008; see Obovaria). In addition
to Hamiota, molecular data suggested the existence of at least
two other paraphyletic clades within Lampsilis as recognized
by Turgeon et al. (1998). Lampsilis cardium, L. ornata, and L.
ovata formed a monophyletic clade sister to Hamiota, and L.
siliquoidea and L. teres were members of a clade sister to the
latter two groups; however, these groupings were not
consistently or strongly supported, and the analyses did not
include other species of putative Lampsilis (Campbell et al.
2005). Additional generic-level changes regarding Lampsilis
will likely occur in the future, but we retain traditional use of
this genus for all species except those reassigned to Hamiota
and Obovaria.
Lampsilis floridensis was not recognized by Turgeon et al.
(1998), and formerly it was recognized as a subspecies
(Clench and Turner 1956) or synonym (Burch 1975) of
Lampsilis teres. We recognize L. floridensis as a full species
based on shell morphology, unpublished molecular data, and
its allopatric distribution (Williams et al. 2008).
Turgeon et al. (1998) recognized nominal Lampsilis
reeveiana along with two subspecies, L. r. brevicula and L.
r. brittsi. Molecular data showed that brittsi populations from
the Missouri River drainage formed a well-supported monophyletic clade separate from nominal reeveiana, but there was
no morphological or genetic distinction between nominal L.
reeveiana and L. r. brevicula (Harris et al. 2004). Based on
these data, we follow McMurray et al. (2012) in recognizing L.
brittsi and L. reeveiana as species and placing L. reeveiana
brevicula into the synonymy of L. reeveiana.
Turgeon et al. (1998) recognized nominal Lampsilis
radiata and one subspecies, L. r. conspicua. However,
molecular and shell morphology data did not support the
distinctiveness of L. r. conspicua (Stiven and Alderman 1992),
and we place this taxon into the synonymy of Lampsilis
radiata. Turgeon et al. (1998) also recognized Lampsilis
fullerkati, but we recognize placement of that species into the
synonymy of L. radiata based on molecular data (McCartney
et al. 2016).
Turgeon et al. (1998) recognized nominal Lampsilis
straminea and one subspecies, L. s. claibornensis. Lampsilis
straminea straminea is restricted to the Black Belt Prairie
region of Alabama and Mississippi and is characterized by a
profusion of fine, concentric ridges on the shell, which are
absent in L. s. claibornensis. However, concentric ridges are
present in some other mussels inhabiting streams in the Black
Belt Prairie region and are most likely environmentally
induced and not due to genetic differences (Williams et al.
2008). We do not recognize the taxonomic validity of these
shell forms and place L. s. claibornensis in the synonymy of
Lampsilis straminea. The common name of Lampsilis s.
straminea, Rough Fatmucket (Turgeon et al. 1998), is
50
WILLIAMS ET AL.
descriptive of individuals in only a small portion of its range
(i.e., the Black Belt Prairie). Therefore, we retain the common
name for L. straminea claibornensis, Southern Fatmucket, for
L. straminea.
In summary, we recognize 24 species of Lampsilis
including one species elevated from synonymy and two
species elevated from subspecies. Lampsilis is the third largest
genus in the family Unionidae following Elliptio (30) and
Epioblasma (28).
Lasmigona Rafinesque, 1831.—Turgeon et al. (1998)
recognized six species and one subspecies. Williams et al.
(2008) elevated Lasmigona complanata alabamensis to
species status based on examination of museum shell material,
and molecular data supported the distinctiveness of this taxon
(King et al. 1999). Williams et al. (2008) also recognized
Mobile Basin populations of Lasmigona holstonia as a distinct
species based on unpublished molecular data and the
occurrence of these populations in two different river systems.
They resurrected from synonymy Lasmigona etowaensis to
refer to Mobile Basin populations and retained L. holstonia to
refer to Tennessee and Ohio River drainage populations. We
recognize all three of these species.
Molecular studies showed that Lasmigona is polyphyletic:
L. alabamensis, L. complanata, and L. costata formed a
monophyletic clade, and L. compressa and L. subviridis
represented another monophyletic clade more closely related
to Alasmidonta (King et al. 1999). However, this study did not
include all species of Lasmigona, and a broader study within
the context of the tribe Anodontini is needed to clarify these
relationships. Populations of Lasmigona costata in the Ozark
Highlands represented a monophyletic clade strongly differentiated from populations east of the Mississippi River,
suggesting the presence of at least one cryptic species within
this taxon; additional investigation across the range of L.
costata is needed to better understand these patterns (Hewitt et
al. 2016). An endemic form of Lasmigona in the Barrens
region of the upper Caney Fork drainage in Tennessee was
recognized by Layzer et al. (1993), but the status of this
putative taxon has not been evaluated further.
Lemiox Rafinesque, 1831.—Turgeon et al. (1998) recognized one species, Lemiox rimosus, and recent evidence
supports no changes to this classification.
Leptodea Rafinesque, 1820.—Turgeon et al. (1998)
recognized three species, and recent evidence supports no
changes to this classification. Smith (2000) proposed moving
Leptodea ochracea into the genus Ligumia based on mantle
margin pigment and size of glochidia. We do not accept this
proposal due to the limited number of taxa (four species in two
genera) in that analysis, and we retain ochracea in Leptodea.
Lexingtonia Ortmann, 1914.—Turgeon et al. (1998)
recognized two species. However, the type species, Lexingtonia subplana, was subsequently relegated to the synonymy of
Fusconaia masoni based on Johnson (1970) and Bogan et al.
(2003). As such, Lexingtonia is a junior synonym of
Fusconaia. The other species recognized by Turgeon et al.
(1998), Lexingtonia dolabelloides, did not group with
Fusconaia in molecular analyses but formed a monophyletic
clade with two other species (Campbell et al. 2005; Campbell
and Lydeard 2012a, 2012b). Pleuronaia was resurrected by
Williams et al. (2008) to accommodate this clade (see
Pleuronaia).
Ligumia Swainson, 1840.—Turgeon et al. (1998) recognized three species. Subsequent molecular studies indicated
the genus is not monophyletic, but further research is needed
to fully elucidate these patterns (Campbell et al. 2005; Kuehnl
2009). We retain the classification of Turgeon et al. (1998), but
as additional information becomes available taxa assigned to
this genus will likely change (see Raley et al. 2007). Gangloff
et al. (2013) identified a genetically divergent clade of Ligumia
recta from the Mobile Basin that may warrant recognition as a
distinct taxon.
Medionidus Simpson, 1900.—Turgeon et al. (1998)
recognized seven species. We no longer recognize Medionidus
mcglameriae, which was placed in the synonymy of Leptodea
fragilis based on examination of the type specimen (Williams
et al. 2008). Campbell et al. (2005) found some evidence for
polyphyly of Medionidus, but this evidence was not
conclusive and we make no other changes to this genus.
Megalonaias Utterback, 1915.—Turgeon et al. (1998)
recognized one species, Megalonaias nervosa, and recent
evidence supports no changes to this classification.
Obliquaria Rafinesque, 1820.—Turgeon et al. (1998)
recognized one species, Obliquaria reflexa, and recent
evidence supports no changes to this classification.
Obovaria Rafinesque, 1819.—Turgeon et al. (1998)
recognized six species. Molecular data showed that Obovaria
as depicted by Turgeon et al. (1998) is polyphyletic (Campbell
et al. 2005). Notably, Obovaria rotulata was not a member of
this group, and it was later reassigned to Reginaia (Campbell
and Lydeard 2012b); we recognize this reassignment. In an
analysis by Campbell et al. (2005), O. olivaria fell outside the
clade containing other Obovaria and Epioblasma, but this
conclusion was not consistently supported. We retain olivaria
within Obovaria, but further work on this species is needed to
resolve its generic assignment.
Evidence also supports reassignment to Obovaria of
species recognized by Turgeon et al. (1998) under other
genera. We reassign Villosa arkansasensis and V. choctawensis to Obovaria based on molecular data (Kuehnl 2009; Inoue
et al. 2013) and marsupial morphology (Williams et al. 2011,
for choctawensis). We also recognize reassignment of Lampsilis haddletoni to Obovaria based on shell morphology of the
type lot (Williams et al. 2008, 2011), but this species is
considered extinct and there are no available soft parts for
anatomical or molecular study. Obovaria jacksoniana was
recognized in Turgeon et al. (1998) but is synonymous with
Villosa arkansasensis (Inoue et al. 2013). Unio jacksoniana
Frierson, 1912, is a junior synonym of Unio arkansasensis
Lea, 1862, and we place O. jacksoniana in the synonymy of
Obovaria arkansasensis. There is also potential for unrecognized taxa within O. arkansasensis in central Gulf Slope
drainages (Inoue et al. 2013).
REVISED LIST OF FRESHWATER MUSSELS
In summary, we recognize seven species of Obovaria,
including four species recognized by Turgeon et al. (1998) and
three species reassigned from other genera, one from Lampsilis
and two from Villosa.
Parvaspina Perkins, Gangloff, and Johnson, 2017.—
Parvaspina was described subsequent to Turgeon et al.
(1998) to accommodate a monophyletic clade of two species
previously recognized as Elliptio steinstansana and Pleurobema collina (Perkins et al. 2017). We recognize these species
as Parvaspina steinstansana and Parvaspina collina.
Pegias Simpson, 1900.—Turgeon et al. (1998) recognized
one species, Pegias fabula, and recent evidence supports no
changes to this classification.
Plectomerus Conrad, 1853.—Turgeon et al. (1998)
recognized one species, Plectomerus dombeyanus, and recent
evidence supports no changes to this classification.
Plethobasus Simpson, 1900.—Turgeon et al. (1998)
recognized three species, and recent evidence supports no
changes to this classification.
Pleurobema Rafinesque, 1819.—Turgeon et al. (1998)
recognized 32 species, making it one of the largest unionid
genera. Molecular data largely support the monophyly of
Pleurobema as depicted by Turgeon et al. (1998) with two
exceptions (Campbell et al. 2005, 2008; Campbell and
Lydeard 2012b). These studies support reassignment of P.
collina to Parvaspina and P. gibberum to Pleuronaia (Campbell et al. 2005, 2008; Campbell and Lydeard 2012b; see
Parvaspina and Pleuronaia). However, Campbell et al. (2008)
and Campbell and Lydeard (2012b) provided evidence that
Pleurobema includes two distinct lineages, one including P.
sintoxia, P. cordatum, P. plenum, P. riddellii, and P. rubrum
and the other including all other species. Further research is
needed to elucidate these relationships; we retain traditional
use of Pleurobema.
Pleurobema rivals Elliptio in its large number of described
species and the intractability of many species concepts,
particularly in the Mobile Basin, but these problems are
compounded for Pleurobema because many putative taxa are
considered extinct. Based on a comprehensive comparison of
shell type specimens and other available material, Williams et
al. (2008) placed into synonymy nine species of Mobile Basin
Pleurobema recognized by Turgeon et al. (1998): P.
chattanoogaense (into P. decisum); P. murrayense (into P.
stabile); P. nucleopsis and P. troschelianum (into P.
georgianum); P. flavidulum and P. johannis (into P.
perovatum); and P. avellanum, P. furvum, and P. hagleri
(into P. rubellum). Some of these synonyms are further
supported by molecular data (e.g., P. chattanoogaense, P.
furvum; Campbell et al. 2008), and we recognize all of these
changes. We do not recognize Pleurobema altum since it was
deemed a nomen dubium because it is not identifiable due to
incomplete description, vague type locality, and lack of type
material (Williams et al. 2008). One Ohio River drainage
species, Pleurobema bournianum, was placed into the
synonymy of Pleurobema clava based on shell morphology
(Watters et al. 2009), and we recognize this change.
51
We recognize four additional Mobile Basin species of
Pleurobema not recognized by Turgeon et al. (1998). Williams
et al. (2008) recognized three species based on examination of
shell type specimens: P. fibuloides, P. hartmanianum, and P.
stabile. We correct the spelling of P. stabilis as used by
Williams et al. (2008) to stabile based on Lee (2008).
Pleurobema athearni Gangloff, Williams, and Feminella,
2006, was described subsequent to Turgeon et al. (1998)
based on morphological data (Gangloff et al. 2006). In
addition, preliminary findings identified an undescribed
species in the upper Tennessee River drainage (Schilling
2015).
In summary, we recognize 23 species of Pleurobema,
including 19 species recognized by Turgeon et al. (1998),
three species elevated from synonymy, and one newly
described species.
Pleuronaia Frierson, 1927.—Pleuronaia was not included
in Turgeon et al. (1998). This was the senior available name
for a monophyletic clade of three species—Fusconaia
barnesiana, Lexingtonia dolabelloides, and Pleurobema
gibberum—identified in a molecular study by Campbell et
al. (2005). We recognize resurrection of Pleuronaia to
accommodate this group and reassignment of these three
species to Pleuronaia as proposed previously (Williams et al.
2008; Campbell and Lydeard 2012a, 2012b). There are likely
cryptic taxa of Pleuronaia in the upper Tennessee River
drainage (Schilling 2015). We correct the gender agreement of
the specific name of Pleuronaia gibberum to gibber (H. Lee,
Jacksonville, Florida, personal communication).
Popenais Frierson, 1927.—Turgeon et al. (1998) recognized one species, Popenais popeii, and recent evidence
supports no changes to this classification.
Potamilus Rafinesque, 1818.—Turgeon et al. (1998)
recognized six species. One additional species, Potamilus
metnecktayi Johnson, 1998, was described subsequently, and
we recognize this species. Potamilus inflatus was referred to as
the Inflated Heelsplitter by Turgeon et al. (1988) but was
changed to Alabama Heelsplitter by Turgeon et al. (1998)
without comment. Alabama Heelsplitter is the established
common name for Lasmigona alabamensis, and we adopt the
original common name Inflated Heelsplitter for P. inflatus.
Roe and Lydeard (1998) found the Amite River population of
P. inflatus to be genetically divergent, and it may warrant
recognition as a distinct taxon.
Ptychobranchus Simpson, 1900.—Turgeon et al. (1998)
recognized five species. Ptychobranchus foremanianus was
elevated from the synonymy of Ptychobranchus greenii (in
part) by Williams et al. (2008) based on shell morphology and
periostracum color. A molecular analysis of this genus
included insufficient material to resolve the relationship
between these two taxa (Roe 2013), but we recognize both
species. We correct the gender agreement of Ptychobranchus
subtentum to P. subtentus following Lee (2008).
Pyganodon Crosse and Fischer, 1894.—Turgeon et al.
(1998) recognized five species. Graf and Cummings (2007)
without comment moved Anodonta implicata to Pyganodon
52
WILLIAMS ET AL.
and omitted P. fragilis and P. lacustris. However, molecular
data demonstrated the validity of P. fragilis and P. lacustris
(Doucet-Beaupré et al. 2012). Based on these results and the
lack of justification for movement of A. implicata to
Pyganodon, we retain the classification of Turgeon et al.
(1998) for Pyganodon.
Quadrula Rafinesque, 1820.—Turgeon et al. (1998)
recognized 18 species and two subspecies. Molecular studies
generally supported the monophyly of Quadrula as depicted
by Turgeon et al. (1998), but they also showed that it is
composed of three deeply divergent monophyletic clades plus
Tritogonia verrucosa, each of which warranted generic
recognition (Serb et al. 2003; Campbell et al. 2005; Campbell
and Lydeard 2012b). The type species for Quadrula is Q.
quadrula, and the clade containing this species also includes
Q. apiculata, Q. fragosa, Q. nobilis, and Q. rumphiana.
Quadrula nobilis was elevated from synonymy based on shell
morphology and unspecified genetic data (Howells et al. 1996)
but not recognized by Turgeon et al. (1998). Relationships
among species in the Q. quadrula group were not clearly
resolved by Serb et al. (2003), but we recognize all five
species. We also recognize within this group Q. couchiana on
the basis of its shell morphology, which is similar to that of Q.
quadrula (see Cyclonaias).
Based on molecular data, we reassign to Cyclonaias 10
taxa recognized by Turgeon et al. (1998) under Quadrula, and
we reassign 5 species to Theliderma (Serb et al. 2003;
Campbell et al. 2005; Campbell and Lydeard 2012b; see also
Graf and Cummings 2007). We also synonymize two taxa
recognized by Turgeon et al. (1998) under Quadrula (see
Theliderma). In summary, we recognize six species of
Quadrula, including five recognized under this genus by
Turgeon et al. (1998) and one elevated from synonymy (Q.
nobilis).
Quincuncina Ortmann, 1922.—Turgeon et al. (1998)
recognized three species. Molecular data showed that the type
species, Quincuncina burkei, belongs in Fusconaia (Lydeard
et al. 2000; Serb et al. 2003; Campbell et al. 2005). As such,
Quincuncina is a junior synonym of Fusconaia, and we
reassign to this genus Q. burkei and Q. mitchelli (see also
Pfeiffer et al. 2016). Based on these findings, we also reassign
Q. infucata to Cyclonaias (see Cyclonaias).
Reginaia Campbell and Lydeard, 2012.—Reginaia was
described subsequent to Turgeon et al. (1998) to accommodate
a monophyletic clade of two species identified in a
phylogenetic analysis of Ambleminae (Campbell and Lydeard
2012b). The two Reginaia species were included in Turgeon et
al. (1998) as Fusconaia ebena and Obovaria rotulata (Campbell and Lydeard 2012b); we recognize assignment of these
species to Reginaia. We follow Watters et al. (2009) in
correcting the spelling of the species name ebena to ebenus. A
third species, Fusconaia apalachicola Williams and Fradkin,
1999, was described subsequent to Turgeon et al. (1998) from
archaeological material; we reassign this species to Reginaia
based on its shell characters, which are similar to those of R.
ebenus and R. rotulata.
Simpsonaias Frierson, 1914.—Turgeon et al. (1998)
recognized one species, Simpsonaias ambigua, and recent
evidence supports no changes to this classification.
Sinanodonta Modell, 1945.—Sinanodonta was not included in Turgeon et al. (1998). This genus was previously
considered to be confined to Asia and not part of the North
America fauna. Molecular data showed that A. beringiana is
more closely related to the Asian species Sinanodonta
woodiana than to other western North American Anodonta
(Chong et al. 2008; see Anodonta). Based on this evidence, we
reassign beringiana to Sinanodonta. In 2010 S. woodiana,
Chinese Pondmussel, was found in Wickecheoke Creek, a
tributary of the Delaware River, New Jersey (Bogan et al.
2011a). Several known glochidial host fishes, native and
introduced species, occur in the watershed (Bogan et al.
2011b). The species appears to have become established in
that stream despite eradication efforts (J. Bowers-Altman, New
Jersey Division of Fish and Wildlife, personal communication). We recognize S. woodiana as established in New Jersey
(Table 2). This is the only nonindigenous unionid mussel
known to have become established in the United States or
Canada.
Strophitus Rafinesque, 1820.—Turgeon et al. (1998)
recognized three species, and recent evidence supports no
changes to this classification. Strophitus undulatus, one of the
most wide-ranging species in the United States and Canada,
likely contains unrecognized cryptic taxa (Watters et al. 2009).
Theliderma Swainson, 1840.—Theliderma was not recognized by Turgeon et al. (1998). This genus was resurrected
from synonymy by Graf and Cummings (2007) to accommodate a monophyletic clade of five species recognized by
Turgeon et al. (1998) under Quadrula (Q. cylindrica, Q.
intermedia, Q. metanevra, Q. sparsa, and Q. stapes; see Serb
et al. 2003). Theliderma is the oldest available name for this
clade and has T. metanevra as its type species. We recognize
placement of all five of these species in Theliderma. No
molecular data are available for Theliderma stapes, but its
shell morphology is very similar to that of other Theliderma,
and we include it in this genus following Graf and Cummings
(2007).
Turgeon et al. (1998) recognized Quadrula tuberosa, but
we place this taxon in the synonymy of Theliderma metanevra
following Parmalee and Bogan (1998, as Q. metanevra).
However, the relationship of tuberosa to other species is
uncertain, and if it represents a valid species, it is considered
extinct (see Haag and Cicerello 2016). Quadrula cylindrica
was recognized in Turgeon et al. (1998) as containing two
subspecies, Theliderma cylindrica cylindrica and T. cylindrica
strigillata. These subspecies traditionally were distinguished
from each other based on shell morphology and distribution,
with strigillata being confined mainly to the upper Tennessee
River system in Tennessee and Virginia (Parmalee and Bogan
1998). However, the distributional limits of strigillata have
never been clearly defined as it grades into typical T. c.
cylindrica in larger streams, suggesting that the shell forms
represent ecophenotypic variation (Ortmann 1920), and
REVISED LIST OF FRESHWATER MUSSELS
molecular data provide no support for recognition of T. c.
strigillata (Serb et al. 2003; Sproules et al. 2006). Based on
this evidence, we do not recognize subspecies within T.
cylindrica. Both T. c. cylindrica (threatened) and T. c.
strigillata (endangered) are federally protected taxa. Synonymizing strigillata under T. cylindrica will not remove the
protection provided by the Endangered Species Act but may
impact the status of populations formerly recognized as
strigillata.
Toxolasma Rafinesque, 1831.—Turgeon et al. (1998)
recognized eight species. Recent evidence supports no changes
at the genus level, but species boundaries within Toxolasma
remain uncertain. Howells et al. (1996) placed Toxolasma
mearnsi in the synonymy of Toxolasma texasiense based on
electrophoretic analysis, a change overlooked by Turgeon et
al. (1998); we recognize placement of T. mearnsi in the
synonymy of T. texasiense. Undescribed species of Toxolasma
have been recognized (e.g., Gulf Lilliput) but have yet to be
formerly described (Williams et al. 2008, 2014).
Lee (2006) concluded that Toxolasma has a neuter gender,
which necessitates correction of spellings from lividus to
lividum, parvus to parvum, and paulus to paulum, without
change to corvunculus, cylindrellus, or pullus; we recognize
these spelling changes. Lee (2006) provided an incorrect
spelling of Toxolasma texasiense (as texasense), but we
correct it based on the spelling presented in the original
description.
Tritogonia Agassiz, 1852.—Turgeon et al. (1998) recognized one species, Tritogonia verrucosa. Molecular data
clearly supported inclusion of T. verrucosa within the tribe
Quadrulini, but its placement within that group was unresolved, and Serb et al. (2003) recommended its placement
within Quadrula (sensu lato) until relationships were better
understood (e.g., see Williams et al. 2008; Haag and Cicerello
2016). Regardless of its relationship to other clades within the
Quadrulini, Tritogonia represents a deeply divergent lineage
(Serb et al. 2003; Campbell et al. 2012b), and our recognition
of three other genera within this tribe (Cyclonaias, Theliderma, and Quadrula sensu stricto) warrants retention of
Tritogonia as a monotypic genus (e.g., see Watters et al.
2009; Sietman et al. 2012).
Truncilla Rafinesque, 1819.—Turgeon et al. (1998)
recognized four species, and recent evidence supports no
changes to this classification.
Uniomerus Conrad, 1853.—Turgeon et al. (1998) recognized three species. Recent evidence supports no changes at
the genus level, but species concepts within Uniomerus are
uncertain (see Williams et al. 2008). Uniomerus columbensis
was not recognized by Turgeon et al. (1998) but was elevated
from synonymy by Williams et al. (2008) based on
unpublished molecular data and shell morphology; we
recognize this change. Species boundaries for other taxa
(e.g., Uniomerus declivis) remain unresolved.
The inappropriate and misleading common name for
Uniomerus carolinianus, Florida Pondhorn, was changed to
Eastern Pondhorn by Williams et al. (2014) because the
53
species occurs not only in Florida but northward along the
Atlantic Coast; we recognize this change.
Utterbackia Baker, 1927.—Turgeon et al. (1998) recognized three species and recent evidence supports no changes to
this classification.
Utterbackiana Frierson, 1927.—Utterbackiana was not
recognized by Turgeon et al. (1998). We resurrect this genus
as the senior available name for a monophyletic clade of four
eastern North American species included in Turgeon et al.
(1998) under Anodonta (A. couperiana, A. heardi, A.
implicata, and A. suborbiculata; Mock et al. 2004; Zanatta
et al. 2007; see Anodonta). The type species for the genus is
Anodonta suborbiculata Say, 1831. In addition to the four taxa
mentioned above, a new species was described subsequent to
Turgeon et al. (1998), Anodonta hartfieldorum (Williams et al.
2009). We also place this species in Utterbackiana because it
appears closely related to U. suborbiculata and was formerly
associated with that species.
Venustaconcha Frierson, 1927.—Turgeon et al. (1998)
recognized two species. Molecular data showed that Villosa
perpurpurea and Villosa trabalis also are members of
Venustaconcha (Kuehnl 2009; Lane et al. 2016). Molecular
data further showed that Venustaconcha perpurpurea is a
junior synonym of Venustaconcha trabalis, and populations of
this species in the Tennessee River drainage are genetically
and morphologically distinct from those in the Cumberland
River drainage (Lane et al. 2016). Based on the type locality of
trabalis, Flint River, Alabama, this name is applicable to the
Tennessee River drainage species. Unio troostensis Lea, 1834,
is the oldest available name for the Cumberland drainage
species (type locality is Stones River, Tennessee), and we
recognize this species as Venustaconcha troostensis (see Haag
and Cicerello 2016; Lane et al. 2016). Cumberland Bean was
the common name used for V. trabalis by Turgeon et al.
(1998), but Lane et al. (2016) proposed Tennessee Bean for
Venustaconcha trabalis and Cumberland Bean for Venustaconcha troostensis; we follow this use. Venustaconcha sima
was not included in Turgeon et al. (1998) but was elevated
from synonymy by Gordon (1995) based on shell coloration
and conchological characters, and its distinctiveness is
supported by molecular data (Kuehnl 2009). This species
was synonymized under Villosa iris by Parmalee and Bogan
(1998), and molecular data support its relationship to Villosa
(Kuehnl 2009). We recognize sima as a species of Villosa.
Villosa Frierson, 1927.—Turgeon et al. (1998) recognized
17 species and one subspecies. Molecular data show that Villosa,
as depicted by Turgeon et al. (1998), is wildly polyphyletic, with
species occurring in as many as seven different clades within the
Lampsilini (Kuehnl 2009). These and other data support
reassignment of Villosa trabalis to Venustaconcha, synonymization of Villosa perpurpurea under Venustachoncha trabalis (see
Venustaconcha), and reassignment of Villosa choctawensis and
V. arkansasensis to Obovaria (see Obovaria). Most other species
will require reassignment to existing genera (e.g., V. vaughniana
to Ligumia; Raley et al. 2007; Kuehnl 2009) or resurrected or
newly described genera, potentially with only Villosa amygdala
54
WILLIAMS ET AL.
and V. villosa remaining in Villosa (Kuehnl 2009). However,
these relationships are not fully understood, and currently
synonymized or newly described generic names have not been
proposed. With the exception of Villosa trabalis, V. perpurpurea,
V. choctawensis, and V. arkansasensis, we retain all other species
recognized by Turgeon et al. (1998) in Villosa.
Villosa vanuxemensis umbrans was elevated to species
status by Williams et al. (2008) based on shell characters and
preliminary molecular data, and subsequent molecular data
support this change (Kuehnl 2009); based on this evidence, we
recognize V. umbrans. There are several undescribed taxa
within Villosa (Kuehnl 2009; Harris et al. 2009). We recognize
correction of gender agreement for Villosa amygdala, as given
by Turgeon et al. (1998), to Villosa amygdalum following
Williams et al. (2011, 2014). We recognize fifteen species of
Villosa.
mussels: John Alderman, Gerry Dinkins, Mike Gangloff, Dan
Graf, Jordan Holcomb, Bob Howells, Sarina Jepsen, Paul
Johnson, Stephen McMurray, Terry Myers, Charles Randklev,
Kevin Roe, Tim Savidge, Daniel Schilling, Brian Watson, and
Jason Wisniewski. We acknowledge Harry G. Lee (Jacksonville, Florida) for providing expert advice on the proper
terminations for numerous species names. We also thank
Sherry L. Bostick for assistance in preparation and review of
several drafts of the manuscript. Although the individuals
mentioned here provided assistance and input, we bear full
responsibility for any errors. The findings and conclusions in
this article are those of the authors and do not necessarily
represent the views of their agencies and institutions. Any use
of trade, firm, or product names is for descriptive purposes
only and does not imply endorsement by the U.S. Government.
DISCUSSION
LITERATURE CITED
Changes in mussel taxonomy compared to Turgeon et al.
(1998) reflect our better understanding of mussel phylogenetic
relationships obtained mainly from molecular genetic data (e.g.,
Serb et al. 2003; Campbell and Lydeard 2012a, 2012b; Inoue et
al. 2013, 2014; Pfeiffer et al. 2016). Molecular genetics
continues to be one of the most important tools for understanding
unionoid relationships and taxonomy, but other data sets (e.g.,
life history, host use, soft anatomy, shell morphology,
zoogeography) are informative and should not be overlooked
when constructing phylogenies and conducting taxonomic
studies (e.g., Roe et al. 2001; Jones and Neves 2010; Lane et
al. 2016).
We recognize a larger number of genera than Turgeon et al.
(1998; 56 vs. 49), but the number of currently recognized species
is similar. However, recent studies show that considerable
cryptic biodiversity exists in the Unionidae (e.g., Cyprogenia,
Lampsilis, Villosa). Most of this biodiversity remains to be
discovered, and its future recognition may result in increased
numbers of species in the United States and Canada (see Haag
2012). Currently unrecognized species may be narrowly
distributed (e.g., one river system) and in need of conservation
measures. Development of additional molecular markers, more
inclusive taxon sampling, advancements in phylogenetic
analyses, and other techniques for species delineation are
facilitating taxonomic recognition of species. More thorough
understanding of life histories with improved husbandry
techniques should also help facilitate species recognition.
Future research will most likely reveal unrecognized taxa.
Conversely, additional synonymy may be warranted for some
currently recognized species. Much more research is needed to
delineate true diversity of the mussels of the United States and
Canada.
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