Research Article |
Corresponding author: Leonardo Santos de Souza ( leosouza2301@gmail.com ) Academic editor: Matthias Glaubrecht
© 2019 Leonardo Santos de Souza, Alexandre Dias Pimenta.
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Citation:
de Souza LS, Pimenta AD (2019) Eulimacrostoma gen. nov., a new genus of Eulimidae (Gastropoda, Caenogastropoda) with description of a new species and reevaluation of other western Atlantic species. Zoosystematics and Evolution 95(2): 403-415. https://doi.org/10.3897/zse.95.33880
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A new genus and a new species of Eulimidae are described based on the shell morphology and on the host-parasite relationship of the type species. Eulimacrostoma microsculpturata Souza & Pimenta gen. nov. and sp. nov. parasitizes a starfish of the genus Luidia and has an elongated, conical, straight, or slightly curved shell, a protoconch with a brownish spiral band and convex whorls, a peculiar large and broad aperture with a strongly protruding outer lip, and microsculpture of axial lines on the teleoconch. Four other species are included in the genus, all from the western Atlantic: Eulimacrostoma chascanon (Watson, 1883), comb. nov., Eulimacrostoma fusus (Dall, 1889), comb. nov., Eulimacrostoma lutescens (Simone, 2002), comb. nov., and Eulimacrostoma patula (Dall & Simpson, 1901), comb. nov. Newly available material of Eulimacrostoma patula expands the known geographic distribution of this species in the Caribbean to the north coast of Brazil. Eulimacrostoma chascanon and Eulimacrostoma fusus and Eulimacrostoma lutescens are known only by the type series which was re-examined. A redescription is provided for Eulimacrostoma chascanon and Eulimacrostoma fusus. Species within Eulimacrostoma differ mainly by teleoconch sculpture, the presence or absence of an umbilical fissure, and shell dimensions. Lectotypes are designated for Eulimacrostoma chascanon, Eulimacrostoma fusus, and Eulimacrostoma patula.
biodiversity, micromolluscs, parasitic snails shell morphology, taxonomy, Vanikoroidea
Eulimidae Philippi, 1853 is a diverse group of marine gastropods comprising more than 1,000 valid species and more than 90 valid genera (
Genera of Eulimidae that parasitize echinoderms of the class Asteroidea are Apicalia A. Adams, 1862, Asterolamia Warén, 1980, Asterophila Randall & Heath, 1912, Niso Risso, 1826, Paramegadenus Humphreys & Lützen, 1972, Parvioris Warén, 1981, Stilifer Broderip, 1832, and Thyca H. Adams & A. Adams, 1854 (
Recently, one eulimid attached to the starfish Luidia ludwigi scotti Bell, 1917 (Luidiidae), collected in the upper bathyal zone off Florida, USA, was studied by the authors and did not correspond to any other species and genus known to parasitize asteroids or other echinoderms. The availability of a single specimen hampered the description of the taxa, but recently we identified shells of the same species from nearby localities in malacological collections, which enabled the present description.
The material examined is housed in the following malacological collections: Academy of Natural Sciences of Philadelphia, Drexel University, Philadelphia, Pennsylvania, USA (
During the course of this study, a fire destroyed several collections of
Some samples were collected by large projects and oceanographic expeditions, such as: (1) Eolis Cruises, organized by John B. Henderson, collected by the yacht Eolis between 1910–1916 in the Florida Keys, USA (see
Taxonomic identifications were based on conchological features in comparison with original descriptions and illustrations and examination of type material. Terminology of shell features follows
Abbreviations of generic names: Eulima Risso, 1826 (E.); Eulimacrostoma gen. nov. (Eu.).
Eulimacrostoma microsculpturata Souza & Pimenta, sp. nov. Recent, northwestern Atlantic and Caribbean.
Eulimids parasitic on asteroids. Shell elongated, conical, straight or slightly curved. Protoconch subcylindrical, smooth. Teleoconch with slightly convex whorls, several incremental scars and microsculpture of axial lines, wide brownish spiral bands, a large and spread aperture, occupying between 60–70% of the body whorl length, and an orthocline outer lip, strongly protruding.
Eulima, due to the systematic affinity and for being one of the most common names of the family, in combination with Macros, Gr. = long; and Stomatos, Gr. = mouth; in reference to the broad shape of the shell aperture.
Melanella patula
auct. non. (Dall & Simpson, 1901):
Holotype:
The epithet alludes to the microsculpture characteristic of the present species.
Puerto Rico: off San Juan, Johnson–Smithsonian Deep-sea expedition stn. 10 (18°29'20"N–18°30'24"N, 66°05'30"W–66°04'15"W, 219–293 m), coll. Yacht Caroline, 02/ii/1933.
Eulimid parasitic on starfish, with an elongated shell, presenting microsculpture of axial lines, dome-shaped apex, a narrow brownish spiral band close to the suture in the protoconch and a wide brownish spiral band along the teleoconch, a high, wide and spread aperture. Umbilicus absent.
Shell conical with an obtuse apex, reaching about 7.3 mm long and 2.0 mm wide. Protoconch vitreous, with a brownish spiral band close to the suture, subcylindrical, about 2.5 whorls, 300 µm wide, 400 µm in height, smooth, transition to teleoconch marked by a subtle incremental scar and the end of the brownish spiral band. Teleoconch with about nine whorls of sinuous outline, convexity more attenuated on the lower region of each whorl; suture deep, well impressed, sloping; subsutural zone occupying about 1/5 of the whorl height; surface glossy, presenting several incremental scars and microsculpture of opisthocline axial lines; incremental scars well developed, appearing in irregular intervals; microsculpture of axial lines present at fairly regular intervals between 80–110 μm. Last whorl occupying about 45% of the shell length; base rounded in outline, elongated. Aperture high, occupying about 70% of the body whorl length, wide, pear-shaped, expanded laterally, acute posteriorly, rounded and spread anteriorly; outer lip thin, very sinuous, orthocline, retracted near the suture, after strongly protruding, and retracted in the distal region, maximum projection at the middle of the outer lip height; inner lip sinuous, sloping and well demarcated. Umbilicus absent. Teleoconch whitish or vitreous, fresh specimens usually have the region near the suture uncoloured and the rest of the whorl yellowish to brownish.
Holotype
USA: Florida; Puerto Rico.
From 128 m to 293 m.
Most specimens of Eu. microsculpturata have a straight spire (Figs
Eulimacrostoma microsculpturata gen. nov. and sp. nov. A. Holotype (
Eulimacrostoma microsculpturata gen. nov. and sp. nov. A–E. Paratype (
Eulimacrostoma chascanon (Watson, 1883), comb. nov. (Fig.
Eulimacrostoma spp. A–C. Eulimacrostoma chascanon (Watson, 1883), comb. nov.: A, B. Lectotype herein designated (
Measurements (in mm, except for number of whorls) of Eulimacrostoma species studied.
Taxon | Catalog number | Status | Wh | SL | BWL | AL | SW | AW |
Eu. microsculpturata |
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Holotype | 8 | 3.16 | 1.60 | 1.06 | 1.08 | 0.60 |
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Paratype | 12 | 7.28 | 3.34 | 2.21 | 1.97 | 1.17 | |
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Paratype | 11 | 6.50 | 3.09 | 2.10 | 1.88 | 1.10 | |
|
Paratype | 11 | 6.55 | 3.04 | 1.99 | 1.79 | 1.15 | |
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Paratype | 10.5 | 6.32 | 2.88 | 1.90 | 1.80 | 1.06 | |
|
Paratype | 10 | 6.03 | 2.94 | 1.97 | 1.75 | 1.03 | |
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Paratype | 10 | 6.10 | 2.94 | 1.97 | 1.75 | 1.03 | |
Eu. chascanon |
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Lectotype | 13 | 4.49 | 1.96 | 1.23 | 1.15 | 0.65 |
Eu. fusus |
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Lectotype | 12 | 11.24 | 5.28 | 3.55 | 2.78 | 1.55 |
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Paralectotype | 13 | 12.29 | 5.63 | 3.81 | 2.75 | 1.62 | |
Eu. lutescens | MNHN-IM 2000-5662 | Holotype | 10 | 8.88 | 4.47 | 3.05 | 2.90 | 1.60 |
MZSP 34514 | Paratype | 10† | 10.62 | 5.00 | 3.22 | 3.15 | 1.82 | |
MNHN-IM | 9 | 7.58 | 3.75 | 2.69 | 2.28 | 1.41 | ||
Eu. patula |
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Lectotype | 9 | 4.53 | 2.20 | 1.50 | 1.50 | 0.91 |
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8.5 | 3.99 | 2.07 | 1.42 | 1.50 | 0.89 | ||
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9 | 4.24 | 2.07 | 1.37 | 1.42 | 0.83 |
Eulimacrostoma fusus (Dall, 1889), comb. nov. (Fig.
Eulimacrostoma lutescens (Simone, 2002), comb. nov. (Fig.
Eulimacrostoma patula (Fig.
Eulimacrostoma patula (Dall & Simpson, 1901), comb. nov. A. Lectotype herein designated (
Eulima chascanon
E. chascanon:
Lectotype (herein designated)
Type material.
Puerto Rico: North of Culebra Island, off St. Thomas, Challenger Expedition stn. 24 (18°38'30"N, 65°05'30"W, 713 m).
Shell whitish, conical with an obtuse apex, reaching about 4.5 mm long and 1.2 mm wide, about 13 whorls. Protoconch vitreous, subcylindrical. Shell with about 13 whorls of slightly sinuous outline, with convexity more attenuated on the lower region of each whorl; suture slightly impressed, sloping; subsutural zone not visible; surface glossy, showing axial lines and incremental scars; incremental scars slightly impressed, appearing in irregular intervals. Last whorl occupying about 45% of the shell length; base rounded, elongated. Aperture high, occupying about 60% of the body whorl length, wide, pear-shaped, expanded laterally, acute posteriorly, rounded and spread anteriorly; outer lip thin, very sinuous, orthocline, strongly retracted near the suture, after strongly project, and retracted in the distal region, maximum projection below the middle of the outer lip height; inner lip sinuous, sloping and well demarcated. Umbilicus absent.
Lectotype
Known only from the type locality.
Known only from 713 m.
Eulimacrostoma chascanon comb. nov. (Fig.
The type material of Eu. chascanon formerly consisted of two syntypes (Fig.
Eulimacrostoma fusus (Fig.
Eulimacrostoma lutescens (Fig.
Eulima fusus
Strombiformis fusus:
Lectotype (herein designated)
Type material.
Yucatan Strait (1170 m).
Shell whitish, conical with an obtuse apex, reaching about 12.4 mm long and 2.8 mm wide, about 12 whorls, apical whorls slightly bent, aperture broad. Protoconch whitish, subcylindrical. Shell with about 12 whorls of slightly sinuous outline, with convexity more attenuated on the lower region of each whorl; suture well impressed, sloping; subsutural zone occupying about 1/5 of the whorl height; surface glossy, showing microsculpture of axial lines and incremental scars; incremental scars well impressed, appearing in irregular intervals. Last whorl occupying about 45% of the shell length; base rounded, slightly truncated. Aperture high, occupying about 65% of the body whorl length, wide, slightly acute and spread anteriorly and acute posteriorly; outer lip thin, very sinuous, orthocline, strongly retracted near the suture, after strongly protruding, and retracted in the distal region; inner lip almost straight, well demarcated. Umbilicus absent.
Lectotype
Yucatan Strait and off Cuba.
From 457 to 1170 m (
The types of Eulimacrostoma fusus comb. nov. (Fig.
Eulimacrostoma lutescens (Fig.
Batheulima lutescens
B. lutescens:
Holotype MNHN-IM 2000-5662. Paratypes: Brazil: Espírito Santo state: MD55 stn. 42 CB76 (18°58'59"S, 37°49'59"W, 637 m), coll. R/V Marion Dufresne, 27/v/1987: MNHN-IM 2000-5664 [1 shell]; Rio de Janeiro state: MD55 stn. 64 CB105 (23°46'59"S, 42°10'00"W, 610 m), coll. R/V Marion Dufresne, 02/vi/1987: MNHN-IM 2000-5663 [2 shells]; São Paulo state: Off São Sebastião Island (23°47'S, 42°10'W, 610 m): MZSP 34514 [1 shell], MZSP 34515 [1 shell].
Type material. Brazil: from type locality: MNHN-IM* (uncatalogued) [2 shells].
Brazil: Espírito Santo: MD55 stn. 54 CB93 (19°36'00"S, 38°53'18"W, 640 m), coll. R/V Marion Dufresne, 30/v/1987.
Holotype MNHN-IM 2000-5662: whorls = 10; SL = 8.88 mm; BWL = 4.47 mm; AL = 3.05 mm; SW = 2.90 mm; AW = 1.60 mm.
Brazil: Espírito Santo, Rio de Janeiro, São Paulo (
From 610 to 640 m.
In addition to the type series of Eu. lutescens, we find two other shells collected from the type locality. One of them is figured here (Fig.
Eulima (Leiostraca) patula
Strombiformis patula:
E. patula:
Lectotype
Type material. Brazil: Amapá state: mouth of Amazonas River, outer shelf (~03°58'42"N, 49°33'24"W), coll. 30/vii/2001:
Puerto Rico: Mayaguez Harbour, Fish Hawk stn. 6062 (46–55 m).
Shell vitreous or with wide brownish spiral bands, conical with an obtuse apex, reaching about 4.5 mm long and 1.5 mm wide, about eight whorls, aperture broad. Protoconch vitreous, subcylindrical, about two whorls, 330 µm in width, smooth, transition to teleoconch marked by a subtle incremental scar. Teleoconch with about six whorls of sinuous outline, with convexity more attenuated on the lower region of each whorl; suture deep, well impressed, sloping; subsutural zone occupying about 1/5 of the whorl height; surface glossy and smooth, except for microsculpture of axial lines and incremental scars; incremental scars well developed, appearing in intervals of about 0.5 whorl. Last whorl occupying about 50% of the shell length; base slightly abrupt in outline. Aperture high, occupying about 70% of the body whorl length, wide, pear-shaped, expanded laterally, acute posteriorly, rounded and spread anteriorly; outer lip thin, very sinuous, orthocline, strongly retracted near the suture, after strongly protruding, and retracted in the distal region, maximum projection at the middle of the outer lip height; inner lip sinuous, sloping and well demarcated. Umbilical fissure present. Shell whitish or vitreous, usually with a wide brownish spiral band along the teleoconch.
Lectotype
Puerto Rico (
From 46 m (
Eulimacrostoma patula comb. nov. (Fig.
The material from the north coast of Brazil fits perfectly with the lectotype of Eu. patula in shape and reaches a similar size (lectotype
As commented above, one shell recorded by
Eulimacrostoma patula differ from the congeners mainly by the presence of an umbilical fissure and by the more truncated base.
Eulimacrostoma gen. nov. is erected to group the eulimids with an elongated, conical shell, possessing a smooth protoconch, a teleoconch with slightly convex whorls and an enlongate and strongly anteriorly spread aperture. The species usually share a similar color pattern of brownish spiral bands in the protoconch and teleoconch, and microsculpture of axial lines in teleoconch. These latter features are more developed in the type species and in Eu. fusus and Eu. lutescens. The anatomy of Eu. microsculpturata is not described, as only one young specimen with soft parts was identified. However, the kind of host (a starfish) and the combination of shell features corroborate the distinction of this genus.
Among the eulimid genera that parasitize asteroids, the most similar to Eulimacrostoma is Niso Risso, 1826, due to its conical shape, presence of brownish spiral bands in several species and axial lines on the shell surface. However, Eulimacrostoma can be distinguished from Niso by the shape of the aperture, which gapes anteriorly and is more elongated in the former, whereas it is usually rhomboid in the latter. In addition, Niso usually has a well-developed umbilicus. The type species of Eulimacrostoma does not present an umbilicus, but Eu. patula has an umbilical fissure, which is a variable feature in relation to its presence or absence in some Eulimidae genera (e.g., Eulimetta Warén, 1992, Fusceulima Laseron, 1955) (
Other similar genera, in relation to conchological features, that parasitize other classes of echinoderms or of unknown hosts are Batheulima, Eulima, and Haliella Monterosato, 1878.
Eulimacrostoma is similar to Batheulima, whose host is unknown (
Eulimacrostoma is also similar to Eulima, but the more typical forms of this species-rich genus that parasitizes ophiuroids have a narrower aperture, that is not so spread anteriorly, and the outline of teleoconch whorls of Eulima is usually flat.
Eulimacrostoma can also be compared to Haliella Monterosato, 1878 by possessing a high aperture, but the latter can be distinguished by having a more cylindrical shell, a more obtuse apex, and by being colorless. The host of Haliella species is doubtful,
Delimitation of genera is a hard task in Eulimidae (
In a revision of the family in the northeast Atlantic,
The description of Eulimacrostoma is based on the combination of shell features and on data about the host of Eu. microsculpturata. Albeit only one species has the host known, all species included in Eulimacrostoma have very similar conchological features.
Recent efforts with molecular data are elucidating many aspects of the evolution of Eulimidae (
We expect that the description of Eulimacrostoma calls the attention of researchers to congeners from other parts of the world. By now, Eulimacrostoma is known only from the western Atlantic (Fig.
Geographical distributions of Eulimacrostoma spp. based on confirmed identifications. A. Eulimacrostoma microsculpturata sp. nov.; B. Eulimacrostoma chascanon (Watson, 1883), comb. nov.; C. Eulimacrostoma fusus (Dall, 1889), comb. nov.; D. Eulimacrostoma lutescens (Simone, 2002), comb. nov.; E. Eulimacrostoma patula (Dall & Simpson, 1901), comb. nov. White circle: type locality; black circle: additional records. Records without geographic coordinates are approximate.
We are grateful to the curators/collection managers for the loans, photographs and support during research: Gary Rosenberg, Nasreen Phillips and Paul Callomon (