Molluscan Research 30(3): 165–175 http://www.mapress.com/mr/ ISSN 1323-5818 Magnolia Press Two similar new species of Alvania Risso, 1826 (Caenogastropoda: Rissoidae) from the late Cenozoic of Italy VITTORIO GARILLI & DANIELA PARRINELLO Vittorio Garilli, APEMA Research and Educational Service, Via Alla Falconara, 34 I-90136 Palermo, Italy Email: vittoriogarilli@apema.eu. (Corresponding author). Daniela Parrinello, Facoltà di Scienze della Formazione, University of Palermo, Via Archirafi, 18 I-90100 Palermo, Italy Abstract Alvania baldoi n. sp. and A. dimitrii n. sp. are described from the Plio-Pleistocene of Italy. A. baldoi n. sp. is characterized by clathrate/cingulated sculpture of delicate axial and spiral elements forming knobs. It is closer to the species placed in Alvania Risso, 1826 s.s. than to those grouped within Acinopsis Monterosato, 1884 which is usually treated as a subgenus or synonym of Alvania. A. dimitrii n. sp. is characterized by an almost globose, conical shell bearing a clathrate pattern of subequal spiral and axial elements forming rounded tubercles. It also shows pronounced denticles and a crenulated outer lip. It is intermediate in shell characters between Alvania s.s. and Acinopsis, and closely resembles A. baldoi n. sp. Both the described species have a paucispiral protoconch indicating a non-planktotrophic larval development. Taphonomic and taxonomic information on the fossil sites indicates that A. baldoi n. sp. lived on the mid to lower shelf, whereas A. dimitrii n. sp. presumably inhabited lower shelf to upper slope environments. The morphological features of the new species described are an example of the difficulties in separating some of the nominal genus-group taxa previously recognized that are now usually treated as synonyms of Alvania. Key words: Rissoidae, taxonomy, new taxa, Pliocene, Pleistocene, Mediterranean area. Introduction Species of the rissoid genus Alvania Risso, 1826 are characterized by small, conical-ovate shells generally bearing axial and spiral elements, forming a weak to strong clathrate sculptural pattern. They inhabit a large variety of environments, from shallow to bathyal depth, in the Mediterranean, Atlantic, Indo-Pacific and the temperate Australian coasts (Ponder 1985), representing one of the most diversified groups within the family Rissoidae. Whereas the upper Cretaceous records of Alvania appear doubtful (Ponder 1985), this genus certainly dates back to the European Paleogene (Cossmann 1921; Lozouet 1998 and 1999) and became common and diversified from the Neogene of the same realm (Sacco 1895; Seguenza 1903; Kowalke and Harzhauser 2004; Landau et al. 2004; Chirli 2006). As an example, Kowalke and Harzhauser (2004) reported more than 30 species from the Middle Miocene of central Paratethys; Chirli (2006) recorded about 30 species from the Pliocene shallow water deposits cropping out in Tuscany (N Italy); and about 60 species from the Mediterranean Sea were recorded by Giannuzzi-Savelli et al. (1996). Due to its high diversification, this genus is still affected by difficult, somewhat problematic systematics, despite numerous papers dealing with its taxonomy (e.g. Bucquoy et al. 1884; Monterosato 1884a, 1884b; Weinkauff 1885; Gofas and Warén 1982; Aartsen 1982a, 1982b; Ponder 1985; Moolenbeek and Hoenselaar 1989, 1998; Palazzi 1997; Gofas 1999, 2007). In particular, attempts to separate Alvania s.l. species within several taxa, e.g. Acinopsis Monterosato, 1884, Acinus Monterosato, 1884, Galeodina Monterosato, 1884, Massotia Bucquoy, Dautzenberg & Dollfus, 1884, turned out to be disputable (Ponder 1985; Oliverio et al. 1986; Garilli 2008), indicating that the taxonomy of this group needs reassessment based on new anatomical and genetic information. The main aim of this paper is to describe two morphologically similar new Alvania species from the Pliocene and the Pleistocene of north and south Italy, one of them illustrated and discussed by Garilli (2008) as Alvania sp. Materials and Methods The examined material consisted of two lots of 41 shells, now housed in the Museo di Zoologia di Bologna (University of Bologna) and the Museo di Zoologia P. Doderlein (University of Palermo). One lot, originally labelled PRC2, contained 21 shells collected by Luca Bertolaso from a sandy layers cropping out at the Campore quarry (Salsomaggiore Terme, Parma, N Italy; 44°39’33’’N 9°59’50’’E). The other lot, originally labelled F095A, consisted of 20 shells collected by Stefano Palazzi from a silty layer cropping out near the small village of Musalà (Reggio Calabria, S Italy; 38°13’05’’N 15°40’21’’E) (see Fig. 1 for locations). Seven and eight shells, from the Campore and Musalà sites, respectively, were studied using LEO 420 SEM and Philips XL30 ESEM scanning electron microscopes to allow their teleoconch microsculpture and protoconch to be examined. These characters have been shown to be taxonomically relevant at species/genus level within Rissoidae (Gofas 2007; Garilli 2008). The protoconch morphology also provides information on the type of larval COPYRIGHT © 2010 MALACOLOGICAL SOCIETY OF AUSTRALASIA & SOCIETY FOR THE STUDY OF MOLLUSCAN DIVERSITY 165 166 development (Jablonsky and Lutz 1980). Protoconch whorls were counted according to Verduin’s (1977). Shell variables GARILLI & PARRINELLO (2010) MOLLUSCAN RESEARCH, VOL. 30 (Fig. 2) were measured using a stereo-microscope provided with a cross-line micrometer eyepiece. FIGURE 1, Schematic location of the Campore and Musalà sites (asterisks); distribution of Alvania florentina (after Chirli 2006) (see concluding remarks) and palaeogeographic reconstruction of Pliocene peninsular Italy (from Pinna 1989 and Bianucci et al. 2009, modified). Abbreviations Institutions: MZB — Museo di Zoologia, University of Bologna; MZDP — Museo di Zoologia P. Doderlein, Univerity of Palermo; MAL — Collection “Malacologia” at the MZDP. Others: Ht — total shell height; Hlw — last whorl height; Ha — aperture height; W — shell width. Stratigraphy and Palaeoenvironment The material collected at the Campore site (see Bianucci 1997; Bertolaso and Palazzi 1996; Channel et al. 1994 and Ceregato et al. 2007 for an overview on this deposit) is from a lens-shaped layer formed by bioclastic, well-sorted sand. The molluscan palaeofauna from that layer probably consists of a transported assemblage (sensu Fagerstrom 1964). In fact it is represented by epibathyal species, such as Microstelma sp., Cirsonella romettensis (Granata-Grillo, 1877), Ledella nicotrae (Seguenza, 1877), L. messanensis (Jeffreys, 1870), mixed with shallower littoral taxa, such as Haliotis sp., Clathrella clathrata (Philippi, 1844), Septifer sp. (L. Bertolaso pers. comm., 2009). The layer also contains valves of Emiliomya malnatensis Corselli & Bernocchi, 1992, previously reported for the higher part of a palaeocanyon of lower circalittoral-epibathyal (sensu Pérès and Picard 1964) transitional palaeoenvironment in a Lower Pliocene (presumably Zanclean) site (Malnate, Lombardia, 167 TWO NEW FOSSIL ALVANIA SPECIES FROM ITALY N Italy) (Corselli and Bernocchi 1992). All this indicates the settlement of gravitational movements of sediments. The lens-shaped layer is presumably one of the three bioclastic sand beds described by Ceregato et al. (2007) as cropping out in the middle part of the Piacenzian section at Campore. As reported by these authors, the bioclastic beds contain infralittoral to bathyal elements deposited by turbiditic events. In the investigated layer, the occurrence of Macromphalina plioastensis (Sacco, 1896), Teinostoma cf. magnoiberica Landau, Marquet & Grigis, 2004, Leucorhynchia cf. iricolor Boettger, 1907, Septifer plioblitus Sacco, 1898 indicates distinctly tropical conditions (L. Bertolaso pers. comm., 2009) which probably occurred before the beginning of the first Pliocene climatic cooling, at around 3 My B.P. (middle Piacenzian) (Lourens et al.1992; Raymo et al. 1992; Tiedemann et al. 1994; Shackleton et al. 1995), or in the interval between this event and the subsequent onset of the continental ice sheet in the Northern Hemisphere, at around 2.5 My B.P. (approximating the Piacenzian/Gelasian boundary) (Shackleton et al. 1984). However, a Lower Pliocene, Zanclean, age of the recovery deposit should be excluded as constrained by the (bio)stratigraphy of the whole Campore section (see Ceregato et al. 2007). FIGURE 2, Shell variables measured: Ht = total shell height; Hlw = last whorl height; Ha = aperture height; W = width. The material from Musalà was collected from a silty layer which contained abundant specimens of Gryphus minor (Philippi, 1836) (Stefano Palazzi, pers. comm., 2006) and should be correlated to the G1584 layer/sample of Gaetani and Saccà (1983), cropping out in the deep valley named Vallone di Musalà, at 190 m a.s.l., and indicating a Lower Pleistocene circalittoral palaeoenvironment. Taxonomy Family Rissoidae Gray, 1847 Subfamily Rissoinae Gray, 1847 Genus Alvania Risso, 1826 Type species: Alvania europea Risso, 1826 [synonym of A. cimex (Linnaeus, 1758)], subsequent designation by Nevill (1885). Alvania baldoi n. sp. Figures 3A–C, 4A–D, 5A–C and G, 6A–C Alvania sp. Garilli, 2008: 28, figs 27–29. Type locality Lower Pleistocene of Musalà, 38°13’05’’N 15°40’21’’E, silty layer with Gryphus minor (Philippi, 1836), Campo Calabro, Reggio Calabria, S Italy (details under Stratigraphy and palaeoenvironment above). Material examined Holotype, MZDP MAL-1968; paratype 1, MZB 45703; paratype 2, MZDP MAL-1970; paratype 3, MZDP MAL1969; paratype 4, MZDP MAL-1971; paratype 5, MZB 45704; paratype 6, MZB 45705; paratype 7, MZDP MAL1972; paratype 8, MZB 45706; paratype 9, MZDP MAL1973; paratype 10, MZB 45707; paratype 11, MZDP MAL1974; paratype 12, MZB 45708; paratype 13, MZDP MAL1975; paratype 14, MZB 45709; paratype 15, MZDP MAL1976; paratype 16, MZB 45710; paratype 17, MZDP MAL1977; paratype 18, MZDP MAL-1978; paratype 19, MZDP MAL-1979. All type material is from the type locality. Description Shell small, sturdy, conical, with moderately high spire, reaching 3 mm in height; 1.6 mm in width (paratype 2), with average Ht/W ratio of 1.72. Protoconch paucispiral of ca 1.5 convex whorls with partially immerged nucleus. Early protoconch slightly angled adapically, almost shouldered, sculptured by 6–7 fine spiral threads, two of them stronger on upper part. Interspaces between threads bearing sparse pustules, irregular in size and distribution. Threads fading towards protoconch/teleoconch boundary, where larval shell is sculptured by numerous fine pustules with rough spiral arrangement. Protoconch/teleoconch boundary well marked and moderately prosocline. In shells more than 2.3 mm high (presumed to be minimum height at terminal growth), teleoconch of 3.0–3.25 convex whorls, separated by deep, moderately inclined sutures. Teleoconch whorls with clathrate sculpture of subequal axial ribs and spiral cords forming at intersections narrow and vertically elongated tubercles on first whorl, nodular tubercles on remaining whorls. Axial ribs slightly prosocline, numbering 26–30 on penultimate whorl. Ribs somewhat narrower near sutures, fading on last whorl towards shell base. Spiral cords 2, 3–4 and 9–10 on first, penultimate and last whorl, respectively. A further discontinuous to weak cord usually occurs in subsutural position. Microsculpture of microscopic tubercles spirally arranged forming granulose, often discontinuous, very fine threads (Figs 6A–B) covering all teleoconch surface. Last whorl well expanded, usually with Hlw/Ht ranging from about 0.6 to 0.7. Aperture ovate, slightly angled posteriorly, with Ha/Ht and Ha/Hlw of about 0.4–0.5 and 0.6–0.7, respectively. Outer lip slightly prosocline to orthocline, internally with four to seven, marked to weak denticles; externally with very thin expansion (present in well preserved shells) bordered with wide varix overrun by 168 GARILLI & PARRINELLO (2010) MOLLUSCAN RESEARCH, VOL. 30 spiral sculpture. In some shells denticulation is hardly detectable. Inner lip arched and thickened in columellar area, where narrow expansion delimits very small umbilical chink. Dimensions given in Table 1. TABLE 1. Dimensions of Alvania baldoi n. sp. Ht — total shell height; Hlw — last whorl height; Ha — aperture height; W — width; AV — average value; σ — standard deviation. Specimen Ht (mm) Hlw (mm) Ha (mm) W (mm) Holotype 2.60 1.70 1.10 1.50 Paratype 2 3.00 1.60 1.10 1.60 Paratype 4 1.60 1.20 0.75 0.90 Holotype and paratypes 119 (AV) 2.42 1.57 1.04 1.40 Holotype and paratypes 119 (σ) 0.31 0.14 0.11 0.14 Palaeoecology This species was recovered in association with abundant (in situ) specimens of the brachiopod Gryphus minor, a characteristic circalittoral species, typical of palaeoenvironment comparable with the Mediterranean biocoenoses DC (coastal dedtritic) and DE (muddy detritic) (sensu Pérès and Picard 1964), and particularly abundant in conditions evolving towards precoralligenous environments (Gaetani and Saccà 1983). In general, material of A. baldoi n. sp. appears well preserved and slight wear is only discernable by SEM observation (Figs 5B–C, G). Thus the material does not seem to have been subjected to prolonged biostratinomic processes by current action or gravitational displacement. Instead it is suggestive of only moderate transport, possibly inside the original palaeobiotope or from close palaeobottoms, and suggests that A. baldoi lived in a mid-lower shelf palaeoenvironment. Distribution This species is only known from the type locality. Remarks The clathrate-nodular to somewhat cingulate sculpture, one of the most characteristic features of A. baldoi n. sp., recalls that described by Monterosato (1884a and 1884b) for A. cingulata (Philippi, 1836). However, as stated by Garilli (2008), the latter species is different, having an inflated last whorl and a wider aperture with no denticulations. Alvania baldoi is certainly closer to the type species of the genus, A. cimex (Linnaeus, 1758) (Fig. 3H). There are, however, some differences between A. baldoi and A. cimex, the latter having a multispiral protoconch (Ponder 1985, figs 86b and c; Verduin 1986), larger size (up to about 6 mm in height), stronger sculpture and an almost pupoid general shape, due to the less convex teleoconch whorls. The same teleoconch differences cited for A. cimex exist between A. baldoi and the non planktotrophic sibling of A. cimex: A. mamillata Risso, 1826 (Verduin, 1986). However, the protoconch of the latter species differs in having evenly rounded, more convex whorls that are sculptured with finer spiral threads (see Verduin 1986, figs 3–4; Giannuzzi-Savelli et al. 1996, figs 388 and 395b). Other comparable Mediterranean Alvania species of similar size to A. baldoi are A. aartseni Verduin, 1986 (see Giannuzzi-Savelli et al. 1996, figs 393–394), A. amatii Oliverio, 1986 (see Oliverio 1986, figs 1–2 and GiannuzziSavelli et al. 1996, figs 396–397) and A. nestaresi Oliverio & Amati, 1990 (see Giannuzzi-Savelli et al. 1996, figs 392a and b). All these taxa have a much more pronounced teleoconch sculpture with strong, somewhat acute, knobs, and their shell is clearly stepped (to evidently turreted), as in the nominal taxon Acinopsis Monterosato, 1884 (which is treated as a synonym of Alvania by Ponder 1985) (Fig. 3G). Their protoconchs have shouldered whorls (see Oliverio 1986, figs 3–4; Verduin 1986, fig. 6 and Giannuzzi-Savelli et al. 1996, figs 395d, 408a), whereas only the early larval shell of A. baldoi shows a less conspicuous shoulder (see Figs 5B– C and G). A vague similarity exists between A. baldoi and A. geryonia (Nardo, 1847 ex Chiereghin ms.) and A. mariae (d’Orbigny, 1852), due to their nodulouse teleoconch sculpture. However, the shells of the last two species are larger (up to about 5 mm in height), with a characteristic pupoid shape as a result of the less convex/almost flat whorl profile (see Giannuzzi-Savelli et al. 1996, figs 389–391; Chirli 2006, pl. 12, figs 9–16). There are also similarities between A. baldoi and A. dimitrii n. sp., which are discussed below. Alvania baldoi shows moderate variation, mainly in the number of spiral cords and axial ribs and the Ht/W, Hlw/Ht, Ha/Ht, Ha/Hlw ratios. One of the most variable ratios is Ht/ W, with values ranging from about 1.65 to 1.85. Thickness and number of denticles on the outer lip are remarkably variable, ranging from seven marked teeth to four extremely weak folds. Etimology The species is named after Baldo Parrinello, the second author’s son. Alvania dimitrii n. sp. Figures 3D–F, 4E–G, 5D–F and H, 6D–F Type locality Middle Pliocene (Piacenzian) of Campore, 44°39’33’’N 9°59’50’’E, Salsomaggiore Terme, Parma, Emilia Romagna, N Italy (see Stratigraphy and palaeoenvironment for details). Material examined Holotype, MZB 45692; paratype 1, MZDP MAL-1958; paratype 2, MZB 45693; paratype 3, MZDP MAL-1959; paratype 4, MZB 45694; paratype 5, MZDP MAL-1960; TWO NEW FOSSIL ALVANIA SPECIES FROM ITALY 169 FIGURE 3, Holotypes of Alvania baldoi n. sp. (MZDP MAL-1968) and A. dimitrii n. sp. (MZB 45692); A. cancellata (Da Costa, 1778) and A. cimex (Linnaeus, 1758), type species of Acinopsis Monterosato, 1884 and Alvania Risso, 1826, respectively. A–C. A. baldoi n. sp., Lower Pleistocene of Musalà, Calabria, S Italy, shell in apertural (A), dorsal (B) and profile (C) view. D–F. A. dimitrii n. sp., Pliocene of Campore, Emilia Romagna, N Italy, shell in apertural (D), dorsal (E) and profile (F) view. G. A. cancellata, DATP 002/15 V. Garilli collection, Lower Pleistocene of Dattilo, Trapani, NW Sicily, shell in apertural view. H. A. cimex, KIGR 027/583 V. Garilli collection, Pleistocene of Kyllini, NW Peloponnesus, Greece, shell in apertural view. Scale bars: 1 mm. 170 GARILLI & PARRINELLO (2010) MOLLUSCAN RESEARCH, VOL. 30 FIGURE 4, Paratypes of Alvania baldoi n. sp. and A. dimitrii n. sp., from the Pleistocene of Musalà, Calabria, S Italy, and Pliocene of Campore, Emilia Romagna, N Italy, respectively. A–D. A. baldoi n. sp. A. Juvenile shell, paratype 4, MZPD MAL-1971, in apertural view. B–D. Paratype 3, MZPD MAL-1969, in dorsal (B), apertural (C) and profile (D) view. E–G. A. dimitrii n. sp. E. Subadult shell, paratype 1, MZPD MAL-1958, in apertural view. F. Paratype 18, MZPD MAL-1966, in apertural view. G. Profile view of paratype 2, MZB 45693. Scale bars: 1 mm. paratype 6, MZB 45695; paratype 7, MZDP MAL-1961; paratype 8, MZB 45696; paratype 9, MZDP MAL-1962; paratype 10, MZB 45697; paratype 11, MZB 45698; paratype 12, MZDP MAL-1963; paratype 13, MZB 45699; paratype 14, MZDP MAL-1964; paratype 15, MZB 45700; paratype 16, MZDP MAL-1965; paratype 17, MZB 45701; paratype 18, MZDP MAL-1966; paratype 19, MZB 45702; paratype 20, MZDP MAL-1967. All type material is from the type locality. Description Shell small, sturdy, conical, with moderately inflated last whorl, up to 2.7 mm in height; 1.65 mm in width (holotype), with average Ht/W ratio of 1.55. Protoconch paucispiral, of ca 1.3 to 1.5 markedly convex and rounded whorls with partially immerged nucleus. Early protoconch sculptured by 8–9 fine, granulose spiral threads with numerous, closely spaced tubercles between threads. Tubercles irregular in size and spacing. Next to protoconch/ teleoconch boundary, threads tend to fade and sculpture is only formed by spirally arranged clusters of tubercles. Protoconch/teleoconch boundary well marked, sometimes moderately curved or orthocline. In shells more than 2 mm high (presumed minimum height at terminal growth), teleoconch of 2.7–3.6 convex whorls, separated by deep, moderately inclined sutures. Teleoconch whorls with clathrate sculpture of subequal axial ribs and spiral cords, forming well marked and acute knobs at their intersections. Ribs slightly to markedly prosocline, numbering 18–22 (in shells over 2.3 mm high) on penultimate whorl, gradually fading out towards shell base. Spiral cords numbering 2, 3 and 8–11 on first, penultimate and last whorl, respectively. Cords gradually becoming more raised towards shell base. Additional discontinuous to obsolete subsutural cord usually TWO NEW FOSSIL ALVANIA SPECIES FROM ITALY present. A very narrow spiral thread may occur very close to lower suture of penultimate whorl. Microsculpture consisting of microscopic tubercles covering all teleoconch surface. Tubercles adapically forming granulose, very discontinuous, fine threads (Figs 6D–E); more pronounced, continuous thread occurs abapically, very close to suture (Fig. 6D). Last whorl well expanded, with Hlw/Ht of about 0.65–0.75. Aperture, ovate, slightly angled posteriorly, with Ha/Ht and 171 Ha/Hlw of about 0.4–0.55 and 0.6–0.75, respectively. Outer lip slightly prosocline, internally with eight to ten marked denticles; externally with very thin and apparently short expansion (present in well preserved shells) bordered with wide varix overrun by spiral sculpture. Inner lip arched and moderately thickened in columellar area, where no umbilical chink occurs in adult shells. Dimensions given in Table 2. FIGURE 5, Protoconch of Alvania baldoi n. sp. and A. dimitrii n. sp., from the Pleistocene of Musalà, Calabria, S Italy, and Pliocene of Campore, Emilia Romagna, N Italy, respectively. A–C, G. A. baldoi n. sp. A–C. Different views of protoconch of holotype (A), MZPD MAL-1968, paratype 4 (B), MZPD MAL-1971, and paratype 3 (C), MZPD MAL-1969. G. Paratype 4 showing a detail of the larval shell. D–F, H. A. dimitrii n. sp. D–E. Different views of protoconch of holotype (D, F), MZB 45692, and paratype 2 (E), MZB 45693. H. Paratype 2 showing a detail of the larval shell. Scale bars: 100 μm. 172 GARILLI & PARRINELLO (2010) MOLLUSCAN RESEARCH, VOL. 30 FIGURE 6, Teleoconch microsculpture and early teleoconch sculpture of Alvania baldoi n. sp. and A. dimitrii n. sp., from the Pleistocene of Musalà, Calabria, S Italy, and Pliocene of Campore, Emilia Romagna, N Italy, respectively. A–C. A. baldoi n. sp. A–B. Holotype, MZPD MAL-1968, showing microsculpture on first whorl. C. Holotype showing sculpture on the first and second whorl. D–F. A. dimitrii n. sp. D– E. Paratype 2, MZB 45693, showing microsculpture on first whorl. F. Holotype, MZB 45692, showing sculpture on the first and second whorl. Scale bars: 200 μm in Figs C and F; 50 μm in Fig. B; 40 μm in Figs A and D; 30 μm in Fig. E. 173 TWO NEW FOSSIL ALVANIA SPECIES FROM ITALY Palaeoecology Shells of A. dimitrii n. sp. were collected from a lensshaped deposit interpreted to be the result of gravitationalturbiditic displacement from very shallow water to a bathyal depth, possibly along a palaeocanyon. The deposit contained palaeocommunities transported from different palaeoenvironments and this makes the original palaeobiotope of A. dimitrii difficult to interpret. The shells observed with the SEM, showed scarce microscopic bioerosional marks on the inner and outer part of the shell surface (Figs 3D and 3F), no biological encrustations and very few scratches. It is likely that that post mortem burial did not occur rapidly and that the shells underwent several short-distance movements and/or sudden transport. A lower shelf to upper slope palaeoenvironment is suggested for A. dimitrii based on the cited molluscan assemblage from the lens-shaped deposit at Campore (see above, section Stratigraphy and Palaeoenvironment) and the deduced taphonomic setting. TABLE 2. Dimensions of Alvania dimitrii n. sp. Ht — total shell height; Hlw — last whorl height; Ha — aperture height; W — width; AV — average value; σ — standard deviation. Specimen Ht (mm) Hlw (mm) Ha (mm) W (mm) Holotype 2.70 1.95 1.45 1.65 Paratype 12 1.90 1.45 0.80 1.30 Holotype and paratypes 1-20 (AV) 2.26 1.59 1.11 1.47 Holotype and paratypes 1-20 (σ) 0.17 0.10 0.13 0.10 Distribution This species is only known from type locality. Remarks Alvania dimitrii n. sp. differs consistently from congeneric species living in the Mediterranean and Atlantic provinces in its globose shape and moderately shouldered whorls, the strong denticulation of the peristome, the well marked spiral cords on the shell base, the distinct, gently clathrate sculpture, with subequal spiral and axial elements, and lack of a strongly crenulated outer lip. Actually this species is intermediate in morphology between species similar to the type species of Alvania and those similar to the type species of Acinopsis (see Figs 3G and 3H). Species from the former group, such as Alvania cimex, A. mamillata, A. mariae, A. geryonia, have a larger (up to 5–6 mm high), slender, usually non stepped shell, with a non-crenulated outer lip (for illustration see Giannuzzi-Savelli et al. 1996 and Chirli 2006). On the other hand, species attributable to the latter group, such as Alvania aartseni, A. amatii, A. cancellata (Da Costa, 1778) (type of Acinopsis, see Fig. 3G), A. clathrella (Seguenza, 1903 ex Monterosato ms.), A. hirta Monterosato, 1884, A. nestaresi, A. sculpta (Philippi, 1844), A. subcrenulata (Bucquoy, Dautzenberg & Dollfus, 1884), A. transiens (Sacco, 1895) (for illustrations see GiannuzziSavelli et al. 1996 and Chirli 2006), have more shouldered whorls with a more pronounced clathrate to rectangular sculpture, consisting of stronger ribs and narrower spiral cords. Cords are very pronounced on the shell base, forming acute, sometimes spiny, knobs at their intersections, and giving a characteristic markedly crenulated profile to the outer lip. Alvania dimitrii resembles A. florentina Chirli, 2006, described from the Pliocene of Tuscany (N Italy). The two species share a similar Ht/W ratio and the same number of ribs and cords; their paucispiral protoconchs are also comparable (see Chirli 2006, pl. 9, figs 3–12). Differences between these two species include the teleoconch and protoconch sculpture and the convexity of the last whorl. A. dimitrii has finer axial ribs (markedly prosocline), more pronounced spiral cords and always rounded knobs, whereas the knobs of A. florentina are acute, narrow, becoming larger and rounded just in the adapical portion of the whorls. A. dimitrii has a more inflated last whorl and its protoconch is characterized by a more numerous, finer, closely packed microtubercles separated by threads covering most of the surface. Alvania dimitrii also resembles A. baldoi n. sp. in its sculptural and microsculptural details and, in some cases (compare Figs 3D–E with Figs 4B–C), in shell shape. The latter species usually has a more elongate shell (average Ht/ W ratio of 1.72 vs. 1.55), a more delicate sculpture with more numerous ribs (26–30 vs. 18–22, on the penultimate whorls of the adult shell) and less robust and less numerous denticulations on the peristome. Also its protoconch is different, having angled early whorls provided with larger and less densely packed microtubercles. Available shells of A. dimitrii do not show significant variation, with the exception of the number of ribs, from 16 (in subadult shells) to 22, and their inclination in respect to the shell axis (compare Fig. 3D with Figs 4E–G). Etymology The species is dedicated to the malacologist Luca Bertolaso, alias Dimitri, a close friend of the first author. Discussion The new species described, the Pleistocene Alvania baldoi n. sp. and the Pliocene A. dimitrii n. sp., are morphologically so similar that it could be speculated that the former taxon evolved from the latter one. An analogous relationship between A. florentina Chirli, 2006 and A. dimitrii could also be suggested, even if the palaeogeographic distributions of these species are disjunct as their respective locations (Tuscan and Emilian sides of northern Apennine) were part of two isolated Pliocene marine palaeoprovinces (see Fig. 1). It is noteworthy that both A. baldoi (currently known only from the Pleistocene of S Italy) and A. dimitrii, as well as A. florentina, have a paucispiral larval shell, indicating a non-planktotrophic larval development and consequently a 174 potential low dispersal capacity. However, a cause-effect relationship between the mode of development and the apparent high degree of isolation shown by these species should be tested. There are few non-planktotrophic Alvania species with a distribution extending throughout the Mediterranean (Giannuzzi-Savelli et al. 1996), a basin comparable with that which occurred during the PlioPleistocene of the same area. However, most of the Mediterranean Alvania species with non-planktotrophic development are limited to the western or the eastern part of that sea, and several of them show much more restricted distributions (e.g. A. dianiensis Oliverio, 1988 and A. dipacoi Giusti & Nofroni, 1989, from the Tuscan Archipelago and A. schwartziana Brusina, 1866, from the Dalmatian coasts; see Giannuzzi-Savelli et al. 1996). Further research to better understand the effective degree of isolation of A. baldoi, A. dimitrii and A. florentina would be helpful in verifying any hypothetical relationships between their limited distributions and the mode of larval development. The morphological features of these three species show a more or less gradual transition between Alvania s.s. species and those for which Monterosato (1884a and 1884b) created Acinopsis, thus testifying to the inappropriateness of the separation at genus or subgenus level of the latter taxon. Garilli (2008) discussed similar extinct taxa transitional between other genus-group taxa (Galeodina and Massotia) that are often treated as synonyms of Alvania (e.g. Ponder 1985). Thus, the careful study of fossil Alvania species can demonstrate the existence of transitional forms between apparently distinct groups of living taxa. Acknowledgments This article would not have been possible without the generous support of Luca Bertolaso (Correggio, Italy) and Stefano Palazzi (Modena, Italy). Both provided the described material with information on the recovery sites. L. Bertolaso also provided useful literature on the Campore site. We thank Angelo Vazzana (Museo di Biologia Marina e Paleontologia, Reggio Calabria, Italy) who provided location and geographic coordinates of the Musalà site. 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