Solariella carvalhoi, Lopes & Cardoso, 1958

Cavallari, Daniel C., Salvador, Rodrigo B. & Simone, Luiz R. L., 2016, Solariella quadricincta Quinn, 1992 and S. staminea Quinn, 1992 are synonyms of S. carvalhoi Lopes & Cardoso, 1958 from the SW Atlantic (Gastropoda: Solariellidae), Zootaxa 4109 (1), pp. 96-100 : 96-99

Solariella quadricincta Quinn, 1992 and S. staminea Quinn, 1992 are synonyms of S. carvalhoi Lopes & Cardoso, 1958 from the SW Atlantic (Gastropoda: Solariellidae )

DANIEL C. CAVALLARI 1, RODRIGO B. SALVADOR 2,3 & LUIZ R. L. SIMONE 1

1Museu de Zoologia da Universidade de São Paulo. São Paulo, SP, Brazil. E-mail: [e-mail]; [e-mail] 2Staatliches Museum für Naturkunde Stuttgart. Stuttgart, Baden-Württemberg, Germany.

3Eberhard Karls Universität Tübingen. Tübingen, Baden-Württemberg, Germany. E-mail: [e-mail]

Solariellidae is a diverse family of small (5–20 mm) marine snails of worldwide distribution. They usually live on fine sediment to unconsolidated substrates in deep-waters of extra-tropical to tropical latitudes ( Hickman 1998; Williams et al. 2013). Initially described as a subfamily of Trochidae , it has been recently raised to family level ( Bouchet et al. 2005; Williams et al. 2008). The evolutionary relationships among solariellids have been extensively investigated in the light of morphological and molecular data, but the family still lacks a comprehensive taxonomic revision that reflects recent discoveries ( Williams et al. 2010, 2013). The family’s fossil record possibly dates back to the Campanian of Torallola, Spain ( Kiel & Bandel 2001; Williams et al. 2013).

In an ongoing study on the deep-water trochoideans from the French-Brazilian Marion Dufresne MD55 expedition off SE Brazil (a joint project of the MNHN and the USU that took place during May and June 1987), the confusing identities of a few species caught our attention: Solariella quadricincta Quinn, 1992 and Solariella staminea Quinn, 1992 . These Western Atlantic congeners are considered distinct taxa, but as we argue below, they are in fact synonyms of a previously described species, Solariella carvalhoi Lopes & Cardoso, 1958 . This species turns out to be more variable and wide-ranging than initially assumed. A list of the examined material can be found at the end of this manuscript.

Solariella quadricincta was described by Quinn (1992: 50, figs 1–4) from the continental shelf off Isla Margarita, northern Venezuela. It was initially known only from that region, based on specimens collected by the R/V John Elliott Pillsbury. Subsequent records have since extended its range to northeastern Brazilian waters, off the states of Ceará, Alagoas and Sergipe at depths of 100–170 m ( Barros et al. 2008). Solariella staminea was also described by Quinn (1992: 53, figs 11–12), based on the Marion Dufresne MD55 expedition specimens from the Davis Seamount, off SE Brazil. The only single additional record of this species is also from SE Brazil ( Benkendorfer & Soares-Gomes 2009). Both species descriptions were based solely on shell characters, as the author had no access to living specimens ( Quinn 1992). Solariella carvalhoi was described by Lopes & Cardoso (1958: 59, figs 1–3) based on two empty shells from SE Brazilian waters off the states of São Paulo (type locality) and Rio de Janeiro (specimen from a private collection). Its known range has subsequently been expanded to northeastern and southern Brazil, respectively off the states of Amapá and Alagoas and Santa Catarina ( Rios 1975; Barros et al. 2008).

The main distinction between Solariella quadricincta Quinn, 1992 and S. carvalhoi concern the shell’s outline, color and particular sculpture patterns ( Quinn 1992). Nonetheless, Quinn (1992) had already pointed out the close similarity between the three congeners. While examining a great number of specimens from the MZSP and MNHN collections attributable to S. carvalhoi , we noticed a considerable morphological variability. In the analyzed material, specimens that closely match Quinn’s (1992) S. quadricincta and S. staminea , as well as S. carvalhoi as described by Lopes & Cardoso (1958), were mixed together, accompanied by a range of intermediate forms. This variation is found not only in distinct geographical areas, but also in specimens from a single locality (Figs 6–21).

The high intraspecific conchological variability in solariellids has already been recognized previously (e.g., Quinn, 1979; Marshall, 1999). This variation concerns the number of sculptural elements (such as cords and ribs) and the strength of the teleoconch sculpture (from nearly smooth shells to specimens with very strong sculpture, sometimes even presenting nodules or spikes). Below we describe the main forms of variation found in shell shape and sculpture of S. carvalhoi , in the light of more abundant material, demonstrating that the concepts of S. quadricincta and S. staminea are both part of the continuum of conchological variation of S. carvalhoi .

The spiral cord sculpture present in all specimens is highly variable in strength. It varies from mostly well-marked cords, bearing nodules (Figs. 18, 20, 22), to a mixture of conspicuous and very thin and smooth, almost absent, cords (Figs. 12, 16); all cords may bear nodules, but the subsutural cord invariably bears them. Nodules may be spirally elongated, or narrower and angular (Figs. 8 and 10, respectively). Spiral cord width is also very variable: cords in the same specimen may vary from 1/10 to 1/5 of whorl height. Some specimens bear evenly wide cords (Fig. 18) while others bear cords of unequal width (Figs. 8, 10, 12, 14). The space between cords may be equal to the cord’s width (Fig. 18), or exceed it by 2–5 times ( Figs. 1 , 8, 10). Again, the width of the cords is variable within the same specimen (Figs. 12, 14, 16, 20). The number of cords on the body whorl varies from 2 to 5 (Figs. 10 and 20, respectively). The width and depth (in case it is concave) of the subsutural shoulder on the body whorl are also very variable; width varies from roughly twice (Fig. 18) as wide as the adapical (subsutural) spiral cord to three to four times wider ( Figs. 1–2 , 8, 10), and depth can be concave ( Figs. 1 , 4, 8, 16) or convex (Figs. 10, 14, 20). Some specimens may show an intermediary thin cord on the shoulder (Figs. 4, 20).

The axial sculpture is also variable among and within specimens. In some specimens, thin but strongly marked, closely packed, prosocline axial striae are present on all whorls, especially visible between the spiral cords, as in Quinn’s (1992) S. quadricincta (Figs. 4, 10, 16). In other specimens, the axial striae are stronger on the initial whorls and become gradually obsolete towards the body whorl ( Figs. 1 , 8). Some specimens also show scarce axial sculpture with almost smooth interspaces between the spiral cords (Fig. 20).

The basal portion of the shell shows several well-marked spiral cords and prosocline axial striae, of which width and strength are highly variable within and among specimens, quite similarly to the ornament of the whorl face ( Figs. 3 , 9, 11, 13, 15, 17, 19, 21, 23). An invariable feature in all specimens is a prominent periumbilical cord, which is usually the widest basal cord; it always bears nodules, forming a carina that effectively divides the shell’s basal surface into a convex peripheral outer part and a concave inner part. The convex outer part is sculptured by 5–7 (including the periumbilical) mostly smooth spiral cords and with axial threads visible in the depressions between cords. The umbilical region is wide and always bears knobby, more closely packed spiral cords on all whorls toward the earliest, crossed by conspicuous axial threads.

The overall shell shape closely reflects the configuration of the spiral cords. Specimens with a keeled outline present uneven cords, with some more conspicuous than the others, as is the case in the holotype of S. carvalhoi and the specimens that resemble it (respectively Figs. 1–3 and 8, 10, 12). Specimens with evenly sized cords have a more rounded, homogeneous profile, more akin to S. staminea and S. quadricincta (Figs 4–5, 16, 18, 20) sensu Quinn (1992). The shell’s width, which was used by Quinn (1992) to distinguish S. staminea from its congeners, is also quite variable and apparently not influenced by the sculpture pattern (compare similarly sculptured narrow and wide specimens in Figs. 18 and 20). The aperture shows little variation, being rounded, with the interior shell surface smooth and homogeneously cream colored, with an iridescent shade. The operculum (Figs. 6–7) is circular, corneous, thin, with a central nucleus and a convex inner and a concave outer surface; it is colored golden to yellowish brown.

The shell’s ground color is cream to light beige, with a mixture of dispersed reddish brown stripes (upper whorls), blotches (upper and body whorls) and spots (all whorls, including the basal portion of the body whorl). An iridescent shade throughout the shell’s surface is visible in wet specimens, which corresponds to the inner nacreous shell layer made visible through transparency. The rather weak coloration of S. staminea (Fig. 5) as emphasized by Quinn (1992) is not uncommon in the MD55 material. Many deep-water specimens coming from the MD55 material are commonly bleached and often covered by a white, calcified substance (not the intritacalx as described by D’Attilio & Radwin, 1971). Bleaching and deposition of salt layers in mollusk shells may be the result of a chemical reaction triggered by long-term exposure to low pH levels, among other factors ( Cavallari et al., 2014). This could explain the much lighter, almost residual color reported by Quinn (1992) as one of the distinctive characters of S. staminea .

In conclusion, Solariella quadricincta Quinn, 1992 and Solariella staminea Quinn, 1992 should be treated as junior synonyms of Solariella carvalhoi Lopes & Cardoso, 1958 . The following emended diagnosis is given for this species: cream to light beige background color, with reddish-brown dispersed blotches, stripes, and spots; whorls sculptured by 2–5 spiral cords and numerous axial striae, usually more evident on the interspaces between spiral cords; a prominent subsutural cord bearing nodules; basal portion of shell sculptured by 5–7 spiral cords, with a prominent, knobby periumbilical cord forming a carina that divides the basal surface into a convex outer part and a concave inner part, the latter sculptured by knobby, closely packed spiral cords crossed by well-marked axial threads; aperture rounded; interior shell surface smooth, cream-colored, with an iridescent shade; operculum golden to yellowish brown, circular, corneous, thin, with a central nucleus and a convex inner and a concave outer surface.

Solariella carvalhoi ranges from Venezuela to southern Brazil ( Barros et al., 2008; Rios, 2009; present paper). Based on the deepest live-specimen records examined here (MZSP 63528), the revised bathymetric range of this species is from 0 to 350 m.

Abbreviations. Shell measurements: H = shell height; D = shell greatest width; d = operculum diameter. Institutional: IOUSP = Instituto Oceanográfico da Universidade de São Paulo (São Paulo, Brazil); MNHN = Muséum National d'Histoire Naturelle (Paris, France); MORG = Museu Oceanográfico Eliézer de Carvalho Rios (Rio Grande, Brazil); MZSP = Museu de Zoologia da Universidade de São Paulo (São Paulo, Brazil); UMML = Rosenstiel School of Marine and Atmospheric Science, University of Miami (Miami, USA); USNM = Smithsonian National Museum of Natural History (Washington, D.C., USA); USU = Universidade Santa Úrsula (Rio de Janeiro, Brazil).

Material examined. Types: Solariella carvalhoi : holotype: Brazil: off São Paulo state: 31°35’08”S, 50°50’00”W, 54 m, MZSP 18446 (Moreira coll., 11.xi.1956). Solariella quadricincta : paratypes: John Elliot Pillsbury sta. P-705, 10 º45’N, 62º00’W, 77–86 m, UMML 30.6376, 1 sh. (18.vii.1968); John Elliot Pillsbury sta. P-718, 11 º22.5’N, 64º08.6’W, 60 m, UMML 30.6528, 1 sh. (20.vii.1968); John Elliot Pillsbury sta. P-727, 10 º20’N, 65º02’W, 64 m, UMML 30.6695, 1 sh. (21.vii.1968). Solariella staminea : holotype: MD55 sta. DC40, 20 °40’S, 34°41’W, 60 m, MORG 26530 (Bouchet, Leal & Métivier coll., v.1987); paratypes: from type locality, MNHN-IM-2012-37682, 3 sh. (Bouchet, Leal & Métivier coll., v.1987); additional material: Solariella carvalhoi : Brazil: off Maranhão: PIATAM Oceano sta. 109, from 01º54.863’S 043º19.844’W to 01º55.249’S 043º21.036’W, 33 m, MZSP 96128, 2 spm. (R/V “Amorim do Valle” coll., 22.xi.2008); off Rio de Janeiro: south of Cabo Frio, MD55 sta. CB101, 22 °59’S, 42°05’W, 50 m, MNHN, 1 sh. (Bouchet, Leal & Métivier coll., 01.vi.1987); MBT sta. 140, 23 °02’S, 43°00’W, 40 m, MZSP 82270, 1 spm. (R/V “W. Besnard” coll., 02.ix.1970). São Paulo: off Ubatuba, 350 m, MZSP 63528, 13 spm. ( IOUSP coll., 1979); 100 m, MZSP 69825, 4 spm. (Femorale coll., vii.2000); 100m, MZSP 73988, 61 sh. (Femorale coll., ix.2001). São Paulo and Paraná states: between Santos (23°55’S) and Paranaguá (25°31’S), MZSP 35334, 1 spm. (C.M. Cunha coll., xi.1999).

Additional type material. Solariella carvalhoi : Paratypes: Brazil: Rio de Janeiro: Cabo Frio, 1 sh. from Paulo de Sá Cardoso Collection (private; specimen likely lost). Solariella quadricincta : holotype: Venezuela: Isla Margarita: John Elliot Pillsbury sta. P-721, 11 º22.5’N, 64º08.6’W, 60 m, USNM 859437 [this specimen was never deposited in the USNM collection and is considered lost (Ellen E. Strong, personal communication)].

Figures

FIGURES 1 – 3. Solariella carvalhoi Lopes & Cardoso, 1958, holotype (MZSP 18446; H = 5.0 mm, D = 6.6 mm). Figure 4. Solariella staminea Quinn, 1992, paratype (MNHN-IM- 2012 - 37682; H = 5.0 mm, D = 5.5 mm) (courtesy of the MNHN). Figure 5. Solariella quadricincta Quinn, 1992, holotype (USNM 859437, specimen never deposited; H = 6.4 mm, D = 6.4 mm) reproduced from Quinn (1992). Figure 6. S. carvalhoi, operculum # 1, internal view (MZSP 73988; d = 3.4 mm). Figure 7. operculum # 2, external view (MZSP 73988; d = 2.9 mm). Figures 8 – 21. Series of specimens (Figs. 8 – 21, MZSP 73988; Figs. 22 – 22, MNHN unnumbered) showing the full spectrum of conchological variation. Figures 8 – 9. H = 6.7 mm, D = 7.0 mm. Figures 10 – 11. H = 7.0 mm, D = 7.1 mm. Figures 12 – 13. H = 6.7 mm, D = 7.3 mm. Figures 14 – 15. H = 7.6 mm, D = 7.5 mm. Figures 16 – 17. H = 5.9 mm, D = 6.1 mm. Figures 18 – 19. H = 7.3 mm, D = 7.2 mm. Figures 20 – 21. H = 7.5 mm, D = 7.8 mm. Figures 22 – 23. H = 7.5 mm, D = 7.7 mm.