Vegrandinia, Salvador & Cunha & Simone, 2013

Salvador, Rodrigo B., Cunha, Carlo M. & Simone, Luiz Ricardo L., 2013, Taxonomic revision of the orthalicid land snails (Pulmonata: Stylommatophora) from Trindade Island, Brazil, Journal of Natural History (J. Nat. Hist.) 47 (13 - 14), pp. 949-961 : 955-956

Vegrandinia gen. nov.

( Figures 2M–S )

Type species

Bulimulus trindadensis Breure and Coelho, 1976 .

Included species

Vegrandinia trindadensis ( Breure and Coelho 1976) .

Etymology

Allusion to the small size of the species, the tiniest native species on Trindade Island. From the Latin word “ vegrandis ”, meaning “tiny, diminutive”. Grammatical gender: feminine.

Diagnosis

Shell elongated-oval; whorls profile flattened; protoconch sculptured by sinuous axial striae; presence of columellar fold reaching aperture and palatal fold on inner portion of body whorl.

Description

Shell diminutive, elongated-oval tending towards conical. Suture weakly marked. Whorls profile flattened. Protoconch rounded, large, sculptured by sinuous axial striae; transition to teleoconch unclear. Teleoconch smooth. Aperture elliptical, prosocline; callus on parietal region. Lip thin, simple, non-reflected, with exception of upper columellar region, reflected and covering umbilicus. Columellar fold on median portion of aperture’s columellar region. Palatal fold on inner portion of body whorl, on median portion of whorl’s palatal region. Umbilicus rimate.

Remarks

Breure and Coelho (1976) described some animals collected at Trindade Island as an endemic new species, Bulimulus trindadensis . Interestingly, these authors made clear in their work that the species “does not resemble any of the other species of Bulimulus ” ( Breure and Coelho 1976: p. 5). The authors also stated that B. trindadensis resembles the fossil genus Itaborahia Maury, 1935 from the Palaeocene of Rio de Janeiro ( Breure and Coelho 1976: p. 5), but the differences between the two are overwhelming: its much smaller size, the oval shell shape and the shape, position and features of the aperture and lip are widely disparate from the single species in the genus, Itaborahia lamegoi Maury, 1935 ; the only feature both species share is the columellar fold ( Maury 1935; Salvador and Simone forthcoming), but this can also be found in many other orthalicid genera ( Simone 2006).

The following features distinguish B. trindadensis from the genus Bulimulus : small size, thin and fragile shell, prosocline aperture, weakly marked suture, the presence of a weak callus on the parietal region of the aperture, the presence of the columellar fold and the palatal fold and the overall shell shape. The combination of shell characters present in B. trindadensis is more closely allied to Subulinidae than to Orthalicidae : a minute, thin and delicate shell; a large and rounded protoconch; and a weakly marked suture. The presence of a columellar fold is also common in Subulininae , but not ubiquitous. However, because of its particular combination of characters, there is no single subulinid genus that can properly house this species; so the new genus is proposed. Vegrandinia seems to be closely allied to the genus Leptinaria Beck, 1837 , but differs from it by its more oval shell shape, flattened whorl profile and by the presence of a palatal fold on the inner portion of the body whorl.

Figures

Figure 2. (A–C) Bulimulus brunoi (holotype, MNRJ 1128; H = 19.4 mm). (D) B. brunoi (MNRJ 1129; H = 20.7 mm). (E, F) B. brunoi, protoconch and teleoconch sculpture (MZSP 101245). (G) Naesiotus arnaldoi (holotype, MNRJ 3105; H = 9.5 mm). (H–J) N. arnaldoi (MZSP 104740; H = 10.8 mm). (K) N. arnaldoi (paratype, MNRJ 3105; H = 10 mm). (L) N. arnaldoi, protoconch sculpture (MZSP 101244). (M–O) Vegrandinia trindadensis (MZSP 104742; 5.2 mm). (P, Q) V. trindadensis (holotype, MNRJ 3711; H = 7 mm). (R, S) V. trindadensis (MZSP 104743), (R) protoconch sculpture, (S) broken aperture showing the lamellae.