Cochlostoma oscitans Gofas, 1989

Gofas, Serge, 2001, The systematics of Pyrenean and Cantabrian Cochlostoma (Gastropoda, Cyclophoroidea) revisited, Journal of Natural History 35 (9), pp. 1277-1369 : 1315-1317

Cochlostoma oscitans Gofas, 1989

(®gures 29±30) Cochlostoma oscitans Gofas, 1989: 46 ±47, ®gure 13±15. Type locality: Seldesuto, near Matienzo (Santander)ÐHOLOTYPE MNHN. PARATYPES MNHN, MNCN, MZB, UPV .

Description

Shell up to 11 Ö 5.5 mm with seven to eight quite rounded whorls. Early whorls with a peripheral angle which is concealed by the suture; body whorl not constricted, well rounded. Sculpture weak, shagreened, on the ®rst embryonic half whorl, then grading to extremely ®ne and crowded (30±35/mm) ribs on the second whorl. Spire whorls with ®ne and regular ribs (10±15 ribs/mm) on third to ®fth whorls; ribs not thickened at their termination along the suture.

Aperture strongly thickened and expanded into a broad collar, with a moderately thickened rim inside the outer lip. Peristome distinctly auriculated, gradually narrowing at the columellar insertion; collar always somewhat distorted.

Shell colour with a purplish brown background, over which the whitish segments of the ribs form colour patterns: two spiral series of dark patches on the spire whorls, and a third one on the peri-umbilical area of the body whorl. Peristome white.

Female and male genital systems as in general description.

Remarks

Cochlostoma oscitans has a spiral colour pattern which resembles that of C. martorelli or C. crassilabrum , contrasting with the uniform colour in the other Cantabrian species. However, the allozyme data (notably MPI and SOD alleles) and the morphology of the columellar insertion (narrowing gradually) support a closer relationship to the C. hidalgoi group.

Cochlostoma oscitans is easily recognized from its comparatively short pro®le, and its broad, irregular outer lip. It has a unique, autapomorphic allele at the very conservative FUM locus.

Habitat

Specimens of C. oscitans are found on exposed, slightly overhanging rock surfaces, usually mixed with C. hidalgoi . The other species found sympatrically overlap

but have a slightly diOEerent preference of habitat, C. bicostulatu m and C. crassilabrum in more shaded places with rock mounds or vegetation.