Alvania vermaasi van Aartsen, 1975

Gofas, Serge, 2007, Rissoidae (Mollusca: Gastropoda) from northeast Atlantic seamounts, Journal of Natural History 41 (13 - 16), pp. 779-885 : 792

Alvania vermaasi van Aartsen, 1975

( Figure 5G )

Material examined

Gorringe—DW08, 2 sh. (2.12×1.22 to 2.46× 1.32 mm).

Remarks

This is the only rissoid species with a paucispiral protoconch shared with the mainland fauna. Gofas and Warén (1982) erred in considering Alvania vermaasi as a synonym of A. imperspicua Pallary, 1920 . The latter is a different species, endemic to a small stretch of coastline between Casablanca and Essaouira, Morocco, and lives among intertidal rocks. Alvania vermaasi is smaller, more delicate and slender, and lives subtidally on rubble; both species, and also A. zylensis , share the peculiar microsculpture of zig-zag lines on the protoconch.

Figures

Figure 5. Alvania species from Lusitanian seamounts, shared with the mainland shelf. (A) A. cancellata (da Costa, 1778), shell from Gorringe seamount, DW33 (55–70 m), actual size 4.90 mm; (B) A. cancellata, protoconch of a shell from Ampère seamount, DE98 (300–325 m); (C) A. zylensis Gofas and Warén, 1982 from Gorringe seamount, CP20 (305–320 m), actual size 2.25 mm; (D) protoconch of the same specimen; (E) A. zylensis from Ampère seamount, DW92 (117–129 m), actual size 2.00 mm; (F) A. punctura (Montagu, 1803), protoconch of a shell from Gorringe seamount, CP 20; (G) Alvania vermaasi van Aartsen, 1975, protoconch of a shell from Gorringe seamount, DW08 (470–485 m). Scale bars: 100 Mm.