Clypeostoma cf. nortoni (McLean, 1984) Herbert, 2012

Herbert, D. G., 2012, A revision of the Chilodontidae (Gastropoda: Vetigastropoda: Seguenzioidea) of southern Africa and the south-western Indian Ocean, African Invertebrates 53 (2), pp. 381-381 : 409-410

Clypeostoma cf. nortoni (McLean, 1984) comb. n.

Figs 8 , 12H–L Agathodonta nortoni: McLean 1984: 122 , figs 1–3; Tsuchida & Kurozumi 1996: 37, fig. 3; Vilvens 2001:

figs 11–13; Vilvens & Héros 2003: figs 12, 13; Poppe et al. 2006: 30, pl. 7, figs 3, 4; Poppe &

Tagaro 2008: 166, pl. 28, figs 4, 6. Type loc.: off Baltazar Is. (13°14'N 121°49'E), Marinduque

Province, Philippines.

A number of Clypeostoma shells resembling C. nortoni have been dredged off Madagascar and obtained ex piscibus from the Sofala Bank, off central Mozambique. Similar material evidently also occurs off Réunion and was recorded there by Jay (2009 as Clanculus ceylonicus ). Compared with C. meteorae , these specimens are consistently larger (mature length 9.6–14.6 mm) and have a larger protoconch (diameter 310–320 µm). In addition, the basal callus shield is more extensive and smoother, bearing (apart from 3–5 strong, in-running parietal ridges overlying the basal sculpture of the previous whorl) only traces of superficial ridging in the parietal region and a small number of granules associated with the medial columella area. C. townsendianum ( Fig. 12F, G ), from the Persian Gulf, is of a similar size (figured syntype, length 10.4 mm), but has stronger apertural dentition more similar to that of C. meteorae . The form of the apertural dentition in the present material is closest to that of the Philippine C. nortoni , but the shell attains a relatively larger size (length up to 14.6 mm) than does C. nortoni , and the suture is slightly less indented and the whorls thus less convex. With the limited amount of material available and the geographical distances involved, it is difficult to assess the significance of these differences. I cannot thus confidently identify this material as C. nortoni , but rather draw attention to its existence and its similarity to that species.

Material examined: MADAGASCAR: West of Nosy Be (13.400°S 47.967°E), - 210–310 m, Campagne Miriky, st’n DW3232, dredged, 03.vii.2009 ( MNHN) ; south of Faux-Cap (26.133°S 45.650°E), - 280–333m, Exped’n ATIMO VATAE, st’n DW3553, dredged Nosy Be 11, 5.v.2010 ( MNHN) ; ditto (26.117°S 45.650°E), - 264–280 m, Exped’n ATIMO VATAE, st’n DW3552, dredged Nosy Be 11, 5.v.2010 ( MNHN) . MOZAMBIQUE: Between Beira and Bazaruto, Sofala Bank (20.123°S 35.543°E), - 90–145 m, ex pisce, J. Rosado 2005–2008 (J. Rosado coll’n) .

Figures

Fig. 8. Distribution of Clypeostoma species in the south-western Indian Ocean. C. meteorae (squares), C. cf. nortoni (circles), C. reticulatum (cross) and C. salpinx (triangles). Each symbol represents one or more records.

Fig.12.Clypeostomaspecies:(A, B) C.meteorae (Neubert,1998),SW of Cap d’Ambre,Antsiranana,northern Madagascar, length 6.9 mm (MNHN); (C–E) C. meteorae, small specimen, off Mahajamba Bay, northern Madagascar, length 5.6 mm (MNHN); (F, G) Euchelus townsendianus Melvill & Standen, 1903, figured syntype, length 10.4 mm (NHMUK 1903.12.15.119); (H, I) C. cf. nortoni (McLean, 1984), west of Nosy Be, northern Madagascar, length 9.6 mm (MNHN); (J–L) C. cf. nortoni, large specimen, Sofala Bank, central Mozambique, length 14.6 mm (J. Rosado coll’n).