Herpetopoma, : Pilsbry, 1890

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 : 429

Key to species of Herpetopoma in the south-western Indian Ocean

1 Basal columella tooth a well-developed peg with a deep U-shaped notch separating it from the first (usually the largest) tooth inside the basal lip ( Fig. 23 )................2

– Basal columella tooth smaller and roundly trigonal; U-shaped notch at base of columella relatively shallow ( Fig. 32 ).......................................................................5

2 Umbilicus remaining patent in adult......................................................................3

– Umbilicus closed in adult.......................................................................................4

3 Adult shell length exceeding 5.0 mm; spire trochiform, usually with reddish brown markings................................................................................................. instrictum

– Adult shell length less than 4.0 mm; spire low, evidently without colour pattern... ........................................................................................................... seychellarum

4 Shell small, adult length rarely>3.0 mm; profile globose with a well-developed serrate spiral cord at periphery; coast of tropical East Africa ........ serratocinctum

– Shell larger, adult length>3.0 mm; spire profile more trochiform; peripheral cord not enlarged or conspicuously serrate; Mascarene Islands ......................... stictum

5 Sculpture relatively coarse with 3 strong spiral cords above and including periphery; beads on spiral cords axially elongate............................................................. helix

– Sculpture fine with 4 or more spiral cords above and including periphery; beads more or less rounded..............................................................................................6

6 Shell relatively low-spired, L/D<1.23; labral denticles largely restricted to thickened inner lip; whorls rounded, sculpture relatively coarse .............................? naokoae

– Shell higher-spired, L/D>1.23, some labral denticles extending into aperture as in-running ridges; whorls rather flat-sided, sculpture fine ....................... xeniolum

Figures

Fig. 23. Herpetopoma instrictum (Gould, 1849): (A, B) holotype of Trochus instrictus Gould, 1849, length 8.3 mm, diameter7.5 mm (USNM 5625);(C, D) Conducia Bay, northern Mozambique,length 9.0mm, diameter 7.7 mm (NMSA J4175); (E, F) lectotype of Monodonta alveolata A. Adams, 1853, length 11.9 mm, diameter 10.0 mm (NHMUK 196872); (G, H) holotype of Monodonta bourcierei Crosse, 1863, length 8.6 mm, diameter 7.0 mm (NHMUK 96.12.1.13).

Fig.32. Herpetopoma helix (Barnard, 1964):(A, B) typically coloured specimen, intritacalx deposit largely missing, off Umzinto, KZN, length 4.0 mm (NMSA D5427); specimen retaining intritacalx deposit, SE of Cape Vidal, KZN, length 4.0 mm (NMSA E7514).