Herpetopoma (s.l.) helix (Barnard, 1964) 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 : 439-442

Herpetopoma (s.l.) helix (Barnard, 1964) comb. n.

Figs 4I , 32–34

Turcica helix: Barnard 1964: 21 , fig. 3e; Kensley 1973: 44, fig. 110. Type loc.: off Cape Vidal , KZN, South Africa, 80–100 fath. [- 146–183 m].

Description:

Shell: Turbiniform (L/D=1.10–1.25), teleoconch of 4–5 whorls; whorls rounded, sutures indented and inserted at level of subperipheral cord; first teleoconch whorl with 14–16 axial pliculae; second and subsequent whorls with axial pliculae and relatively strong spiral cords, 2 on second whorl, 3 on subsequent ones; cords bearing axially elongate beads where crossed by pliculae; last adult whorl with 40–50 axial pliculae and 3 spiral cords above and including periphery, occasional specimens with weaker intermediaries; intervals between cords equal to or wider than cords themselves and rendered obliquely cancellate by axial pliculae; interval between second and third cords frequently wider than others. Base with 4–5 somewhat less well developed spiral cords, sometimes with a sixth close to columella; axial pliculae of base progressively less elevated toward shell axis and cords thus less obviously granular. Umbilicus lacking in adult specimens, but sometimes evident as a narrow chink in juveniles; umbilical region usually at least partially covered by parietal/columella callus. Peristome oblique; aperture subcircular, flattened at paries; columella with a single simple tooth at its base; interior of outer lip thickened, bearing approx. 12 ridge-like denticles, one where basal portion of lip joins columella frequently larger, with a shallow notch separating it from columella tooth; an additional small granule is usually present just external to this notch; exterior of outer lip thickened subterminally but not distinctly varixed; interior nacreous, deeper region lacking in-running ridges, but cords of outer surface showing through.

Microsculpture ( Fig. 33A–C ): Vermiform spiral threads not evident on apical whorls; microsculpture between axial pliculae instead comprising numerous crisp granules, frequently connected by thread-like axial elements; adult microsculpture similar but rather more irregular and often completely obscured by thick intritacalx deposit.

Protoconch ( Fig. 33C ): Translucent white; diameter 260–280 µm; moderately exsert and relatively globose; worn in all available material; terminal lip shallowly convex; superficial sculpture mostly eroded, but with traces of granulation remaining near suture.

Colour: Shell evidently more or less uniformly greyish white to yellowish white and somewhat translucent; intritacalx deposit usually yellowish white to buff-brown, but some specimens patterned with broad bands in shades of brownish grey.

Dimensions: Largest NMSA specimen length 4.0 mm, diameter 3.4 mm.

Operculum ( Fig. 4I ): Relatively tightly multispiral throughout.

Radula ( Fig. 33D, E ): Formula ∞+4+1+4+∞; ca 40 transverse rows of teeth; transition from lateral to marginal series not well defined, the fourth lateral could also be interpreted as a marginal. Rachidian with broad, trigonal cusp and well-developed hood, but lacking a distinct transverse basal ridge and near-basal medial indentation; cutting edge with a very long, acuminate, central denticle and 2 or 3 smaller, likewise elongate denticles on each side. Lateral teeth progressively decreasing in size from first to last, but not markedly so, their cusps obliquely trigonal with coarse lateral denticles on both margins (3–5). Marginals closely resembling those of H. scabriusculum , but a little more elongate; cusps of inner marginals with well-developed pectinate outer margin; outermost marginals shorter and with a somewhat dilated, fringed cusp.

External anatomy: Evidently chilodontid, but material insufficiently well preserved to provide meaningful detail.

Type material: SOUTH AFRICA: KwaZulu-Natal: Holotype of Turcica helix Barnard, 1964 ( SAMC) off Cape Vidal (Zululand), 80–100 fath. [- 146–183 m] (A9295), and one paratype, off Umkomaas, 40 fath. [- 73 m] (A9256, broken).

Material examined (all NMSA unless indicated otherwise): MADAGASCAR: Secteur de Manantenina (24.3833°S 47.5330°E), - 158–168 m, dredged Nosy Be 11, Exped’n ATIMO VATAE, st’n DW3522, 1.v.2010 ( MNHN) ; ditto, (24.3833°S 47.5170°E), - 200–220 m, dredged Nosy Be 11, Exped’n ATIMO VATAE, st’n DW3523, 1.v.2010 ( MNHN) . MOZAMBIQUE: Inhambane transect, Campagne MAINBAZA, RV Vizconde de Eza , dredged, st’n CP3144 (23.550°S 35.683°E), living, - 171–180 m, 11.iv.2009 ( MNHN) ; Maputo transect, Campagne MAINBAZA, RV Vizconde de Eza , dredged, st’n CP3130 (25.883°S 33.117°E), living, - 112–127m, 9.iv.2009 ( MNHN) ; ditto, st’n CP3131 (25.933°S 33.117°E), - 193–194 m, 9.iv.2009 ( MNHN) ; off Ponta Techobanine (26.68132°S 32.95093°E), - 100–135 m, dredged J. Rosado, xii.2005 and i.2010 (D. Slater coll’n) . SOUTH AFRICA: KwaZulu-Natal: off Boteler Point (27.0133°S 32.9183°E), - 70 m, some coarse sand, some shell rubble, dredged NMDP, RV Meiring Naude, st’n ZB4, 6.vi.1987 (D7412) ; off Dog Point (27.1083°S 32.8817°E), living, - 70 m, sandstone conglomerate, dredged NMDP, R. V. Meiring Naude, St’n ZC 3, 4.vi.1987 (E1740) ; Sodwana Bay (27.533°S 32.683°E), - 100 m, dredged, CSIR Water Research (A5793); off Gipsy Hill (27.8117°S 32.6570°E), - 100–125 m, broken shell, dredged NMDP, RV Meiring Naude, st’n ZK9, 11.vi.1988 (E3247) ; NE of Leven Point (27.9167°S 32.6467°E), - 250 m, coarse sand, dredged NMDP, RV Meiring Naude, st’n ZL5, 9.vi.1988 (S1143) ; SE of Cape Vidal (28.1183°S 32.6100°E), living, - 145 m, medium sand, dredged NMDP, RV Meiring Naude, st’n ZM7, 10.vi.1988 (E7514) ; ditto (28.1400°S 32.6067°E), - 165 m, moderately fine sand, dredged NMDP, RV Meiring Naude, st’n ZM8, 11.vi.1988 (E7599) ; off Mission Rocks (28.2917°S 32.5700°E), - 100 m, medium sand, dredged NMDP, RV Meiring Naude, st’n ZN7, 11.vi.1988 (E3828) ; SE of Neill Peak [ Cunge Hill ] (28.7400°S 32.5367°E), - 320–340 m, sandy mud, dredged NMDP, RV Meiring Naude, st’n ZP5, 12.vi.1988 (E3976) ; Port Durnford–Richard’s Bay (29.0067°S 32.2000°E), - 152 m, mud and stones, dredged NMDP, RV Meiring Naude, st’n ZQ7, 13.vi.1988 (V3920) ; SE of Port Durnford (29.0150°S 32.2017°E), - 215 m, glutinous sandy mud, dredged NMDP, RV Meiring Naude, st’n ZQ8, 13.vi.1988 (E3118) ; off Sheffield Beach (29.6442°S 31.4783°E), - 110 m, muddy sand, dredged NMDP, RV Meiring Naude, st’n ZU14, 19.vi.1989 (E9446) ; SE of Green Point (30.250°S 30.905°E), living, - 100 m, fine sand, rubble, dredged NMDP, RV Meiring Naude, st’n XX92, 8.vii.1986 (D5990) ; off Umzinto (30.3600°S 30.8500°E), living, - 84 m, dredged NMDP, RV Meiring Naude, st’n X2, 15 vii.1982 (D5427) ; off Park Rynie (30.375°S 30.855°E), - 100 m, sand & sponge rubble, dredged NMDP, RV Meiring Naude, 04.iii.1981 (B3717) ; off Mtamvuna River (31.1650°S 30.2516°E), living, - 140 m, sponge rubble, dredged NMDP, RV Meiring Naude, st’n A6, 18.viii.1981 (E224) . Eastern Cape: off Port Grosvenor (31.41°S 29.95°E), - 80 m, worn coral nodules, dredged NMDP, RV Meiring Naude, st’n D17, 16.viii.1981 (E176) ; ditto (31.4360°S 29.9516°E), - 100–115 m, sand, some mud, solitary coral, shells, dredged NMDP, RV Meiring Naude, st’n D3, viii.1981 (C1338) ; off Mgazi River (31.7450°S 29.5617°E), - 180 m, soft mud, dredged NMDP, RV Meiring Naude, st’n J1, 15.vii.1982 (E281, E7540) ; off Shixini Point (32.5267°S 28.8833°E), - 500 m, muddy sand, coral rubble, dredged NMDP, RV Meiring Naude, st’n T17, 13.vii.1984 (V2789, shells very old) .

Distribution and habitat ( Fig. 34 ): Southern Madagascar and south-eastern Africa, from southern Mozambique (Inhambane area) to the central Transkei region, Eastern Cape, South Africa (Shixini Point); - 70–500 m, living specimens - 70–180 m, on varied hard substrata.

Remarks: Relatively little fresh material of this species is available considering the amount of dredging that has been done between - 50–200 m off KwaZulu-Natal and the Transkei region of Eastern Cape. Its small size, rounded whorls and strong spiral sculpture render it easily separable from other local chilodontid taxa. There is some resemblance to H.? naokoae (below), but H. helix has fewer spiral cords above the suture (three compared with four in H.? naokoae ) and the cords are stronger. The relatively smooth, globose protoconch, granular microsculpture and weak basal columella tooth place this species apart from Herpetopoma (s.s.).

Figures

Fig. 4. Operculum morphology in the Chilodontidae: (A) Littorina littorea (Linnaeus, 1758), Cancale, Brittany,France,max.diameter 10.2mm (NMSA G778);(B) Euchelus asper (Gmelin,1791),Bombay, India,max.diameter 9.0 mm (NMSA J8066);(C) Granata sulcifera, Mtwalume,KZN, max.diameter 3.58 mm (NMSA V3927); (D) Clypeostoma salpinx, off Whale Rock, Eastern Cape, max. diameter 2.59 mm (NMSA C9502); (E) Danilia textilis, max. diameter 2.97 mm (holotype, NMSA E7756/ T2595); (F) Ascetostoma providentiae, off Boteler Point, KZN, max. diameter 2.52mm (NMSA S4904); (G) Herpetopoma (s.s.) instrictum, Low Isles, GreatBarrier Reef, Queensland,max.diameter 3.17 mm (AMS C.304699); (H) H. (s.s.) scabriusculum, Bradleys Head, Sydney Harbour,Australia, max. diameter 1.78 mm (AMS C.30695); (I) H. (s.l.) helix, off Umzinto, KZN, max. diameter 1.01 mm (NMSA D5427); (J) Vaceuchelus cretaceus, SE of Kosi Bay, KZN, max. diameter 2.52 mm (paratype, NMSA S4006/T2638); (K) V. natalensis, off Umzinto, KZN, max. diameter 0.99mm (NMSA D5428); (L) V.semilugubris, Réunion, max. diameter 1.28 mm (M.Jay coll’n MNHN); (M) Perrinia angulifera, off Boteler Point, KZN, max. diameter 4.44 mm (NMSA D9209); (N) P.konos, off Port Grosvenor, Eastern Cape, max. diameter 1.23 mm (NMSA E177); (O) P.stellata, Kosi Bay main coral reef, KZN, max. diameter 1.14 mm (NMSA S1985).

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).

Fig. 33. Herpetopoma helix (Barnard, 1964): (A) adult microsculpture of cleaned shell, SE of Cape Vidal, KZN, bar= 250 µm (NMSA E7514); (B) uncleaned shell with thick intritacalx deposit,off Mtamvuna River, Eastern Cape, bar = 250 µm (NMSA E224); (C) protoconch and juvenile microsculpture, SE of Cape Vidal, KZN, bar = 200 µm (NMSA E7154); (D, E) radula, SE of Green Point, KZN (NMSA D5990): (D) central field and right marginals, bar = 50 µm; (E) central field and pectinate cusps of inner marginals, bar = 25 µm.

Fig. 34. Distribution of Herpetopoma helix. Each triangle represents one or more records.