Ilanga laevissima ( Martens, 1881 )

Vilvens, Claude & Williams, Suzanne T., 2020, New species of Ilanga (Gastropoda: Trochoidea: Solariellidae) from the Indo-West Pacific, Zootaxa 4732 (2), pp. 201-257 : 208-210

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Ilanga laevissima ( Martens, 1881 )


Ilanga laevissima ( Martens, 1881)

( Figs 4 View FIGURE 4 A–I, Key 1: 3)

DNA ref: Ilanga laevissima ( Williams et al. 2013; Sumner-Rooney et al. 2016)

COI sequence data: GenBank Accession number: HF586293 View Materials

Trochus laevissimus Martens, 1881: 65 . Type locality: South Africa, 33°59’S, 17°51’E, 50 fathoms (91 m).

Minolia (Machaeroplax) congener Sowerby, 1903: 223 , pl. 5, fig. 2. Type locality: South Africa, off Cape Infanta, at 82 miles, 40 fathoms (73 m).

Solariella nitens Thiele, 1925: 48 (14), pl. 1 (13), fig. 16. Type locality: South Africa, South-west of Cape Point, 34°33’S, 18°21’E, 318 m.

Ilanga laevissima — Herbert, 1987: 310–313 , figs 1–3, 34–50.

Type Material. Herbert (1987) suggested that a specimen labelled ‘possible type’ at the NHMUK 1903.7.27.69 is the one illustrated by Sowerby (1903: plate 5, fig. 1), but suggested that it was unlikely to be type material. A single specimen at ZMB was found to match the original description as suggested by Herbert (1987), and is here considered to be the holotype ( Trochus laevissimus ZMB /Moll 29315, S. Africa Gazelle 50 fms; Fig. 4 View FIGURE 4 G–I).

Material examined. South Africa, Cape Province, NMDP (Africana): stn A 18178 View Materials D, 34°25’S, 24°00’E, 115 m, 2 lv ( NMSA V3139 View Materials ) GoogleMaps . —Stn A 18994 View Materials D, 34°19.5’S, 23°30’E, 104 m, 1 lv ( NMSA V4397 View Materials ).—Local diver, False Bay , 50–60 m, 1 lv GoogleMaps


Distribution. South Africa, from Zululand to Atlantic Cape Province ( Herbert 1987), 60–350 m, lv at 50– 270 m.

Description (supplementary—based on the original description and specimens sequenced). Shell: Rather tall for genus (H up to 15 mm, W up to 22 mm), height 0.65–0.79×width, about 2.4×aperture height, wider than high, shape conical to slightly cyrtoconoidal, thin-shelled, glossy; spire moderately elevated; periphery rounded; umbilicus broad, deep. Protoconch ca. 300–350 μm wide, 1.25 whorls, rounded, with about 5 weak spiral threads on abapical part and straight, poorly visible terminal lip. Teleoconch of up to 5.8 convex, smooth whorls with weak subsutural ramp with rounded rim vanishing on last whorl; whorls nearly smooth (only very weak spiral on first whorls) with poorly marked growth lines. Suture canaliculated. Aperture subcircular; peristome incomplete; outer, inner lip thin; inner lip with basal thickening against umbilical rim. Base moderately convex, smooth. Umbilicus broad (diameter 20–25% of shell width), central, with perspective to apex, with subangulate to rounded rim, with or without axial pleats; convex wall with thin axial threads, without spiral cords.

Colour: Teleoconch greyish to yellowish white with variable brown flames, usually with two spiral bands, subsutural one whitish with regular brown spots, other whitish one at mid adapical half with brown chevron markings; base whitish with irregular, variable axial flames; protoconch white.

Operculum: Corneous, multispiral with central nucleus, brown.


Natural History Museum, London


Museum für Naturkunde Berlin (Zoological Collections)


KwaZulu-Natal Museum














Ilanga laevissima ( Martens, 1881 )

Vilvens, Claude & Williams, Suzanne T. 2020

Ilanga laevissima —

Herbert, D. G. 1987: 310

Minolia (Machaeroplax) congener

Sowerby, G. B. & III 1903: 223

Trochus laevissimus

Martens, E. von 1881: 65