Viriola alboguttata Tomlin, 1926

Albano, Paolo G., Bakker, Piet A. J. & Sabelli, Bruno, 2019, Annotated catalogue of the types of Triphoridae (Mollusca, Gastropoda) in the Natural History Museum of the United Kingdom, London, Zoosystematics and Evolution 95 (1), pp. 161-308 : 161

Viriola alboguttata Tomlin, 1926

Figure 99

Viriola alboguttata Tomlin 1926: 294, pl. 16, fig. 7.

Original localities.

Scottburgh and Port Shepstone, Natal, South Africa.

Type material.

Syntypes: NHMUK 1926.12.6.7, Scottburgh, Natal, South Africa, 1 specimen (glued on paper) ; NMW 1955.158.1124, 1 specimen (fide Trew 1990; not seen) .

Original description.

Shell sinistral, consisting of 13½ whorls, 4½ of which form the protoconch; the whorls of the protoconch have an extremely sharp, central, raised keel, from each side of which numerous short, raised, waved lines run to the sutures at right angles; the other nine whorls have a series of three outstanding spiral cords equally spaced; the two outer cords are of much the same strength throughout, but the central one starts as quite a fine line and approximates gradually to the strength of the other two; the interstices between the cords are crossed at right angles by fine raised lines, which are more distant than those on the protoconch and not waved.

The colour of the protoconch is dark reddish, that of the rest of the shell light chocolate brown, the uppermost of the 3 spiral cords being spotted broadly with white at regular intervals-about 4 or 5 times on each whorl.

At the summit of the aperture there is a strong sinus, and the interior is marked with three pairs of brown lines running outwards to the edge of the peristome.

Length 5 mm., max. diam. 1.75 mm.

Hab.-Scottburgh (C.W. Alexander), apparently living; Port Shepstone (Burnup).

This distinct little species belongs, together with ima Bartsch and fuscescens Smith, to Jousseaume’s genus Viriola, which is exactly analogous to Seila in having a spiral ribs plain, without tubercles.

Diagnosis.

Syntype 4.4 mm high. Shell conical with flat sides. Teleoconch of eight whorls with three smooth spiral cords. The second cord develops initially as a fine thread and attains full size only on the last whorl. Among the spiral cords, orthocline obsolete axial ribs are visible. Peristome with additional spiral cords and a pronounced posterior sinus. Siphonal canal short. Base with four additional smooth spiral cords. Protoconch multispiral of five whorls; the first two with tiny granules, the last three with a strong spiral keel and axial riblets. Colour brown with white blotches more pronounced on the first spiral cord.

Remarks.

Viriola fallax Kay, 1979 (p. 215) is a junior synonym.

Figures

Figure 99. Viriola alboguttata Tomlin, 1926, Scottburgh, Natal, South Africa. A-C, F-I Syntype NHMUK 1926.12.6.7: front (A, B), side (C), protoconch (F, G), aperture (H), peristome (I). D, E Original labels. Scale bars: A-C: 1 mm; F, G: 0.1 mm; H, I: 0.5 mm.