Strepsitaurus manduensis, Taylor & Johnson & Stankowski, 2015

Taylor, James P. A., Johnson, Michael S. & Stankowski, Sean, 2015, Molecular phylogenetics and complementary geographical distributions of species of the Western Australian land snail genera Plectorhagada Iredale, 1933 and Strepsitaurus Solem, 1997 (Gastropoda: Camaenidae), Zoological Journal of the Linnean Society 174 (2), pp. 305-321 : 319-320

STREPSITAURUS MANDUENSIS SP. NOV.

FIGURES 1 , 3 , 7, 12

Type locality

Western Australia, Cape Range, Mandu Mandu Gorge (22°08′59.7″S, 113°53′14.7″E) .

Material examined

Holotype WAM S67369 . Paratypes WAM S67370, S67371 .

Etymology

Refers to Mandu Mandu Gorge.

Description

Holotype: shell 7.4 mm wide, 3.3 mm high, H / D ratio 0.45, with 3.5 whorls. Based on ten measured adults, shell small, adult diameter 6.8–7.6 mm (mean 7.19 mm, SD 0.26 mm), with 3.33–3.63 (mean 3.5) whorls. Apex and spire evenly elevated, shell height 3.0– 3.5 mm (mean 3.23, SD 0.13 mm), H / D ratio 0.407 –0.479 (mean 0.449, SD 0.020). Body whorl rounded, without trace of angulation. Protoconch densely pustulose. Early spire with prominent pustules but only weak axial ridges. Lower spire and body whorl with faint, deeply pustulose diagonal ridges above periphery, ridges becoming even less prominent on shell base. Umbilicus wide, regularly decoiling, slightly narrowed by columellar lip, width 1.5–1.9 mm (mean 1.67 mm, SD 0.15 mm). Body whorl descending sharply behind aperture. Palatal and basal lips sharply reflected and broadly expanded, and columellar lip wide, parietal lip free of wall and strongly elevated. Basal lip without knob on top of lip. Shell colour white on top of ridges, reddish to purplish brown in interstices.

Comparative remarks

Strepsitaurus manduensis sp. nov. is similar to S. milyeringus and S. susieae sp. nov., with these three species differing from S. ningaloo , S. rugus , and S. williami by their smaller size, lower whorl count, lips distinctly detached from the body whorl, and lack of setae on the shell. They also lack the prominent knob on the basal lip, which characterizes S. williami ( Solem, 1997) . Strepsitarus manduensis sp. nov. is distinguished largely from S. milyeringus and completely from S. susieae sp. nov. by its relatively low spire [mean H / D 0.449 (0.407 –0.479), compared with 0.484 (0.443 – 0.548) and 0.575 (0.544 –0.597)], and its less developed ridges.

Distribution

This species is known only from Mandu Mandu Gorge, on the western side of Cape Range, where it was found on vertical rock faces on the north side of the gorge, at two sites 560 m apart. It was not found above the gorge, where the larger S. ningaloo occurs.

Figures

Figure 1. Sample sites for Plectorhagada and Strepsitaurus. Large map (between North West Cape and Cape Range in the north and Shark Bay in the south) shows sites for Plectorhagada and southernmost sample sites of Strepsitaurus ningaloo (SNA, SNB). The shaded area is the known distribution of Strepsitaurus. The expanded map shows central Cape Range, with the sample sites of Strepsiaurus. Dotted lines indicate recorded distributions of species, based on Solem (1997). Open circles indicate sites for species restricted to gorges on the western side of the Cape Range, the shells of which are shown in the lower right corner. Site codes as described in Table 1.

Figure 3. Maximum-likelihood (ML) tree for Plectorhagada and Strepsitaurus based on concatenated sequences of COI and 16S. Inset shows relationships with the out-groups. Numbers indicate bootstrap support for the ML tree, all of which were less than or equal to the posterior probabilities from the Bayesian analysis.

Figure 12. Shells of Strepsitaurus milyeringus (A–C), and holotypes of Strepsitaurus susieae sp. nov. (D–F) and Strepsitaurus manduensis sp. nov. (G–I).