Craspedochiton, Shuttleworth, 1853

Dell’Angelo, Bruno, Landau, Bernard M., Sosso, Maurizio & Taviani, Marco, 2020, Late Pleistocene Red Sea Mollusca: 1. Polyplacophora, Zootaxa 4772 (3), pp. 401-449 : 434-435

Craspedochiton sp.

( Fig. 21 )

Craspedochiton (Notoplax) involutus ; Selli 1973, p. 257, pl. 11, figs 6–7.

Material examined. Eritrea, Massawa North (Abd-el-Cader): 2 valves (1 intermediate, width 3.3 mm, and 1 tail, width 3.7 mm), described and illustrated by Selli, 1973 ( Fig. 21A , not seen at MGGC) . Egypt, Hurghada : St. 14bis: 1 intermediate valve, width 1,4 mm ( Figs 21 B–C) ( MZB 50561) ; St. 16: 1 intermediate valve, width 3 mm ( Figs 21 D–E) ( MZB 50562) .

Remarks. Selli (1973) recorded Craspedochiton from Massawa based on one intermediate and one posterior valve ( Fig. 21A ). The attribution of this material to Craspedochiton (Notoplax) involutus was based on the similarity of the shape of the valves figured by Pilsbry (1893, vol. XV: 35, pl. 1, figs 27–35). Craspedochiton involutus was synonymised with C. productus (Carpenter in Pilsbry, 1892) by Kaas (1989), a species characterised by having intermediate and tail valves of trapezoidal shape. These valves of Craspedochiton productus differ significantly from those figured by Selli (compare with the valves of a specimen of C. productus from S. Africa figured by Dell’Angelo et al. 2014: figs 8A–F). A search for Selli’s (1973) material in MGGC was unsuccessful and we consider that this material is probably lost. We suspect that the intermediate valve (worn and without any diagnostic feature) might not belong to Craspedochiton . The only extant species of Craspedochiton present in the Red Sea is C. laqueatus ( Sowerby, 1842) ( Strack 1993; Anseeuw & Terryn 2004), a widespread Indo-Pacific species known from the northern Red Sea to the Philippines, whose type material was recently figured by Dell’Angelo et al. (2010a: figs 10A–F, 12M–Q). The valves figured by Selli (1973) differ from those of C. laqueatus in the shape of the valves and the position of the mucro (“somewhat anteriorly” in C. laqueatus, Strack 1993 vs much more posteriorly in in Selli’s figures).

We have collected two small and eroded intermediate fossil valves ( Figs 21 B–E), without any diagnostic feature, of which only the presence of large granules could justify the attribution to the genus Craspedochiton .

For the reasons discussed above, and considering that we could not find the specimens figured by Selli in MGGC, species identification for the valves here discussed is impossible. Craspedochiton species from the Indian Ocean are a difficult group to understand, due to scarcity of the material available, the high variability of the species, and the often inadequate original description (see discussions by Kaas (1979) and Schwabe & Els (2019) on C. isipingoensis ( Sykes, 1901) , by Schwabe (2006) on C. tetrica (Carpenter in Pilsbry, 1893)) ..

Distribution. Late Pleistocene: Eritrea, Massawa North (Abd-el-Cader); Egypt (Hurghada: Selli 1973; this study).

Figures

FIGURE 21. Craspedochiton sp. A. Erythrea, Massawa North, Abd-el-Cader, 2 valves (intermediate and tail) figured by Selli (1973: pl. 11, figs 6-7) as Craspedochiton (Notoplax) involutus (Carpenter in Pilsbry, 1893). B–E. Egypt, Hurghada, Late Pleistocene (last interglacial MIS5e). B–C. MZB 50561, head valve (St. 14bis), width 1.4 mm, dorsal views. D–E. MZB 50562, intermediate valve (St. 16), width 3 mm, dorsal views.