Dardanus substriatus (A. Milne Edwards, 1861)

Authors, The, 2014, Short communications, Natural History Sciences 1 (2), pp. 139-144 : 142-143

Dardanus substriatus (A. Milne Edwards, 1861)

Fig. 1 A, B

Material and measurements: one right propodus in situ (MUSNAF 7077 – hpa: 8 mm; ld: 6 mm; li: 5 mm; lpa: 8 mm).

Description: Palm as long as high, with upper and lower cristate margins slightly converging anteriorly; palm covered with sinuous transverse crests, dentate anteriorly; index and dactylus only partially preserved; subtriangular index, wider at the base; subtriangular and curved dactylus slightly longer than the index.

Discussion. The studied propodus has a shorter subsquare palm with upper and lower margins converging anteriorly with numerous raised crests interlaced each other like “scale fish”, differing in outline and ornamen- tation from those of the similar fossil and extant Mediterranean species Dardanus arrosor (Herbst, 1796) having more elongate palm longer than high, with upper and lower margin almost parallel. Based upon the subsquare palm with upper and lower margins converging anteriorly the studied propodus is assigned to D. substriatus (A. Milne Edwards, 1861) , previously reported from the Pliocene of Piedmont ( Sismonda, 1846; A. Milne Edwards in Sismonda, 1861); Tuscany ( Ristori, 1886; De Angeli et al., 2009); from the Early Pliocene (now Early Pleistocene, see Baldanza et al., 2013) of Umbria ( Pasini & Garassino, 2010b); and from the Early Pleistocene of Calabria ( Garassino et al., 2014). Due to the poor preservation of the shell, a systematic attribution of the hosting gastropod is impossible. We point out, however, that the margin of the external edge shows some alternate rounded tubercles, character common to the representatives of many different marine gastropod families. The interior surface of the peristoma is typically encrusted by bryozoans (observables as cast on the surface of the shell mould), as it is usually recorded in fossil and extant “hermitted” shells (sensu Walker, 1992) ( Fig. 1 B ). Finally, this report results to be the first in the fossil record for an in situ specimen of D. substriatus from the paleo Mediterranean area.

Figures

Fig. 1 - Maja cf. M. squinado, MSNM i27874, right dactylus. Scale bar 17 mm.