Odostomia cf. dalli (Hornung & Mermod, 1925)

Albano, Paolo G., Steger, Jan, Bakker, Piet A. J., Bogi, Cesare, Bosnjak, Marija, Guy-Haim, Tamar, Huseyinoglu, Mehmet Fatih, LaFollette, Patrick I., Lubinevsky, Hadas, Mulas, Martina, Stockinger, Martina, Azzarone, Michele & Sabelli, Bruno, 2021, Numerous new records of tropical non-indigenous species in the Eastern Mediterranean highlight the challenges of their recognition and identification, ZooKeys 1010, pp. 1-95 : 1

Odostomia cf. dalli (Hornung & Mermod, 1925) Figure 22

New records.

Israel • 4 spcms; west of Rosh HaNikra Islands; 33.0704°N, 35.0926°E; depth 12 m; 29 Oct. 2018; rocky substrate; suction sampler; HELM project (samples S52_1F, S52_2F); size: H 2.1 mm, W 1.0 mm (illustrated specimen) • 1 spcm; west of Rosh HaNikra Islands; 33.0725°N, 35.0923°E; depth 19 m; 29 Oct. 2018; rocky substrate; suction sampler; HELM project (sample S53_1F).

Remarks.

The shell of this species is white and rather solid, with convex, unkeeled whorls and a deep, narrow suture. The columellar tooth is visible in frontal view; there are no lirae inside the aperture. The outer surface appears smooth at first sight but bears numerous very fine spiral lines. The protoconch is of type A2, tending to type B. In ethanol-preserved specimens, the soft body is yellowish-white, with the eyes well visible through the shell (Figure 22A ). Odostomia cf. dalli differs in its shell morphology from all known Mediterranean Odostomiinae , but bears close resemblance to the illustration of the type specimen of Odostomia dalli from Sarad Island ("Ile de Sarato"), Dahlak Archipelago, Eritrean Red Sea ( Hornung and Mermod 1925). In contrast to our material, however, O. dalli was described as lacking both, spiral sculpture and a visible columellar fold, although a columellar tooth seems to be indicated in the line drawing accompanying the original description. A rigorous assessment of potential conspecificity between O. dalli and our material therefore awaits a thorough study of the type material of the former, but the close similarity suggests that this is a new non-indigenous species in the Mediterranean Sea. This interpretation is also supported by the lack of empty shells in death assemblages (see Discussion).

Figures

Figure 22. Odostomia cf. dalli (Hornung & Mermod, 1925), west of Rosh HaNikra Islands, Israel, HELM project (sample S 52 _ 2 F): front (A) and back (B) views. Scale bar: 0.5 mm.