Spinaxinus cf. sentosus Oliver & Holmes, 2006b

Olive, Graham, Rodrigues, Clara F. & Cunha, Marina R., 2011, Chemosymbiotic bivalves from the mud volcanoes of the Gulf of Cadiz, NE Atlantic, with descriptions of new species of Solemyidae, Lucinidae and Vesicomyidae, ZooKeys 113, pp. 1-38 : 12

Spinaxinus cf. sentosus Oliver & Holmes, 2006b Fig. 8 A–D

Material examined.

One live collected specimen, MSM01.03, Stn 190, deep-water field, Captain Arutyunov MV, 35°39.665'N, 07°19.970'W, 1322m, 28 April 2006, NMWZ.2010.4.7

Description.

(Fig. 8 A–D). This specimen measures only 2.3 mm in length and is damaged. The outline agrees with that of Spinaxinus sentosus in being extended anteriorly with a long lunule depression and in the presence of a long but shallow posterior sulcus. These features are in contrast to the juveniles of Thyasira vulcolutre ( Rodrigues and Oliver 2008), which also occurs at similar depths and settings.

The periostracal spines are typical of Spinaxinus but are not seen in this specimen. The periostracum is coarse and the vestiges of lamellae and projections can be seen on the extreme edges of the shell especially on the ventral margin.

Remarks.

Although the identification is not conclusive the likelihood that this shell is a juvenile Spinaxinus is high and as such represents the first finding of this species in a non-anthropogenic setting. The proximity of the type locality (off northern Portugal) to the Cadiz mud volcanoes makes this supposition more reasonable.