Lobianchia Gatti 1904

Genus Lobianchia Gatti, 1904

The otoliths of Lobianchia gemellarii (Cocco, 1838) show an apparent ontogenetic variability (Fig. 6, Recent specimens). The small specimens of L. gemellarii are rather similar to those of the same-sized Lobianchia dofleini (Zugmayer, 1911), from which they differ in having a narrower sulcus and an obliquely inclining antero-dorsal rim that runs downwards to the antirostrum (Figs 5Q, 6 vs Nolf 2013: pl. 81). In large otoliths of L. gemellarii, the posterior rim becomes straight and the depression after the postero-dorsal angle is more pronounced (Figs 5P, 6). Otoliths of such a dimension (length about 8 mm) are derived from fish attaining a length of about 11 cm (IRSNB collection), which is very huge compared to the average individual’s maximum length of 6 cm (Nafpaktitis et al. 1977; Whitehead et al. 1986 –1989). In the slope water off New England, Nafpaktitis et al. (1977) noted a number of specimens of L. gemellarii ranging in length between 85 and 100 mm. Such large individuals are occasionally found outside the spawning area. Studies on comparative morphology of Recent Lobianchia otoliths have obtained similar results (Schwarzhans 2013 a: pl. 15, figs 6, 7). Based on these observations, the studied material testifies to the occurrence of both species, L. dofleini (Fig. 5V) and L. gemellarii (Fig. 5P, Q), in the Tortonian sediments.