Halicnemia geniculata Sarà 1958

Small and thin, yellow-ochre encrustation (1 cm2) on a coralligenous block. Skeleton. Not observed. Spicules. Long tylostyles, 405 (1351.7) 1976 × 1.5 (2.7) 4 μm, generally straight, with terminal or subterminal swellings variable in shape; irregular and polytylote forms are to be found (Fig. 13A). Rabdhotylostyles with heads as above, 147(242)705 × 1.5 (2.7) 4 μm (Fig. 13B); oxeas long, sinuous and thin, 460 (757) 1118 × 1.5 (2.5) 5 mm (Fig. 13C); acanthoxeas slightly curved or bent, uniformly spined, 42.5 (51.8) 62.5 × 1.5 (1.8) 2 μm (Fig. 13D).

This species, originally described from a superficial cave of the Gulf of Naples (Sarà 1958) was recorded at 60–70 m depth in the same area (Sarà and Siribelli 1962) and in caves close to Marseille (Pouliquen 1972). It is a Mediterranean endemic species (Pansini and Longo 2008) and a new finding for the Ligurian Sea and the coralligenous community.