Forcepia (Leptolabis) brunnea (Topsent 1904)

Thin, smallencrusting sponges (up to 0.5 cm2) on the surface of coralligenous blocks. Colour in life yellow-orange. Skeleton. Basal acanthostyles erect on the substrate in a hymedesmioid arrangement. Other spicule types not detectable from the skeleton. Spicules. Megascleres: anisotylotes straight or faintly curved, with slightly different extremities and a few malformations along the shaft (Fig. 10A), 127.5 (157.7) 280.5 × 1.25 (2.3) 2.5 μm; acanthostyles straight, conical with discrete but not swollen heads. Spines evenly distributed, slightly stouter on the spicule head (Fig. 10B), 61.2 (92.2) 142.8 × 5.2 (7.5) 10.4 μm. Microscleres: acanthose symmetric forceps with straight legs, ending in small, button-like swellings with toothed margin (Fig. 10C). They measure 12.5 (15.8) 17.5 × 2.5 μm in length, the distance between the legs being 5.2 (7.2) 7.5 μm. Acanthose asymmetric forceps, very thin, have unequal legs (Fig. 10D), the longer of which is straight or curved inward, 20.4 (22.3) 25 × 1.5 μm. Sigmas in two size categories: the larger ones, “C" shaped (Fig. 10E) or more rarely “S" shaped, 40.8 (64.3) 80 × 2.5 μm are very abundant, the smaller, 17.5–25.5 μm are rare. Palmate isochelae (Fig. 10F), 18 (20) 20.8 μm long.

Topsent (1904) describes three species of Leptolabis from the Azores: Leptolabis forcipula var. brunnea, Leptolabis arcuata and Leptolabis assimilis. The same author in 1928 states that the former three species actually belong to a single species: Leptolabis brunnea which showsa high variability in the large forceps shape. Leptolabis brunnea was afterwards recorded from the Far-Oer Islands, the Azores, Spain (NW coast, Strait of Gibaltar, Castellón, Girona), France (Marseille, Monaco), Italy (Gulf of Naples), between 4 and 1360 m depth. It lives in caves, detritic bottoms, coralligenous concretions and epibiotic on other organisms (Topsent 1904, 1928, Sarà 1960, Pouliquen 1972, Carballo 1994, Cristobo 1996). This is the second finding for the Italian seas and a new finding for the Ligurian Sea.