Clathria (Microciona) armata (Bowerbank, 1862)

Bertolino, Marco, Cerrano, Carlo, Bavestrello, Giorgio, Carella, Mirco, Pansini, Maurizio & Calcinai, Barbara, 2013, Diversity of Porifera in the Mediterranean coralligenous accretions, with description of a new species, ZooKeys 336, pp. 1-37 : 8

Clathria (Microciona) armata (Bowerbank, 1862) Figs 6 A–F

Microciona armata Bowerbank, 1862; 1866: 129.

Material examined.

Specimen IG-F-BL4-sp2-fot.; alcohol preserved, Gallinara Island (station 2, Falconara) 44°01'22"N, 8°13'34"E, depth 35 m, collected 31-7-2009.

Description. Thickly encrusting sponge (3-5 mm thick) covering a surface of 1.5 cm2 on a coralligenous block (Fig. 6A). Surface irregular, smooth. Consistency soft. The red-orange colour of the living specimen slightly fades when alcohol preserved.

Skeleton. Not observed.

Spicules. Macroscleres: acanthostyles in two size categories: I) large acanthostyles slightly curved, with obtuse spines concentrated on the head (Fig. 6B), 220 (484.5) 830 × 3.75 (8.5) 12 μm; II) small acanthostyles, with scattered spines, but more concentrated on the head (Fig. 6C), 100 (110) 122.5 × 3.75 (5) 6 μm; subtylostyles straight, often with slightly spined head (Fig. 6D), 440 (503.7) 550 × 2.5 (2.9) 3.8 μm. Microscleres: palmate isochelae (Fig. 6E), 10 (12.5) 13.5 μm long. Toxas of variable size, with more or less wide central curvature and slightly reflexed smooth points (Fig. 6F), 80 (114.5) 210 μm long.

Distribution and discussion.

This species has been recorded on rocky walls and on mollusc shells from 10 to 180 m depth ( Bowerbank 1866, Arndt 1934, Pulitzer-Finali 1983, van Soest and Stone 1986). It is widely distributed in the Mediterranean Sea (Northern Adriatic Sea, Alboran Sea and Ionian Sea ( Pansini and Longo 2003, 2008) and along the Atlantic coast of Europe: Arctic, Sweden, Ireland, United Kingdom, France ( van Soest et al. 2013).

This specimen, like that described by van Soest and Stone (1986), differs from the type material in the toxa dimensions. Actually Bowerbank measured small toxas 50 µm long and large toxas 130 µm long dividing them in two size categories. Van Soest and Stone (1986) confirm the large variability of spicule size. The species is a new finding for the coralligenous community and the Ligurian Sea.