Cacospongia scalaris Schmidt, 1862

Manconi, Renata, Cadeddu, Barbara, Ledda, Fabio & Pronzato, Roberto, 2013, An overview of the Mediterranean cave-dwelling horny sponges (Porifera, Demospongiae), ZooKeys 281, pp. 1-68 : 40-42

Cacospongia scalaris Schmidt, 1862 Fig. 33

Cacospongia scalaris Schmidt, 1862: 27.

Description.

Growth form massive, globose, lobate, large (up to 20-30 cm in diameter). Colour constantly dark grey with bluish shades. Surface conulose (conules 1-2 mm high, 2-4 mm apart) with smooth scattered circular depressions; supported by tips of primary fibres. Oscules surrounded by a short collar (up to 1 cm in diameter) abundant and irregularly scattered on the sponge’s upper part. Skeleton network lax with hard, not elastic spongin fibres. Primary fibres almost parallel, interconnected by quite perpendicular secondary fibres looking like rungs in a scale (this peculiar character originated the specific name); primary fibres (90-200 µm in diameter) cored by abundant inclusions; secondary fibres (30-80 µm in diameter) laminated with an evident fibrous core. Flagellate chambers of 30-45 µm in diameter.

Habitat.

Cave, rocky/detritic/muddy bottom, coralligenous community, Posidonia oceanica meadow, lagoon, artificial reefs, epibiotic on Pinna nobilis . Often on the sponge surface it is possible to find specimens ofthe nudibranch Hypselodoris fontandraui (Pruvot-Fol, 1951) actively grazing. Bathymetric range 1-250 m.

Mediterranean caves.

J1 Cave (Balearic Sea); Bear, Troc, Endoume, Figuiers, Trèmies, Niolon, Carrieres caves (Gulf of Lions); Eastern-Bonassola, Piccola Zoagli-Chiavari caves (Ligurian Sea); Mago, Secca delle Formiche-Vivara, Gaiola caves (Central Tyrrhenian Sea); Porto Cesareo Cave (Ionian Sea); Croatian, Columbera, Stražica caves (Northern Adriatic Sea); Arenile, Coccodrillo, Bue Marino caves (Southern Adriatic Sea) ( Laborel and Vacelet 1958; Vacelet 1959, 1976; Sarà 1961a b, 1964a; Boury-Esnault 1971; Pouliquen 1972; Pulitzer-Finali and Pronzato 1976; Pansini et al. 1977; Pulitzer-Finali 1977; Bibiloni et al. 1989; Corriero et al. 2000, 2004; Novosel et al. 2002; Faresi et al. 2006; Pronzato and Manconi 2011; Bakran-Petricioli et al. 2012).

Remarks.

We do not accept that Cacospongia scalaris and Cacospongia proficens belong to the genus Scalarispongia on the basis of the genus diagnosis by Cook and Bergquist (2002). Indeed the comparative analysis of diagnostic traits of Scalarispongia vs. Cacospongia Schmidt, 1862 clearly indicates that no diverging morphological characters exist among them except for the ladder-like arrangement of skeletal polygonal meshes that in some species, i.e. Cacospongia scalaris , are mostly but not always rectangular. Rectangular meshes are displayed less frequently also in other species of Mediterranean cacospongias. We consider the trait 'skeleton ladder-like with rectangular meshes’ not diagnostic at the genus level in agreement with Schmidt (1862), Vacelet (1959), Pulitzer-Finali and Pronzato (1976) and Pronzato and Manconi (2011). Moreover molecular data (see Borchiellini et al. 2004) indicate that C. scalaris belongs to the genus Cacospongia . Cacospongia proficens and Cacospongia scalaris belong therefore to the genus Cacospongia .