Callopora rylandi Bobin & Prenant 1965

Callopora rylandi Bobin & Prenant, 1965

(Fig. 3)

Callopora rylandi Bobin & Prenant, 1965, fig. 36a, b; Prenant & Bobin 1966: 231; Hayward & Ryland 1998: 162, fig. 41.

Material examined. MNCN 25.03/4281: BV12, 112– 120 m; coll. Universidad de Málaga (UMA); one living fragment, one dead fragment.

Description. Colony encrusting, unilaminar (Fig. 3A). Zooids oval [L 306–424–511 (N 21, SD 48), W 211– 268–342 μm (N 21, SD 34)] with a narrow, smooth gymnocyst, more easily visible at the proximal border; cryptocyst reduced (Fig. 3A–E). Peripheral spines broad and flattened, commonly 11–13, arched over the opesia, meeting the opposite spine in the midline, and expanding and merging with each other (Fig. 3B, C). The most distal pair of spines sometimes forms a small bifurcate tip directed towards the orifice (Fig. 3B, C). Distal region of the zooid bearing four to six additional erect, hollow, strong spines in both non- and ovicellate zooids (Fig. 3A, B, E). Small avicularium [L 64–69–75 μm (N 3, SD 6)] on the gymnocyst with a triangular, pointed rostrum, directed laterally, distally or proximally (Fig. 3D, see arrow). Ovicell hyperstomial [L 175–186–211 (N 6, SD 13), W 159–182–218 μm (N 6, SD 21)], subglobular with a nodular endooecial surface and a smooth marginal ectooecial band; aperture opening above the maternal orifice (Fig. B–D). Ancestrula smaller than the autozooids [L 249, W 185 μm (N 1)], oval, with a narrow gymnocyst bearing 10 erect spines around the opesia (Fig. 3E, see asterisk).

Remarks. Callopora rylandi was described from Roscoff (France) and there are other records in the North Atlantic (British Isles and Ireland), although this is the first record for the Alboran Sea. Despite zooids being larger in the original and other North Atlantic material (original: L 400–550, W 250–385; NA: L 400–600, W 260–360 μm), and despite the presence of six oral spines in the ovicellate zooids (four in the original description), the remaining morphological characters are very similar, supporting the identification. This species is very similar to Membraniporella nitida (Johnston, 1838), also recorded from the Mediterranean and the Strait of Gibraltar (López de la Cuadra & García-Gómez 1994; Rosso & Di Martino 2016), regarding the position and shape of the spines and shape of the ovicell, but in M. nitida the ovicell is closed by the maternal operculum, and there are fewer spines.