Crassimarginatella solidula (Hincks, 1860)

(Fig. 5A–D)

Membranipora solidula Hincks, 1860: 75; Hincks 1880: 158, pl. XX, figs 7, 8.

Crassimarginatella solidula: Barroso 1948: 515, fig. 4; Harmelin 1973: 487, figs 1 h–k, 2a–i, 3a–d, 4b, c; Harmelin & d’Hondt 1992a: 27 (listed); Hayward & Ryland 1998: 170, figs 46, 47b.

Material examined. MNCN 25.03/4287: BV12, 112– 120 m; coll. UMA; one living fragment, one dead fragment.

Description. A small colony formed by ca. 30 zooids, encrusting and unilaminar (Fig. 5A, B). Zooids oval to pyriform, longer than wide [L 316–363–420 (N 13, SD 34), W 201–292–349 μm (N 13, SD 42)], separated by shallow grooves; a narrow and crenulate cryptocyst around the opesia; short, smooth gymnocyst bearing proximally one or two prominent knobs (Fig. 5A–C). Autozooids following the ancestrula bearing delicate spines, numbering up to four on the distal region of the autozooid (Fig. 5A, C). Large septula, one distal and one pair on each side of the lateral wall (Fig. 5A, C). Ovicell and avicularium not observed. Ancestrula similar in shape, but smaller than autozooids [L 281, W 243 μm (N 1)], with 12 spines around the opesia (Fig. 5D).

Remarks. Despite the small size of the colony found on the Alboran platform, and the absence of ovicells, the zooids are similar in size and features to the material attributed to this species. Crassimarginatella solidula was previously recorded in the northeastern Atlantic, the Gulf of Cadiz, the Strait of Gibraltar and the Mediterranean (Harmelin 1973; Harmelin & d’Hondt 1992a; López de la Cuadra & García-Gómez 1994; Hayward & Ryland 1998; Rosso & Di Martino 2016), but not in the Alboran Sea. This species is considered sublittoral, occurring down to a depth of 80 m in the Mediterranean and 115 m in the Strait of Gibraltar, and found at a similar depth (112–120 m) in the Alboran platform.