Mycale (Grapelia) vansoesti Hajdu, 1995

Figs 58 a–c, 59a–e

Mycale (Grapelia) vansoesti Hajdu, 1995: 93, figs 6.65–69.

Material examined. Holotype ZMA Por. 10711, Seychelles, Mahé, NE coast, Cap Maçons and Anse de Forbans, 4.7667°S 55.5167°E, reef slope, depth 0–6 m, snorkeling, coll. R. W.M. van Soest, Netherlands Indian Ocean Expedition stat. 612, field nr. IOP-E 612/11, 12 December 1992 (pale blue-grey).

Summary description (Partially after Hajdu 1995). Pale, blue-grey mass (Fig. 58a) encrusting on a coralline algal nodule. Size 3.5 x 1.5 cm in lateral expansion, thickness about 0.4–0.5 cm. Surface microconulose, with a few small oscules of 2 mm diameter. Consistency compressible, fragile. Choanosomal skeleton plumose (Fig. 58 b–c), consisting of straight, mostly undivided, spicule tracts of 100 µm diameter, near the surface dividing into thinner tracts 20–50 µm in diameter carrying the surface membrane. No clearly visible tangential ectosomal skeleton of megascleres, but a concentrated presence of rosettes of anisochelae I forms a replacement skeleton. Spicules (Fig. 59 a–d) mycalostyles (Fig. 59a,a 1), straight, comparatively thin, with elongate heads, 324– 350.1 –391 x 3– 4.4 – 5 µm, anisochelae I (Figs 59b) comparatively elongate and less strongly curved, with relatively small upper unguiferous alae and squarish lower alae, 51– 61.3 – 81 µm (arranged in rosettes (Fig. 58b) of 144– 155.8 – 170 µm diameter), anisochelae II (Figs 59c,c 1) bipocilla-like with thin shaft, thin-bladed fused serrated upper alae and lower alae with median serrated / short-teethed alaee (Figs 59c) or multiple-teethed alae (Figs 59c 1 and 59c 2), possibly in two size categories, 9– 17.2 – 28 µm (arranged in irregular rosettes (Fig. 58c) of 44–51 µm diameter, occasionally clustered into larger masses), anisochelae III (Fig. 59d), shaped conventionally palmate, faintly spurred, 14– 16.2 – 20 µm, and thin sigmas (Fig. 59e) 45– 50.6 – 59 µm.

Distribution. Mahé, Seychelles, depth 0– 6 m.

Remarks. This is a very distinct species on account of the elongate anisochelae I and the quite peculiar bipocilla-like anisochelae II. The closest species are M. (G.) trichophora and M. (G.) menylloides, with more curved and thicker-shafted anisochelae I, and short-shafted bipocilla-like anisochelae II of a more globular thicker form with incurved elaborate alae.

Additional Mycale (Grapelia) species from the region