Mycale (Grapelia) vansoesti Hajdu, 1995

Van, Rob W. M., Aryasari, Ratih & De, Nicole J., 2021, Mycale species of the tropical Indo-West Pacific (Porifera, Demospongiae, Poecilosclerida), Zootaxa 4912 (1), pp. 1-212 : 93-95

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

Figures

FIGURE 1. A. Numbers of available specimens for the present study from the collections of the Naturalis Biodiversity Center distributed over Indo-West Pacific Marine Ecoregions (MEOWS, cf. Spalding et al. 2007). B. Ditto for type specimens and additional specimens from other institutions consulted for this study.

FIGURE 2. Mycale (Aegogropila) gravelyi Burton, 1937, ZMA Por. 07864 from Ambon Bay, Indonesia, a, habitus encrusting on coral rubble (arrows) (scale bar = 1 cm), b–f, SEM images of spicules, b, mycalostyle, b1, details of mycalostyle, c, anisochela I in side view, d, anisochela II, d1, anisochela II enlarged, e, anisochela III, e1, anisochela III enlarged, f, sigma I.

FIGURE 58. Mycale (Grapelia) vansoesti Hajdu, 1995, holotype ZMA Por. 10711, from the Seychelles, a, preserved habitus (scale bar = 1 cm), b, light microscopic view of subsurface skeleton and multiple rosettes of anisochelae I, c, light microscopic view of rosette of anisochelae II.

FIGURE 59. Mycale (Grapelia) vansoesti Hajdu, 1995, holotype ZMA Por. 10711, from the Seychelles, a–e, SEM images of spicules, a, mycalostyle, a1, details of mycalostyle, b, anisochelae I, b1, reduced incipient anisochela I, c, bipocilla-like anisochelae II with serrated upper and lower alae, c1, ditto with multiple-teethed lower alae, c2, detail of multi-teethed lower ala, d, spurred anisochelae III, e, sigma.