Mycale (Paresperella) sceptroides sp.nov.

Figs 110 a–c, 111a–e

Mycale (Paresperella) spec. Van Soest & Hajdu 2002: 684, figs 11B–F.

Material examined. Holotype ZMA Por. 01739, Indonesia, Jawa, Jawa Sea, Northwest of Pulau Sabi, 6.6083°S 114.925°E, depth 83 m, muddy bottom, trawl, coll. Siboga Expedition stat. 318, field nr. SE483, 22 February 1900.

Description (Fig. 110a). Elongate growth, collected as a detached object, but presumably attached to an unidentified branching substratum. Color in preservation red-brown. Surface smooth but slightly bumpy and grooved. No visible openings. Size about 6.5 x 3 x 1 cm. Consistency soft, easily damaged.

Skeleton (Fig. 110b). Choanosomal skeleton consisting of plumose spicule tracts, 120–180 µm in diameter, dividing and fanning out towards the surface into thinner tracts (20–30 µm), which carry the tangential ectosomal skeleton. This is an aegogropila-type skeleton with intercrossing thin tracts of 20–40 µm diameter (3–4 spicules thick) delimiting meshes of 250–400 µm in widest dimension. Rosettes of anisochelae I (90–102 in diameter) are scattered between the tracts (cf. Fig. 110b).

Spicules (Figs 110c, 111 a–e). Mycalostyles, two categories of anisochelae, sigmas, toxas.

Mycalostyles (Fig. 110c, 111a,a 1–3), ‘cladotylostylote’ in shape, with elongated heads with barely constricted neck, with slightly swollen opposite ends, polyaxone with four or more rounded or spined projections, 298– 324.3 – 423 x 8– 10.8 – 14 µm.

Anisochelae I (Fig. 111b), well-developed, with curved shaft, free part 30–35 % of spicule length, 37– 44.8 – 57 µm.

Anisochelae II (Fig. 111c), well-developed, free part of the shaft 20–25% of spicule length, upper frontal alae more than 50% of spicule length, lower frontal alae with small projection on upper rim, 22– 26.5 – 30 µm.

Sigmas (Fig. 111d,d 1), narrow-shaped, asymmetrical, about 2 µm thick, with flattened spines on both endings, 63– 68.0 – 87 µm.

Toxas (Fig. 111e), rare, thin (about 1 µm or less), curved gradually and widely, 19– 23.2 – 28 µm.

Distribution and ecology. Indonesia, deeper water, down to 83 m.

Etymology. The name was coined by Maurice Burton in an unpublished manuscript on the sponges collected by the Siboga Expedition. The name refers to the polyaxone scepter-like endings of the megascleres.

Remarks. The new species differs from other toxa-bearing Mycale (Paresperella) from the region by having the toxas very small and thin, and by having ‘cladotylostylote’ megascleres. Both, Indian M. (P.) serratohamata (Carter, 1880) and East South African M. (P.) toxifera (Lévi, 1963) have ‘normal’ mycalostyles, without polyaxone endings, and their toxas, respectively 50 µm and 60–175 µm, are distinctly larger.

Australian Mycale (Paresperella) penicillium shares the two categories of anisochelae, but lacks toxas.

The South Atlantic species Mycale (Paresperella) curvisigma (Lévi, 1969) has a similar spiculation as the present species, but shapes and sizes differ: megascleres are smaller (310–325 x 5–8 µm), more distinctly stylote, with the pointed end bifid; the two anisochelae categories are clearly smaller (20–23 and 9–10 µm); the toxas are shaped differently from the present species and measure 35 µm. Together with the distance between localities (Vema Seamount vs Jawa Sea) we conclude that the differences are sufficient to consider both separate closely related species.