Dercitus Stoeba arubensis, Van Soest, Rob W. M., Beglinger, Elly J. & De Voogd, Nicole J., 2010

Van Soest, Rob W. M., Beglinger, Elly J. & De Voogd, Nicole J., 2010, Skeletons in confusion: a review of astrophorid sponges with (dicho-) calthrops as structural megascleres (Porifera, Demospongiae, Astrophorida), ZooKeys 68, pp. 1-88 : 39-41

Dercitus Stoeba arubensis sp. n. Figs 21 A–F

Material examined.

Holotype ZMA Por. 08984, Netherlands Antilles, Aruba, Lagoon Boekoeti, underneath coral rubble, 0-1 m, coll. P. Wagenaar Hummelinck, nr. 1004, 29 December 1948.

Description.

Small soft patches of a brown-red colour insinuating in three coral fragments (Fig. 21A), occupying spaces less than 5 mm in diameter. No remarkable macroscopical features.

Skeleton: Confused mass of calthrops and microscleres, no explicit structure.

Spicules: Calthrops, sanidasters and microrhabds.

Calthrops (Figs 21 B–C) with gradually curved cladi, the apices of the cladi variously sharply pointed or blunt, occasionally displaying three-claded forms. Cladi: 60 –119.2– 174 × 9 –14.9– 21 µm, cladomes: 96 –192.7– 264.

Sanidasters (Fig. 21D) variable in shape and size, varying from thin amphiaster-like forms with clusters of spines at the ends or at least separated in the middle by a stretch with few spines, to fusiform or fat simple spined forms, size 16 –20.8– 26 × 1 –2.1– 3.5 µm.

Microrhabds (Figs 21F) short and thick, almost smooth, with only scattered very short spines, 5 –7.7– 9 × 3-4 µm. The microrhabds very likely derive from the sanidasters as there are some stages (Fig. 20E) which appear intermediate.

Etymology.

Named after the holotype locality.

Habitat.

Shallow-water, under coral rubble.

Distribution.

So far known only from the island of Aruba, Southern Caribbean.

Remarks.

The microrhabds are unique among species of the genus Dercitus s.l. The genus Pachastrella also possesses short and thick acanthose microrhabds, but in that genus the microrhabds are much more regularly spined, not of the irregular type found in the present species. Furthermore, Pachastrella species possess oxeas as megascleres next to calthrops or short-shafted (dicho-)triaenes and various types of streptasters such as amphiasters and spirasters. Calthropella (Pachataxa) species (family Calthropellidae ) have ataxasters which may look similar in shape, but in addition these possess euasters (see below).