Dercitus Stoeba japonensis, 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 : 35-36

Dercitus Stoeba japonensis sp. n. Figs 17 A–D18A–C

Stoeba extensa ; Phuwapraisirisan et al. 2004: 2128

Material examined.

Holotype ZMA Por. 17646 (voucher fragment of a specimen used in natural products research) Japan, near Anami-oshima Island, 157-161 m, 28.873°N; 129.5532°E, coll. N. Fusetani, dredge, field nr. S01-111, 7 November 2003.

Paratype ZMA Por. 19889 (voucher fragment of a specimen used in natural products research), Japan, Kagoshima Prefecture, Ooshima-shinsone, 150 m, 28.8667°N; 122.55°E, coll. Y. Nakao, dredge, field nr. S01-118, 16 July 2001.

Description.

Holotype (Fig. 17A) is a blackish brown fragment of 3.5 ×3× 1 cm (live colour also noted as black). Surface lumpy but smooth, shiny. Consistency firm, compressible.

Skeleton: at the surface a crust of microscleres, overlying a dense confused mass of calthrops.

Spicules: calthrops, sanidasters, compressed sanidasters (pseudasters).

Calthrops of holotype (Fig. 17B) equiangled, regular, 105 –170.8– 223 × 14 –20.7– 28 µm (cladomes 182 –286.3– 365 µm); of the paratype (Fig. 18A), equiangled, some with ‘hooked’ apices, 33 –177.2– 252 × 5 –23.9– 37 µm (cladomes 63 –319.0– 451 µm).

Sanidasters of holotype (Fig. 17C) long, relatively slim, 27 –28.8– 31 × 2.5 –3.9– 4.5 µm; of the paratype (Fig. 18B), similarly slim, 19 –25.7– 33 × 2 –4.5– 6 µm.

Compressed sanidasters of the holotype (Fig. 17D), mostly elongated-oval, only few are more or less globular, 7.5 –10.1– 15 µm; of the paratype (Fig. 18C), similarly oval or even shaped as ‘double’ asters, 7 –9.3– 14 µm.

Etymology.

Named after the Japanese type locality.

Habitat.

Dredged from deeper water, at approx. 150 m.

Distribution.

Both specimens came from nearby locations, so the distribution so far appears limited to offshore Japan.

Remarks.

It is with some hesitation that these two Japanese sponges are assigned to a new species, rather than to Dercitus (Halinastra) berau sp. n. The two species appear generally similar, but sanidasters are shorter and slimmer than in Dercitus (Halinastra) berau sp. n. and the compressed sanidasters are few and consist mostly of oval rather than globular shapes. Combined with the clearly deeper occurrence and the considerable geographic distance we believe it is justified to consider both distinct at the species level. The two are obviously closely related to Dercitus (Halinastra) exostoticus (see Table 3) with which they form a species complex.