Dercitus Stoeba xanthus Sutcliffe, Hooper & Pitcher, 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 : 30

Dercitus Stoeba xanthus Sutcliffe, Hooper & Pitcher, 2010

Dercitus xanthus Sutcliffe, Hooper and Pitcher 2010: 6, figs 4-5.

Material examined.

None.

Holotype.

QMG329976 (SBD513022), south of Rock Cod Shoal, off Gladstone, Great Barrier Reef, 23.725°S; 151.6647°E, 34 m depth, epibenthic sled, coll. FRV 'Lady Basten’, 20 September 2004.

Description

(from Sutcliffe et al. 2010). A thin sponge agglutinating biogenic rubble such as remains of worm tubes, gastropods and bivalves. Usually fist-sized or smaller. Live color red to yellow, surface uneven, no visible oscules.

Spicules: three-claded calthrops and sanidasters.

Calthrops small, divisible in two size classes with means of approximately 25 and 72 µm. Only 20% of the 163 specimens recorded possessed calthrops, usually in high densities, in the remaining 80 % these spicules were lacking. Sanidasters universally present in all specimens, displaying a wide variation in length and width, 10-20 × 1-2.5 µm, densely spined with relatively short spines up to 1 µm.

Habitat.

Sandy bottoms between 16 and 86 m depth.

Distribution.

Great Barrier Reef, occurring over the entire range.

Remarks.

As Sutcliffe et al. (2010) point out, there is only one species among the Dercitus s.l. species that is similar, viz. Dercitus (Stoeba) syrmatitus , sharing the possession of three-claded calthrops, the small size of the calthrops and the agglutinating habit. The differences are nevertheless quite clear and compelling, the rarity of the megascleres, the lack of normal fourc-claded calthrops and the distinctly larger sanidasters.

The only other Australian record of the genus, Dercitus (Stoeba) occultus , from West Australia, differs sharply in having exclusively dichocalthrops megascleres.