Dercitus Stoeba dissimilis ( Sara , 1959)

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 : 19

Dercitus Stoeba dissimilis ( Sara, 1959)

Nethea dissimilis Sarà 1959: 3, fig. 1.

Stoeba dissimilis ; Maldonado 2002: 156.

Material examined.

None (no response from an online form request to the Stazione Zoologica, Naples).

Description

(from Sarà 1959). Numerous specimens (but only one was preserved, the holotype GG907, present whereabouts unknown) in a cave, depth 0-7 m, 30 m from the entrance. Whitish encrustations filling interstices between oysters and barnacles. Individual size 1-6 cm2, total size of all specimens 43 cm2.

Skeleton: no data.

Spicules: calthrops, dichocalthrops, sanidasters, oxeas (but see discussion).

Calthrops with the fourth cladus often shorter, occasionally triactines, cladi 45-175 × 5-21 µm.

Dichocalthrops, cladome 77-102 µm, thickness of cladi 3.5-6 µm, no individual proto-, deuteroclad or rhabd measurements provided.

Sanidasters, amphiaster-like with spines concentrated on both sides, length 8-15 µm, thickness 3-4 µm (with spines) 0.7-1.5 µm (without spines).

Oxeas, extreme size variation, 65-930 × 1.8-21 µm, no indication what their structural position is within the sponge.

Habitat. In shallow-water caves.

Distribution. Naples, Italy.

Remarks. Because no material has been examined and previous authors assigned this to Stoeba we retain this as a valid species of Dercitus (Stoeba) for the time being on account of the reported oxeas. However, apart from the oxeas the description perfectly fits that of Dercitus (Stoeba) plicatus (Schmidt, 1862) (see above). Especially the white colour, the Mediterranean occurrence and the combined presence of dichocalthrops and calthrops are telltale signs that they could be conspecific.