Dercitus Stoeba lesinensis (Lendenfeld, 1894)

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 : 18

Dercitus Stoeba lesinensis (Lendenfeld, 1894) Figs 7 A–D

Pachastrella lesinensis Lendenfeld 1894: 18, pl. II fig. 18, pl. III fig. 44, pl. IV figs 67-68.

Dercitancorina lesinensis ; Topsent 1902: 15.

Stoeba lesinensis ; Maldonado 2002: 156.

Material examined.

Syntype fragment ZMB 2409, dredged near Lesina, Croatia.

Description.

Encrusting and insinuating among stones and coralline algae, with oscular elevations. The fragment examined by us was a thin rounded papilla-like extension (probably from the larger of the two type specimens described by Lendenfeld). Consistency slightly rubbery. Colour (alcohol) orange.

Skeleton: at the surface consisting of a dense crust of microscleres, subdermally the skeleton consists of a mass of calthrops, embedded in a fibrous-organic groundmass.

Spicules: calthrops, dichocalthrops and sanidasters, no complete oxeas are found in the fragment examined, but a few broken monaxones were present.

Calthrops (Fig. 7A), with occasional bifid cladus endings, cladi 92 –130.9– 165 × 14 –21.3– 31 µm (Lendenfeld: up to 160 × 40 µm), cladomes 180-210 µm.

Dichocalthrops (Fig. 7B), rare, small, mentioned by Lendenfeld, but no measurements given. Our preparations contained a few, with protocladi 16-18 × 3-8 µm, deuterocladi 15-32 × 3-6 mm, cladome diameters 70-74 µm, rhabdi 40-47 µm.

Sanidasters (Figs 7 C–D), with short low spination, size 11 –15.2– 18 × 2 –2.45– 3 µm (Lendenfeld: 12-15 × 1.6 µm).

Habitat.

No data.

Distribution.

Adriatic. So far there is only a single record of this species.

Remarks.

A major difference with the original description is the lack of giant oxeas (4000 × 70 µm), some centrotylote, reported and pictured by Lendenfeld (1894); also tylostyles and strongyles were reported. The fragment of the type specimen received from ZMB did not contain any such spicules, except for some broken fragments. For Maldonado (2002) the alleged presence of oxeas in a species otherwise considered by him a typical Stoeba was the reason to accept species with structural monaxone megascleres within the definition of Stoeba . We maintain that such spicules, if they would be proper, are auxiliary, not structural.

This species is similar in most respects to Dercitus (Stoeba) plicatus , but the orange colour has not been reported for that species (although Pulitzer-Finali (1983) mentions brown specimens of Dercitus (Stoeba) plicatus ). Based on our observations of the sanidasters, it is possible that these are slightly different from Dercitus (Stoeba) plicatus in spination, with the latter having more profused spines. In view of this, we are forced to retain Dercitus (Stoeba) lesinensis as a valid species for the time being.