Suberites virgultosus

Suberites virgultosus (Johnston 1842)

Halichondria virgultosa: Johnston 1842, pp. 137–138; Pl. XV, figs. 1–3.

Hymeniacidon virgultosa: Bowerbank 1866, pp. 193–195; Bowerbank 1874, pp. 89–90; Pl. XXXV, figs. 1–5.

Description. Halichondria virgultosa was described by Johnston in 1842. His specimens were collected in the North Sea, off Scarborough. Johnston (1842) gave some notes about general habit of a new species, describing several rodshaped, somewhat compressed and twisted sponge fragments with an uneven surface and a grayish-white color.

Later Bowerbank (1866; 1874), who examined new material dredged at Dogger Bank in the North Sea and re-examined type material, pushed the original description by Johnston (1842) much forward. Bowerbank (1866; 1874) described elongate, erect, more or less laterally compressed sponge specimens with a corrugated surface. The upper parts of the sponge are rather broad, gradually narrowing towards the basal attachment, which closely embraces a substrate, usually the dead shell of a mollusk. Consistency is fairly soft, flesh-like and very flexible. Among other things, Bowerbank described the skeletal architecture and spicules in some detail. He mentioned that tightly packed centrotylote microscleres form a thin layer at the sponge surface. In the underlying tissues (choanosome) microscleres were absent. Choanosomal skeleton consists of monactinal monaxons (styles). Though Bowerbank didn’t mention any spination of the microscleres, it is possible that he overlooked it.

Remarks. Unfortunately there was no material on this species in our possession, yet here are a few comments on it. In the WPD (de Voogd et al. 2022) some of the arctic records of Suberites lütkenii (Hentschel 1929; Alander 1942; Topsent 1913; Schmidt 1870) were misleadingly assigned to S. virgultosus. So far S. virgultosus is only known to inhabit the North Sea—it’s a truly boreal species. As is the case with other boreal congeners, and as opposed to the arctic S. lütkenii, the only type of microscleres found in S. virgultosus are microstrongyles.