Stryphnus Sollas

Genus Stryphnus Sollas

Stryphnus Sollas, 1886: 193.

Type species. Stryphnus niger Sollas, 1886: 193 (by subsequent designation).

Diagnosis. Thickly encrusting, massive, lobate, or cup-shaped Ancorinidae, typically purplish brown, brownish black, brown, or grey in life, frequently with differential colouration of the choanosome. Surface typically rough with projecting megascleres, and simple oscules are usually grouped. Ectosome is not detachable, but well-differentiated and translucent, with a diaphanous, gauzy, almost gelatinous cellular structure with pigmented and granular cells. Triaenes and oxeas lie obliquely or paratangentially to the surface. The deep ectosomal boundary is highly granular. Choanosome moderately heavily pigmented, moderately packed with oxeas and triaenes in some species, without strict radial orientation, cladomes of triaenes lie at the choanosome/ectosome boundary when they occur here. Megascleres are large oxeas and short-shafted dichotriaenes and/or plagiotriaenes, rarely, anatriaenes and protriaenes. Microscleres are large acanthose oxyasters usually confined to the choanosome, sanidasters, and/or amphisanidasters that form a crust at the sponge surface (emended from Uriz 2002).

Remarks. Sollas (1886) originally described the ectosome of Stryphnus as a ‘vesicular collenchyme containing pigment cells’. However, the term collenchymatous, as used in Uriz (2002), is from the botanical literature and relates strictly to the appearance of a specific plant tissue, the collenchyma, that strengthens and supports the plant. Even though the term perfectly describes the appearance of the ectosome of Stryphnus, we have chosen to describe this character in the diagnosis rather than use a term inherited from the early botanical literature. The New Zealand species, S. atypicus sp. nov. has rare anatriaenes and protriaenes in addition to the characteristic short-shafted dichotriaenes, and we have modified the diagnosis to include these additional megascleres.

In addition to the non-euasterose microscleres and true long sanidasters, the type species S. niger, possesses short microscleres that have traditionally been called ‘amphiasters’. These microscleres may take the shape of a true amphiaster (with a short thick axis clear of any protrusions and with rays emanating from the ends of the axis) or an amphisanidaster, which has rays protruding at various angles and lengths from the shaft. Because the two forms of this short microsclere intergrade in many species, we do not consider them to be true amphiasters or true sanidasters. We call this form of microsclere an ‘amphisanidaster’ to remove this source of confusion.