(Johnston, 1842)
Species Overview
Raspaciona aculeata (Johnston, 1842) is a red, strongly hispid crust or cushion with a strongly indented, almost honeycombed surface, growing on rocks and shells in the sublittoral. It is mainly a southern species recorded from Galicia and the Mediterranean, but the type is reported from the east coast of the British Isles.
Taxonomic Description
Colour: Red or bright rose.
Shape, size, surface and consistency: (Raspaciona aculeata large) (Raspaciona aculeata Tops) (Halichondria aculeata Johnston) (Dictyocylindrus aculeatus Bow.) Encrusting to massive, thickness from about 2 mm to 2 cm, lateral size up to 6 x 2 cm. Cushion-shaped specimens have a strongly indented, almost honeycombed surface. In fact, such specimens seem to consist of fused conical masses. Surface very hispid, easily observed with the naked eye.
Spicules: (Raspaciona aculeata spics) Tylostyles or styles, smooth, slightly curved, elongate but clearly developed head: 1105-3000 x 15-20 µm; styles, smooth, straight, some are oxeote (they may be regarded as anisoxeas): 350-450 x 5-6 µm; acanthostyles, covered densely with small spines: 118-388 x 8-9 µm (heads 14 µm).
Skeleton: Long megascleres form a dense palisade at the substrate in thin crusts, but form strongly plumose bundles; individual tylostyles protrude far beyond the surface producing the hispidation. At the base and along their course through the sponge they are echinated by acanthostyles. At the surface they are surrounded by bouquets of styles/oxeas.
Ecology: Sublittoral, on stones and shells, 15 m.
Distribution: E coast of England, Galicia; Mediterranean.
Etymology: Aculeatus (Latin)= sharp-pointed, referring to the nature of the surface.
Type specimen information: The type is in the Natural History Museum, London.
Remarks
This is a fairly easily recognizable species due to its strongly hispid surface and characteristic spiculation. Conspecificity of the Mediterranean and E England specimens remains uncertain because of difference in long megascleres (apparently styles in E England specimens, tylostyles in Mediterranean and Spanish specimens) and the presence of very thin oxeas in E England specimens. A further reason for doubt is the absence of any records between the North of Spain and England (notably the Roscoff area). Possibly the records of Raspaila virgultosa may be attributed to this species. For the time being we assume that R . aculeata indeed has the large distribution it appears to have from published records.
Source: Topsent, 1925a