Marine Species Identification Portal : Raspailia ramosa

(Montagu, 1818)

Species Overview

Raspailia (Raspailia) ramosa (Montagu, 1818) is a dark brown, hairy, branching-erect sponge, with rather thick (1 cm) branches rounded at the tip. As far as is known this is the only species with such characters making it easy to recognize. It is common along the rocky west coasts of the British Isles and the Atlantic coasts of France.

Taxonomic Description

Colour: Dark brown. This sponge gives a greenish sheen to alcohol and may stain the label purple. The dark brown colour of the tissue is still evident after sectioning and clearing. (Arndt (1935 says it is orange or red, but this must be a mistake).
Shape, size, surface and consistency: (Raspailia ramosa MCS2) Branching-erect, the branch diameter variable in thickness (averaging about 1 cm), maintaining the same thickness almost to the tip. More or less circular in cross-section, sometimes a little flattened. Branching is typically irregular, in all planes; branches rarely fuse. Stalked. Surface bristly (villose) with hairs of uniform length, which trap particles of silt. Ragged remnants of membrane may be seen clinging to the surface. Oscules are apparent in the field on close inspection, scattered on the branches and often sub-terminal. They are obvious as dark spots, but lost on preservalion. Consistency firm, elastic. The soft layer is easily rubbed from the strong axial core.
Spicules: (Raspailia ramosa spics) Megascleres of axial and extra axial skeletons are subtylostyles: 900-1600 µm. The echinating spicules are acanthostyles: 90-125 µm, best seen in longitudinal sections (these spicules are always frequent or common in this species. The divergent brushes consist of styloids (anisoxeas): up to ca. 350 µm.
Skeleton: Plumoreticulate, with a dense axial condensation of reticulating spongin fibres, which are cored by subtylostyles and echinated by acanthostyles. There is a soft, extra-axial skeleton of long spicules radiating out at right angles from the core to pierce the surface. Divergent brushes of slender spicules surround the projecting spicules at the surface. The spongin becomes more abundant as the animal ages.
Reproduction: September (Lévi, 1956)
Ecology: Common on sublittoral rock and boulders from moderately exposed sites to sheltered sites with some tidal current. Tolerates some silt. The only Raspailia species sofar known from harbours. Co-exists with Raspailia hispida and stalked Axinellids in open water.
Distribution: Recently known from Cornwall; Lundy; Anglesey; Strangford Lough; Mull; W coast of Ireland; Roscoff; Sussex; Channel Isles. Beach worn specimen reported from Holland.
Type specimen information: No type material in BMNH; type probably lost. MCS Voucher BELUM Mc101, Portrush, N Ireland.

Remarks

This is the only dark brown, branched, bristly sponge which is common, but beware of other rarer Raspailia specics whose live appearance is currently unknown. The presence of the typical acanthostyles will confirm Raspailia spp. and their shape and size are diagnostic for Raspailia (R.) ramosa. Other branching erect Raspailiids, which may be valid species, include: Raspailia (R.) pumila, Raspailia (R.) rectangula, Raspailia (R.) radiosa, Raspailia (R.) viminalis, and Raspailia (R.) virgultosa. The latter occurs in the North Sea and has much larger acanthostyles.
On Brittanny coasts both Raspailia (R.) ramosa and R. (R.) pumila (Bowerbank, 1866: 114) have been distinguished. The former has longish well-separated cylindrical branches rounded at their extremities. The latter is bushy and compact, with short branches, more or less flattened, terminating in a trapezium-shaped club. R. (R.) ramosa colours alcohol green and stains paper labels purple. R. (R.) pumila would not colour alcohol. In the MCS collection of 13 "R. ramosa " specimens 7 could be assigned to the French concept of R. (R.) ramosa and 6 to R. (R.) pumila on form characters. However, all specimens coloured the alcohol green and stained labels purple. It is likely that both are synonymous and are treated here as such.
Source: Ackers at al., 1992 (B.E. Picton, S.M. Stone, D. Moss).

Raspailia ramosa