Home|Search|Identify|Taxonomic tree|Quiz|About this site|Feedback
Developed by ETI BioInformatics
Characteristics, distribution and ecology
Taxonomische classification
Synonyms and common names
Literature references
Images, audio and video
Links to other Web sites

Bowerbank, 1864

Species Overview

Hymeraphia stellifera Bowerbank (1864) forms thin red sheets closely adhering the substrate. It has a bumpy, villose surface due to protruding spicules. Microscopic examination is necessary to distinguish it from related Eurypon species. It has a wide distribution along the coasts of Britain and France, but is not commonly recorded.

Taxonomic Description

Colour: Typically orange/red.
Shape, size, surface and consistency: Very thin sheet, less than 1 mm thick, almost impossible to remove from the substratum except in tiny pieces. Surface usually silt covered with regularly spaced red raised bumps showing through, occasionally clean with these raised bumps. Villose, due to scattered long spicules which penetrate the surface. The oscules are small, at the summits of the raised bumps mentioned above. No ostia visible. Consistency too thin to determine.
Spicules: (Hymeraphia stellifera spics) Three categories of megascleres are present and there are no microscleres. The largest megascleres are long tylostyles with rounded heads and smooth shafts, 500-2000 µm long. Shorter tylostyles with distinctive spined ends bearing 7-12 thorn-like spines and flask-shaped rounded heads are abundant, 50-126 µm Fine thin anisoxeas (oxea-like styles) of ca. 100 µm long are freqent forming brushes at the surface.
Skeleton: (Hymeraphia stellifera BowI) (Hymeraphia stellifera BowIII) The skeleton consists of a basal layer of the short stout tylostyles with distinctive spined heads mixed with scattered long tylostyles which penetrate the surface. Where the latter penetrate the surface there is a brush of fine anisoxeas.
Ecology: Mostly found in deeper water below 30 metres but occasionally as shallow as 20 m. Tolerant of silt and found in sheltered places on dead shells as well as on bedrock in both exposed and sheltered locations.
Distribution: British Isles; France; Mediterranean. Reported recently from Strangford Lough, St. Kilda, Skomer, Stags of Broadhaven, Co. Mayo and Lough Ine. Probably common but rarely recorded because of its extremely thin nature.
Etymology: The name refers to the long spined tylostyles, which resemble stalked asters.
Type specimen information: BMNH 1910.1.1.97 (dry) Norman Collection + slide unregistered (Bk 460) "from Type". MCS voucher BELUM Mc.1451.

Remarks

The short spicules with spined ends are very distinctive and are not found in any other Western European species. In the field the thin red sheet often silt-covered is difficult to distinguish from some Eurypon species, but it is even thinner than most of these.
Sources: Ackers et al., 1992 (B.E.Picton).

Hymeraphia stellifera