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(Stephens, 1912)

Species Overview

Haliclona (Gellius) rava (Stephens, 1912) is a thinly encrusting, greyish yellow sponge with very few characteristics. It is not well known: only a few records from Ireland and England are found in the literature. It is chiefly distinguishable on its spiculation, which includes sigma-and toxa-microscleres. The only other sympatric Haliclona species with such microscleres, H. (G.) angulata, differs in being purple and much more coarse in structure.

Taxonomic Description

Colour: Greyish-yellow alive and in alcohol.
Shape, size, surface and consistency: Thinly encrusting patches, probably not exceeding 4 cm in diameter. Osculiferous processes may be present (Haliclona rava BandW). Oscules also level with the surface, small. Surface smooth, even. Consistency soft, somewhat fragile, but not friable.
Spicules: (Haliclona rava skeldraw2) Megascleres: Oxeas slender, with long and sharp points: 130-230 x 4.8-9.5 µm.
Microscleres: Sigmas irregularly bent, very small: 4.8-12 x ca. 0.5 µm. Toxas very slender, with an indistinct and irregular angle, sometimes almost straight, with slightly recurved apices: 38.5-120 x ca. 0.5 µm.
Skeleton: (Haliclona rava skeldraw1) Ectosomal skeleton: irregularly disposed oxeas make up a confused tangential reticulation. Choanosomal skeleton is somewhat confused, with irregular paucispicular primary and unispicular secondary lines. Many spicules in confusion. Spongin scarce, nodal.
Ecology: Possibly confined to the intertidal zone, under stones.
Distribution: Only known with certainty from South Ireland and Wales. Possibly Mediterranean-Atlantic.
Etymology: ravus (Latin) = grey-yellow.
Type specimen information: Holotype: National Museum of Ireland, Dublin (cf. [t]O'Riordan and O'Connor, 1985[/t]); slide of type in BMNH: 1913.5.12.1, Clare Island (Ireland).

Remarks

The ZMA holds specimens which conform in every respect to Stephens' description of Gellius ravus and to the BMNH slide of the type. The ZMA material described in De Weerdt (1986) is the first published Irish record after Stephens' descriptions, but the species seems to be rather common in Anglesey, Wales (Dr. W. C. Jones, pers. comm.). H. (G.) rava is morphologically characterized by its small size and encrusting habit. The irregularly curved toxas, which are sometimes almost straight, distinguish the species from the other two sytnpatric, microsclere bearing chalinids, H. angulata and H. (G.) fibulata. It is easily distinguished from H. (G.) angulata by its habit, colour and consistency. H. angulata is much more massive, purplish and friable. The oxeas are of a smaller size in H. (G.) rava H. (G.) angulata has oxeas of 200-350 x 3.5-14 µm), the sigmas are slightly smaller (in H. (G.) angulata they measure 7-15 x 0.2-1.2 µm), but the toxas are clearly different. In H. (G.) rava they are very weakly bent, sometimes almost straight, and rather large (up to 120 µm). In H. (G.) angulata they are characteristically strongly curved and much smaller, viz. 43-75 x 0.2-2.5 µm.
H. (G.) rava differs from H. (G.) fibulata by the absence of a reticluated surface, by the colour (H. (G.) fibulata is light purple) and by the presence of both sigmas and toxas (H. fibulata has only sigmas). Furthermore the sigmas are of a much smaller size than in H. (G.) fibulata. Pulitzer-Finali (1983) reported an 0rina sp. from the Mediterranean, which he compared with H. (G.) rava. He did not describe the skeletal architecture, but his figure of the spicules, as well as his description of the morphological features correspond to Stephens' species. A Mediterranean-Atlantic distribution of H. (G.) rava is therefore possible.
Source: De Weerdt, 1986

Haliclona rava