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(Esper, 1791-1794)

Species Overview

Ulosa stuposa (Esper,1794) is an yellowish/orange-coloured cushion shaped to digitate sponge with a slimy finely conulose surface, compressible and easily damaged. The skeleton consists of a regular reticution of spongin fibres cored by styles. It is a moderately rare shallow-water sponge with a wide distribution in the Eastern Atlantic and the Mediterranean.

Taxonomic Description

Colour: Pinky orange, salmon pink or yellowish in life, pale yellow in alcohol.
Shape, size and consistency: (Spongia stuposa) (Ulosa stuposa BandW) Digitate cushions to ramose forms, up to 8 cm thick, branches up to 17 cm long and with a diameter up to 1.5 cm. Irregular in ouline. Surface finely conulose, in places honey-combed, somewhat slimy. Consistency softly spongy, compressible, easily torn or damaged.
Spicules: (Ulosa stuposa spics) Predominantly styles, but oxeote and strongylote modifications are common. Size rather variable, especially the thickness, both within a single specimen and among different specimens, 115-260 by 2-10 µm.
Skeleton: Ectosome: The organic ectosome is carried by the endings of choanosomal fibres, giving a conulose surface. Choanosome: An irregular rectangular fibre system with relatively few soft parts and large open spaces; frequently digitations and branches are partly hollow. Fibre reticulation consisting of barely distinguishable main and secondary fibres, which connect at right angles. Fibres heavily cored, but spongin coat normally well-developed. Meshes of the reticulum vary in size between 100 and 1000 µm, fibre diameter in the different specimens varies between 15 and 70 µm, coring extent between 3 and 20 spicules per cross section.
Ecology: Occurring on rocks and surrounding algae in the deeper sublittoral, 15-55 m.
Distribution: Ireland, S England, Atlantic coasts of France and Spain, Western Mediterranean, probably also North West Africa.
Etymology: stuposus (Latin) = rope-like, stringy, referring to the sometimes ramose shape of the sponge.
Type specimen information: Type material considered lost.


Both cushion-shaped and digitate ramose specimens occur in this species and there appears to be no correspondence between habit and skeletal characters. Moreover, the specimens show a neat gradient between cushion-shapes and long-ramose forms, which inevitably leads to the conclusion that all belong to onle and the same Mediterranean-Atlantic species.
Related forms (U. tenellula and U. tubulosa) have been recently described from the Mediterranean by Pulitzer-Finali (1983). The first of these two seems hardly distinct from U. stuposa; more evidence is needed for its specific identity.
The genus Ulosa erected by De Laubenfels (1936) for the species Spongia angulosa
Lamarck, 1814 (redescribed by Topsent (1933) as Cacochalina angulosa) is used for quite different sponges in recent West Indian literature. Particularly, the extremely common reef form "Ulosa"ruetzleri Wiedenmayer (1977), seems to be widely divergent from U. angulosa and U. stuposa. Van Soest (1987) recently compared material of "U". ruetzleri with a specimen of U. angulosa. The latter is an upright-lobate sponge with finely conulose surface, spongy compressible consistency, a rectangularly meshed reticulation of spongin fibres thickly cored with short, blunt-ending styles and strongyles of 125-180 by 8 µm (Topsent, 1933) or 130-150 by 7-9 µm (ZMA 3042). It has a convincing overall similarity with U. stuposa. In contrast "U " ruetzleri is an incrusting sponge, fleshy-conulose, with a high content of organic material and a very loose system of irregularly anastomosing spongin-fibres cored by rather few, long, sharply pointed styles. It does not resemble U. angulosa but conforms quite well with the Halichondrida genus Scopalina.
The genus Stylaxinella Vacelet, 1960 is a junior synonym of Ulosa because the present species was named as the type.
Source: Van Soest, 1987; Ackers et al., 1992 (as U. digitata).

Ulosa stuposa