Sarcotragus spinosulus

Schmidt, 1862

Species Overview

Sarcotragus spinosulus Schmidt, 1862 is a massive, often horizontally flattened blackish sponge with regular finely conulose surface. The oscules are distinct and regularly distributed. It is a southern species recorded from the Atlantic coasts of Spain and Portugal.

Taxonomic Description

Colour: Black or dark grey-brown (light-brown inside).
Shape, size, surface and consistency: (Sarcotragus spinosulus big) (Sarcotragus spinosulus Schmidt) Regularly massive to rounded, often with a slightly retracted base making it subspherical, up to 6 cm thick and wide. Surface finely and regularly conulose, with conules 0.3-2 mm high, spaced 1.5-2.5 mm apart. Oscules fairly large, distinct, regularly distributed: 2-3.5 mm in diameter. Consistency firmly compressible, resistant to tearing or cutting; rough to the touch.
Spicules: Absent.
Skeleton: (Sarcotragus spinosulus fibres) The ectosome is a tough thick epidermis charged with a reticulation of sand grains. The choanosomal skeleton is a system of primary and secondary fibres, which are free from foreign inclusions, but have a distinct pith in primary fibres, mostly transparent in transmitted light. Primary fibres 80-190 µm in diameter. Secondary fibres, sometimes forming perforated spongin sheets, are 50-130 µm. Filaments are extremely fine and numerous: 0.7-2.0 µm
Reproduction: November (Carballo et al., 1994).
Ecology: Rocky substrate, between 1 and 300 m, especially common between 8 and 25 m.
Distribution: Portugal, Galicia; Mediterranean.
Etymology: The name refers to the relatively fine conules of the surface in this species.
Type specimen information: Type specimens are in the Graz Museum, LMJG 15428-15431, 15482-15483. Specimen in BMNH: 1867.7.26.76 (dry), Adriatic. Purchased of O. Schmidt—Type?

Remarks

This species is close to S . muscarum but differs in the much finer conules and more regular subspherical shape. Usually, S . spinosula is much darker coloured.
Source: Vacelet (1959).