(Martens, 1824)
Species Overview
Mycale (Aegagropila) contareni (Martens, 1824) is a yellowish cushion or sheet under littoral boulders and on rocks and shells in the sublittoral. It has a firm, compressible consistency and a fibrous interior. With a hand lens a characteristic reticulate surface pattern is discernible. It is a common sponge in the SW British Isles, Atlantic coasts of France and Spain and in the Mediterranean.
Taxonomic Description
Colour: Yellow, yellow green, ochrous yellow (never red). Preserved: white to light brown.
Shape, size, surface and consistency: Varies from sheets or cushions of unequal thickness to massive-lobose. The lobes may become elongate and anastomose, leading to a superficially ramose appearance. Specimens can grow to a considerable size—at least 10 cm diameter and thickness. Surface typically covered by small conules, raised up by the skeletal fibres, giving the surface a somewhat reticulate appearance. Oscules few, large when open, found at summits of the lobes or scattered and carried on membraneous fistules on encrusting forms. Consistency firm to soft, even, compressible. Smell quite marked, sweetish-pungent. Contraction slight.
Spicules: (Mycale contareni spics) The megascleres typically are slightly curved (sub)tylostyles (so-called mycalostyles), thicker towards the pointed end, with a more or less pronounced head: 220-357 x 7-11µm, varying between individuals.
Microscleres include palmate isochelae in three size groups: the largest, when present in any numbers, are grouped into rosettes in the surface: 31-47 µm; the middle size are solitary and variable in number (and may even be absent): 12-25 µm; the smallest are solitary, often abundant, with one tooth characteristically standing out from the shaft giving the spicule a noticeable angular profile: 13-15 µm. Sigmas of two sizes are present: the larger are numerous, robust and somewhat twisted, sizes generally in the range 40-65 µm; the smaller (if present) are thinly scattered and very slender and consequently sometimes hard to find: 16-22 µm. Toxas are either single and scattered or, nearly always, in small bundles forming toxodragmata; they are small and fine, with a widely extended central flexion; they are always present but sometimes rare and difficult to detect; size 20-70 µm.
Skeleton: Plumoreticulate. The ectosomal skeleton is a tangential, comparatively feeble, triangular or polygonal reticulation of multispicular fibres. The choanosomal skeleton is an irregular reticulation of stout multispicular fibres. Spongin reinforces the skeletal fibres to a varying degree.
Reproduction: Sexual reproduction in summer. Asexual reproduction also in summer by budding, buds located at summits of the conules.
Ecology: Littoral to 37 m, growing on stones, shells, algae, sessile coelenterates and scallop shells, boulders, cobbles, at sheltered sites with moderate tidal streams.
Distribution: British Isles, Atlantic coast of France and Spain, Mediterranean, Azores.
Type specimen information: No type material in BMNH. MCS voucher BELUM: Mc1620. Lough Hyne, SW Ireland.
Remarks
The appearance alive is distinctive but probably not diagnostic. That, combined with a microscopic examination, should provide a ready identification.
Source: Ackers et al., 1992.