(Waller, 1880)
Species Overview
Mycale (Carmia) minima (Waller, 1880) is a thinly encrusting yellow sponge, distinguished from other such sponges by its even, more or less unmarked surface (excepting a few small oscules) and very soft consistency. For a certain identification a microscopic examination of the spicules, which include very long raphides, is necessary. It is a littoral and shallow subtidal southern species, occurring along the coasts of the British Isles and France, and into the Mediterranean.
Taxonomic Description
Colour: Bright or dull yellow-ochre.
Shape, size, surface and consistency: Thinly or more thickly encrusting. Surface smooth, pierced by small oscules. Consistency soft, not sticky.
Spicules: Megascleres are subtylostyles ("mycalostyles"), non-fusiform, straight, with thick ovoid head, with short point, sometimes the axal canal is visible: 185-260 x 2-7 µm.
Microscleres : Palmate anisochelae in three size classes, the largest has long outcurved alae and are arranged in rosettes of 10-35 chelae each: 29-36 µm; the middle sized are 17-22 µm and they also have long alae, but these are parallel to the shaft; the smallest have relatively short alae: 11-13 µm. Long thick raphides in trichodragmas are somewhat toxiform, flexuous, but do not form true toxas with a central flexion and recurved apices, size of individual raphides: 350-400 x 1-1.5 µm.
Skeleton: No special ectosomal skeleton. The choanosomal skeleton consists of multispicular tracts running from the substrate to the surface which do not anastomose, but subdivide near the surface to carry the dermal membrane.
Reproduction: In July and August, dark yellow or orange embryos and larvae have been observed.
Ecology: Intertidal and shallow-water, underneath boulders, on holdfasts of brown weeds, on Bryozoans and Ascidians.
Distribution: A southern species: West and South coasts of the British Isles, West coasts of France and Spain, Mediterranean.
Etymology: The name refers to the size of the type specimen.
Type specimen information: No type material in BMNH.
Remarks
This species stands out among thinly encrusting Mycale species by its possession of very long raphides, and through the absence of sigmas.
Source: Topsent, 1924