(Bowerbank, 1874)
Species Overview
Antho coriacea (Bowerbank, 1874) (also known as Plocamilla coriacea ) is an orange-red crust with faint venal pattern and slightly rugose surface. Consistency rather firm, but crumbly. Difficult to tell apart from similar red or orange encrusting microcionids: microscopic examination (spicules, skeletal architecture) is necessary for definite identification.
Taxonomic Description
Colour: Bright orange-red or ochre yellow.
Shape, size, surface and consistency: Moderately thin sheets, with a rounded rugose surface, typically ca. 5 mm thick. Surface fairly smooth in appearance, with moderate friction; tuberculate, uneven. (N.B. Lévi (1960) describes it as "finely hispid"). Oscules are inconspicuous. Contraction slight—difficult to determine. Consistency fairly firm, holds together well when collected, but somewhat crumbly and easily torn.
Spicules: (Antho coriacea spics) Megascleres : Ectosomal subtylostyles: ca. 200-250 x 2-4 µm; choanosomal styles: ca. 300-400 µm; acanthostrongyles: 80-100 µm; acanthostyles: 110-190 µm, the larger being very lightly spined at the head only.
Microscleres : Palmate isochelae: ca. 11-15 µm and toxas which predominantly fall into two size groups: 30-60 µm (relatively fine) and 130-180 µm (more sturdy). The larger toxas may have micro-spined points.
Skeleton: The main skeletal feature is a fairly regular, isotropic and dense reticulation of acanthostrongyles, with acanthostyles also present, the latter often in "upright" positions. There are also larger styles associated with ascending fibres and penetrating the surface (sometimes quasi-echinating the fibres). Slim subtylostyles form brushes at the surface. Very variable quantities of spongin reinforce the spicule fibres.
Ecology: Vertical or steeply inclined rock faces from the shallow sublittoral downwards. Often found encrusting other sponges, such as Stelletta grubii and Stryphnus ponderosus . Most frequent in sites with moderate to strong tidal streams.
Distribution: British Isles [recorded recently from Ireland and Anglesey (Wales)], Bretagne, NW Spain.
Etymology: Coriaceus (Latin): firm, leathery, referring to the consistency.
Type specimen information: The type is in the Natural History Museum, London; MCS voucher BELUM: Mc890. Saltee Islands, Wexford.
Remarks
In appearance this species is quite similar to many other of the troublesome 'red crust' microcionids (especially Antho involvens) , but a bright orange red surface with a bumpy appearance is fairly recognisable. The spicule complement, with a predominance of acanthostrongyles, is almost identical to that of A . inconstans , but differs in the existence of a second category of styles echinating the nodes of the reticulation of the acanthostrongyles (see also Antho involvens and Antho inconstans ).
Source: Ackers et al., 1992; Lévi, 1960.