Acarnus cf. nicoleae van Soest, Hooper & Hiemstra, 1991

Synonymy and references. Acarnus nicoleae van Soest, Hooper & Hiemstra, 1991: 68 (including synonymy); Acarnus (Acanthacarnus) souriei (Lévi, 1962): van Soest, 1984a: 63, fig. 23.

Material. USNM 1191321, Carrie Bow Cay, back reef near crest, 0.3 m; inside and underside of platy coral rubble ( Acropora palmata). K. Ruetzler, col. 23 Apr 1974.

External morphology. Thin crusts covering 2–20 cm 2 area; porous surface shows outlines of the larger, exhalant canals. Color deep red.

Skeleton structure. Indistinct tracts of styles and cladotylotes, tangential spicules (tylotes) in the ectosome.

Spicules. Ectosomal tylotes with well developed, microspined heads: 310 –390 x 5–8 (357 x 6) Μm; choanosomal styles and subtylostyles, also with microspined heads: 430–460 x 6–10 (442 x 8) Μm; cladotylotes with spined shaft and 4–5 clads: 140–220 x 13–22 (187 x 17) Μm; acanthostyles, densely covered by small spines: 70– 90 x 3–6 (79 x 5) Μm; chelae: 15–18 (17) Μm; toxa: 110–210 x 1– 2 (150 x 2) Μm.

Ecology. Found on lower surfaces of platy coral rock in wave-exposed backreef habitats, 0.2 –1.5 m.

Distribution. Reported from many locations in the Caribbean, particularly the southern region.

Comments. Our specimen differs from the description of the type material by having only one size category of cladotylotes; a smaller (often rare) kind was not seen. Likewise, only one type and size class of toxas was found (and no “oxhorn” toxas), and that rarely, although our preparations are rich in all other spicule types.