Strongylacidon rubrum van Soest, 1984

Synonymy and references. Strongylacidon rubra van Soest, 1984a: 44, fig. 15.

Material. USNM 1229044, Carrie Bow Cay forereef, spur and groove zone, cryptic, 6 m; K. Ruetzler col. 1 Feb 1997.

External morphology. A very thin (0.1–1 mm) crust covering about 20 cm 2. Surface smooth, porous under high magnification but without obvious oscula. A few circular openings belong to overgrown serpulid worm tubes. Soft consistency, bright red color in life.

Skeleton structure. A crossection shows wisps of thin megascleres (strongyles) ascending brush-like from the base to the surface; sigmoid microscleres are dispersed throughout the tissue.

Spicules. Very thin, mostly straight strongyles with wide axial canal (black under transmitted light): 185–220 x 1–3 (200 x 2) Μm; sigmas in two size classes (some s-shaped), I: 27–30 (29) µm; II: 13–17 (15) µm.

Ecology. Overgrowing the base of a massive specimen of the sponge Svenzea zeai (Alvarez, van Soest and Ruetzler), 20 m.

Distribution. Caribbean Sea.