Spiroxya spiralis Johnson 1899

Spiroxya spiralis (Johnson, 1899)

(Figure 12)

Synonymy and References. Scantilla spiralis Johnson, 1899: 462, pl. 6: 5, 5a.

Material. USNM 1228921, Carrie Bow Cay East, outer reef ridge cave, in Agaricia coral rubble, 12 m; K. Ruetzler col. 12 May 1975.

Examined in the field (not preserved, 12-24B): Curlew Bank, forereef slope (wall), 50-150 cm inside framework cave, ceiling, 20 m; C. Piantoni & M. Parrish, col. 22 Aug 2012.

External morphology. No papillar structures were observed on the substratum surface, only ovoid chambers filled with tissue, measuring 1.5–5 mm in diameter but may be confluent, following the porous structure of the substratum. Soft consistency, tan color (live as well as in alcohol).

Skeleton structure. Oxeas throughout the choanosome, some in bundles but most without orientation, accompanied by numerous spiral microscleres. Abundant tylostyles are foreign, apparently incorporated from other, neighboring clionaids.

Spicules. Oxeas are rather thick and blunt, a few have one rounded (styloid) end, many are bent sharply in the center: 380–520 x 15–28 (471 x 22) Μm; microscleres are microspined spirasters (spines only detectable by SEM, measuring about 0.2 Μm at the base and in height), with spination mainly on the convex sides and at the end of the spirals: 23– 80 x 2–7 (47 x 3) Μm (length by thickness of axis), 7–11 Μm overall width, and 4–7 turns. Ecology. Found in various calcareous substrata (oyster shells, coral rubble) to about 30 m depth. Distribution. Eastern Atlantic, off West Africa (Madeira, Canary Islands, Azores); now Caribbean (Belize). Comments. We did not examine the type specimen but the oxeas described by the original author (Johnson, 1899) seem to be more slender and acerate than ours and occur in two size classes. More material and study will be needed to confirm conspecificity.

Spiroxya spiralis was synonymized with S. levispira (Topsent) by Rosell & Uriz (1997) and van Soest & Beglinger (2009), who assumed that Johnson’s description was incomplete as it does not mention acanthomicrorhabds. However, absence of spiny, amphiaster-like rhabds in our material seems to confirm the original description.