Diplastrella megastellata Hechtel 1965

Diplastrella megastellata Hechtel, 1965

(Figure 19)

Synonymy and references. Diplastrella megastellata Hechtel, 1965: 58, fig. 12, pl. 7: 2.

Material. USNM 1228946, 1228947, 1228948, Carrie Bow Cay, back reef near crest, inside and underside of Acropora palmata coral rubble, 0.3 m; K. Ruetzler col. 23 Apr 1974. USNM 1228949, 1228950, Carrie Bow Cay south back reef, lower surface of rock slab, 1m; K. Ruetzler col. 13 Mar 2009. USNM 1228946, 1228946, Curlew Bank forereef slope cave, 20 m; C. Piantoni and M. Parrish col. 23 Aug 2012.

External morphology. Thin crusts spreading over 100 cm 2 and more, 1 mm thick. Surface slightly rough to the touch, with exhalant canals meandering vein-like toward small, slightly raised oscula (all contract strongly upon collecting). Color ranges from bright orange to grayish and brownish olive, subsurface canals and oscula are more yellowish.

Skeleton structure. Asterose microscleres occur throughout but form dense layers near the surface and at the base of the sponge. Megascleres (tylostyles) are embedded in the choanosome, more or less perpendicular to the substratum, some protruding from the surface.

Spicules. Tylostyles are robust and a bit curved, some are thickest near the center of the shaft or one third of the length from the point. Most tyles are slightly depressed, appearing sub-spherical or ovoid. The spicules have a large size range: 284–1100 x 8–35 (576 x 19) Μm; head width is 15–29 (22) Μm. Large spherasters, which inspired the species’ name, are present in great variety, the smaller ones with simple rays, larger ones increasingly complex, with rays of unequal lengths and branching to various degrees: 26–120 (75) Μm; small spirasters and diplasters: 13–60 (20) Μm.

Ecology. A cryptic, shallow reef species, 0.3– 27 m.

Distribution. Caribbean.

Comments. Spicules in our material are on average larger than those of the holotype but all other characteristics agree well with the original description.