Corticium quadripartitum Topsent, 1923

Rützler, Klaus, Piantoni, Carla, Van, Rob W. M. & Díaz, Cristina, 2014, Diversity of sponges (Porifera) from cryptic habitats on the Belize barrier reef near Carrie Bow Cay, Zootaxa 3805 (1), pp. 1-129 : 13

Corticium quadripartitum Topsent, 1923

( Figure 5 )

Synonymy and references. Corticium quadripartitum Topsent, 1923: 14 , fig. 3B.

Material. USNM 1228889, Carrie Bow Cay back reef near reef crest, underside of Acropora palmata coral rubble, 0.3 m; K. Ruetzler col. 23 Apr 1974.

External morphology. A thin cushion covering about 16 cm 2, 3– 5 mm thick. Surface rough, cork-like to the touch, bumpy, with small (1 mm) oscula slightly elevated, pores in small depressed areas in between. Greenisholive color in life, darker brownish on the oscular bumps.

Skeleton structure. Spicules are condensed in a cortex at the surface and along the canals where they contain a large percentage of candelabras. Throughout the interior of the sponge, spicules are distributed in less dense fashion and are dominated by calthrops, mainly lophocalthrops.

Spicules. Basic calthrops (equiangular tetraxons with equal rays): 50–70 (57) Μm; lophocalthrops (one or more of the rays branch into two, three, or four spines, the latter of which led to the species‘ name): 21–60 (44) Μm; candelabras (lophocalthrops with branching, microspined rays): 26–33 (30) Μm; spheres, rare: 4–6 (5, n=5).

Ecology. Only one specimen found under coral rock in a high-energy habitat behind the reef crest, 0.3 m.

Distribution. Previously known only from St. Vincent, in the Grenadine (Windward) Islands; now presumed to be Caribbean-wide.

Comments. The siliceous spheres seen in our SEM micrographs were not part of the original species description but they are easily overlooked by light microscopy.

Figures

FIGURE 5. Corticium quadripartitum, spicules (SEM): a, calthrops; b, lophocalthrops; c, candelabras; d, spheres.