Clathria (Thalysias) venosa ( Alcolado, 1984 )

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 : 62-63

Clathria (Thalysias) venosa ( Alcolado, 1984)

( Figure 2 a)

Synonymy and References. Microciona venosa Alcolado, 1984: 6 , fig. 4A.

Material. USNM 1229019, Carrie Bow Cay, reef flat East, 0.5 m, underside of coral plate; K. Ruetzler col. 1 May 1974. USNM 1229020, 1229021 Carrie Bow Cay, under concrete dock; K. Ruetzler col. 12 May 1978. USNM 1229022, Carrie Bow Cay, South reef, lower surface of coral slab, 1 m; K. Ruetzler col. 9 Jan 1988. USNM 1191357, Carrie Bow south barrier back reef, underside of platy coral rubble, 0.5 m; K. Ruetzler col. 6 Mar 2006. USNM 1191358, Carrie Bow Cay, under CBC concrete dock, 1 m; K. Ruetzler col. 3 Jul 2007.

External morphology. Thin, soft and somewhat mucous crusts, 25–40 cm 2, with vein-like canals leading toward small oscula (1mm, fully contracted in alcohol). Live color gray to yellow-orange on the surface, red below.

Skeleton structure. Megasclere tracts (subtylostyles echinated by small acanthostyles) extending from the substrate toward the surface; brushes of small subtylostyles protruding from ectosome. Very thin toxas (toxashaped raphids) and chelas throughout the tissue.

Spicules. Subtylostyles I, some with minute spines (only seen by SEM) on the heads: 190–450 x 3–7 (274 x 4) Μm; subtylostyles II, some are styles: 60–150 x 1–3 (138 x 2) Μm; acanthostyles: 43– 60 x 3–8 (48 x 5) Μm; toxas: 30–325 x <1 (164 x <1) Μm; palmate isochelas, 9–15 (13) Μm long, some of them twisted.

Ecology. Found under a concrete dock in the lagoon and on the lower surface of dead Acropora palmata plates in a wave-exposed exposed zone of the barrier-reef crest, in 0.5 –1 m depth.

Distribution. Gulf of Mexico and Caribbean.

Comments. Chelae are rare or absent in some specimens.

Figures

FIGURE 2. The most common cryptic habitats studied in the Carrie Bow Cay vicinity (measurements in parentheses are picture widths): a, lower surface of platy coral rock showing the characteristic red foraminiferan Homotrema rubrum, calcareous serpulid polychaete tubes, and two encrusting sponges, Clathria (Thalysias) venosa (left) and Clathria (Thalysias) curacaoensis (10 cm); b, wall inside a forereef framework cave, showing the massive Smenospongia cf. echina (yellow) and Topsentia bahamensis, and encrusting Clathria (Microciona) bulbotoxa (17 cm); c, ceiling of the drowned karst cave in the barrier reef lagoon near Columbus Cay, about 20 m away from the entrance (“ blue hole ”), showing cemented (mostly dead) serpulid tubes, a branching form of Geodia gibberosa (center) and a few knobby specimens of Gastrophanella cavernicola (far left and right; 20 cm); d, broken-up rock from a forereef cave bottom, showing deserted polychaete borings that are colonized by Cryptosyringa membranophila specimens (6 cm); e, broken-up coral rock showing chambers of excavating sponge Cliona cf. mucronata (7 cm); f, Queen conch (Strombus gigas) shell discarded by local fishermen are a common cryptic habitat on the shallow reef (the slot cut by machete near the apex (arrow) to remove the conch assures good ventilation inside the shell); this shell is colonized outside by Chondrilla caribensis, which occurs fully light exposed as well as in darkness (20 cm); g, peat cave (undercut) in the Twin Cays mangrove, the wall covered by Scopalina ruetzleri (80 cm).