Cliona cf. mucronata Sollas, 1878

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 : 28-29

Cliona cf. mucronata Sollas, 1878

( Figures 2 e, 13)

Synonymy and references. Cliona mucronata Sollas, 1878 : Thomas (1972): 347, pl. 1: 8, 8A–D.

Material. USNM 1228928, Carrie Bow Cay forereef slope, coral rock underside, 30 m; K. Ruetzler col. 26 Apr 1974. USNM 1228929, 1228930, Carrie Bow Cay forereef, spur and groove zone, Agaricia coral base, 8-10 m; K. Ruetzler col. 11 May 1975.

External morphology. Small, circular and well-separated papillae (1–3 mm), fairly large, densely spaced chambers (up to 5 mm), rounded or angular in outline. The color in life of the papillae and chambers is grayish to dull yellow or orange yellow.

Skeleton structure. Slim tylostyles are arranged brush-like in the papillae. In the chambers they are without orientation and are accompanied by a second, stout type of mucronate tylostyles.

Spicules. Tylostyles I are slender, acerate, with a small spherical but usually subterminal head, sharply pointed at the opposite end: 170–290 x 3–11 (208 x 8) Μm. Tylostyles II are short, stout, and mucronate, with a pear-shaped to spherical head that is generally slightly subterminal, with a shaft widening until it almost reaches the opposite end (where it is the thickest, thicker than the head), then narrowing abruptly to a sharp point (mucron): 110–190 x 9–18 (132 x 12) Μm (the head diameter averages 12 Μm).

Ecology. Cryptic in coral rock on the forereef, 8– 30 m.

Distribution. Previously known only from the Indian Ocean, now also in the Caribbean.

Comments. The combination of regular and mucronate spicules is quite unique and seems to justify our identification until more detailed studies of Indian Ocean and tropical Atlantic populations are available. The species’ author ( Sollas, 1878) described the presence of small spirasters but Thomas (1972) could not find these in his material from India. Presence/absence of spirasters is not unusual in clionaids. Delicate spirasters found by us in our slide preparations are foreign, attributed to a neighboring specimen (excavating stage) of Spheciospongia vesparium .

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).