Clathria (Microciona) bulbotoxa

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 : 59-60

Clathria (Microciona) bulbotoxa van Soest, 1984

( Figures 2 b, 33)

Synonymy and references. Clathria (Microciona) bulbotoxa van Soest, 1984a: 103, fig. 41, pl. 7: 5–8.

Material. USNM 1229006, Carrie Bow Cay, North channel, underside of coral rock, 6 m; K. Ruetzler, col. 23 May 1979. USNM 1229007, Curlew Bank, forereef framework cave wall, 20 m; C. Piantoni col. 29 Jun 2007.

External morphology. Thinly encrusting, covering up to 60 cm 2 substratum. Soft consistency, slightly mucous; smooth surface, except for protruding substrate structure and a few subectosomal canals; numerous, very small (ca. 1 mm) oscula. Bright red, uniform color in life, only oscular rims being slightly less pigmented (appearing pink).

Skeleton structure. Disorderly strands of spongin cored and echinated by (sub-)tylostyles; in places, these megascleres are arranged in criss-cross fashion. Microscleres were found throughout the ecto- and choanosome. An irregular network of spongin fibers cored by (sub-) tylostyles, echinated by stubby acanthostyles. Smaller tylostyles are in the ectosome, some forming brushes at the surface.

Spicules. All megascleres have more or less pronounced heads (subtylostyles), the larger ones rough or with a few spines on top, many of the smaller category with distinctly microspined heads. Subtylostyles I (choanosomal): 132–550 x 10–20 (357 x 14) Μm; subtylostyles II (ectosomal): 120–390 x 3–8 (290 x 6) Μm; bulbous toxas: 58–182 (104) Μm; their thickness measures 3.0–8.0 (5) Μm in the bulbous parts, as compared to 2.0–5.7 (3) Μm at the center of the arch; smaller, regular toxas (possibly early developmental stages of the bulbous kind, as suggested by van Soest in the description of the type): 20–47 (29) Μm length, 1.1–4.7 (2) Μm thick, at the center of the arch; palmate isochelas (most of them twisted): 13.4–14.0 (14) Μm.

Ecology. Occurs under rock and in cave habitats in deeper parts of reefs, to 25 m.

Distribution. Found in the Netherlands Antilles and Belize, so apparently Caribbean-wide. Comments. Both the original author (van Soest, 1984a) and our group found the characteristic bulbous toxas as foreign spicules in some preparations made from other reef sponges.

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).