Prosuberites carriebowensis, Rützler, Klaus, Piantoni, Carla, Van, Rob W. M. & Díaz, Cristina, 2014

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 : 41-44

Prosuberites carriebowensis new species

( Figures 3 d, 23)

Material. Holotype: USNM 1228972, Curlew Bank forereef cave, 20 m; C. Piantoni col. 28 Jun 2007.

Paratypes: USNM 1228973, Curlew Bank forereef cave, 20 m; C. Piantoni col. 29 Jun 2007. USNM 1228974, Curlew Bank, forereef slope, 50-150 cm inside framework cave, ceiling, 20 m; C. Piantoni and M. Parrish, col. 22 Aug 2012. USNM 1228975, Curlew Bank, forereef cave, 20 m; C. Piantoni and M. Parrish col. 23 Aug 2012. USNM 1228976, Curlew Bank, forereef cave, 20 m; C. Piantoni and M. Parrish col. 23 Aug 2012.

Diagnosis. Prosuberites , thinly encrusting but with warty surface structure caused by folds of the basal spongin layer. Tylostyles of great size range (230– 1520 x 9–30 Μm), separable in two shapes, that is, short and stout, with neck almost as thick as the head, and long and slim, with head well offset from the neck. Color bright orange, overlaid with a whitish ectosomal membrane containing crystalline inclusions.

External morphology. Thin crusts, to 5 mm thick, extending 4–60 cm 2 or more. Surface slightly rugose and warty, bristly from protruding spicules. Oscula irregularly dispersed, slightly elevated, 1–4 mm diameter. Pores in small groups (cribiporal), each about 0.2 mm when open. Live color orange, overlaid by a whitish, very thin ectosomal membrane that blends in with the orange base color as soon as the sponge is touched or removed from the water.

Skeleton structure. Tylostyles, single and in bunches, stand erect, embedded with their heads in the basal spongin plate. Folds in the spongin causes elevations of spicule tracts and bumps on the sponge surface. All sizes of tylostyles are mixed together, without specific localizations.

Spicules. Tylostyles are straight or gently curved, and can be separated into two types, even though they overlap in dimensions (measurements of holotype). The more common type I is relatively thick and stout, the shaft widest at the neck, right below the spherical head, and tapering gradually to a sharp point: 240–840 x 15–30 (568 x 23) Μm; type II is long and thin, with the small head more clearly set off, the shaft very gently tapering to a point: 230– 1550 x 9–25 (963 x 15) Μm. In a few of either type of tylostyle, heads can be subterminal, although this condition is rare.

Ecology. A reef species incrusting coral rock and cave walls and ceilings, 7– 35 m. Oftentimes found overgrown by other crustose sponges, such as Desmacella polysigmata and Monanchora arbuscula .

Distribution. So far only known from the Mesoamerican Barrier Reef of Belize.

Etymology. Named after the type locality, Carrie Bow Cay, Belize.

Comments. This species shows similarities in color and ecology with Prosuberites psammophilus (Pulitzer- Finali, 1986: 89, figs. 17, 18) from the Dominican Republic and Puerto Rico, and with P. laughlini (Diaz, Alvarez & van Soest, 1987: 33, fig. 2; as Eurypon ) from Venezuela and The Netherlands Antilles. However, the former species is distinguished by its incorporation of large quantities of sand and much thinner tylostyles with well set-off heads, the latter by visible subsurface canals that radiate toward the oscula and tylostyles with poorly developed heads, approaching the shape of styles. Neither species seems to have the bumpy surface or the whitish ectosomal membrane with pore sieves.

We examined a peel of the ectosomal membrane by compound light microscope, using both transmitted and polarized ligh, and found that the reflective white appearance is caused by calcareous crystals, unlike any particles seen in nearby reef sediments. Our colleague Jeffrey Post (Department of Mineralogy, National Museum of Natural History) confirmed this observation by analytical SEM (personal communication) and showed that the euhedral calcium carbonate crystals (assumed to be aragonite) are accompanied by smaller crystals of calcium sulfate (perhaps gypsum). We suspect that these crystals are the product of endosymbiotic calcifying bacteria, similar to those discovered in species of Hemimycale ( Uriz et al., 2012) , along with artifacts from histological fixation (M. J. Uriz, Centre d’Estudis Avançat, Spain, personal communication). We hope to clarify this process using new material.

Figures

FIGURE 3. In-situ photographs of new sponge species reported in this contribution (measurements in parentheses are picture widths): a, Tetralophophora mesoamericana (3 cm); b, Geodia cribrata (12 cm); c, Placospongia caribica on “ pseudostalactite ” made up by calcareous serpulid tubes (5 cm); d, Prosuberites carriebowensis (adjacent to Monanchora arbuscula to the lower right) (4 cm); e, Timea diplasterina (8 cm); f, Timea oxyasterina (4 cm); g, Rhaphidhistia belizensis (14 cm).