Xestospongia muta (Schmidt, 1870)

Figures 25 a–c

Restricted synonymy:

Schmidtia muta Schmidt, 1870: 44 .

Petrosia muta; Topsent 1920: 8.

Xestospongia muta; De Laubenfels 1936: 70; Wiedenmayer 1977: 115, pl. 14 figs 6–7, pl. 15 figs 1–2, text-fig. 129; Van Soest 1980: 66, pl. XI fig. 1, text-fig. 23.

Material examined. RMNH Por. 9784, 9805, Guyana, ‘Luymes’ Guyana Shelf Expedition, station 65, 7.55°N 57.0833°W, depth 63 m, sandy bottom, 31 August 1970; RMNH Por. 9914, Suriname, ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station G7, 7.28°N 56.7933°W, depth 64 m, bottom sand, 7 May 1966 .

Description. Two small damaged specimens and a fragment of this common West Atlantic species. The larger specimen (Fig. 25 a) is a cup-shaped column, 14 cm high, 12 cm in widest diameter. Surface grooved and pitted. Color (in alcohol) brown-red outside, pale beige inside. Consistency hard, crumbly.

More complete and larger, barrel-shaped specimens, up to 50 cm high and 45 cm in diameter, were obtained in French Guyana waters by the CREOCEAN expedition.

Skeleton. (Fig. 25 b) Surface cover is a dense tangential reticulation of intercrossing single spicules. Choanosomal skeleton a dense mass of spicules arranged in irregular rounded meshes.

Spicules. Oxeas only.

Oxeas (Fig. 25 c,c1), curved, bluntly pointed, in a limited size range, 384– 421 –462 x 15 – 18.3 –22 µm.

Distribution and ecology. Guyana Shelf, Florida, and throughout the Greater Caribbean, also in NE Brazil, on reefs and on hard bottoms in deeper water, down to 94 m depth (Guyana Shelf, 63–64 m, CREOCEAN specimens were from 72–76 m).

Remarks. The present specimens share the predominance of oxeas over strongylote forms with Schmidt’s type and the specimens described by Van Soest (1980) from Curaçao and Puerto Rico, Zea (1987) from Colombia, and Hajdu et al. (2011) from NE Brazil . In fact no strongyles were observed in the present specimens, contrary to Wiedenmayer’s (1977) description of the species from the Bahamas.