Sponges of the Guyana Shelf Author Van, Rob W. M. text Zootaxa 2017 1 1 225 journal article 37320 10.5281/zenodo.272951 e2c88f4c-3ac2-45f9-95e4-99b75561a081 1175-5326 272951 6D68A019-6F63-4AA4-A8B3-92D351F1F69B 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 1518.3 –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.