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 Chelonaplysilla americana sp. nov. Figures 8 a–b Chelonaplysilla erecta sensu Van Soest 1978 : 71 , pl. XIV fig. 1, text-fig. 24; Zea 1987 : 50 , Pl. 6 fig. 4; Hajdu et al. 2011: 218, with unnumbered figures; Moraes 2011: 201, with unnumbered figures; Muricy et al. 2011: 54. Not: Megalopastas erectus Row, 1911 ; nec: Chelonaplysilla erecta Tsurnamal, 1967 . FIGURE 8. Chelonaplysilla americana sp. nov. , a, habitus of holotype RMNH Por. 9812 (scale bar = 1 cm), b, light microscopic image of surface sand grain reticulation. Material examined . Holotype RMNH Por. 9812, Suriname , ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station F41, 6.9133°N 56.4767°W , depth 55 m , Agassiz trawl, 6 May 1966 . Description . Conulose cushion ( Fig. 8 a), size 3 x 2 x 0.5 cm . Color (in alcohol) dark purple, internal color darker, almost black. Surface provided with the characteristic sand grain reticulation, between conules of 2 mm high and 3–4 mm diameter. Fibers protruding from the apices of the conules. Several rimmed oscules are present, with diameter 2–3 mm . Skeleton . Surface reticulation ( Fig. 8 b) of tracts composed of sand particles and spicule fragments, 40–70 µm in thickness, enclosing pore fields 110–240 µm in diameter. Dendritic fibers, growing out of a basal plate of spongin. Fibers divide sparingly at the base, but more prolific at the surface, length 2.5–4.5 mm , thickness at the base up to 160 µm diameter tapering towards the surface to about 30 µm diameter. Fibers dark purple in color, pithed and laminated. Distribution and ecology. From shallow water mangroves and reefs down to 55 m depth (previously down to 50 m ). Etymology. The name reflects its distribution in the seas surrounding the eastern coast of both Americas. Remarks . The species has already been extensively described by Van Soest (1978) , Zea (1987) , Hajdu et al. (2011) and Muricy et al. (2011). The name Chelonaplysilla erecta sensu Tsurnamal, 1967 was chosen for it by Van Soest (1978) , who noted the similarity with Tsurnamal’s description of his Eastern Mediterranean species (cushion shaped and with ramified fibers), as opposed to thinly encrusting shape and single undivided fibers in the type of Chelonaplysilla , the deep-water Atlantic species C. noevus ( Carter, 1876 ) . Subsequently, Zea (1987) pointed out that according to Bergquist (1980) (p. 486) Tsurnamal’s C. erecta was synonymous with the Red Sea species Megalopastas erectus Row, 1911 , and reassigned the present species to C. erecta ( Row, 1911 ) . Later authors followed Zea’s decision and ignored the unlikely synonymy of a southern Red Sea species with a species from the tropical West Atlantic. A second Central West Atlantic species of Chelonaplysilla is the yellow C. betinensis Zea & Van Soest, 1986 from the Colombian Caribbean. Apart from being yellow it is thinner and has less long fibers.