Clathria (Microciona) snelliusae, Van, Rob W. M., 2017

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 148-149

Clathria (Microciona) snelliusae sp. nov.

Figures 92 a–g

Material examined. Holotype RMNH Por. 9868, Suriname, ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station F45, 6.4417°N 56.5467°W, depth 34 m, Van Veen grab, 7 May 1966 .

Description. ( Fig. 92 a) Holotype seemingly ramose, but it is in reality thinly encrusting on branching bryozoans and wormtubes, thickness 0.5–1 mm, lateral expansion 2–6 cm. Color in alcohol dark brown-red. Surface smooth, no apparent oscules. Consistency soft.

Skeleton. Hymedesmioid, with single styles and acanthostyles erect on the substratum, occasionally forming groups of styles echinated by the acanthostyles, consolidated by a little spongin. Surface skeleton a loose tangential arrangement of subtylostyles.

Spicules. ( Figs 92 b–g) Styles, subtylostyles, acanthostyles, palmate isochelae, toxas.

Styles ( Figs 92 b,b1), usually curved, entirely smooth, with head narrower than the shaft, relatively uniform in size and thickness, 201– 293 –332 x 3 – 7.1 –9 µm.

Subtylostyles, straight, with elongate swollen heads, provided with one or two spines, in a large size range, divisible with some overlap into (1) larger ( Figs 92 c,c1), 240– 304 –354 x 3 – 4.4 –6 µm, and (2) smaller ( Figs 92 d,d1), 162– 178 –202 x 1.5– 2.5 –3 µm.

Acanthostyles ( Figs 92 e), rather sparsely spined, heads not swollen, barely thicker than the shaft, 89– 101 –114 x 5 – 6.1 –7 µm.

Palmate isochelae ( Figs 92 f), normal shaped, with rather long alae, 12– 15.7 –18 µm.

Toxas ( Fig. 92 g), rare, thin, deeply curved, with upturned apices, less than ten were found in the slides, 33–48 µm.

Distribution and ecology. Guyana Shelf, sandy bottom, encrusting other sessile organisms at 34 m depth.

Etymology. Named after the Netherlands Navy research vessel HMS ‘Snellius’ and its crew in recognition of many valuable contributions to marine science.

Remarks. Of the Clathria (Microciona) species described by Van Soest (1984), C. (M.) affinis sensu Topsent, 1889 , renamed subsequently by Hooper (1996) as C. (M.) campecheae , shows the greatest resemblance to the present material by having essentially the same spicule package. However, the choanosomal styles of C. (M.) campecheae have warty heads and the toxas reach 190 µm, while in the present specimen the styles are entirely smooth and the toxas do not reach more than 50 µm.

C. (M.) hymedesmioides Van Soest, 1984 and C. (M.) spinosa Wilson, 1902 lack acanthostyles, the former has warty choanosomal styles and the latter has oxeote toxas over 200 µm long. Some similarity in spiculation exists with Clathria (Clathria) calypso Boury-Esnault, 1973 (as redescribed by Vieira de Barros et al. 2013). This species forms small low bushes and spicules include smooth choanosomal styles, subtylostyles, acanthostyles, palmate isochelae and toxas, like the present material. However, compared with the present specimen, C. (C.) calypso has a diversity of longer (up to 700+ µm) and smaller toxas (up to almost 200 µm), and the acanthostyles are significantly smaller (less than 80 µm in length). Also, C. (C.) calypso has a reticulated skeleton of sponginencased tracts, while the present specimen has a hymedesmioid arrangement. Additional Clathria s.l. species described from the Central West Atlantic show obvious, essential differences with the present material.

Figures

FIGURE 92. Clathria (Microciona) snelliusae sp. nov., a, habitus of holotype RMNH Por. 9868 (scale bar = 1 cm), b – f, SEM images of spicules, b, style, b 1, details of b, c, large subtylostyle, c 1, details of c, d, small subtylostyle, d 1, details of d, e, acanthostyles, f, palmate isochelae, g, light microscopic image of toxas (not found on the SEM stub).