Clathria (Thalysias) zeai, Van, Rob W. M., 2017

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 153

Clathria (Thalysias) zeai sp. nov.

Figures 95 a–g

Material examined. Holotype RMNH Por. 9885, Suriname, ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station G56, 7.26°N 56.6667°W, depth 67–68 m, Agassiz trawl, 10 May 1966 .

Description. ( Fig. 95 a) Thinly encrusting worm tubes and coral debris. Three small pieces are considered fragments of a single specimen, together less than 1 cm 2, thickness 0.3–0.6 mm. Surface hispid. No apparent oscules. Color in alcohol pale orange-brown. Consistency soft.

Skeleton. Hymedesmioid, with single styles and acanthostyles erect on the substratum, heads embedded in the basal spongin plate. At the surface there are bouquets of longer subtylostyles carrying smaller subtylostyles; the surface is penetrated by long choanosomal styles causing the hispidation.

Spicules. ( Figs 95 b–g) Styles, subtylostyles, acanthostyles, palmate isochelae, toxas.

Styles ( Fig. 95 b,b1), curved, with heavily warty head and smooth shaft, sharply pointed, 261– 426 –719 x 13 – 16.1 –18 µm.

Subtylostyles with faintly swollen, microspined heads, divisible in two distinct size classes, (1) larger ( Figs 95 c,c1), 332– 451 –546 x 4 – 5.8 –7 µm, (2) smaller ( Figs 95 d,d1), 146– 199 –282 x 1.5– 2.45 –3.5 µm

Acanthostyles ( Fig. 95 e), curved, with heavily warty head and lightly spined shaft, 98– 133 –164 x 4 – 7.9 –10 µm.

Palmate isochelae ( Figs 95 f,f1), tiny, strongly or weakly twisted, with short alae and long naked shaft, 9– 11.2 –14 µm.

Toxas ( Figs 95 g,g1), deeply curved, with slightly upturned, rugose apices, 89– 104 –149 µm

Distribution and ecology. Guyana Shelf, soft bottom at 67–68 m depth.

Etymology. Named after Professor Sven Zea S., (INVEMAR, Colombian National University), in recognition of his important contributions to sponge taxonomy.

Remarks. The closest species to this thinly encrusting hispid Clathria (Thalysias) species is C. (T.) minuta ( Van Soest, 1984) (as Rhaphidophlus ), distributed over the Caribbean and NE Brazil. This shares most of the properties of the new species, but differs decisively in having the palmate isochelae normal, not twisted. Apart from the description of that species in Van Soest (1984) (p. 115, fig. 45, as Rhaphidophlus minutus ), there is a SEM plate of the spicules of the holotype in Van Soest et al. 2013 (p. 335, fig. 30) as part of a discussion of the status of another close species, the Cape Verdian C. (T.) minutoides Van Soest, Beglinger & De Voogd, 2013 . Differences in these Amphi-Atlantic minuta -like species are apparently small and subtle. Further such small differences between C. (T.) zeai sp. nov. and C. (T.) minuta are the rounded-warty style heads (more spinose in C. (T.) minuta ), the spined nature of the toxa endings (smooth in C. (T.) minuta ) and the upper size of the styles (only up to about 430 µm in C. (T.) minuta ) against up to 700+ µm in the new species).

A species also close, but less similar, is NE Brazilian Clathria (Thalysias) basiarenacea ( Boury-Esnault, 1973) (as Rhaphidophlus ), as redescribed by Galindo et al. (2014). Differences are the smooth styles, the diversity of toxas and the normal-shaped palmate isochelae. A second NE Brazilian species, C. (T.) repens Galindo, Hooper & Pinheiro, 2014 , does have twisted palmate isochelae like the present new species but also normal-shaped chelae, and differs further in habitus, in having smooth styles and straight-ended toxas.

Figures

FIGURE 95. Clathria (Thalysias) zeai sp. nov., a, habitus of holotype RMNH Por. 9885 (scale bar = 1 cm), b – g, SEM images of the spicules, b, style, b 1, details of b, c, large subtylostyle, c 1, details of c, d, small subtylostyle, d 1, detail of d, e, acanthostyle, f – f 1, twisted palmate isochelae, g, toxa, g 1, detail of toxa ending.