Timea tylasterina, Van, Rob W. M., 2017

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 180-181

Timea tylasterina sp. nov.

Figures 112 a–e

Material examined. Holotype RMNH Por. 9776, Suriname, ‘ Luymes O.C.P.S. II’ Guyana Shelf Expedition, station I115, 7.21°N 54.8617°W, depth 81 m, triangular dredge, 24 April 1969 .

Description. ( Fig. 112 a) Thin ecrustation cementing calcareous rubble. Surface optically smooth. Size about 2 cm 2, consisting of dispersed patches. Color (in alcohol) whitish to greyish.

Skeleton. Thin single tylostyles arise from the substratum erect or in small diverging groups, protruding barely beyond the surface. Microscleres form a dense mass at the base of the sponge.

Spicules. ( Figs 112 b–e) Tylostyles, tylasters.

Tylostyles ( Figs 1 12 b,b1), thin, slightly curved, with rather elongated tyle, sometimes subapical, 204– 292 –388 x 2 – 3.2 –4 µm.

Tylasters in two categories, (1) larger ( Figs 112 c), with 8–10 thick, truncated, smooth rays each ending in a crown with 3–7 conical spines, 13– 14.1 –15.5 µm, and (2) smaller ( Figs 112 d), with 7–11 short truncated rays each ending in a profusedly spined crown often consisting of double circles of spines, 7– 8.4 –10 µm. A few middle-sized tylasters ( Fig. 112 e) occurred with thinner rays, presumably juveniles of the large tylasters.

Distribution and ecology. Guyana Shelf, on sandy bottom at 81 m depth.

Etymology. The name refers to the tylasters.

Remarks. Among the many (13) species of Timea recorded from the Central West Atlantic, there are no descriptions matching all aspects of the above described material. Using Leite et al. ‘s (2015) key to the Timea species of the Tropical West Atlantic the new species keys out as Timea stenosclera Hechtel, 1969 . There are indeed several similarities with this species, originally described from Barbados: thin optically smooth encrustation, small sized tylostyles, loose arrangement of megascleres, and two categories of asters. However, the large asters of T. stenosclera are oxyspherasters of up to 25.9 µm (average 19.7 µm) whereas the large asters in the present species are tylasters of up to 15.5 µm. The small asters of T. stenosclera are ‘euasters’ (drawn as thin-rayed oxyasters) of up to 11.8 µm (average 9.7 µm), whereas the small asters in the present species are tylasters with squat, profusedly ornamented rays, 7–10 µm in size.

The asters of the new species on paper appear similar in shape and size to those of Timea perastra ( De Laubenfels, 1936) (as Halicometes ), but the tylostyles of that species may be up to 1888 µm long.

Figures

FIGURE 1. Map of the northeast coast of South America showing the Guyana Shelf with 200 m depth contour and in the inset the area covered by the Dutch HMS ‘ Snellius’ O. C. P. S. 1966, HMS ’ Luymes’ O. C. P. S. II 1969, and HMS ‘ Luymes’ Guyana Shelf 1970 expeditions. Arrows indicate predominant current direction. Map courtesy of www. prima. com (map collection Free Edition).

FIGURE 2. Overview of stations on the Guyana Shelf made by the Dutch HMS ‘ Snellius’ O. C. P. S. 1966, HMS ’ Luymes’ O. C. P. S. II 1969, and HMS ‘ Luymes’ Guyana Shelf 1970 expeditions (black dots), with numbered stations where sponges were obtained. Details for each station are provided in the text with each described sponge species.

FIGURE 3. Chondrilla caribensis Rützler, Duran & Piantoni, 2007, RMNH Por. 9816, a, habitus (scale bar = 1 cm), b, SEM image of spherasters.

FIGURE 4. Chondrosia collectrix (Schmidt, 1870), RMNH Por. 9338, a, habitus (scale bar = 1 cm), b, light microscopic image of cross section of peripheral region.

FIGURE 5. Aplysina caissara Pinheiro & Hajdu, 2001, RMNH Por. 9340, a, habitus (scale bar = 1 cm), b, light microscopic image of skeleton of pithed fibers.

FIGURE 6. Aplysina cauliformis (Carter, 1882), RMNH Por. 9340, a, habitus of two specimens (scale bar = 1 cm), b, light microscopic image of skeleton of pithed fibers.

FIGURE 7. Aiolochroia crassa (Hyatt, 1875), RMNH Por. 9819, a, habitus (scale bar = 1 cm), b, light microscopic image of skeleton of pithed fibers.

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.

FIGURE 9. Igernella notabilis (Duchassaing & Michelotti, 1864), RMNH Por. 9337, a, fragments (scale bar = 1 cm), a 1, one of the fragments enlarged (scale bar = 1 cm), b – c, light microscopic images, b, peripheral skeleton, c, horny spicule.

FIGURE 10. Ircinia felix (Duchassaing & Michelotti, 1864), a, habitus of RMNH Por. 9333 (scale bar = 1 cm), b, habitus of RMNH Por. 9936 (scale bar = 1 cm), c – d, light microscopic images of skeleton of RMNH Por. 9904, c, cross section, d, filaments.

FIGURE 11. Dysidea etheria De Laubenfels, 1936, a, habitus of RMNH Por. 9353 (scale bar = 1 cm), b. light microscopic image of cross section of skeleton of RMNH 10510.

FIGURE 12. Callyspongia (Callyspongia) cf. pallida Hechtel, 1965, a, habitus of RMNH Por. 9894 (scale bar = 1 cm), a 1, habitus of RMNH Por. 9900 (scale bar = 1 cm), b, light microscopic image of surface skeleton of RMNH Por. 9894, c – c 1, SEM images of skeleton of RMNH Por. 9900, c, surface skeleton, c 1, detail of c, d, SEM image of oxeas.

FIGURE 112. Timea tylasterina sp. nov., a, habitus of holotype RMNH Por. 9776 (scale bar = 1 cm), b – e, SEM images of the spicules, b, tylostyle, b 1, details of b, c, large tylasters, d, small tylasters, e, middle-sized thin-rayed tylaster.