Hemiasterella camelus, Van, Rob W. M., 2017

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 174-176

Hemiasterella camelus sp. nov.

Figures 109 a–e

Material examined. Holotype RMNH Por. 9924, Suriname, ‘ Luymes O.C.P.S. II’ Guyana Shelf Expedition, station M97, 7.3083°N 54.1667°W, depth 130 m, bottom coarse sand, 16 April 1969 .

Description. The holotype ( Fig. 109 a) is bilobate, pale orange-brown in alcohol, with a punctate micronulose surface. Lobes crowned by apical oscules, which appear irregularly compound with several smaller and larger partially connected openings, likely caused by collapse of wider openings. Maximum height of specimen 7 cm, maximum width 6 cm, lobes 4–5 cm diameter at the base, approximately 2 cm diameter at the top. Consistency firm, rather incompressible.

Skeleton. At the surface there is a thick cover of aster microscleres carried by loose bundles of both smaller and larger oxeas, which push up the surface into low blunt conules. Inbetween these conules there is a network of inhalant openings 0.2–0.4 mm in size. The skeleton of the choanosome is largely confused, consisting of individual larger oxeas strewn without obvious direction, and crowded asters. Smaller asters rare, found in dissoluted spicule mounts, but not readily detected in a thick sections.

Spicules. ( Figs 109 b–e) Oxeas, oxyspherasters.

Oxeas, straight, fusiform, sharply pointed, occasionally with stylote heads, in two size categories, (1) large and thick ( Figs 109 b,b1), 1740– 2006 – 2220 x 27 – 49.6 –58 µm, and (2) small and thin ( Figs 109 c,c1), 597– 798 –963 x 9 – 17.4 –24 µm.

Oxyspherasters, smooth, with sharply pointed conical rays, in two size categories, (1) larger ( Figs 109 d), 35– 61 –78 µm, ray number 6– 11.8 –16, and (2) smaller ( Figs 109 e), 7– 13.8 –18 µm, ray number 10– 11.4 –12.

Distribution and ecology. Guyana Shelf, on sandy bottom at 130 m.

Etymology. Camelus (L.) = camel, referring to the shape of the holotype resembling a camel’s two humps.

Remarks. The only other Central West Atlantic Hemiasterella is H. ajax ( De Laubenfels, 1950) (originally Epallax ajax ) from an inland mangrove pond in Bermuda . A paratype, BMNH 1948.8 .6.49, was examined. It shows considerable similarity to the new species: it is a globular mass with large fusiform oxeas as megascleres and two distinct size categories of oxy(spher)asters as microscleres. There are also compelling differences between the two species. The Bermuda specimen is white (in life as well as in alcohol), the larger oxeas are thinner and longer (1500–3300 x 15–32 µm), there are no small oxeas in the size range below 1000 µm, and the larger oxyasters are not oxyspherasters and all have a small number of rays (usually 3–4). Furthermore, the Bermuda species is only known from a shallow water inland pond, quite the opposite of the new species, which was taken at 130 m depth.

Some resemblance is also apparent with the recently described Jaspis atolensis Lira & Pinheiro, 2015 from the Atol das Rocas in NE Brazil (depth given as ‘loose above the reef’, thus probably from shallow-water). The shape is dissimilar, but irregularly massive, so not too distinct from H. camelus sp. nov. Its skeleton and spicule complement is not unlike the above-described specimen, but the larger oxeas are only up to 1400 x 13 µm (against up to 2220 x 58 in H. camelus sp. nov.). In view of this and the different depth occurrence, it is likely a related but different species. Assignment to Jaspis Gray, 1867 appears unjustified as the smaller oxeas are not arranged tangentially as in the type species, J. johnstonii ( Schmidt, 1862) . Lira & Pinheiro’s (2015) redescription of the type specimen of Schmidt rather contrasts with those of earlier authors ( Topsent 1900 as Coppatias johnstonii , and Uriz 2002) by its emphasis on an ‘undifferentiated’ ectosome. This probably relates to the quality of the dry type material rather than to the true properties of Jaspis johnstonii , which does have an ectosomal tangential or paratangential crust of the smaller oxeas. Jaspis atolensis fits probably better in Hemiasterella .

Figures

FIGURE 109. Hemiasterella camelus sp. nov., a, habitus of holotype RMNH Por. 9924 (scale bar = 1 cm), b, large oxea, b 1, details of b, c, small oxea, c 1, details of c, d, large oxyspherasters, e, small oxyspheraster.