Mycale (Mycale) cf. laevis (Carter, 1882)

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 158-160

Mycale (Mycale) cf. laevis (Carter, 1882)

Figures 99 a–i

Restricted synonymy: Esperia laevis Carter, 1882a: 291 , pl. XI fig. 16.

Mycale laevis ; De Laubenfels 1936: 116; Hechtel 1965: 46, pl. VI fig.2.

Mycale (Mycale) laevis ; Van Soest 1984: 14, pl. I figs 1–4, text-fig. 2; Hajdu & Rützler 1998: 763, figs 14–15,17g.

Material examined. RMNH Por. 9850, 9919, 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. ( Fig. 99 a) Globular, oval, to irregularly massive individuals, largest specimen (of eight) approximately 4 x 2 x 2 cm in size. Color in alcohol red-brown. Surface optically smooth to irregular, with traces of (pore-)grooves, and with a few small oscules; microscopically slightly hispid. Consistency firm, compressible to crumbly.

Skeleton. ( Fig. 99 b) The surface skeleton is a crust of intercrossing individual megascleres, carried by the endings of choanosomal spicule tracts. Individual spicules from these tracts penetrate the surface. Choanosomal tracts originating in a central spicule core, subdividing and radiating towards the surface to carry the surface crust. Spicule tracts about 200 µm in diameter, thinning out towards the surface. Loose megascleres and microscleres are found in the spaces between the tracts.

Spicules. ( Figs 99 c–i) Styles, anisochelae, sigmas, trichodragmas.

Styles ( Figs 99 c,c1), mycalostyles, uniform in shape and size, fusiform, with subterminal constriction and elongate head, sharply pointed at the opposite end, 542– 606 –654 x 11 – 12.7 –15 µm.

Anisochelae ( Figs 99 d–f) in three distinct size categories, (1) anisochela I ( Fig. 99 d), with relatively long shaft and short alae, especially at the lower end, 87– 94.1 –99 µm, (2) anisochela II ( Fig. 99 e), overall similar to anisochela I, but with upper alae longer and unoccupied shaft shorter, 31– 35.6 –42 µm, and (3) anisochela III ( Figs 99 f,f1), spurred, and with lower end devoid of side alae, 16– 19.4 –23 µm.

Sigmas in two distinct size categories, both with incurved apices, (1) larger ( Fig. 99 g), 48– 57.4 –66 µm, and (2) smaller ( Fig. 99 h), 13– 18.5 –33 µm.

Trichodragmas ( Fig. 99 i), in elongate, pointed packages, 43– 46.2 – 52 x 6 – 13.4 –19 µm, individual raphides robust, about 1 µm in thickness.

Distribution and ecology. Guyana Shelf, soft bottom at 130 m depth.

Remarks. Preliminarily, these sponges were identified as Mycale (Mycale) laevis Carter, 1882 , the common widespread Central West Atlantic reef Mycale . However, the consistent presence of a third anisochela (of type II) differs from previous descriptions of this species ( Hechtel 1965; Van Soest 1984; Pulitzer-Finali 1986; Zea 1987; Hajdu & Rützler 1998), which report only anisochelae categories of type I and type III. Further, more subtle differences are the longer and sharply pointed styles, longer anisochelae I, the presence of definitely distinct categories of large and small sigmas, a single size of shorter trichodragmas, and the small oval body. Research into variability of shape and color in Mycale (M.) laevis by Loh et al. (2012) did not yield genetic markers for infraspecific morphotypes. However, none of their specimens from different habitats showed the presence of a third type of anisochelae, so the present differences could point to separate specific status. For the time being the data are interpreted as variation due to the deep occurrence at 130 m, where the normal depth occurrence is 1– 25 m .

Figures

FIGURE 99. Mycale (Mycale) cf. laevis (Carter, 1882), a, habitus of RMNH Por. 9850 (scale bar = 1 cm), b, light microscopic image of cross section of the skeleton, c – I, SEM images of the spicules, c, style, c 1, details of c, d, anisochela I, e, anisochela II, f, anisochela III, f 1, detail of f, g, large sigma, h, small sigma, i, trichodragma.