Abyssocladia oxyasters

Description: Growth form: Erect pedunculate sponge with a long thin stem. The body is a plano-convex disc on the upward surface parallel to the substrate, and conical lower surface (Figure 4 A). This disc is encircled by radiating filaments (Figure 4 B). The stem is 140 mm in length and only 0.6 mm in width in the holotype, and 160 mm in length and also 0.6 mm in width in the paratype. In both specimens the sponge body has a diameter of 14 mm, and the lower half of the body is a downwards pointing cone of a height of 6.5 mm. The filaments on the holotype are 12 mm long but only 4.2 mm long on the paratype. The basal holdfast is an enlarged disc 9 mm in diameter. Colour: When collected alive the sponge body is orange with a yellowish stem and colourless filaments. After preservation in ethanol the sponge is a light brown colour. Ectosomal skeleton: The ectosomal skeleton of the sponge body is a thin membranous sheet covered with cleistochelae (Figure 5 A). The ectosomal skeletons of the filaments also include cleistochelae and abundant sigmancistras (Figure 5 D), whilst the ectosome of the stem only shows the remains of the cleistochelae (Figure 5 C). Endosomal skeleton: The endosomal skeleton of the sponge body consists mainly of oxyasters that encrust spermatocyst spheres 300 – 600 µm in diameter. In the stem and filaments the endosomal skeleton consists of longitudinal bundles of mycalostyles 1, with occasional oxyasters in the subectosome. The basal holdfasts contain oxeote anisostyles 2 which are smaller, thicker with greater curvature than megascleres in the rest of the sponge. Megascleres: Very long slender mycalostyles with long tapering points and bases, thickest in the basal third of the spicule, found in the axis of filaments and stem, size range 1380 – 3810 x 15 – 54 µm. Styles found in the basal holdfast are oxeote, asymmetrical, curved, with the basal end more abruptly tapering than the apical end, size range 392 – 1560 x 20 – 50 µm. Microscleres: Cleistochelae, palmate with three alae. The frontal alae nearly completely detached from the lateral alae, the latter completely fused to the shaft. The shaft is slightly curved. Size range 62 – 123 x 17 – 37 µm. Sigmancistras with slight contortion, size range 21.5 – 40 x 2 – 7 µm. Oxyasters with only slight central swelling and short slender rays, size range 74 – 136 µm in diameter (see Table 2). Molecular data: 28 S see Figure 1.