Clathria (Clathria) ramsayiensis, Samaai & Pillay & Janson, 2019

Samaai, Toufiek, Pillay, Ruwen & Janson, Liesl, 2019, Shallow-water Demospongiae (Porifera) from Sodwana Bay, iSimangaliso Wetland Park, South Africa, Zootaxa 4587 (1), pp. 1-85 : 29-32

Clathria (Clathria) ramsayiensis sp. nov.

( Fig. 11 A–H)

Material examined. Holotype. SAMC–A24739 (cross-reference TS 903 & Saf 03-Sod 01); Ramsay reef, Sodwana Bay (27.4466°S, 32.7152°E), 0 3 November 2003. Collected by T Samaai, depth 18 m. Type locality. Ramsay reef, Sodwana Bay, east coast of South Africa.

Description. Thickly encrusting to lobate sponges with multiple digitate lobes, 60 x 30 x 40 mm diameter ( Fig. 11A ). Surface is conulose with randomly scattered sunken oscules, with distinct membranous lip, 1–3 mm in diameter. Texture firm, tough and cartilaginous, compressible. Ectosomal membrane present stretched across lobes, lost in preservative. Colour in life pale yellow orange; in preservative light brown.

Skeleton ( Fig. 11B, C ). Choanosomal skeleton is wide-meshed; nearly reineroid reticulate with undifferentiated spongin fibres, cored by uni-, bi- or pauspicular tracts of choanosomal styles. Acanthostyles echinating slightly and evenly dispersed over fibres, mesohyl matrix heavier in peripheral skeleton than at core, containing few principal styles, subtylostyles and numerous microscleres. The ectosomal skeleton consists of sparse erect plumose brushes of subectosomal auxiliary subtylostyles. Subtylostyles mostly paratangential and occasionally protruding through the surface. Detritus is scattered over surface and embedded in ectosome.

Spicules. Megascleres ( Fig. 11D ). Styles, thick, curved midway, distally hastate or fusiform, occasionally mucronate: 125 (106–143) × 5 (5) µm n=10. Subtylostyles ( Fig. 11E ), straight, thin, distally fusiform with smooth subtylote bases: 127 (85–144) × 1 (1) µm. Acanthostyles, 43 (37–54) × 4 (4) µm ( Fig. 11F ); fusiform, aspinous to finely spinous on base and tip of shaft; midsection finely spinous, spines small and blunt. Auxillary Acanthostyles, slightly subtylote, 52 (46–62) × 2 (2) µm, fusiform, spined from base to tip, spines granular. Microscleres ( Fig. 11G ). Toxas in 2 size categories: I) Long accolada toxas, with sharply angular central curvature and straight arms, 183 (157–192) × 1 (1) µm. II) Short accolada toxas, with sharply angular central curvature and straight arms, 92 (81–109) × 1 (1) µm. Palmate isochelae ( Fig. 11H ) small, unmodified, numerous.

Substratum, depth range and ecology. The sponge is found on coral rubble or rocky ledge, sheltered between or under overhangs at a depth of 18 m.

Etymology. Named for the type locality of the species, Ramsay reef, Sodwana Bay.

Remarks. The genus Clathria is well defined ( Hooper 1996 a; Hooper 2002) and currently 64 species of Clathria are recorded from the WIO (including Arabian Gulf-Red Sea region) and South Africa respectively ( Hooper et al. 2002). Clathria (Clathria) ramsayiensis sp. nov. clearly sits within the subgenus Clathria given its possession of a reticulate skeletal architecture. Currently, 20 Clathria (Clathria) species are described from South Africa, four C. (C) irregularis Burton, 1931, C. (C) juncea Burton, 1931 , C. (C) oculata Burton, 1933 a and C. (C) typica Kirkpatrick, 1903 are described from the east coast. Six species are described from the WIO region; C. (C) arbuscula ( Row, 1911) , C. (C) foliascens Vacelet & Vasseur, 1971, C. (C) inhacensis Thomas, 1979 , C. (C) spongodes Dendy, 1922, C. (C) transiens Hallmann, 1912 and C. (C) indica Dendy, 1889 (see Hooper et al. 2002). Clathria (C) inhacensis and C. (C) indica were recorded from Mozambique while C. (C) spongodes and C. (C) foliascens were recorded from Madagascar.

Clathria (C) inhacensis is similar to C. (C) ramsayiensis sp. nov. in having a lobate encrusting growth form, well developed fibres skeleton with embedded styles, conulose surface, and interstitial subtylostyles (124–181 × 4– 5 µm), although these are smooth, which also occur in brushes at the tips of the main fibres. The principal styles of C. (C) inhacensis have smooth bases (121–172 × 4–5 µm), as do the subectosomal sub-tylostyles (124–181 × 2–4 µm). The echinating acanthostyles have variably spined shafts and spined bases (51–58 × 3–5 µm) while small palmate isochelae are present (8–10 µm). Clathria (Clathria) inhacensis also have hair-like accolada toxas (110– 145 × 0.5–1.5 µm). Clathria (C) inhacensis therefore differs from C. (C) ramsayiensis sp. nov. by possessing only a single class of acanthostyles (51–58 × 3–5 µm) and a single class of accolade toxas (110–145 × 0.5–1.5 µm).

Clathria (C) indica has an erect, branching growth form and is bright red. No microscleres were found in the type specimen described by Dendy (1889) or that recorded by Thomas (1979) from Mozambique. Clathria (C) indica also differs from C. (C) ramsayiensis sp. nov. in that the principal styles of C. (C) indica have smooth bases (140 × 7 µm) and only in one category (124–181 × 2–4 µm) and that the echinating acanthostyles are entirely spined (84 × 7 µm) as oppose to variably spined in C. (C) ramsayiensis sp. nov.

Clathria (C) foliascens differs from C. (C) ramsayiensis sp. nov. in being massive erect blade-shaped and dark orange in colour, have larger ectosomal subtylostyles (150 – 200 × 2.5 µm) and acanthostyles (70–80 × 7.5 µm). Clathria (Clathria) ramsayiensis sp. nov. also have much larger toxas [(C. (C) foliascens 25–37 µm)]. Vacelet & Vasseur (1971) did not record any chelae present.

Clathria (Clathria) juncea has an erect, branching growth form and possesses toxas with slightly roughened ends. Clathria (Clathria) oculata has an erect branching anastomosing growth form, dull colouration with tinges of purple. The principal styles (140– 7 µm) and subectosomal auxiliary subtylostyles (160 × 3 µm) have smooth nontylote bases. The echinating acanthostyles are evenly spined and have small spines (65 × 4 µm), the accolada toxas are slightly curved (160 µm) and the palmate isochelae are very small (6 µm). This species is only similar to C. (C) ramsayiensis sp. nov. in possessing accolada toxas.

Clathria (Clathria) conica Levi, 1963 from the south coast South Africa is similar in external morphology to C. (C) ramsayiensis sp. nov. but differs by possessing echinating quasitylotes and indistinct choanosomal fibre sheaths, characters not occurring in the new species. Clathria (C) ramsayiensis sp. nov. is similar to C. (C) squalorum Wiedenmayer, 1994 from Australia (Leeuwin) in external morphology and, to some extent, spiculation ( Hooper 1996). However, fibre characteristics differ markedly between the two species, particularly the density of coring and echinating spicules on fibres and the degrees to which peripheral fibres radiate from the skeletal axis.

Key diagnostic characters.

• Sponge with lobate encrusting growth form and cartilaginous texture.

• Presence of large thick accolada toxas.

Figures

FIGURE 11. Clathria (Clathria) ramsayiensis sp. nov. A. In situ; B & C. Skeletal architecture (B, x5; C, x10); D. Styles; E. Subtylostyles; F. Acanthostyles; G. Toxas; H. Palmate isochelae.