Clathria (Thalysias) hirsuta Hooper & Levi, 1993

Fig. 21

Clathria hirsuta Hooper & Levi, 1993: 1259, figs 19–20.

Material examined

PONTA DO OURO • 1 very small sample covering a hydroid; 26°49′29.579″ S, 32°53′51.072″ E; Blacks; 19.2 m deep; 4 Feb. 2017; Cerrano leg.; PO10 • 1 small fragment; 26°49′16.561″ S, 32°53′52.979″ E; Tea Garden; 19.7 m deep; 6 Mar. 2017; Cerrano leg.; PO78 .

Description

The sponge is massive (Fig. 21 A–B), digitiform and arborescent (Fig. 21C). The exhalant channels converge in numerous, large oscula (Fig. 21 A–B). The color may vary from bright orange to vivid red (Fig. 21 A–C). Both samples preserved in alcohol changed their color to beige. The surface is verrucose and the consistence is elastic.

SKELETON. The ectosome consists of a layer of small styles. The choanosome is formed by an irregular reticulation from pauci- to multispicular primary fibers, 52–73 µm in section, and secondary unispicular fibers, 24–41 µm. Both are spongin rich and are cored by smooth styles. Echinating acanthostyles are present on the primary fibers (Fig. 21D).

SPICULES. Smooth and straight styles (Fig. 21E), sometimes modified in subtylostyles, 82.5–(93.25, 11.8)– 137.5 µm × 4–(5.2, 0.7)– 6 µm; smooth and slightly curved styles (Fig. 21F), 70–(109.5, 23.4)– 147 µm × 4.5–(5.2, 0.7)– 6.1 µm; straight acanthostyles (Fig. 21G) with sharp spines on the terminal parts, close to the tips and scattered on the head, 40–(56.3, 10.3)– 72 µm; raphidiform toxas (Fig. 21H) slightly curved in the middle, 100–(104.5)– 120 µm ×4.75–(6)– 7.5 µm; palmate chelae (Fig. 21I) 5–7.5 µm.

Remarks

Clathria (Thalysias) hirsuta Hooper & Levi, 1993 was exclusively known from New Caledonia and Australia (Great Barrier Reef); this is the first record in the Indian Ocean. The spicule shape, size and the morphology fit the original description of the species. However, Hooper & Levi (1993) recognized two distinct populations, with some morphological differences, one from Queensland and one from New Caledonia. The morphological characters (especially spicule size) make the specimens, here examined, closer to the population from New Caledonia.

On the specimen PO78 the hydroid Zyzzyzus warreni Calder, 1988 (Class Hydrozoa, Phylum Cnidaria) was detected.