Iotrochota birotulata (Higgin, 1877)

Figures 89 a–f

Restricted synonymy:

Halichondria birotulata Higgin, 1877: 296, pl. 14 figs 11–15.

Iotrochota birotulata; Ridley 1884: 443; Van Soest 2002: 598, with further synonyms); Rützler et al. 2007c: 175, figs. 1–3.

Material examined. RMNH Por. 9940, Guyana, ‘Luymes’ Guyana Shelf Expedition, station 63, 7.5833°N 57.0667°W, depth 71 m, sandy bottom, 31 August 1970 .

Description. Two ramose fragments (Fig. 89 a), each about 4 cm long and 0.6–2 cm wide. Surface conulose, with an oscule of 3 mm in diameter. Color greyish black in alcohol. Consistency soft, fragile.

Skeleton. Thick spongin-enforced spicule tracts, 70–200 µm in diameter, cored by 20–30 spicules form a reticulation with elongately squarish meshes of 300–500 x 200–300 µm. No special ectosomal skeleton.

Spicules. (Figs 89 b–f) Styles, strongyles, birotules.

Styles, smooth straight, with conical pointed end, occurring in a longer/thinner category (Fig. 89 b,b1), 232– 262 –284 x 3 – 4.6 –6 µm, and a thicker/shorter category (Fig. 89 c), 178– 184 –192 x 7 – 9.0 –10 µm.

Strongyles, curved, smooth, variably in size and thickness, thicker (Fig. 89 d) and thinner (Fig. 89 e,e1) spicules about equally long, 138– 182 –202 x 2 – 5.4 –7.5 µm.

Birotules (Fig. 89 f), straight shaft, usually about 12 alae, quite uniform in size, 15– 16.2 –18 µm.

Distribution and ecology. Guyana Shelf, Greater Caribbean, NE Brazil, on various bottoms at 0.1–90 m depth (Guyana Shelf 71 m).

Remarks. The specimen keys out in Rützler et al. ’s 2007b key as I. birotulata, having branching habitus and possessing birotules..