Iotrochota birotulata ( Higgin, 1877 )

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 143-144

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..

Figures

FIGURE 89. Iotrochota birotulata (Higgin, 1877), a, habitus of RMNH Por. 9940 (scale bar = 1 cm), b – f, SEM images of spicules, b, long thin style, b 1, details of b, c, short thick style, d, thick strongyle, e, thin strongyle, e 1, detail of e, f, birotule.