Halicnemia

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225 : 53

Halicnemia sp.

Figures 34 a–c

Material examined. RMNH Por. ex 9973 (slide only), Suriname, ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station B23A, 7.297°N 55.3883°W, depth 99–101 m, Van Veen grab, 27 April 1966 .

Description. Encrusting, hispid. The tiny specimen was so small that no material was left after light microscopic and SEM slides had been made. No further material of this species was found after a careful search.

Skeleton. No details can be provided, but presumably the megascleres were arranged perpendicularly on the substratum, with acanthoxeas scattered in the near-substratum part of the sponge.

Spicules. ( Figs 34 a–c) Tylostyles, tornotes, acanthoxeas.

Tylostyles ( Figs 34 a,a1) long straight, except near the tyles where a slight gradual bend may be present, with prominent globular heads, 1344– 1843 – 2286 x 15 – 19.3 –28 µm.

Tornotes ( Figs 34 b,b1) with a peculiar twisted bend in the middle, occasionally with an additional central tyle, 663– 1009 –1236 x 8.5– 12.5 –15 µm.

Acanthoxeas ( Figs 34 c), curved gradually or more often with angular bend in the middle, provided with strong conical spines, 78– 91 – 97 x 5.5– 7.4 –10 µm.

Distribution and ecology. Guyana Shelf, sandy bottom, at around 100 m depth.

Remarks. This is the first record of the genus Halicnemia in the Western Atlantic. The genus has a chequered distribution in the Northwest Atlantic, Western Indian Ocean and South East Pacific ( Van Soest et al. 2016). The present species stands out among the known species of Halicnemia by the twisted bends in the tornotes. It is doubtless an undescribed species, but I refrain from naming it in the absence of a proper specimen.

Figures

FIGURE 34. Halicnemia sp., a – c, SEM images of spicules, a, tylostyle, a 1, detail of a, b, tornote, b 1, detail of b, c, acanthoxeas.