Leucaltis clathria Haeckel, 1872

Figures 125 a–g

Leucaltis clathria Haeckel, 1872: 159, pl. 28 fig. 3; Borojevic & Peixinho 1976: 1002, fig. 8; Van Soest & De Voogd 2015: 44, fig. 31.

Material examined. RMNH Por. 9314, Guyana, ‘Luymes’ Guyana Shelf Expedition, station 107, 7.7°N 57.5°W, depth 65 m, muddy sand bottom with shells, 5 September 1970 .

Description. This specimen has been described and pictured previously in Van Soest & De Voogd (2015) (p. 44, fig. 31d), in a comparison with the Indo-West Pacific species Leucaltis nodusgordii (Poléjaeff, 1883) . The habitus, skeleton and spicule details are summarized here, and the illustration is copied from that paper for completeness sake. The habitus (Fig. 125 a) is a mass of dirty-white or light beige (in alcohol) anastomosed, coarse tubes, 5 x 4 x 3 cm in size, individual tubes 5–8 mm in diameter, some are blind-ending, a few are open to form oscules. Skeleton of the tube walls consists of an outer cortical layer formed by the actines of giant tetractines and triactines, a choanosomal layer of small equiradiate tri-and tetractines, and an atrial skeleton of strongly sagittal ‘abruptly curved’ tri-and tetractines. These latter spicules occur in two distinct size categories, which is the main difference with Indo-West Pacific Leucaltis nodusgordii . Spicules (Figs 125 b–g): actines of giant tri- and tetractines: 210–530 x 15–63 µm, actines of small equiangular tri- and tetractines: 40– 55 x 2–3 µm, large abruptly curved triactines (Fig. 125 d) with unpaired actines 111–126 x 6–10 µm, paired actines 122–141 x 8.5–10 µm, small abruptly angled tri- and tetractines with unpaired actines 40– 45 x 3–4 µm, paired actines 50– 65 x 3–4 µm. A few trichoxeas (Fig. 125 g) were found, not certainly proper to the species.

Distribution and ecology. Guyana Shelf, Florida,? Bermuda,? Portugal, NE Brazil, on shelly bottoms at 21–93 m depth (Guyana Shelf 65 m).

Remarks. As pointed out by Van Soest & De Voogd (2015), the present specimen is almost indistinguishable in habitus, size, skeletal structure and spicule categories and sizes from Leucaltis nodusgordii (Poléaeff, 1883) (as Heteropegma). The one obvious difference is the presence in L. clathria of a second category of large ‘abruptly angled’ triactines with actines clearly twice as long and thick as the smaller atrial spicules. These spicules are not very common, so they might have been overlooked in older descriptions, (Haeckel 1872; Borojevic & Peixinho 1976) of this species.