Leucandra aff. hentschelii Brøndsted, 1931

Figures 132 a–h

? Leucandra hentschelii Brøndsted, 1931 (1929): 40, fig. 31;

Leuconia hentschelii; Borojevic & Peixinho 1976: 1030, fig. 26.

Material examined. RMNH Por. 9740, Guyana, Guyana, ‘Luymes’ Guyana Shelf Expedition, station 103, 7.9°N 57.5167°W, depth 85 m, triangular dredge, 4 September 1970.

Description. (Fig. 132 a) Thin tube with rough surface, sitting on a dead coral branch. Length of tube 12 mm, diameter 2.5 mm, atrial opening less than 0.5 mm. Color (in alcohol) dirty white, consistency firm.

Skeleton. The cortical region (Fig. 132 b) is built of tangentially arranged large sagittal triactines (occasionally also tetractines), overlying tangential giant triactines of the subcortical region. The choanosomal region is supported by small triactines, the atrial skeleton consists of similar triactines and small tetractines.

Spicules. (Figs 132 c–h) Triactines of various sizes and shapes, tetractines.

Large triactines (Fig. 132 c) of the cortical region, sagittal, with straight unpaired actines, 183– 306 –426 x 12 – 15.6 –20 µm, and curved paired actines, 177– 259 –354 x 11 – 14.5 –21 µm.

Giant triactines (Fig. 132 d) of the subcortical region, sagittal or almost equiangular, unpaired actines sharply pointed, paired actines often blunt, 326– 504 –710 x 15 – 34.4 –55 µm, paired actines 164– 325 –594 x 15 – 31.9 –53 µm.

Large tetractines (Fig. 132 e) of the cortical region, rare, equiangular (n=3), actines of the basal radiate system 200–220 x 12–15 µm, apical actines up to 59 x 9 µm.

Small triactines of the choanosomal region (Figs 132 f), sagittal, often almost T-shaped, unpaired actines 36– 59 – 84 x 6 – 8.6 –12 µm, paired actines 69– 93 –121 x 5 – 8.4 –13 µm.

Small triactines of the atrial region (Fig. 132 g), sagittal, not easily distinguished from the choanosomal triactines, but tending to have three unequal actines, unpaired actines 80– 96.4 –144 x 6 – 8.2 –11 µm, paired actines 63– 81 –101 x 6 – 7.4 –8.5 µm.

Tetractines of the the atrial region (Fig. 132 h), sagittal, unpaired actines 46– 77 –120 x 6 – 7.4 –11 µm, paired actines 43– 80 –111 x 5 – 7.2 –9 µm, apical actines, 18– 28 – 39 x 5 – 7.1 –8 µm.

Distribution and ecology. Guyana Shelf, NE Brazil, gravel bottom at 14–85 m depth (Guyana Shelf 57–85 m).

Remarks. The present identification is uncertain. The species was originally described from South Africa, at considerable distance from the Guyana Shelf. Borojevic & Peixinho (1976) record this species from NE Brazil, and their description conforms to a large extent to the Guyana material. Differences are the greater length of the actines of the giant triactines (up to 900 x 60 µm) and the general diversity of triactines and tetractines, which seems smaller than in the present specimen. Still, among the known Brazilian and Caribbean Leucandra ’s this is the only one lacking diactines, like the present specimen. The correspondence with Borojevic & Peixinho’s (1976) specimens, however, still does not mean the Central West Atlantic material conforms to the South African specimens of Brøndsted. It is likely that the two are different species, e.g. because tetractines are apparently rare in Brøndsted’s type material. Borojevic (1967) described specimens from South Africa under this name, but he mentioned the presence of microdiactines, not reported by Brøndsted.

There is also a rather close similarity with Leuconia typica Poléjaeff, 1883. Poléjaeff described this species from Bermuda in two varieties, the var. tuba (conforming to the present form) and the var. massa. Poléjaeff did not indicate which of his varieties is the typical variety, which would then take the name of the species, Leucandra typica typica. The various authors that treated this species ignored the varieties or considered them as belonging to the same species. The properties of the present specimen conform fairly well to those of the tubiform variety with a few exceptions: Poléjaeff mentioned the presence of diactines in the choanosome, which are lacking from the present material. The size range of the choanosomal triactines including sagittal smaller triactines is not clearly mentioned, as only the upper size, here called giant triactines is given by Poléjaeff. Von Lendenfeld’s (1885) (p. 1130) record of the species from the east coast of Australia differs considerably from both Poléjaeff’s and the present specimen, and it is unlikely to be the same species.

Other reports of Leucandra species from the Central West Atlantic differ by having large diactines as a prominent part of the spiculation.