Leucandrilla wasinensis (Jenkin, 1908)

Figs 64a–e, 65a–g.

Leucilla wasinensis Jenkin, 1908: 454, figs 104A–B.

Leucandra wasinensis; Dendy 1913: 24, pl. 2 fig. 5.

(Not: Leuconia wasinensis; Burton 1959: 181 = Sycettusa cf. simplex).

Material examined. ZMA Por. 11561, Seychelles, Amirantes, N of Poivre island, 5.7°S 53.3°E, depth 42–45 m, calcareous gravel bottom , 2.4 m Agassiz trawl, coll. R.W.M. van Soest, field nr. NIOP-E stat. 776/ 21, 31 December 1992.

Description. White, sycon-like sponge (Fig. 64a), with prominent fringe and hairy surface. Size 2 cm high, 1.2 cm in diameter, atrial lumen 1–2 mm in diameter. Consistency firm.

Aquiferous system. Leuconoid.

Skeleton. (Figs 64b–e) The cortical region (Figs 64b–c) consists of a layer of smaller triactines covering a layer of subcortical tetractines. The cortical skeleton is pierced by single giant diactines causing the hispidation. The main skeleton (Fig. 64b,d) contains a mass of large and small triactines, and some tetractines. The atrial skeleton (Fig. 64d) consists of smaller tri- and tetractines. The fringe (Fig. 64e) consists of a mixture of giant diactines, trichoxeas and sagittal tri– and tetractines.

Spicules. (Figs 65a–g) Triactines, tetractines, giant diactines, trichoxeas.

Large triactines (Fig. 65a), equiangular, usually slightly sagittal, actines 286– 340 –448 x 21 – 30.9 –38 µm.

Smaller cortical and choanosomal triactines (Fig. 65b), 210– 241 –279 x 18 – 25.5 –31 µm.

Smaller choanosomal and subatrial triactines (Fig. 65c), sagittal or irregular, unpaired actines 122– 170 –203 x 14 – 18.1 –22 µm, paired actines 63– 171 –249 x 12 – 16.4 –21 µm.

Large subcortical tetractines (Figs 65d), sagittal, unpaired actines 212– 389 –521 x 11 – 20.4 –26 µm, paired actines 116– 194 –252 x 10 – 17.6 –24 µm, apical actines 12– 49 – 66 x 4 – 5.9 –9 µm.

Small atrial tetractines (Figs 65e), sagittal, with curved paired actines, and straight or curved apical actines; unpaired actines 32– 97 –164 x 4 – 8.7 –14 µm, paired actines 49– 105 –136 x 4 – 8.4 –11 µm, apical actines 38– 61 –112 x 4 – 7.2 –10 µm.

Trichoxeas (Fig. 65f), straight, thin, invariably broken in the slides, fragments 200–515 x 2–5 µm.

Giant diactines (Figs 65g), curved, endings tapering to sharp points, 1390– 2072 – 2520 x 20 –52.3–62 µm.

Distribution and ecology. Seychelles, Wasini Island off Kenya, Saya de Malha, on gravelly bottom at greater depth (> 40 m). Burton (1959) reported Leuconia wasinensis from the South Arabian region (38 m), but he did not provide a description. Its identity was re-examined and the record is reassigned here, see below.

Remarks. The specimen described above resembles previous descriptions of Jenkin (1908) and Dendy (1913) in most details. Jenkin’s material had the larger triactines up to 950 x 40 µm (in our material 448 x 38 µm). Likewise, the subcortical tetractines of Jenkin’s specimen were larger, up to 700 x 28 µm (ours 521 x 26 µm), and also the atrial tetractines were considerably larger than ours. Dendy’s (1913) decription lacks detailed spicule measurements, but he admits that the spicules of his specimen were ‘a good deal smaller’ than Jenkin’s. We assume here that spicule sizes are subject to variation.

Burton (1959) recorded this species (as Leuconia), but after re-examination this was found to be very similar to Sycettusa simplex (Jenkin, 1908), see the Remarks of that species below.

Unfortunately, our attempt to obtain partial 28S sequences of this species failed.