Leucetta microraphis Haeckel 1872

Leucetta microraphis Haeckel, 1872

Figs 45a–f, 46a–e

Leucetta primigenia var. microraphis Haeckel, 1872: 119, pl. 21 figs 10–17.? Leucandra primigenia var. microraphis; Row 1909: 186. Leucetta microraphis; Van Soest & De Voogd 2015: 54, figs 39a–d, 40a–d, with further synonyms. Material examined. RMNH Por. 8318, Mayotte, Ankazoberavina, Roland Point, 12.9731°S 44.9793°E, coll. A. Bialecki, field nr. MAY01 -018, 4 May 2013; RMNH Por. 8341, Mayotte, Passe Boueni Sud, 12.9265°S 44.9668°E, coll. A. Bialecki field nr. MAY03-41, 5 May 2013; RMNH Por 8717, Madagascar, Riva Be, 12.9849°S 48.3910°E, depth 2–3 m, coll. A. Bialecki, field nr. MAD12-IM047, 27 December 2012.

Description. Because this species was extensively treated recently by Van Soest & De Voogd (2015), we provide here only a summary treatment. The in situ habitus (Figs 45a–d) with its pinkish red-green-brown masses of tubular outgrowths with lighter colored undersides and tube rims, is quite characteristic, leaving no doubt that it is conspecific with Indonesian specimens previously described by us. Tubular outgrowths are 3–6 cm high and 1–2 cm in diameter. Surface optically smooth, but rough. Consistency is firm. On deck habitus (Fig. 45e) similar in color to in situ habitus.

Aquiferous system. Leuconoid

Skeleton. (Figs 45f, 46a) A dense mass of triactines of various sizes, with tetractines lining the atrial cavities. Giant triactines concentrated at the surface.

Spicules. (Figs 46b–d) These include a large size range of giant triactines, small triactines, and tetractines.

Giant triactines (Fig. 46b), equiradiate, equiangular, actines measuring 480– 846 –1260 x 65 – 107 –155 µm

Small triactines (Figs 46c,c 1), equiradiate, equiangular, possibly in two overlapping sizes, actines measuring overall 124– 171 –216 x 10 – 15.1 –22 µm.

Tetractines (Figs 46d), basal triadiate system with actines 78– 119 –148 x 8 – 10.3 –12 µm, apical actines wobbly (Fig. 46e) or curved, relatively small and thin 14– 36 – 48 x 4 – 5.7 –7 µm.

Distribution and ecology. Mayotte, Madagascar, Red Sea, Indonesia, Australia, Papua New Guinea, New Caledonia, on reefs in shallow depths.

Remarks. This species is reported throughout the Indo-West Pacific tropical region, but the identities of all these records need critical re-examination. The present specimens conform closely in habitus and color to the Indonesian specimens described by us previously (Van Soest & De Voogd 2015), but the giant triactines are smaller and thinner in the present specimens. The habitus does not seem to match in some aspects with e.g. Wörheide & Hooper’s (1999) Australian record and with Voigt et al. ’s (2017) Red Sea records, as these specimens lack the redbrown-greenish pink-with-white coloration characteristic of our concept of this species. Spicule sizes of the triactines of these latter records do match better with those of the present specimens. Critical comparison with uniformly pinkish white specimens is made below.

We obtained partial 28S rRNA sequences from several Western Indian Ocean specimens (Mayotte and Madagascar), downloaded several more from Indonesia and Australia. Oliver Voigt’s Red Sea sequences were made available to us. All are presented in Fig. 2C. They are discussed below in the Remarks of a new species, L. sulcata sp.nov. from Rodrigues.

Row’s (1909) records of two specimens from the northern and southern parts of the Red Sea were not described, so these remain incertae sedis.

Thacker et al. (2013) reported the West Indian species Leucetta primigenia Haeckel, 1872 from Malaysia. This likely concerns Leucetta microraphis.