Leucetta microraphis Haeckel, 1872

Van, Rob W. M. & De, Nicole J., 2018, Calcareous sponges of the Western Indian Ocean and Red Sea, Zootaxa 4426 (1), pp. 1-160 : 80-82

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 .

Figures

FIGURE 1. Marine Ecoregions in the Western Indian Ocean with localities (numbered blue squares) from where the studied calcareous sponges were obtained. 1, Israelian Red Sea, Gulf of Aqaba, 2, Saudi Arabian Red Sea, off Jeddah, 3, Eritrean Red Sea, Dahlak Archipelago, 4, Oman, Gulf of Arabia, 5, Maldives, 6, India, Lakshadweep, 7, Seychelles, Mahé region, 8, Seychelles, Amirantes, 9, Mayotte, 10, Mozambique Channel, 11, Mauritius, 12, Rodrigues, 13, South Africa, Kwazulu Natal, 14. South Africa, Port Elizabeth, 15. Nosy Be, Madagascar.

FIGURE 2. Maximum-likelihood tree based on analysis of sequences of the partial 28S gene (C2–D2 region, comprising 442 sites) of Western Indian Ocean Calcinea newly generated by the Naturalis Biodiversity Center and sequences additionally obtained from GenBank, the Sponge Barcode Project and from Oliver Voigt (München) from the Red Sea, Indonesia, Australia, and a few sequences from other parts of the world, to demonstrate the affiliation of the compared species. Please note that Arturia sequences do not appear in the same clade, indicating Arturia is non-monophyletic. Numbers at the root of clades are bootstrap values of 1000 replicates. Since the high number of sequences were difficult to read in detail, we subdivided the present tree in three detailed sections 2A, 2B, and 2C.

FIGURE 45. Leucetta microraphis Haeckel, 1872, from Mayotte and Madagascar, a–d, habitus in situ (photos N.J. de Voogd and A. Bialecki), a, Mayotte RMNH Por. 8341, b, ditto, c, Mayotte RMNH Por. 8318, d, Madagascar RMNH Por. 8717, e, Mayotte RMNH Por. 8341, on deck, f, Mayotte RMNH Por. 8341, SEM image of overview of the spicules showing giant and small triactines from the main skeleton, and tetractines (arrows) from the atrial wall.

FIGURE 46. Leucetta microraphis Haeckel, 1872, RMNH Por. 8318 from Mayotte, a, light microscopic overview of surface skeleton, b–e, SEM images of the spicules, b, giant triactine, c, small triactines, largest sizes, c1, small triactines, smallest sizes, d, tetractines, e, detail of apical actine of tetractine.