Leucetta sulcata

Van, Rob W. M. & De, Nicole J., 2018, Calcareous sponges of the Western Indian Ocean and Red Sea, Zootaxa 4426 (1), pp. 1-160: 85

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Leucetta sulcata


Leucetta sulcata  sp.nov.

Figs 49a–dView FIGURE 49, 50a– dView FIGURE 50

Material examined. Holotype, RMNHAbout RMNH Por. 11639, Mauritius, Rodrigues, Mourouk Ebony, Castel Rock , 19.76203°S 63.46273°E, depth 10 m, scuba, coll. N.J. de Voogd, field nr. ROG042, 17 October 2016.GoogleMaps 

Paratypes, RMNHAbout RMNH Por. 11643, Mauritius, Rodrigues, Mourouk Ebony, Castel Rock , 19.76203°S 63.46273°E, depth 10 m, scuba, coll. N.J. de Voogd, field nr. ROG046, 17 October 2016GoogleMaps  ; RMNHAbout RMNH Por. 11645, Mauritius, Rodrigues, Mourouk Ebony, Castel Rock , 19.76203°S 63.46273°E, depth 10 m, scuba, coll. N.J. de Voogd, field nr. ROG048, 17 October 2016GoogleMaps  .

? Additionally : ZMAAbout ZMA Por. 1 6368, Madagascar, Nosy Bé, Ambariobé, N of Kosy Komba, depth 6–8 m, scuba, coll. J.H. Stock, 28 December 1963. 

Description. The in situ shape is a massive lumpy sponge ( Fig. 49aView FIGURE 49) with irregular grooves and deep holes. Live color pale greyish white with pink rims in the peripheral parts. Surface irregular, in places somewhat conulose. Oscules inconspicuous, almost flush with the surface. Color of specimens on deck ( Fig. 49b–cView FIGURE 49) and preserved ( Fig. 49dView FIGURE 49) remains the same. Size of preserved specimens up to 13 x 8 x 8 cm, oscules 5 mm in diameter. Grooves and ridges up to 1 cm wide. Consistency coarse, harsh and hard.

Aquiferous system. Leuconoid.

Skeleton. A dense mass of giant triactines and small triactines. The oscules lead to into round atrial cavities lined with tetractines and triactines.

Spicules. ( Figs 50a–dView FIGURE 50) Giant triactines, small triactines, tetractines.

Giant triactines ( Figs 50aView FIGURE 50) equiradiate, equiangular, 408– 984 –1380 x 43 – 107.2 –204 µm.

Small triactines ( Figs 50bView FIGURE 50) equiradiate, equiangular, 124– 186 –241 x 10 – 16.8 –22 µm; small sagittal triactines with wavy paired actines (not shown), 83– 106 –133 x 7 – 10.2 –14 µm.

Tetractines ( Figs 50c–dView FIGURE 50) with basal triradiate system similar to triactines, 102– 163 –204 x 9 – 12.6 –16 µm, apical actines thin, curved ( Fig. 50dView FIGURE 50), 29– 58 – 96 x 3 – 5.2 –8 µm.

Distribution and ecology. Rodrigues, possibly Madagascar, on reefs in shallow depth.

Etymology. Sulcatus (L.) meaning grooved, referring to the habitus.

Remarks. The spicule sizes and shapes are similar to those of Leucetta microraphis  , to which the present species is most closely related. Two small irregular fragments of a white sponge, ZMAAbout ZMA Por. 16368, collected near Nosy Bé, Madagascar, could belong to the present species based on its skeleton and spicules, but the small material without a definite shape precludes a definite conclusion.

We obtained sequences of the holotype and two of the paratypes and in our phylogenetic analysis ( Fig. 2CView FIGURE 2) they grouped together (at 85% bootstrap value) in a larger clade containing sequences of L. microraphis  from Mayotte, Madagascar, Australia and the Red Sea. Aligned and trimmed sequences of this larger L. microraphis  - group (length 396 sites), showing 19 non-conserved sites, resulted in observed differences of 2–8 sites between L. sulcata  sp.nov. and various sequences of L. microraphis  s.l. The four sequences of L. sulcata  sp.nov. shared two unique non-conserved sites. The three sequences of L. microraphis  with pinkish red-brown-green color, described above from Mayotte and Madagascar, shared three unique non-conserved sites. These were not shared by the one Indonesian sequence of a specimen with similar morphology as the Mayotte and Madagascar specimens.

Remarkably, Oliver Voigt’s Red Sea sequences did not have any uniquely shared sites, individual sequences sharing non-conserved sites variously with L. sulcata  sp.nov. or Western Indian Ocean L. microraphis  , and the Australian and Indonesian sequences. Clearly, the morphological discrepancies and inconsistencies in L. microraphis  s.l. are not easily solved by molecular sequence data. L. microraphis  s.l. are likely a complex of sister species. The morphological differences of the present new species (white color, grooved and holed habitus) with L. microraphis  s.s. (pinkish red-brown-green tubular masses) preclude conspecificity. The pink-white Red Sea specimens and L. pyriformis  specimens described above are additional members of the group, differing in shape, color and e.g. in the long straight vs. curved condition of the apical actines of the tetractines. More study is necessary to differentiate the species.

Leocorny et al. (2016) recently studied the Leucetta  species from (sub-)tropical Australian waters: Leucetta prolifera ( Carter, 1878)  (originally as Teichonella  ), L. insignis Row & Hozawa, 1931  , L. infrequens Row & Hôzawa, 1931  , L. expansa Row & Hôzawa, 1931  , L. villosa Wörheide & Hooper, 1999  , L. foliata Leocorny et al., 2016  and L. purpurea Leocorny et al., 2016  . Of these species, two are slightly similar to the new species in having a folded habitus, L. prolifera  and L. foliata  , but the former has the folds broadly bladed with rows of oscules on the upper surface of the folds, whereas the latter has the folds sharply and thinly bladed. Both do not really resembly the irregularly grooved-holed specimens of the new species. Both species have next to the usual complement of giant triactines, small triactines and small tetractines also large tetractines of the same size or larger as the giant triactines. The remaining species have a more compact or globular habitus, also unlike our new species: L. insignis  is shaped like L. chagosensis  but has tripod-like giant triactines, L. infrequens  is a small erect clump, which apparently lacks small tetractines, L. expansa  is also a small, but squat clump, possessing ectosomal microdiactines in addition to the usual spicule complement, L. villosa  is provided with villous hair-like outgrowths on the surface, and finally L. purpurea  is a small globular purple-colored sponge with giant tripods, sharing this feature with L. insignis  .


National Museum of Natural History, Naturalis


Universiteit van Amsterdam, Zoologisch Museum