Leucascus schleyeri

Van, Rob W. M. & De, Nicole J., 2018, Calcareous sponges of the Western Indian Ocean and Red Sea, Zootaxa 4426 (1), pp. 1-160: 73-76

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Leucascus schleyeri


Leucascus schleyeri  sp.nov.

Figures 41a–g View Figure , 42a–h View Figure

? Clathrina reticulum  ; Borojević 1967: 189, fig. 2 (not: Schmidt 1862).

Clathrina aff. reticulum  ; Rudi et al. 2000: 1434.

Material examined. Holotype, ZMAAbout ZMA Por. 15734, South Africa, Kwazulu Natal, Sodwana Bay, 27.55°S 32.6833°E, coral reef, depth 22–27m, scuba, coll. M. Schleyer, field nr. TASA53 -S52, year 2000, undated.GoogleMaps 

Description. Massive lobate cormus ( Fig. 41a View Figure ), consisting of densely and tightly anastomosed tubuli, with oscules on top of the lobes leading to atrial spaces. Color pink in situ. Preserved material consists of two fragments, each 2 x 2 x 1 cm of the much larger specimen, estimated to be 6 x 4 x 2 cm, most of which was used for natural products research. The preserved fragments are white or cream colored ( Fig. 41b View Figure ) and comprise several contracted lobes.

Aquiferous system. Asconoid, limited to the anastomosed tubuli.

Skeleton. In cross section ( Figs 41c–d View Figure ) the skeleton shows the dense arrangement of contracted tubuli of 0.1–0.2 mm in diameter surrounding shallow atria ( Fig. 41d View Figure ). The atrial walls are separated from the walls of the tubuli by their own layer of tri- and tetractines, as is visible in some parts of Figs 41c–d View Figure . There is a cortical surface layer ( Figs 41e–f View Figure ) recognizable by the presence of erect banana-shaped diactines, detailed also in Figs 15c–d View Figure . The walls of the tubuli are built by several layers of triactines and tetractines. The latter protrude with their apical actines into the tubule lumen ( Fig. 42a View Figure ). We noticed the presence of parasitic or commensal copepods in the cormus ( Fig. 42b View Figure ).

Spicules. ( Figs 42e–h View Figure ) Triactines and tetractines, the latter with spined apical actines.

Triactines ( Fig. 42e View Figure ) equiradiate and equiangular, with cylindroconical actines measuring 54– 74.6 – 90 x 4.5– 6.7 –8.5 µm.

Tetractines ( Figs 42f–g View Figure ) similar in shape and size to the triactines, occasionally somewhat sagittal, with thin straight apical actines provided with three rows of strong spines the position of which is matching the basal triradiate system ( Figs 42g View Figure ), actines of the basal triradiate system 63– 78 – 91 x 5 – 6.5 –8.5 µm, apical actines 31– 49 – 76 x 2 – 4.4 –7 µm.

Diactines, asymmetrical, curved, ‘banana’-shaped, often eroded (probably artefactual) and grooved, 48– 76 – 98 x 8 – 9.6 –12 µm.

Distribution and ecology. Natal coast of South Africa, deep reef.

Etymology. Named after Dr Michael Schleyer, Oceanographic Research Institute, Durban, South Africa, who collected the material, and in recognition of his important work on the marine ecology of South Africa.

Remarks. Although we do not have molecular sequence data for this specimen, the overall similarity of the present material with Leucascus  , reviewed by Cavalcanti et al. (2003), makes it likely that the present new species is also a member of that genus. Our SEM cross sections ( Figs 41c–d View Figure ) show the characteristic structure of short atrial cavities surrounded by tightly anastomosed tubuli, with the whole cormus covered with a cortex of erect short diactines. Of the described species of Leucascus  , only South Australian L. clavatus Dendy, 1892  possesses diactines, but these are much larger and thicker (350–850 x 99 –140 µm) than those of the new species, while also the tri- and tetractines are significantly larger (actines 70–160 x 9–19 µm).

Borojević (1967) reported Ascaltis reticulum ( Schmidt, 1862)  (as Clathrina  ) from South Africa, from both the Indian Ocean coast (‘Natal shore’) and from the Atlantic coast (False Bay). He gave a general description for these specimens, which fits our material except for the diactines, which measured 100–200 x 15–20 µm, well in excess of our diactines. No mention was made of spines on the apical actines of the tetractines. A. reticulum  is originally described from the Mediterranean ( Schmidt, 1862). It is possible that at least the Natal specimens could be conspecific with our specimen rather than with A. reticulum  . Klautau et al. (2016) redescribed Adriatic Ascaltis reticulum ( Schmidt, 1862)  and provided molecular sequence data. The spicule types and sizes described by Klautau et al. conform rather closely to those cited above for our specimen, except for the diactines which were longer and thinner (60–142 x 4–6 µm) and not eroded. Of course, Ascaltis  differs from Leucascus  in lacking a lined atrial cavity ( Borojević et al. 2002a), and generally is less elaborate in shape and structure. Molecular sequence data of Ascaltis reticulum  provided by Klautau et al. (2016), and downloaded from GenBank were found to group at a rather low bootstrap value with sequences of the Indonesian Leucascus flavus  described by us previously (Van Soest & De Voogd, 2015) in our Calcinea phylogeny ( Fig. 2C View Figure ). This would confirm a close relationship of Ascaltis  and Leucascus  as postulated by Borojević et al. (2002a). Nevertheless, there are no molecular sequence data available for the type species of Ascaltis  , A. lamarcki ( Haeckel, 1872)  , so the true affiliation of Leucascus  and Ascaltis  remains uncertain.

Dendy’s (1913) Leucosolenia gardineri  from the Western Indian Ocean on paper looks close to the present new species, the major obvious difference appearing to be the lack of banana-shaped diactines in L. gardineri  . The species is currently assigned to Ascaltis  .

Novel natural products, clathculins A and B, have been described from this specimen by Rudi et al. 2000.


Universiteit van Amsterdam, Zoologisch Museum














Leucascus schleyeri

Van, Rob W. M. & De, Nicole J. 2018


Clathrina reticulum

: 189


Clathrina aff. reticulum

: 1434