Vosmaeropsis glebula

Van, Rob W. M. & De, Nicole J., 2018, Calcareous sponges of the Western Indian Ocean and Red Sea, Zootaxa 4426 (1), pp. 1-160: 128-130

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Vosmaeropsis glebula


Vosmaeropsis glebula  sp.nov.

Figs 79a–g View Figure

Material examined. Holotype, ZMAAbout ZMA Por. 10608, Seychelles, La Digue Island , S coast, 4.3833°S 55.8333°E, depth 2 m, reef, snorkeling, coll. R.W.M. van Soest, field nrGoogleMaps  . NIOP-E stat. 735/ 28, 23 December 1992.

Paratypes, ZMAAbout ZMA Por. 10553, Seychelles, Aride Island, S coast, 4.2167°S 55.6667°E, snorkeling, coll. J.C. den Hartog, field nrGoogleMaps  . NIOP-E stat. 711/ 12, 18 December 1992; ZMAAbout ZMA Por. 10637, Seychelles, Amirantes , St. François Atoll, Île Bijoutier, depth 3 m, reef, scuba, coll. R.W.M. van Soest, field nr  . NIOP-E stat. 792/ 20, 6 January 1993.

Description. Small lobes and short thick-walled tubes ( Fig. 79a View Figure ), occurring singly or in coalescent groups. The holotype consists of five such lobes, which were originally grouped together. Each lobe or tube carries a terminal oscule. Color in situ yellow-brown, in preservation they are similarly light brown. Size 1–2 cm in height, 0.5–1 cm in diameter, oscules about 2 mm in diameter, flush, without rim or fringe. Consistency soft.

Aquiferous system. Leuconoid.

Skeleton. ( Figs 79b–c View Figure ) In our SEM cross section ( Fig. 79b View Figure ), which is admittedly rather confused, from surface to atrium there is a cortical skeleton of smaller sagittal and larger regular triactines ( Fig. 79c View Figure ), supported by subcortical pseudosagittal triactines replaced by giant triactines in the main skeleton. In the atrial region there are larger triactines rather similar to the cortical triactines but supported by smaller, more or less regular triactines.

Spicules. ( Figs 79d–h View Figure ) Triactines only, tentatively divisible into cortical triactines, giant triactines, pseudosagittal triactines, subatrial triactines and atrial triactines.

Cortical triactines ( Fig. 79d View Figure ), regular, usually with straight actines, intermediate in size, actines 76– 168 –258 x 8 – 15.1 –31 µm.

Pseudosagittal triactines ( Fig. 79f View Figure ), longest actines 270– 474 –662 x 18 – 36.7 –47 µm, middle sized actines 167– 261 –330 x 17 – 32.1 –40 µm, shortest (=unpaired) actines 81– 129 –292 x 18 – 32.8 –41 µm.

Giant or large triactines ( Fig. 79e View Figure ) of the main skeleton, tending to be more or less equiangular and equiradiate, 302– 567 –779 x 32 – 57.4 –78 µm.

Subatrial and atrial triactines ( Figs 79g View Figure ), slightly sagittal, intermediate and smaller triactines, often with incurved paired actines; unpaired actines 93– 141 –233 x 15 – 20.3 –26 µm, paired actines 111– 195 –271 x 15 – 19.6 –24 µm.

Distribution and ecology. Known only from several localities in the Seychelles, reefs, shallow water.

Etymology. Glebula (L.) meaning small lump, referring to the habitus.

Remarks. The new species is assigned to Vosmaeropsis  on account of the confused choanosomal skeleton in combination with pseudosagittal triactines. So far, no Vosmaeropsis  species are known from the Western Indian Ocean (cf. Cavalcanti et al. 2015; Van Soest et al. 2018). The new species differs from most Indo-West Pacific Vosmaeropsis  species, including e.g. V. grisea Tanita, 1939  as described by us from Indonesia (cf. Van Soest & De Voogd 2015), in the lack of (giant) diactines and tetractines. Only two species in that wide area share the lack of diactines and tetractines with our new species. In Philippine deeper water occurs V. connexiva ( Poléjaeff, 1883), which differs from our specimens in the apparent lack of small cortical and atrial triactines, while the pseudosagittal triactines are smaller than those of the new species, with longest actines not exceeding 400 x 20–25 µm (in our specimens up to 662 x 47 µm). The habit of the species is not clear as Poléjaeff only had a few fragments. New Caledonian V. hozawai Borojević & Klautau, 2000  is a larger (5 cm) dark brown, sac-shaped sponge from 20–25 m depth. It differs especially in the much larger size of the giant triactines, which are up to 1500 x 100 µm (ours 779 x 78 µm); likewise the regular cortical and atrial triactines are larger, up to 420 x 17 µm (ours up to 271 x 26 µm). Despite the lack of illustrations for these two species, the differences are here considered sufficiently great to judge them to be different from our new species. In the area considered here there are no reports of additional Vosmaeropsis  species.

Unfortunately, our attempt to obtain a partial 28S sequence of the type material failed.


Universiteit van Amsterdam, Zoologisch Museum