Tylosigma ostreicola, Van, Rob W. M., 2017

Van, Rob W. M., 2017, Sponges of the Guyana Shelf, Zootaxa 1, pp. 1-225: 128-129

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http://doi.org/ 10.5281/zenodo.272951

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scientific name

Tylosigma ostreicola

sp. nov.

Tylosigma ostreicola  sp. nov.

Figures 79View FIGURE 79 a –e

Material examined. Holotype RMNH Por. 9955, Suriname, ‘ Snellius O.C.P.S. ’ Guyana Shelf Expedition, station G7, 7.28°N 56.7933°W, depth 64 m, bottom sand, 7 May 1966GoogleMaps  .

Description. ( Fig. 79View FIGURE 79 a) Encrusting eroded rims and holes of a dead oyster. Surface hispid-conulose. Colour in alcohol beige. Size several mm2. Consistency soft.

Skeleton. ( Fig. 79View FIGURE 79 b) Single tylostyles penetrating the surface, heads embedded in the substratum. Low spicular density. Tissue crowded with sigmas.

Spicules. ( Figs 79View FIGURE 79 c –e) Tylostyles, sigmas.

Tylostyles ( Figs 79View FIGURE 79 c –d), curved, thin, with prominent round tyles, in a large size range, but not clearly divisible in categories, 342– 779 – 1092 x 6 – 9.1 –13 µm (diameter of tyles 8.5–15 µm).

Sigmas ( Fig. 79View FIGURE 79 e), with incurved apices, one of which may be faintly rugose, 16– 21.8 –27 µm.

Distribution and ecology. Guyana Shelf, on a dead shell at 64 m depth.

Etymology. The name ‘ostrea’ (L.) means oyster, and suffix cola (Gr.) means ‘living on’ or ‘in’, together the compound name refers to its habitat.

Remarks. The new species was compared to a slide of Tylosigma campechianum  (originally Hymedesmia campechiana  , see Topsent 1889, p. 14, fig. 8c) in the Paris Museum, registered as MNHN D.T. 1844. The new species differs from it by the lack of a separate small category of tylostyles three/four times as short as the larger tylostyles, and a separate category of very small thick sigmas. The short tylostyles are also provided with a few microspines on the head, which is lacking in the present material. These differences appear too great to assume variability and thus I propose here a new species. Alcolado & Gotera (1986) report T. campechianum  from Cuba (as Desmacella  ).

The two species are of uncertain affiliation, as the tylostyles remind of the genera Eurypon  ( Raspailiidae  ) or Prosuberites  ( Hymerhabdiidae  ), but these genera do not have sigmas or other sigmiform microscleres. A combination of tylostyles and sigmas is found in the family Desmacellidae  and thus I propose to reassign Tylosigma  to that family, until molecular analysis will have been done.


National Museum of Natural History, Naturalis


Museum National d'Histoire Naturelle