Tethya topsenti, Sarà & Bavestrello & Calcinai, 2000

Sarà, Michele, Bavestrello, Giorgio & Calcinai, Barbara, 2000, New Tethya species (Porifera, Demospongiae) from the Pacific area, Zoosystema 22 (2), pp. 345-354 : 351-354

Tethya topsenti n. sp.

TYPE MATERIAL. — Holotype ( LBIM / N 814 ) labelled “ T. japonica ” from MNHN.

ETYMOLOGY. — After Émile Topsent, the great French spongologist who has contributed greatly to our knowledge of Tethya .

TYPE LOCALITY. — Îlot Testard Sud. Baie de Saint- Vincent, New Caledonia, 17.XI.1961, coll. B. Salvat.

DESCRIPTION

Morphology

Body irregularly globose, about 1.5 cm in diameter with irregular surface and indented tubercles. Smooth, yellow ochre in alcohol. Large cortical lacunae.

Skeleton ( Fig. 7 )

Strongyloxea bundles distorted in their cortical tract running obliquely to the sponge surface. They branch and terminate in fans. Megasters diffused throughout the entire cortex and more rare and scattered in the choanosome. One category of micrasters in the cortex and in the choanosome, where they coat the sponge surface.

Spicules

Main strongyloxeas 800-1500 × 10-26 µm. Often these strongyloxeas have their distal end more or less rounded and are then transformed to anisostrongyles (Fig. 8A). Auxiliary strongyloxeas 450-600 × 3-12 µm. The two categories intergrade.

Megasters. (Fig. 8B-D) Spherasters 15-70 µm (generally 30-60) in diameter. R/C = 0.4-0.8. Size variable with many young spicules. In the choanosome 15-44 µm in diameter with R/C = 0.2-0.5. Ray number 16-22. The short rays are conical but sometimes flask-shaped.

. Micrasters. (Fig. 8E, F) Tylasters generally 10- 12 µ m both in the cortex and in the choanosome. The more frequent shape has rays rather thick with a swollen tylote tip formed by a tuft of spines which are lacking on the stem. Variants have more slender, and sometimes tapering rays with less distinct terminal knobs. Ray number is generally eight to ten, with a range from six to ten. In two spicular slides we found chiasters with short rays and a big centrum, 15 µ m in diameter. As they are absent in the other spicular slides and in the sponge sections, they are likely foreign to this species.

REMARKS

T. topsenti is only roughly similar to T. japonica Sollas, 1888 but can be separated by the clear distinction in the size and shape of its micrasters. The tylasters of topsenti have a greater size, stouter and shorter rays, and more distinct terminal knobs. Other distinctive traits in T. topsenti are the megaster distribution and the megaster shape; the megasters are present throughout the whole cortex and even the choanosome and have shorter rays. T. topsenti is comparable to T. deformis Thiele, 1898 for the irregular body shape and distorted megasclere bundles, but these growth characters occasionally occur in a range of different species. In spicular traits, as the tylasters thick rays and absence of a centrum, T. topsenti is different from T. deformis .

Other Tethya species described from New Caledonia are T. levii Sarà, 1992 and T. novaecaledoniae Sarà, 1992 , both from deep waters, and T. sollasi Bergquist & Kelly-Borges, 1991 found under plate-coral rubble of intertidal flats. From this last species T. topsenti differs in several traits but especially for the micrasters features, and for the lack of a category of small microxyasters.

Figures

FIG. 7. — Tethya topsenti; schematic drawing of the skeletal arrangement Scale bar: 0,2 mm.