Sycetta Haeckel, 1872

Borojevic, Radovan, Boury-Esnault, Nicole & Vacelet, Jean, 2000, A revision of the supraspecific classification of the subclass Calcaronea (Porifera, class Calcarea), Zoosystema 22 (2), pp. 203-263 : 217-218

Genus Sycetta Haeckel, 1872

TYPE SPECIES. — Sycetta sagittifera Haeckel, 1872 by subsequent designation (this work).

DIAGNOSIS. — Sycettidae with a central atrial tube decorated with short, completely separate radial tubes. There is no defined inhalant aquiferous system. The skeleton of the radial tubes is composed of triactines and tetractines, and diactines may be found in the distal cones.

DESCRIPTION

The genus Sycetta , as defined by Dendy & Row (1913), comprised three species described under the names Sycetta primitiva Haeckel, 1872 , S. sagittifera Haeckel, 1872 and Sycaltis conifera Haeckel, 1872 . Dendy & Row 1913 designated Sycetta primitiva as the type species. Haeckel (1872) characterized this species by the presence of regular, equiangular and equiradiate spicules, which are clearly described and represented as such in the corresponding figure. In the same figure, Haeckel (1872: vol. III, pl. 41) shows that the choanocytes are closer to the basinucleate than to the apinucleate type. Although Haeckel’s descriptions may be taken with some reservation, and S. primitiva has not been observed since that time, the original description indicates quite clearly that this is a calcinean sponge, and should be classified as a typical member of the family Levinellidae (Borojevic & Boury-Esnault 1986) . Haeckel (1872) classified Sycetta primitiva in the subgenus Sycettaga , and we propose to transfer it as a genus to the family Levinellidae , with a single species Sycettaga (Sycetta) primitiva Haeckel, 1872 . Sycetta sagittifera being an originally included nominal species is designated here as the type species of Sycetta . This species displays all the characteristics of the genus as understood by Dendy (1893), Dendy & Row (1913), and subsequent authors.

BrØndsted (1931) described two sponges from the Deutsche Südpolar Expedition collection, Sycetta antarctica and Tenthrenodes primitivus . Whilst the former one is a typical Sycetta , the latter is characterized by the presence of diactines and the occasional coalescence of the radial tubes, which, however, are not fused. We have now placed the genus Tenthrenodes Jenkin, 1908 in synonymy with Sycantha Lendenfeld, 1891 . Tenthrenodes primitivus BrØndsted, 1931 is however much closer to a typical Sycetta and we propose to transfer this species to the genus Sycetta . Sycetta (Tenthrenodes) primitiva (BrØndsted, 1931) should be distinguished from Sycettaga (Sycetta) primitiva Haeckel, 1872 , which belongs now to the family Levinellidae . Dendy & Row (1913) specified that sponges in the genus Sycetta have no diactines, as all the sponges described in the genus up to their time were devoid of them. Their presence in Sycetta primitiva (BrØndsted, 1931) leads us to modify this point accordingly in the definition of the genus Sycetta .