The genus Hymerhabdia Topsent, 1892 (Porifera : Halichondrida : Axinellidae) with some remarks on related genera

The genus Hymerhabdia hitherto contained the species H. typica, H. oxytrunc a, H. intermedia, H. contracta, H. papillosa and H. topsenti. Based on our material, a new species is described, Hymerhabdia diversicolor, and H. typi ca and H. papillosa are redescribed. Moreover, it is proposed to synonymize H. oxytrunca and H. typica, and to assign H. topsenti to the genus Bubaris . The new species, N. diversicolor, is distinguished by having very particu lar anisodiametric oxeas, that is, one half tapering to a sharp lanceolate point, the other half uniformly thick and abruptly ending in a tip. This fe ature clearly distinguishes the species from other known species. The affin ity of Hymerhabdia to other closely related genera such as Axinysa, Colloca lypta and Bubaris is discussed based mainly on their different types of spi cules and choanosomal skeletons. Hymerhabdia and Collocalypta have a clearl y plumose choanosomic skeleton, which consists of erect plumose columns of spicules in Hymerhabdia, from which spicule tracts in Collocalypta diverge. In the other genera the choanosomal skeleton is disorganised with spicules strewn in confusion and/or composed of vaguely ascending tracts in Axinyss a, and with a condensed reticulation of flexuous or vermiform strongyles, w ith projecting bundles or individual styles ascending to the surface in Bub aris.