Tylosigma Topsent, 1894

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

Genus Tylosigma Topsent, 1894

Remark. The genus Tylosigma was synonymized with Hymedesmia (Hymedesmia) in the Systema Porifera (chapter Hymedesmiidae by Van Soest 2002b), but it is here proposed to be revived as a valid genus. The discovery of a second species with similar characters as the type species H. campechiana Topsent, 1889 , and the considerable difference with Hymedesmia s.s. (no tornotes, no echinating acanthostyles) support the valid status. The definition of the genus Tylosigma needs emendation from Topsent’s original definition: Desmacellidae (?) with single tylostyles erect on the substratum, pointed ends outwardly directed, and with sigmas as microscleres.

Type species Hymedesmia campechiana Topsent, 1889 .