Hymedesmia is a genus of sponges belonging to the family Hymedesmiidae. The genus is divided into two subgenera, Hymedesmia (Hymedesmia) for species with microscleres, usually chelae, and Hymedesmia (Stylopus) for species lacking microscleres and having only acanthostyles and smooth spicules which are described as tylotes, tornotes or oxea, but are clearly homologous. This distinction is probably artificial and the genus is in need of revision.

The genus has cosmopolitan distribution.

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