Genus Oscarella Vosmaer, 1884

Diagnosis: Homosclerophorida without skeleton, with a variable development of the ectosome with a collagen layer between ecto- and choanosome. The aquiferous system has a sylleibid-like or leuconoid organization, with spherical to ovoid eurypilous or diplodal choanocyte chambers arranged around large exhalants canals (Muricy & Díaz 2002). Mitochondrial genomes that have been sequenced so far encode a gene absent in other animal mitochondrial genomes: tatC (Ereskovsky et al. 2017).