Thyonella Verril, 1872

Martins, Luciana, 2018, Taxonomy of the genus Thyonella (Holothuroidea: Dendrochirotida), with mention of the first record of T. sabanillaensis from the southwestern Atlantic Ocean, Zootaxa 4527 (1), pp. 75-86 : 76

Genus Thyonella Verril, 1872

Type species. Thyonella gemmata ( Pourtalès, 1851) [ Colochirus ] type by original designation.

Included species. Thyonella pervicax ( Théel, 1886) [ Thyone ]; Thyonella sabanillaensis ( Deichmann, 1930) [ Thyone ] and Thyonella mexicana ( Deichmann, 1941) [ Thyonacta ].

Diagnosis. (amended from Panning, 1971). Tentacles 10, ventral-most two much reduced. Calcareous ring not tubular, radial and interradial plates united only at base, posterior processes short or absent. Radial plates undivided, notched anteriorly and interradial plates narrow anteriorly. Body wall ossicles four-holed or multilocular cups, knobbed buttons and perforated plates smooth or knobbed. Tentacle ossicles are a combination of rods, plates and rosettes. The introvert holds a combination of buttons, rosettes and rods. In tube feet end plate rudimentary or absent, and supporting rods present.