Diagnosis. Several cerata per row in unbranched rows, notal edge completely reduced, anus acleioproctic, pharynx narrow, radula uniserial, central teeth with predominantly low cusp and long lateral denticles, penial (supplementary) gland inserts to the penis base, penis bear hollow stylet.
Included genera. Catriona Winckworth, 1941, Diaphoreolis Iredale & O'Donoghue, 1923, Phestilla Bergh, 1874, Tenellia Costa, 1866, Trinchesia Ihering, 1879, Zelentia gen. nov.
Remarks. See under Discussion. Comparison of the diagnostic characters of the family Trinchesiidae is presented in the Table 2.