A full description of the subadult male holotype of the diastylid Ektonodia
stylis robusta, new genus, new species, is presented, as well as of the adu
lt male and adult female of E. nimia. Ektonodiastylis nimia is transferred
from Brachydiastylis to Ektonodiastylis. The family definition of Diastylid
ae is expanded. The implications of this expansion on the systematics of th
e Cumacea in general, and Diastylidae and Gynodiastylidae in particular, ar
e discussed.