Females: In lateral view distal part of seminal receptacles not bilobed. More characters can be accessed by backtracking the key:
Males of Subeucalanus are poorly known morphologically, and their morphology is also highly variable. The following males cannot be separated in the identification key, but their sizes and figure references are as follows:
Subeucalanus pileatus (total length 1.80-2.25 mm);
Subeucalanus monachus (total length 2.2 mm);
Subeucalanus longiceps (total length about 3.2 mm);
Subeucalanus crassus (total length 2.9-3.1 mm).