Four previously unknown hypogean species of cyclopoid copepods were collected in cenotes and wells of the Yucatn Peninsula, Mexico.
Diacyclops chakansp. n. and D. puucsp. n. differ from their congeners in combining 3-segmented swimming legs, 11-segmented antennules, and legs 14 endopodite segment 2 all with 2 setae. Species of Diacyclopsrarely occur in tropical regions, and the Diacyclopsdescribed here are only the second and third species recorded from Mexico. The benthic D. puucwas found in the large underground reservoir of a cenote. Diacyclops chakanwas encountered in such large open subterranean water basins, but more frequently and abundantly in wells.