NEW HYPOGEAN CYCLOPOID COPEPODS (CRUSTACEA) FROM THE YUCATAN PENINSULA, MEXICO

Four previously unknown hypogean species of cyclopoid copepods were co llected in cenotes and wells of the Yucatan Peninsula, Mexico. Diacycl ops chakan sp. n. and D. puuc sp. n. differ from their congeners in co mbining 3-segmented swimming legs, Ii-segmented antennules, and legs 1 -4 endopodite segment 2 all with 2 setae. Species of Diacyclops rarely occur in tropical regions, and the Diacyclops described here are only the second and third species recorded from Mexico. The benthic D. puu c was found in the large underground reservoir of a cenote. Diacyclops chakan was encountered in such large open subterranean water basins, but more frequently and abundantly in wells. The two Mesocyclops speci es, M. chaci sp. n. and M. yutsil sp. n., most closely resemble their epigean benthic congener M. reidae Petkovski, but are modified by loss of some body ornament and attenuation of swimming legs and mouthparts . Mesocyclops chaci sp. n, occupies crevicular spaces (wells and small caverns). The second species, M. yutsil sp. n., with more pronounced attenuation of legs, has a planktonic life in large subterranean water volumes. The extremely attenuated appendages of both species distingu ish them from all other Mesocyclops, and resemble those of the hypogea n Kieferiella delamarei Lescher-Moutoue. These three species are consi dered as a species-flock which have radiated as specialists within a h ighly dynamic geomorphological environment.