Proceedings of the Biological Society of Washington

ABSTRACT

The calanoid copepod family Epacteriscidae is represented by species from tropical marine and anchialine environments. Surveys of the anchialine invertebrate fauna of the Yucatan Peninsula, Mexico, have resulted in a number of interesting records of crustaceans during the last decade, but no records of Epacteriscidae. However, recent collections from hypogean environments of the Yucatan have yielded specimens of a new species of the previously monotypic genus Balinella. The specimens were included in this genus by having three outer spines on the third exopodal segment of legs 3 and 4, a biramous mandibular palp, and an antennal endopod longer than the exopod, among other characters. The new species, B. yucatanensis, is described on the basis of male and female specimens collected in caves associated with three different karstic sinkholes. The new species is distinguished from its only known congener, B. ornata Fosshagen, Boxshall and Iliffe, 2001, by the strong asymmetry of the caudal rami in females, a modified left fifth leg of the male in which the proximal and middle exopodal segments are attenuate at the point of origination of the outer spine, and by differences of the armature of mouthparts (mandibular palp, maxilla, maxilliped). This report extends the range of Balinella from anchialine caves of the Bahamas to hypogean waters of the Yucatan Peninsula. The introduction of epacteriscid copepods onto the Yucatan Peninsula may be an old event; diversification by genera into non-cave habitats appears to be secondary.