Alona pectinata (Crustacea : Anomopoda ; Chydoridae), a new freshwater cladoceran from Southeast Mexico

A new species of the chydorid cladoceran genus Alona is described herein Fr om parthenogenetic females. The material was collected from several freshwa ter lagoons and pools in the southern portion of the Yucatan Peninsula, Mex ico at an altitude less than 100m above sea level. The new species can be d istinguished from other species of Alona by the combination of several feat ures: a well-developed armature of the antennae, postabdomen, and postabdom inal claw, the outer distal lobe of the first thoracic limb bears two pecte n-like setae. and the exopod of thoracic limb III has only five setae. This new taxon is related to other species of Alona described from South Americ a. and the Old continent.