Beltheca

Abstract: Beltheca oni, new species, is described from the Atlantic lowlands of Costa Rica. The adult female is similar to that of B. picolella Busck, but the former lacks a signum. The male can be distinguished from that of Beltheca phosphoropa (Meyrick) by its longer vinculum and larger aedeagus. Adults of both sexes "dance" on leaves of different plants by anchoring one of their forelegs to a substrate and rotating around this pivot point. The anchored leg shifts slightly when the moth dances in large circles, moves to another region of the leaf, or changes the direction of rotation. There is no preference for rotating clockwise or counterclockwise. Dancing occurs all over the adaxial leaf surface, but it can be localized. An adult was observed dancing around a water droplet and drinking from it. We hypothesize that dancing is a courtship behavior or a predator avoidance tactic. A photograph of the adult and illustrations of the head, wing venation, and genitalia of both sexes are included along with a diagram of a dancing path.