ANCIENT BUTTERFLY-ANT SYMBIOSIS - DIRECT EVIDENCE FROM DOMINICAN AMBER

Although symbiotic association with ants is pervasive in the butterfly families Lycaenidae and Riodinidae the age of these symbioses has nev er been estimated explicitly. Here we report the first known fossil ri odinid caterpillar. This fossil can be dated minimally between 15 and 20 Ma old, and confidently placed in the extant genus Theope. Differin g little from modern day Theope, this fossil from Dominican amber prov ides direct evidence that secretory and acoustical organs used by mode rn caterpillars to mediate symbioses with ants have been highly develo ped at least since the Miocene. This fossil therefore becomes the poin t of reference for future studies using molecular clock methods for da ting these symbioses within the riodinid butterflies. Modern evidence, and the abundance of dolichoderine ants in Dominican amber (now extin ct in the West Indies) imply that specialized symbiotic relationships between Theope caterpillars and these ants were likely in existence at least 15 Ma ago. The current distribution of neotropical riodinid but terfly and ant faunas indicates the extinction in the West Indies of a t least two unrelated taxa that formed a tightly linked symbiotic asso ciation, which persisted to the present elsewhere.