Species richness of Costa Rican Cenocoeliini (Hymenoptera: Braconidae): a latitudinal and altitudinal search for anomalous diversity

Latitudinal patterns of species diversity of New World Braconidae have been scarcely surveyed to date. Such patterns may be of biogeographical and ecological interest because some literature data suggest that some braconid subfamilies do not show an increase in species diversity towards the equator despite an increase of potential host species (i.e., "anomalous diversity"). In the present study, species diversity of a "presumptive" anomalous diverse braconid taxa, Cenocoeliini, was surveyed in Costa Rica. The results were compared with published distribution data of North American Cenocoeliini. Also, species richness and abundance of Cenocoeliini from sealevel to 3400 m altitude in Costa Rica were analyzed to compare latitudinal and altitudinal gradients in species diversity. Costa Rican Cenocoeliini were five times more speciose than those in Canada and USA combined. The increase in estimated species richness per unit area towards the equator of North American Cenocoeliini was similar to that of their most common hosts, Cerambycidae and Scolytidae, but exceeded that of the potential hosts in Costa Rica. Diversification in Costa Rican Cenocoeliini was partly influenced by adaptation to different host families and host substrates. Most species and individuals of Cenocoeliini were found at low altitudes (<500 m) in Costa Rica. Cenocoeliini were not encountered above 1600 m in Costa Rica, this being in contrast to their most likely hosts, Cerambycidae and Scolytidae, which also occurred at high altitudes. Larger-sized Costa Rican Cenocoeliini were often brightly colored suggesting an aposematic function towards visually-oriented predators. New World Cenocoeliini appeared to be tropical lowland-centered and this is expected to be rather an effect of temperature requirements than an effect of host-limitation.