MITOCHONDRIAL-DNA SEQUENCING REVEALS EXTREME GENETIC DIFFERENTIATION IN A CRYPTIC SPECIES COMPLEX OF NEOTROPICAL PSEUDOSCORPIONS

The neotropical pseudoscorpion Cordylochernes scorpioides (Chernetidae : Lamprochernetinae) is currently described as a single species rangin g from Central America to northern Argentina. However, interpopulation crosses have recently demonstrated that C scorpioides actually repres ents a complex of cryptic species. Here we present mitochondrial COI g ene sequence data from C. scorpioides individuals from Panama, Trinida d, and French Guiana which demonstrate little or no intrapopulation va riability but divergence ranging from 2.6 to 13.8% between geographic populations. Phylogenetic analysis provides evidence of a major split between C. scorpioides lineages from Central and South America. Levels of interpopulation mtDNA divergence correspond well with previously e stablished patterns of postzygotic reproductive incompatibility betwee n geographically distinct units within the C. scorpioides complex. By contrast, multivariate morphometric analysis demonstrates that extensi ve sequence divergence has occurred in the absence of appreciable morp hological differentiation between the populations. To provide a framew ork for assessing the scale of geographic divergence in C. scorpioides , Cordylochernes sequences were compared with homologous sequence from its presumed sister taxon, Lustrochernes, and from Parachernes and Se meiochernes, representatives of the second chernetid subfamily, the Ch ernetinae. Our preliminary, generic-level analysis suggests that COI s equence data may prove useful in resolving relationships within this p roblematic family. (C) 1997 Academic Press.