Biogeography and divergence time estimation of the relict Cape dragonfly genus Syncordulia: global significance and implications for conservation.

Syncordulia (Odonata: Anisoptera: Libelluloidea) inhabits mostly cool mountainous streams in the Cape Floristic Region of South Africa. It is found at low densities in geographically restricted areas. Syncordulia is endemic to South Africa and, until recently, only two species were known, S. venator (Barnard, 1933) and S. gracilis (Burmeister 1839), both considered Vulnerable by the World Conservation Union (IUCN). Two new species, S. serendipator Dijsktra, Samways & Simaika 2007 and S. legator Dijsktra, Samways & Simaika 2007, were described from previously unrecognized museum specimens and new field collections. Here we corroborate the validity of these two new species using multiple genes and propose intergeneric relationships within Syncordulia. Molecular data from two independent gene fragments (nuclear 28S and ribosomal and cytochrome oxidase subunit I mitochondrial data) were sequenced and/or downloaded from GenBank for 7 libelluloid families, including 12 Syncordulia specimens (2 Syncordulia gracilis, 4 S. serendipator, 2 S. legator and 4 S. venator). The lower libelluloid group GSI (sensu Ware et al. 2007), a diverse group of non– corduliine taxa, is strongly supported as monophyletic. Syncordulia is well supported by both methods of phylogenetic analyses as a monophyletic group deeply nested within the GSI clade. A DIVA biogeographical analysis suggests that the ancestor to the genus Syncordulia may have arisen consequent to the break–up of Gondwana (>120 Mya). Divergence time estimates suggest that Syncordulia diverged well after the breakup of Gondwana, approximately 60 million years ago (Mya), which coincides with the divergence of several Cape fynbos taxa, between 86 – 60 Mya. DIVA analyses suggest that the present distributions of Syncordulia may be the result of dispersal events. We relate these phylogenetic data to the historical biogeography of the genus and to the importance of conservation action.