Systematics and conservation of Colophon Gray (Coleoptera: Lucanidae)

Abstract

The flightless Cape High-mountain stag beetle genus Colophon (Coleoptera: Lucanidae) is studied. Represented by 17 species, which are restricted to the highest mountain peaks of the Cape Floristic Region in the Western Cape, South Africa, and show a strict association with the fynbos biome. The study aimed to determine the specific and phylogenetic status of the described species of Colophon and to determine the main factors driving their evolution by testing hypotheses of relationship and of a lowland origin. This was achieved by analysing DNA sequence data from three gene regions, the mitochondrial COI and 16S rRNA and the nuclear CAD, using a Maximum Likelihood (ML) and Bayesian approach. Timing of key biogeographical events in the diversification of Colophon was estimated in BEAST. The study also undertook to determine diagnostic larval characters for Colophon species and also to determine their phylogenetic implications for the sub-familial placement of the genus. Lastly, the study aimed to collate biological information on Colophon species so as to make suggestions for their revised conservation status in terms of IUCN and ToPS criteria. Most species of Colophon showed an allopatric distribution, although contact zones between geographically adjacent species are likely. Climate seems to be the main driving factor behind Colophon evolution and the hypothesis of a lowland origin appears to be supported. Larvae are soil-living and feed on humus, a habit unique to the family. There are only small inter-specific differences between larvae, with larval characters contributed little equivocal information from which phylogenetic support for family placement of Colophon could be deduced. The main threats to Colophon survival include overexploitation by commercial collectors, decline in habitat quality and habitat loss due to projected changes in climate. It is suggested that out of the 17 currently described species, eight should be listed as Critically Endangered, seven as Endangered, two as Data Deficient. Lastly, in light of this project‟s findings, it is suggested that future considerations in terms of Colophon research should focus on obtaining more information on their biology, behaviour and population size and in so doing contribute knowledge for the effective conservation management of each species. A taxonomic revision of the species, focusing on the C. stokoei varieties and C. eastmani subspecies, should be done and a complete taxonomic key of all described species compiled. Future fieldwork should focus on sampling the five species that remained elusive during the project, to eventually be included in phylogenetic analyses.