Biogeographical and evolutionary patterns in the Macaronesian shield-backed katydid genus Calliphona Krauss, 1892 (Orthoptera: Tettigoniidae) and allies as inferred from phylogenetic analyses of multiple mitochondrial genes

We investigated the phylogenetic patterns, evolutionary processes, and their taxonomic implications, of two closely related shield-backed katydid genera endemic to the Macaronesian archipelagos: the monotypic Psalmatophanes Chopard, 1938 endemic to Madeira and Calliphona Krauss, 1892, which includes three species restricted to the Canary Islands. Two main hypotheses have been proposed to explain the origin and colonization pathways of these two genera: a single origin with subsequent sequential colonization of the islands, or three independent colonization waves from continental Africa. We used DNA sequence information from the mitochondrial genes cox 1, tRNAleucine, rrnL and nad1 to infer phylogenctic relationships among Psalmatophanes and Calliphona species. Our results provide support for the independent colonization of Madeira and the Canary Islands, and suggest that Psalmatophanes is actually more closely related to the continental genus Tettigonia than to the Canarian representatives. Deep genetic divergence among Canarian species provides further support for the assignment of the Canarian species into two subgenera. Tree topology along with Bayesian-based estimates of lineage age suggest a pattern of colonization from Tenerife to La Palma, and from Tenerife to Gran Canaria with subsequent dispersal to La Gomera. We report the first collection of a Calliphona specimen in the island of El Hierro, which molecular data suggest is a recent immigrant from. La Gomera. We hypothesize that the patterns of distribution and genetic divergence exhibited by Calliphona in the Canary Islands are compatible with a taxon cycle process. Our results have further implications for the higher level phylogeny of the subfamily Tettigoniinae and suggest that some of the tribes as currently delimited may not correspond to natural groups.