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Free keywords:
Aniara; Australia; cicindelid; habitat; Megacephala; monophyletic group; phylogenetic tree; South America
Abstract:
The pantropical subtribe Megacephalina represented by more than 100 species is the most diverse of the basal cicindelid groups. Today, most taxonomists recognize eight genera within the subtribe. This is in contrast to Horn who, back in 1910, conceded only two genus-level taxa: the monospecific Aniara and Megacephala sensu Horn (a genus which united the seven other taxa). In the present study we provide a molecular phylogeny of Megacephalina based on the nuclear 18S and the mitochondrial 16S and cytochrome oxidase III genes. The dataset includes 60 specimens of more than 40 mostly South American and Australian taxa. Three cicindelid species of derived lineages were used as outgroups. The resulting phylogenetic trees are basically in agreement with the current classification system. Megacephala and Grammognatha are placed basal in the dendrogram. Pseudotetracha and Australicapitona form a monophyletic Australian clade. Phaeoxantha, Tetracha and Aniara also form a monophyletic group. The position of Metriocheila remains uncertain. The most striking deviation from the traditional classification is the well-supported placement of Aniara within Tetracha, rendering the latter a paraphyletic taxon. Several monophyletic subgeneric species groups are observed in Pseudotetracha, Phaeoxantha and Tetracha/Aniara. Within the latter the monophyletic sobrina, carolina and brasiliensis clades together represent a monophyletic group. Additionally, habitat types were assigned to the taxa and mapped on the phylogenetic tree. The basal African species inhabit non-flooded uplands. The Australian species moved to inland and/or coastal salt plains. The American groups were most likely first confined to river margins and then colonized secondarily and independently non-flooded uplands and/or coastal habitats.
