Phylogenetic relationships among Scirtothrips species and related genera (Thysanoptera, Thripidae) based on morphology

Abstract

Scirtothrips, one of the largest genera of Thripinae, includes several species that are important pests for agricultural and horticultural plants. Scirtothrips genus-group comprises 11 genera, but phylogenetic relationships among these are unclear, as are the interspecific relationships within Scirtothrips. We used 61 morphological characters to study the morphological variation and phylogenetic relationships among the members of this genus-group. Phylogenetic analysis supported the inclusion of eight genera in Scirtothrips genus-group but excluded Ajothrips and Scirtidothrips, although the monophyly of Scirtothrips was not well-supported. Our analysis strongly supported two different species-groups both comprising species associated with Acacia in Australia, suggesting the occurrence of at least two separate radiations onto this plant genus. The monophyly of Scirtothrips perseae species-group was not supported; members of this group are involved in damage to avocado in the New World. The Scirtothrips aurantii species-group was recognised as comprising S. aurantii, Scirtothrips dodonaeae and Scirtothrips mugambii, based on one synapomorphic character, male hind femora with a comb of setae. We demonstrated that the conspicuous drepanae that occur in males of some Scirtothrips species evolved separately in New and Old World species. We discussed the relationships among Scirtothrips species together with data on geographic distributions and host plants, and noted inconsistencies that presumably result from homoplasy.