Morphometric Differentiation in the East African Grasshopper Genus Afrophlaeoba JAGO, 1983 (Orthoptera: Acrididae)

Abstract

Research on speciation processes in tropical evergreen forests is of high importance for the understanding of the genesis of biodiversity. The Eastern Arc Mountains in Tanzania are a biodiversity ``hotspot{''}, including many single mountain endemics. One endemic genus of this area is the flightless grasshopper genus Afrophlaeoba. The morphologically very similar species of this genus were studied by means of multivariate morphometrics. Although significant differences were found between all species in each character studied as well as in multidimensional space, there was a slight degree of overlap between some of the species. This was particularly true for the species A. nguru and A. longicornis, while the sister genus Parodonomelus differed in many regards from the Afrophlaeoba species. The phenetic distance between the species correlates well with the genetic distances based upon mtDNA sequences. The genus seems to represent a neoendemic radiation with uncertain species status. Although genetic, ecological and morphometric differences are rather low, the differences in courtship behaviour are pronounced. Based upon the phenetic and phylogenetic relationships, a typophylogeographic scenario can be proposed, in which riverine and coastal forests acted as habitat corridors in humid periods. The rainshadow of Zanzibar island might be the most important barrier for southern and northern sister taxa endemic to the coastal forests and the Eastern Arc.