A comparison of geometric morphometic analyses and cross-breeding as methods to determine relatedness in three Amblyomma species (Acari: Ixodidae)

Abstract

Amblyomma gemma (Dönitz, 1909), A. hebraeum (Koch, 1844) and A. variegatum (Fabricius, 1794) and A. are generally accepted as distinct species. The three species, however, correspond in many aspects, overlapping in distribution, altitude and rainfall tolerances, occurring in the same habitat type, preferring the same hosts and using the same predilection sites. Amblyomma variegatum differs from the other two species in appearance. There is, however, a close resemblance in the scutal pattern of the males of the other two species and the females of A. gemma and A hebraeum are almost indistinguishable. The degree of similarities between the three species was therefore investigated through morphological comparison, geometric morphometric analyses and attempts to cross breed. The geometric morphometric analyses based on ventral body shape of the malesand females of the three species indicate that A. variegatum and A. gemma are similar, suggesting that the two ticks might not be distinct species as is presently recognized. The geometric morphometric analyses indicate that A. hebraeum differs in ventral body shape from the other species and that the ventral body shape of the A. gemma - A. hebraeum cross Fl adults shows a greater resemblance to that of A. gemma than to that of A. hebraeum. This is contrary to the outcome of the crossbreeding experiments that suggests that A. variegatum is not genetically compatible to either of the other two species but that the species A. gemma and A. hebraeum are genetically compatible.

Key words:

• Acari
• Ixodidae
• Amblyomma spp.
• geometric morphometric analysis
• ticks
• South Africa