Comparative micro-morphological and phylogenetic analysis between Rhinoestrus purpureus and Rhinoestrus usbekistanicus (Diptera: Oestridae) larvae and its adults

Abstract

Rhinoestrus purpureus and Rhinoestrus usbekistanicus (Diptera: Oestridae) cause specific nasal myiases of family equidae and are of importance in the horse medicine since it causes severe respiratory diseases. During an epidemiological survey in donkeys from Beni Suef government, Egypt; some morphological and taxonomical doubts arose concerning the identification of Rhinoestrus spp. 1st, 2nd and 3rd stage larvae based on the features of the posterior spiracles and the distribution of dorsal spines on the third segment. Four different morphotypes were retrieved: R. usbekistanicus, R. purpureus and two morphotypes with shared features. The genes encoding for the mitochondrial cytochrome oxidase I (COI) and for the ribosomal subunits 16S and 28S of the four morphotypes of Rhinoestrus were investigated to determine whether they belonged to a single taxon or they displayed genetic differences indicative of more than one species. The genes showed a very low level of sequence variation (COI 0–0.43%, 16S 0–1.45%, 28S 0–0.23%) falling within the intraspecific ranges. Finally, the peritreme features and the spinulation of the third segment of the two morphotypes examined could not be used to differentiate the Rhinoestrus spp.