Tick

Abstract

Taxonomy and phylogeny of Iranian ticks of the genus Hyalomma (Acari: Ixodidae) with morphologic and molecular methods

Asadollah Hosseini Chegeni

 The ticks of the genus Hyalomma (Acari: Ixodidae) are the main vector of theileriosis, anaplasmosis, Crimean Congo haemorrhagic fever also external parasite of domestic mammals cause anemia, sensitivity and paralysis in their host. In spite of their importance in veterinary and medicine the taxonomic status and phylogeny of the Iranian species have not been cleared, properly. For this reason, the present study was conducted to determine morphological variation, molecular identification and to define phylogenetic relationships of the species of the genus Hyalomma based on COI and ITS2 genes. The tick specimens were collected on different hosts from different regions in Iran. The 960 male adult of Hyalomma tick from all collected specimens were identified morphologically to the level of species and their taxonomical characters and variations were studied with morphological methods. Out of this number, 105 tick specimens were selected for subsequent molecular methods. DNA of specimens was extracted by Phenol/Chloroform method and subsequently a part of COI and ITS2 gene region amplified for each. For amplification of a part of ITS2, three new primers were designed and tested. All newly designed primers could successfully amplify the target sequence. Twenty three and 24 amplified fragments for COI and ITS2 respectively were sequenced. All sequences were edited manually and after BLAST in GenBank, aligned using MEGA6 software and intra and inter species variation calculated. The phylogenetic tree was constructed with neighbor joining and parsimony methods using PAUP 4.0 software and Baysian inferences using MrBayes 3.0 software. The results of morphological studies showed that nine Hyalomma species occur in Iran. An identification key was compiled for the Iranian species. Based on molecular results, intra and inter species variation was calculated 0-1% and 7-19% for COI and 0-2% and 6-23% for ITS2, respectively. The phylogenetic results supported the identity of two closely related species H. asiaticum and H. anatolicum. Nevertheless, the validity of H. rufipes and H. excavatum species were challenged and suggested this “morphological species” transfer to subspecies level or in the subset of H. marginatum and H. anatolicum, respectively.

Keywords: Taxonomy, Phylogentic tree, Hyalomma tick, Iran, Morphological variation, COI, ITS2