Genetic evidence for conspecificity between Dermacentor marginatus and Dermacentor niveus

Abstract

Ticks are hematophagous arthropods transmitting several harmful human and animal pathogens like viruses, Rickettsia, bacteria, and protozoa. The identification and speciation of ticks were normally performed in Iran using identification key of Arthur (1960) and Kaiser and Hoogstraal (J Parasitol 49:130-139, 1963) or on the basis of morphological characteristic keys recommended by Walker et al. (2003). Although these identification keys are well prepared, but there are in some cases due to the strong overlapping characteristics between species like Dermacentor marginatus and Dermacentor niveus accompanied with serious problems. D. marginatus and D. niveus have been intermittently used synonymously and there is no a generally agreement with the specification of these species. To find out more about these two species, we have analyzed the complete nucleotide sequence of ITS-2 region. Interestingly, we found indeed a sequence homology of 99% between nucleotide sequence of ITS-2 region of D. marginatus and D. niveus. Since the nucleotide sequence of ITS-2 region of D. marginatus in Iran has 98% sequence homology to the other in GenBank registered ITS-2 sequence of D. marginatus, and the morphological characteristics between both examined species showed minimal differences, therefore we believe that the D. marginatus and D. niveus could belong to the same species and 1% differences in nucleotide sequence of ITS-2 region between these two species can be understand as an intra-species polymorphism.

Molecular characterization of Ribosomal DNA (ITS2) of hard ticks of Iran, in understanding the conspecificity of Dermacentor marginatus and D. niveus

“…In addition, based on the comparison of morphological characteristics and examination of the syntype series of D. niveus, it was concluded that D. niveus is conspeci c with D. marginatus [13]. Also the molecular results obtained from the current study revealed a high similarity (> 98%) between D. marginatus and D. niveus based on the different populations of both species across this study and other sequences obtained from Iran [16] or elsewhere [25] ( Fig. 2).…”

“…This study is one of the few studies that have focused on the molecular characterization of Ixodidae ticks in Iran. Previously, the ITS2 fragment of different populations from two species of hard ticks of Iran (R. sanguineus and D. niveus) has been characterized [11,16].…”

“…Among the published lists of ticks, the position of some species and the validity of their names are questionable [24,2]. The species D. marginatus and D. niveus were previously distinguished solely based on morphological evaluations, but the limitation of the morphological characters was expressed [16]. In addition, based on the comparison of morphological characteristics and examination of the syntype series of D. niveus, it was concluded that D. niveus is conspeci c with D. marginatus [13].…”

“…Some authors treat D. niveus as a synonym of D. daghestanicus while other authors consider D. niveus a valid species and D. daghestanicus as its junior synonym [14]. In some cases both D. daghestanicus and D. niveus are listed as valid species [15], but this opinion has not generally been accepted [2].Also, the separation of D. marginatus and D.niveuswas evaluated by molecular tools using ITS2 [16], in which the conspeci city of these two species were suggested, but since other authors continue to treat them as separate species (e.g. [2]) the validation of the suggestion of conspeci city awaits results from further studies.…”

The Argasidae, Ixodidae and Nuttalliellidae (Acari: Ixodida) of the world: a list of valid species names

“…Dermacentor niveus Neumann, 1897. lists this species as a synonym of D. daghestanicus Olenev, 1928, but, in fact, the latter name is a junior synonym of D. niveus(Guglielmone et al 2009). Estrada-Peña and Estrada-Peña (1991) examined part of the syntype series of D. niveus (Cherestanek, Iran, ex Ovis aries, 1882, loaned by Prof. P.-C. Morel), concluding that this species is conspecific with D. marginatus, a view shared byMoshaverinia et al (2009). A wider comparative study of D. marginatus, D. niveus and D. ushakovae appears to be needed to further demonstrate the validity of these taxa.…”