Dichotomous key to larvae of the genus Amblyomma (Parasitiformes: Ixodidae) in Brazil, with morphological description and redescription of the larval stage of 30 Amblyomma species

Ticks of the genus Amblyomma are of great medical and veterinary importance in Brazil, where they regularly parasitize wild and domestic animals and will bite humans that enter rural and forest areas for work and recreation purposes. This study provides morphological descriptions and redescriptions of the larval stage of 30 Amblyomma species occurring in Brazil, using morphometry, chaetotaxy and porotaxy. A dichotomous key with important characteristics illustrated by light and scanning electron microscopy was constructed for larvae of 31 species of Amblyomma from Brazil, including Amblyomma monteiroae, a recently described endemic species. The larvae of the following 11 species are described for the first time: Amblyomma aureolatum, Amblyomma cajennense, Amblyomma coelebs, Amblyomma fuscum, Amblyomma goeldii, Amblyomma humerale, Amblyomma incisum, Amblyomma latepunctatum, Amblyomma naponense, Amblyomma pseudoconcolor, and Amblyomma scalpturatum. In addition, the larvae of the following 19 species are redescribed: Amblyomma auricularium, Amblyomma brasiliense, Amblyomma calcaratum, Amblyomma dissimile, Amblyomma dubitatum, Amblyomma geayi, Amblyomma longirostre, Amblyomma nodosum, Amblyomma oblongoguttatum, Amblyomma ovale, Amblyomma pacae, Amblyomma parkeri, Amblyomma parvum, Amblyomma romitii, Amblyomma rotundatum, Amblyomma sculptum, Amblyomma tigrinum, Amblyomma triste, and Amblyomma varium. Together with the recent description of A. monteiroae, these results formed the basis for the formulation of a dichotomous key encompassing 31 Amblyomma species occurring in Brazil. Undoubtedly, the results of this study will assist future fieldwork aimed at identifying Amblyomma larvae collected from hosts and the environment.