Topographical and numerical study of the idiosomal integumentary structures of the larva of four Neotropical species of Amblyomma Koch, 1844 (Acari: Ixodidae).

Integumentary structures of the larvae of Amblyomma longirostre (Koch, 1844), A. parvum Aragão, 1908, A. rotundatum Koch, 1844 and from three populations of A. cajennense (Fabricius, 1787) were studied using light microscopy. A new nomenclature for the localisation of the integumentary structures is proposed. Three types of integumentary structures were identified in the larval idiosoma of the four Amblyomma species: lyrifissures, small glands and large wax glands. These structures were observed isolated or associated over the entire idiosoma, except in the scutum, which lacked lyrifisures and large wax glands. Large wax glands were the most stable within and between the tick species, followed by lyrifissures and small glands. Small glands, although relatively stable, showed the highest number of numerical variations within and between the tick species. Even though there were intra-population variations in the topographical and numerical pattern of some integumentary structures of A. cajennense larvae, there was a definitive pattern for most of the specimens, as showed by the similar modal and mean numbers of integumentary structures per tick side. The patterns of lyrifissures, small glands and large wax glands showed little differences when compared between the four Amblyomma species; however, a few differences were well evident. These differences were sufficient to differentiate larvae of the four species. Thus, we expect that the study of integumentary structures on the larvae of other Amblyomma species will be useful in future taxonomic keys for the identification of Amblyomma larvae from the Neotropical region.