Description of the larva of Amblyomma calcaratum Neumann, 1899 (Acari: Ixodidae) by light and scanning electron microscopy

Abstract

The larval stage of Amblyomma calcaratum Neumann is described using optical and scanning electron microscopy. Unfed larvae were obtained from a colony of A. calcaratum originating from engorged females collected on Tamandua tetradactyla in the Jaraguá Mountain (23°40'S, 45°44'W), São Paulo County, Brazil. Eleven larvae were prepared and mounted on slides and observed under a light microscope equipped with a drawing tube. Three specimens were prepared for SEM. Several morphological characters are described, including the chaetotaxy of the idiosoma, palpi, and Haller's organ, as well as morphological features of the idiosoma, gnathosoma, and legs of A. calcaratum larvae. In addition, topographical and numerical patterns of integumentary structures on the larval idiosoma are described using a recently proposed nomenclature. On the idiosoma, setaes, lyrifissures, small glands, and large wax glands were found. These structures were observed isolated or associated over the entire idiosoma, except on the scutum, which lacks large wax glands. The topographical and numerical patterns of integumentary structures of the A. calcaratum larva showed only minor differences when compared with patterns of other Amblyomma larvae; however, a few key features can be used to differentiate A. calcaratum from other members of this genus.

Keywords: Amblyomma calcaratum; Chaetotaxy; Description; Integumentary structures; Larva; Morphology.