Description on the larva of Amblyomma ovale Koch, 1844 (Acari: Ixodidae) by light and scanning electron microscopy

Abstract

The larval stage of Amblyomma ovale Koch is described using optical and scanning electron microscopy. Unfed larvae were obtained from a colony of A. ovale originating from engorged females collected on domestic dogs from Monte Negro County, state of Rondônia, Western Amazon, Brazil. Fifteen larvae were prepared and mounted on slides, and observed under a light microscope equipped with a drawing tube. Five specimens were prepared for scanning electron microscopy. Several morphological characters are described for the first time, inc1uding the chaetotaxy of the idiosoma, palps and Haller's organ, as well as morphological features of the idiosoma, gnathosoma and legs. In addition, topographical and numerical patterns of integumentary pores (porotaxy) on the idiosoma of larval A. ovale are described using a recently proposed nomenc1ature. Three types of integumentary pores were identified on the idiosoma of A. ovale larvae: lyrifissures, small glands, and large wax glands. These structures were observed isolated or associated over the entire idiosoma, except on the scutum, which lacks large wax glands. Larvae of A. ovale showed similar topographical and numerical patterns of integumentary structures, with 6 pairs of large wax glands (I pair dorsal/5 pairs ventral), 24 pairs of Iyrifissures (11 pairs dorsal/13 pairs ventral), and 54 pairs of small glands (32 pairs dorsal/22 pairs ventral). These topographical and numerical patterns of integumentary structures of larval A. ovale showed only minor differences when compared with patterns of other Amblyomma larvae; however, a few key features can be used to differentiate A. ovale from other members of its genus