Morphometric differentiation between larvae of Amblyomma sculptum Berlese, 1888 and Amblyomma dubitatum Neumann, 1899

Ticks are involved in biological processes of a wide variety of pathogenic organisms. The genus Amblyomma presents the greatest medical importance, with the species Amblyomma sculptum Berlese, 1888 involved in the transmission cycle of Brazilian Spotted Fever (BSF). In this study, we performed a molecular validation of the morphometric differentiation based on the idiosomal length of the larvae of A. dubitatum and A. sculptum. Unfed larvae were collected in two BSF-transmission areas, using the attractive CO2 trap technique. Larvae were identified at the species level by comparative morphometry, molecular analysis by PCR and genomic sequencing, with validation through agreement analysis by the Kappa test. The larvae of A. dubitatum showed a significantly longer idiosomal length than A. sculptum larvae. Although no other species of the genus Amblyomma has been tested in this study, this technique can be applied to places where previous acarological surveillances based on adult and nymphal ticks stages have indicated the presence of only A. sculptum and A. dubitatum, usually sustained by capybaras. Noteworthy, this condition is very common among many BSF-endemic areas in southeastern Brazil.