Comparative Morphometric and Biosystematic Analysis of Kyasanur Forest Disease Vectors (Haemaphysalis bispinosa and H. turturis) from South India

Haemaphysalis ticks are significant vectors of multiple pathogens and pose substantial threats to both public and veterinary health. Haemaphysalis bispinosa and Haemaphysalis turturis, key vectors of Kyasanur Forest Disease Virus (KFDV), are considered cryptic species due to their close morphological resemblance. This study aimed to differentiate these two species through a combination of morphological, morphometric, and statistical approaches, using specimens collected from two geographically distinct populations in South India. Standard taxonomic keys were employed for initial identification, followed by detailed morphometric measurements across all life stages (n = 15 per stage). Scanning Electron Microscopy (SEM) provided high-resolution structural comparisons, while Principal Component Analysis (PCA) was used to assess morphometric variation and distinguish key diagnostic features. The results revealed clear interspecific differences, particularly in the scutum and idiosoma. H. bispinosa exhibited a broader basis capituli, while H. turturis displayed a wider and shorter body form, along with a distinct ventral spur morphology on the third coxal segment. These findings confirm that H. bispinosa and H. turturis are morphometrically distinct species and underscore the value of integrative morphological and statistical tools for resolving cryptic species complexes. This work contributes to the biosystematic understanding and accurate identification of medically important Haemaphysalis ticks in endemic regions.