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. Among them, H. bispinosa and H. turturis are important vectors of Kyasanur Forest Disease Virus (KFDV) in South India. Although both species are well recognized, detailed comparative descriptions of their morphological and morphometric characteristics remain limited. This study aimed to expand the current understanding of these species by describing and quantifying morphological differences across all developmental stages (n = 15 per stage) through a combination of morphological, morphometric, and statistical approaches, using specimens collected from two geographically distinct populations in South India. 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. Haemaphysalis 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 coxa III 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.