Morphological and Ultrastructural Characterisation of Hippoboscid Flies (Diptera: Hippoboscidae) from Assam, India

Abstract

This study examined the morphological and ultrastructural characteristics of hippoboscid flies collected from Assam, India. Specimens representing Hippobosca longipennis, Pseudolynchia canariensis and Lipoptena cervi were obtained from different hosts and localities between October 2024 and October 2025 and preserved for taxonomic examination. Adult flies were studied using stereo-zoom microscopy, and selected specimens were processed for scanning electron microscopy to document diagnostic characters of the head, antennae, mouthparts, thorax, wings, legs and terminalia. Light microscopic observations enabled species-level recognition based on overall body form, wing venation, antennal morphology, pretarsal structures and sex-specific terminal characters. Scanning electron microscopy provided additional resolution of fine surface features, including antennal sensilla, labellar sensilla, prestomal teeth, cuticular sculpturing, claws, pulvilli and genital structures. The three species showed distinct combinations of morphological and ultrastructural characters that supported their identification and comparison with existing descriptions. These observations were particularly useful for recognising subtle traits that may be difficult to resolve during routine examination. The findings provide baseline taxonomic information on hippoboscid flies from Assam and indicate the usefulness of combining conventional morphology with scanning electron microscopy for documenting diagnostic traits. This work may support future ecological, epidemiological and molecular investigations of hippoboscid ectoparasites in the region while contributing to improved recognition of medically and veterinary relevant fly species.