Integrative Taxonomy of a New Species of the Genus Coriophagus Kinzelbach from West Bengal, India, with a tentative phylogenetic relationship within the genus (Strepsiptera: Halictophagidae)

Introduction: Kinzelbach (1971) established the genus Coriophagus based on the type-species Halictophagus zanzibarae Bohart, 1962, in the family Halictophagidae, of the order Strepsiptera. To date, 16 species of Coriophagus are known. Most of them are restricted to the Gondwanan countries (Kathirithamby 2023). In this study, an integrative taxonomy of a new species in the genus is made. A cladistic analysis of the genus Coriophagus using the discrete morphological characters to hypothesise a possible phylogeny is also conducted. A revised world key to the adult males of Coriophagus is also designed to accommodate the new taxon.

Methods: One adult male was captured in Dudhia, Darjeeling, West Bengal, with the aid of an open light trap and preserved in absolute alcohol for DNA analysis. A small sample of tissue was cut from the underside of the thorax of the specimen for sequencing (outsourced). The rest of the specimen was mounted on a glass slide following the phenol–balsam technique of Wirth and Marston, 1968, for traditional taxonomy. The cladistic analysis of 16 species including the new one (as ingroup) was performed, considering two species, Halictophagus prominens Roy & Hazra and Tridactylophagus sufflatus Hui, Mukherjee & Hazra, as an outgroup. Analysis was carried out using TNT 1.5 (Goloboff & Catalano 2016).

Result: The new species is named C. bulbous owing to its bulbous proctiger. The only species of the genus Coriophagus in the world is separated by an R₂ detached vein that is half as long and the same thickness as the R₃ detached vein, a unique irregular quadrilateral-shaped tarsomere I of the forelegs, and a unique spherical bulge on the edge of the proctiger from where the aedeagus arises. The genus Coriophagus has been recovered as a monophyletic group in this cladistic analysis.

Conclusion: India is a megadiverse country with three biodiversity hotspots. However, this country has not thoroughly been explored to determine the actual diversity of these enigmatic, often overlooked, obligatorily endoparasitic, endopterygote insects. The discovery of the new species has certainly enriched the species inventory of India vis-à-vis the world. The tentative phylogeny is likely to change upon finding out the other life stages of these species, incorporating their characteristics, as well as the discovery of more new species.