Description of a New Species of Caliscelidae from the High Altitude Region of Xizang Based on Morphological and Molecular Evidence

This study describes a new species of the family Caliscelidae (Hemiptera) from the Xizang region of China—Peltonotellus lasaensis sp. nov. Through integrated morphological examination (including external morphology and genitalia dissection) and mitochondrial gene (COI) sequence analysis, the taxonomic status of this species was determined. Morphological results reveal that the male aedeagus terminates in valvular lobes, with ventral processes comprising a pair of spinous projections. In females, the type IX arcuate process bears approximately 15 ridge teeth on the dorsal margin, a feature that distinctly differentiates it from congeners. Molecular phylogenetic analysis demonstrated a substantial genetic divergence (K2P = 16.5%) between the new species and its closest relative, Peltonotellus sp. (MW928530.1), far exceeding the species-level threshold (< 2%). Additionally, the new species formed a monophyletic clade with high bootstrap support (>97%) in the maximum likelihood tree. This study represents the first record of Caliscelidae in the high-altitude regions of Xizang (3 650–3 800 m), thereby enriching the diversity data of Hemiptera in Asia and providing valuable insights into the biogeography of the Qinghai-Xizang Plateau.