Species delimitation in the morphologically conserved Coecobrya (Collembola: Entomobryidae): A case study integrating morphology and molecular traits to advance current taxonomy

Traditional species delimitation only based on morphological diagnostics does not fully meet the needs of modern taxonomy. Cryptic diversity revealed by molecular evidence has been increasingly discovered in many groups; however, subsequent species description is often lacking because of inadequate taxonomy and being devoid of operational criteria. In this study, we focus on the collembolan Coecobrya which has been suspected to be a species complex living on cave guanos. Our study aimed to integrate both morphological and molecular character traits to explore this group across geographically separated cave populations. Among seven sampled populations, only minor chaetotaxic differences were detected, and between populations, there was partial overlap of discriminating characters. However, using three genes (COI, 16S and 28S), we consistently recovered across distance‐ and evolutionary model‐based molecular delimitations seven molecular lineages, corresponding to seven candidate morphospecies. A final seven‐species hypothesis was validated and seven new species were described: Coecobrya phanthuratensis sp. n., Coecobrya ranongica sp. n., Coecobrya donyoa sp. n., Coecobrya khaopaela sp. n., Coecobrya specusincola sp. n., Coecobrya khromwanaramica sp. n. and Coecobrya promdami sp. n. A tentative taxonomic workflow integrating multiple lines of evidence is proposed to facilitate the subsequent formal species description for Collembola. Unified species concept is preferable to accommodate most species concepts, delimitation criteria and data analysis methods. In practice, DNA‐based diagnoses are recommended as the standard component for the current taxonomy of Collembola, particularly within morphologically conserved groups.