A Comprehensive Morphological Description and Phylogenetic Analysis of First Instar Larvae: Clarifying the Intergeneric Relationships of Microfalcula , Salina and Akabosia (Collembola: Entomobryidae)

Considerable controversy has long surrounded Paronellidae. Previous morphological studies suggested a close connection between Microfalcula and Salina ; concurrently, molecular phylogenetic analyses have indicated a closer relationship between Salina and Akabosia . However, a comprehensive analysis encompassing all three genera has been limited, leaving their precise interrelationships unclear. This study comprehensively examines and describes the first instar larval characteristics (antennae, dorsal cephalic chaetotaxy, labial chaetotaxy, leg, tergal chaetotaxy, ventral tube, tenaculum and furcula) of all three genera. We then reconstructed phylogenetic trees primarily based on dorsal chaetotaxy and other features. Our study suggested that these three genera belong to a single clade, forming the sister taxa between Salina and Akabosia . We identified five key morphological features supporting the monophyly of these three genera: absence of scales, enlarged tenent hairs, discrete eyes, unilobed antennal bulbs and reduced tergal S‐chaetae from Th. II to Abd. III (10|000 in Microfalcula , 11|000 in Akabosia and 11|001 in Salina ). Additionally, tergal chaetotaxy strongly supports a sister group relationship between Salina and Akabosia . This study partially supports and successfully validates the Entomobryidae taxonomic framework, affirming that primary chaetotaxy is a robust and comparable morphological characteristic for Collembola classification.