Morphological and molecular analysis of four indicator species of Chironomus (Chironominae) larvae from Korea with morphological identification trait on Mouth part

Abstract

Chironomid larvae are important bioindicators of freshwater ecosystems and health, but their morphological similarities often hinder species-level identification. This study employed a combined morphological and molecular approach to differentiate four common Chironomus species: Chironomus flaviplumus, Chironomus dorsalis, Chironomus nipponensis, and Chironomus plumosus. Morphological analysis revealed distinct head appendage features: C. dorsalis possesses unique mentum lateral teeth alignment, while C. flaviplumus and C. nipponensis share a distinct mandible type, and C. flaviplumus and C. plumosus have a unique pecten-epipharyngis tooth type. Phylogenetic Bayesian inference and molecular data produced a divided clade for each species group, confirming their distinct evolutionary lineagesPairwise genetics distances revealed ranges similar to previous intra- and inter-specific variation research, further supporting species delimitation. This study demonstrates the utility of combining morphological and molecular methods for accurate species identification. It paves the way for developing a pictorial key for Chironomus species, facilitating more precise biomonitoring of freshwater ecosystems.