Comparative Analysis of Antennal, Foreleg Morphology and Molecular Phylogeny of Carpenter Ants Camponotus sp. (Formicidae: Hymenoptera)

Abstract

Background: Carpenter ants of the genus Camponotus exhibit considerable morphological diversity, particularly in antennal and foreleg structures, which are important for sensory perception, locomotion, and species-level comparison. Although morphological and molecular approaches have been used independently to study Camponotus, comparative information integrating these characters with molecular phylogenetic relationships remains limited for species occurring in southern India. Therefore, examining morphological variation together with COI-based phylogenetic relationships can provide a more comprehensive understanding of the studied Camponotus species. Aim: This study aims to identify variations in the antennae and forelegs of different Camponotus ant species and to construct a molecular phylogram of Indian Camponotus species. Methodology: Ant specimens were collected from Abishekapatti from January to March 2026 (Latitude 8° 7686 N and Longitude 77° 6440 E), Tamil Nadu, India. The antennae and forelegs were dissected from ants stored in 4% formalin and labelled in plastic vials. Diagrammatic sketches were prepared using a camera lucida mounted on an Olympus Trinocular Microscope (Model: CH20i). The prepared sketches were illustrated, and nucleotide sequences representing 45 species were obtained from NCBI GenBank to construct a phylogram. The dataset comprised 41 species of the Camponotus genus and four species of the Polyrhachis genus used as an outgroup. ClustalX2 and MEGA 11 software were used for further phylogenetic analysis using the neighbour-joining (NJ) method with 1,000 bootstrap replicates. Results: Camponotus sericeus (Fabricius, 1798), Camponotus compressus (Fabricius, 1778), Camponotus variegatus (Smith, F., 1858), and the endemic species Camponotus nirvanae (Forel, 1893) were identified from Abishekapatti, Tamil Nadu, India. All four species have 12 antennal segments, and variations were noted in the lengths of the scape and pedicel and in their colours (reddish-black, yellowish-brown, and reddish-brown). Variations were also observed in femur length, width, and colour. Camponotus sericeus grouped with C. opaciventris with 100% bootstrap support, indicating a close relationship between these two taxa in the phylogenetic reconstruction. Conclusion: This study provides information on the structures of the antennae and forelegs of the ant species and on the phylogenetic position of Indian Camponotus species.