Morphological variation and mermithism in female castes of Colobopsis sp. nrSA, a Bornean "exploding ant" of the Colobopsis cylindrica group (Hymenoptera: Formicidae)

Abstract

Colobopsis sp. nrSA is an ant species of the Southeast Asian Colobopsis cylindrica group (formerly in the genus Camponotus), which is currently being studied in the course of a long-term project focusing on the ecology and evolution of its members. We herein describe the morphological diversity of a colony fragment in an artificial nest established at the Kuala Belalong Field Studies Centre, Brunei Darussalam. The caste composition of the nest fragment was analysed and species conformity was proved by Dna barcoding. We describe the morphological traits in both worker subcastes, gynes, an intercaste individual, and aberrations of gyne morphology caused by mermithid parasitism with a focus on morphometry. Mermithogynes were examined by micro-CT imaging to confirm the presence of parasitic nematodes. The high morphological diversity of Colobopsis sp. nrSA in comparison with more distantly related species of Colobopsis is discussed in the light of the recently revised phylogeny of Camponotini, and ecological as well as evolutionary questions are addressed.