Nest structure variation and morphology of adult castes of weaver ants Polyrhachis (Cyrtomyrma) rastellata (Latreille, 1802) (Hymenoptera: Formicidae) in Sri Lanka

Structural variation of P. rastelleta nests constructed on a Citrus crenatifolia Lush trees that were in the premises of a farm in Gonapola, Western Province of Sri Lanka, a polydomous nest unit on a folded single leaf, a monodomous horizontal nest between two leaves, a hanging nest between two leaves and a nest on the underside of a single leaf, with silk and plant fragments or “spider silk”, is described with appropriate colour images. Distinguishing morphological features of dealate queen, winged females and males, workers and the morphology of pupae and larvae are described with their dimensions and colour images. Workers were observed in the highest numbers in each nest. Based on the bimodal frequency histograms of the total length and pronotal width of the workers and significant differences observed (z test; p < 0.01) between the mean total length and mean pronotal width of the two groups of workers, major and minor workers were recognized in the species. In addition, several morphological features that distinguish major and minor workers are also described.