Stingless bees (Hymenoptera: Apidae) in South and West Sulawesi, Indonesia: morphology, nest structure, and molecular characteristics

Abstract

Being part of the Wallacea region, Sulawesi has many endemic fauna, including five species of stingless bees. However, their morphology, nest structure, and molecular characteristics have not been documented fully. Therefore, this study aimed to examine the morphology, nest structure, and molecular characteristics of stingless bees in South and West Sulawesi. Samples were collected from seven sampling sites and identified based on ten morphological features supported by morphometric analysis and the cytochrome c-oxidase I (COI) gene from mitochondrial DNA. We identified five stingless bee species based on morphological features: Tetragonula sapiens, T. clypearis, T. fuscobalteata, Lepidotrigona terminata, and Wallacetrigona incisa. Furthermore, we observed the shape, diameter, length, ornamentation, and color of the nest entrance and the arrangement, cells, and color of brood cells. We provide the first report of high variations in the type of entrance opening (irregular, round, oval, ellipse, and triangle) and three different brood cells arrangements (semi-cluster, cluster, and semi-comb) for Tetragonula sapiens, which occurs abundantly in Sulawesi. In addition, for the first time, we documented the nest structure of the endemic stingless bee W. incisa, which had a slit longitudinal entrance with lamellate pillar structures in a 2-m cavity of a tree trunk. We also found that the COI gene sequence can be used to distinguish the five stingless bee species in Sulawesi, and it is especially accurate at separating the species in the genus of Tetragonula.