Investigating leaf beetles (Coleoptera, Chrysomelidae) on the west coast islands of Sabah via checklist-taking and DNA barcoding

Sabah, northern Borneo is one of the world’s most well-recognized biodiversity hotspots famous for the incredible diversity of its flora and fauna. Plenty of studies of leaf beetle fauna from this region have been conducted over the past 30 years. Yet, our knowledge of the leaf beetle fauna from island habitats remains scarce despite Sabah having the highest number of islands in Malaysia ( ca . 500 islands). In this study, we collected leaf beetle fauna from 13 islands off the west coast of Sabah between January 2016 and March 2017. All specimens were identified to species level. Species names were assigned when the specimens fitted the description of species in the literature and morpho-species were assigned when the species names could not be determined. In addition, DNA barcodes – mitochondarial COI gene – of the species were sequenced. A total of 68 species from 31 genera and 5 subfamilies were collected with 12 species name being determined. From the data it was established that Pulau Gaya has the highest species richness (42 species), followed by Pulau Tiga (22 species) and Pulau Sapangar (18 species). Furthermore, a total of 64 Barcode Index Numbers consisting of 101 DNA barcodes were obtained from 60 leaf beetle species. The mean intraspecific and interspecific distances were determined as 0.77 % and 16.11 %, respectively. In addition, DNA barcoding also reveals phenotypic variation in leaf beetle species, particularly in the case of the subfamily Galerucinae. This study provides baseline knowledge and information about the DNA barcodes of leaf beetle species on Sabah’s island habitats for use in future studies.