The "rings" belonging to the genus Ypthima are amongst the most common butterflies in Peninsular Malaysia. However, the species can be difficult to tell apart, with keys relying on minor and often non-discrete ring characters found on the hindwing. Seven species have been reported from Peninsular Malaysia, but this is thought to be an underestimate of diversity. DNA barcodes of 165 individuals, and wing and genital morphology, were examined to reappraise species diversity of this genus in Peninsular Malaysia. DNA barcodes collected during citizen science projects-School Butterfly Project and Peninsular Malaysia Butterfly Count-recently conducted in Peninsular Malaysia were included. The new DNA barcodes formed six groups with different Barcode Index Numbers (BINs) representing four species reported in Peninsular Malaysia. When combined with public DNA barcodes from the Barcode Of Life Datasystems, several taxonomic issues arose. We consider the taxon Y. newboldi, formerly treated as a subspecies of Y. baldus, as a distinct species. DNA barcodes also supported an earlier suggestion that Y. nebulosa is a synonym under Y. horsfieldii humei. Two BINs of the genus Ypthima comprising DNA barcodes collected during citizen science projects did not correspond to any species previously reported in Peninsular Malaysia.
Over the past 50 years, Southeast Asia has suffered the greatest losses of biodiversity of any tropical region in the world. Malaysia is a biodiversity hotspot in the heart of Southeast Asia with roughly the same number of mammal species, three times the number of butterfly species, but only 4% of the land area of Australia. Consequently, in Malaysia, there is an urgent need for biodiversity monitoring and also public engagement with wildlife to raise awareness of biodiversity loss. Citizen science is "on the rise" globally and can make valuable contributions to long-term biodiversity monitoring, but perhaps more importantly, involving the general public in science projects can raise public awareness and promote engagement. Butterflies are often the focus of citizen science projects due to their charisma and familiarity and are particularly valuable "ambassadors" of biodiversity conservation for public outreach.