Tackling the Taxonomic Challenges in the Family Scoliidae (Insecta, Hymenoptera) Using an Integrative Approach: A Case Study from Southern China

SIMPLE SUMMARY: The scoliid wasps are larval parasitoids of scarabaeoid beetles and pollinators of various plants and therefore are important in biological control and pollination. However, some species of these wasps are extremely morphologically similar and difficult to identify. In this study, we used an integrative approach of species delimitation, combining morphology with molecular data, to investigate the species of Scoliidae from southern China. On the basis of both morphological and molecular evidence, we recognized 22 morphospecies of 9 genera in two tribes, among which one undescribed cryptic species of the polytypic species Solia (Discolia) superciliaris Saussure, 1864, five newly recorded species and one pending subspecies were discovered. Our study indicates that such an integrative approach is a potent tool in the effort to tackle the taxonomic challenges in Scoliidae, and even in other diverse groups of Aculeata, of which sexual dimorphism and cryptic species are common. ABSTRACT: Species of the family Scoliidae are larval parasitoids of scarabaeoid beetles and pollinators of various plants. Despite their great importance in pest biological control and plant pollination, the taxonomy and systematics of these parasitoids are far from clear. Some species of the family are extremely morphologically similar and difficult to identify, especially in males. In this study, an integrative taxonomic approach, combining morphology and molecular data, was used to discriminate the species of Scoliidae from southern China. In total, 52 COI sequences belonging to 22 morphospecies of 9 genera in two tribes were obtained. The COI sequences worked well for the identification of all the studied species, with intraspecific genetic distances generally less than 2%, while interspecific distances ranged between 5.3% and 20.8%. The delimitations of the problematic species and subspecies of Scolia and Megacampsomeris are well solved by COI sequences, suggesting that DNA barcoding could be a useful identification tool for Scoliidae. Based on both morphological and molecular evidence, we discovered one undescribed cryptic species of the polytypic species Solia (Discolia) superciliaris Saussure, 1864, five newly recorded species, i.e., Scolia (Discolia) sikkimensis Bingham, 1896, Sericocampsomeris flavomaculata Gupta and Jonathan, 1989, Megacampsomeris asiatica (Saussure, 1858), Megacampsomeris pulchrivestita (Cameron, 1902) and Megacampsomeris shillongensis (Betrem, 1928) and one pending subspecies of Scolia (Discolia) watanabei (Matsumura, 1912) from China. Our study indicates that such an integrative approach, combing both molecular and morphological evidence, is a potent tool to tackle the taxonomic challenges in the family Scoliidae, or even, in other diverse groups of Aculeata, of which sexual dimorphism and cryptic species are common.