First support for phylogenetically segregated ecotypes and delineating thresholds for inter‐ and intraspecific ranks in phytophagous Central Asian beetles (Coleoptera)

Abstract As defining various taxonomic ranks, especially at and within a specific level, can often be difficult, we used an evolutionarily young group of Central Asian beetles, the genus Anoplistes , to examine the limits between species, subspecies and ecotype. The molecular data (COI genetic distance, haplotype network and species delimitation) and detailed morphology (using SEM) of taxa assigned to the rank of species, subspecies and ecotype were used to verify their taxonomic status and attempt to more precisely establish the boundaries between these concepts. The minimum threshold for the COI genetic distance between species was found to be approximately 3%, while at the threshold of 4%–5% the morphology left no doubt as to the species distinctiveness. The threshold of approximately 2% was accepted as adequate for a subspecies rank, whereas intraspecific variability among individuals of the same subspecies (including its ecotypes) ranged from 0% to 2%. A newly presented colour/elytral pattern form, possibly another ecotype of A . halodendri distributed in western Mongolia, exemplifies adaptation to different environmental conditions via ecological speciation. Our results provide support that ecotypes can form phylogenetically distinct clades. Based on the results of the haplotype network, it can be tentatively concluded that the sand ecotype was the incipient form from which further ecotypes and subspecies developed.