Underestimated cryptic diversity in the Caryocolum tricolorella species complex (Lepidoptera, Gelechiidae)

The taxonomy of the Caryocolum tricolorella species complex, an informal subsection of the diverse Caryocolum interalbicella species group, is revised and four species are separated from DNA barcodes of the mitochondrial COI (cytochrome c oxidase subunit 1) gene and adult morphology: C. tricolorella (Haworth, 1812), C. fibigerium Huemer, 1988, C. herwigvanstaai sp. nov., and C. olekarsholti sp. nov. These species show a vicariant distribution pattern, with C. tricolorella widely distributed in Central and Northern Europe, C. fibigerium restricted to the Iberian Peninsula and southern France, C. herwigvanstaai sp. nov. to the Italian Peninsula, and C. olekarsholti sp. nov. to the Balkans. All species are described in detail, and the adults and genitalia of both sexes are illustrated.