Open Access

Deborah L. Matthews, Jacqueline Y. Miller, Andrew D. Warren, James K. Toomey, Roger W. Portell, Terry A. Lott, Nick V. Grishin

• We review the genus Cyclargus Nabokov (Lepidoptera: Lycaenidae) based on detailed comparative analyses of wing patterns, genitalia, and mitochondrial COI DNA barcode sequences, and suggest that Cyclargus is composed of four species: C. thomasi (Clench), C. woodruffi (W. Comstock and Huntington), C. ammon (Lucas), and C. dominica (Möschler). The following new subjective synonyms are proposed: C. erembis Nabokov syn. n. and C. kathleena K. Johnson and Matusik syn. n. are C. thomasi noeli (W. Comstock and Huntington); C. sorpresus K. Johnson and Matusik syn. n. and C. shuturn K. Johnson and Bálint syn. n. are C. ammon; and Cyclargus oualiri Brevignon syn. n. is C. woodruffi. Additionally, we report the discovery of C. thomasi noeli in Cuba (where this taxon was previously confused with C. ammon), report C. ammon from Hispaniola for the first time, and document the widespread sympatry of C. thomasi and C. ammon in the northern Caribbean (including south Florida, Cuba, Cayman Islands, Hispaniola, Lucayan Archipelago). Finally, we provide a provisional synonymic list of Cyclargus taxa, which may serve as a taxonomic framework to assist efforts to conserve the Miami blue (C. thomasi bethunebakeri (W. Comstock and Huntington)), a taxon listed as "Endangered" under the Endangered Species Act in the United States.