What Azure blues occur in Canada? A re-assessment of Celastrina Tutt species (Lepidoptera, Lycaenidae)

The identity of Celastrina species in eastern Canada is reviewed based on larval host plants, phenology, adult phenotypes, mtDNA barcodes and re-assessment of published data. The status of the Cherry Gall Azure (Celastrina serotina Pavulaan & Wright) as a distinct species in Canada is not supported by any dataset, and is removed from the Canadian fauna. Previous records of this taxon are re-identified as Celastrina lucia (Kirby) and Celastrina neglecta (Edwards). Evidence is presented that both Celastrina lucia and Celastrina neglecta have a second, summer-flying generation in parts of Canada. The summer generation of Celastrina lucia has previously been misidentified as Celastrina neglecta, which differs in phenology, adult phenotype and larval hosts from summer Celastrina lucia. DNA barcodes are highly conserved among at least three North American Celastrina species, and provide no taxonomic information. Celastrina neglecta has a Canadian distribution restricted to southern Ontario, Manitoba, Saskatchewan and easternmost Alberta. The discovery of museum specimens of Celastrina ladon (Cramer) from southernmost Ontario represents a new species for the Canadian butterfly fauna, which is in need of conservation status assessment.