Data from: Genomic and ecological divergence support recognition of a new species of endangered Satyrium butterfly (Lepidoptera, Lycaenidae)

<p>We describe a highly isolated population of hairstreak butterfly from Waterton Lakes National Park, Alberta, Canada, previously recognized as the Half-moon Hairstreak (<em>Satyrium semiluna</em>), as a new species, <em>Satyrium curiosolus</em> sp. nov. We propose “Curiously Isolated Hairstreak” as the common name due to its disjunct and unusual distribution. Previous whole-genome analyses revealed <em>S. curiosolus</em> has extremely low genomic diversity and is highly divergent from the nearest <em>S. semiluna</em> populations in British Columbia and Montana, more than 400 km distant. Further analysis suggests prolonged inbreeding and isolation for up to ~40,000 years BP. Ecological niche modeling indicated that <em>S. curiosolus</em> occupies environmental conditions that are distinct from <em>S. semiluna</em>, suggesting niche divergence driven by long-term geographical and ecological separation. While host plant and ant associations have not been definitively resolved, they likely differ between <em>S. curiosolus</em> and <em>S. semiluna</em>. As part of this description, we provide whole-genome consensus sequences for each individual of the type series and identify 21,985 single nucleotide polymorphisms (SNPs) that are divergently fixed between <em>S. curiosolus</em> and <em>S. semiluna</em>, including 117 unlinked SNPs distributed across the genome as putative diagnostic markers. Previously listed as endangered in Canada as the Waterton population of <em>S. semiluna</em>, <em>S. curiosolus</em> should retain this conservation status due to its extreme isolation, small population size, and flatlined genomic diversity. We propose species recognition as a testable hypothesis under the General Lineage Concept, and recommend further research to explore the taxonomy, ecological relationships, and conservation of the greater species complex, including <em>S. semiluna </em>and <em>S. fuliginosa</em>.</p>