Recognition of the Spring Flight of Celastrina (Tutt) (Lycaenidae: Polyommatinae) in Southern New England as an Introgressed Hybrid Species.

Populations of Celastrina (“Azure”) butterflies in southern New England have historically been referred to as either Celastrina ladon (Cramer) or Celastrina lucia (W. Kirby) by various authors. Following the discovery of elongated dorsal wing scales in males of C. ladon (D. Wright & Pavulaan, 1999; Ômura et al., 2015)—structures that replace the androconia that are typically present in most Celastrina species—it was believed that this trait was restricted to C. ladon, C. nigra (W. Forbes), and, more recently, C. iryna (Pavulaan, 2025). Microscopic examination of male “Spring Azure” specimens from across southern New England has revealed the presence of these elongated dorsal wing scales. The present author initially interpreted this population as representing a northern subspecies of C. ladon. However, comprehensive life history characteristics indicate that this population belongs within the lucia guild of Celastrina. It is therefore proposed that the elongated wing scale trait introgressed into northeastern populations of C. lucia, replacing androconia and making C. isadora (new species) the fourth species within the Celastrina complex known to possess this distinctive scale morphology.