Speyeria hesperis

(W.H. Edwards, 1864)

northwestern fritillary

Species Guides

Speyeria hesperis, the northwestern fritillary, is a in the Nymphalidae. It is relatively small for a fritillary, with distinctive bright orange uppersides in males and yellow in females. The is found in the northwestern United States and western Canada. Its taxonomic status has been debated, with some sources treating it as a synonym of Speyeria atlantis.

Speyeria hesperis ssp. capitanensis by Casey H. Richart. Used under a CC BY 4.0 license.

FRITILLARY, NORTHWESTERN (Speyeria hesperis) (6-14-13) 8800ft, hannigan ck, 2 m north of hannigan lodge, greenlee co, az (90) (9061076983) by ALAN SCHMIERER. Used under a CC0 license.

FRITILLARY, NORTHWESTERN (Speyeria hesperis) (6-14-13) 8800ft, hannigan ck, 2 m north of hannigan lodge, greenlee co, az (9061084229) by ALAN SCHMIERER. Used under a CC0 license.

Pronunciation

How to pronounce Speyeria hesperis: /ˈspaɪəriə ˈhɛspərɪs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from similar fritillaries by its smaller size (45–58 mm wingspan versus 60–75 mm for great spangled fritillary), brighter orange or yellow uppersides, and thinner black markings. Most similar to Speyeria atlantis (Atlantis fritillary) and Speyeria aphrodite (Aphrodite fritillary), with which it may be confused; precise identification often requires examination of genitalia or geographic context.

Images

Appearance

Wingspan 45–58 mm. Uppersides bright orange in males, yellow in females. Black markings thinner than most fritillaries. Pattern typical of Speyeria fritillaries but with reduced black markings relative to larger .

Distribution

Northwestern United States and western Canada, extending east to Manitoba and the Dakotas. Range overlaps with but is generally west of Speyeria atlantis.

Similar Taxa

Speyeria atlantisVery similar in appearance and overlapping in range; historically treated as with S. hesperis by some authorities.
Speyeria aphroditeAnother similar fritillary with which it may be confused in areas of range overlap.
Speyeria cybeleLarger (60–75 mm wingspan) with more extensive black markings; shares orange and black color pattern but readily distinguished by size.

More Details

Taxonomic Status

The taxonomic status of S. hesperis remains unresolved. GBIF lists it as a synonym of Speyeria atlantis, while other sources maintain it as a distinct . The two forms are very similar morphologically and may represent geographic variants or cryptic species.

Research Context

Studies of Speyeria navigation and visual perception have focused on S. cybele and S. atlantis, demonstrating strong reliance on vision for detection. These findings likely apply to S. hesperis given shared ecological traits within the .