The Silver-bordered Fritillary is the only lesser fritillary with silver spots on the underside of the wings. The species often has melanic, aberrant individuals.
Scudder (1889a) first described the immatures in detail. The egg is dull yellow and taller than it is broad; it has strong reticulation on the chorionic surface. The mature larva is dark brown/green with a pale, wide dorsal band. The body is covered with elaborately branched black tubercles. This is the general appearance of all Clossiana larvae, with some variation in colour pattern.
The BC subspecies is the Dark-bordered Fritillary, C.s. atrocostalis (Huard, 1927) (TL: Chicoutimi, PQ). This is a widespread boreal forest subspecies.
Reuss (1922) stated that he named the genus Clossiana for the recognized entomologist Herr Adolf G. Closs, but it appears that Closs was only a minor worker on Lepidoptera. The common name "lesser fritillaries" refers to the small size compared with Speyeria.
Under the restricted generic usage of Boloria, we state why we recognize the genus Clossiana and define the genus. On the upperside, the wings are very similar to those of Speyeria. Some males of one species of Speyeria, S. mormonia, are as small as the largest females of our largest Clossiana, C. tritonia. Only one species, Clossiana selene, has silver spots on the ventral hindwing. This genus is Holarctic, with at least 21 species; 13 are found in North America and 12 of these occur in BC. Nine BC species are Holarctic. The 4 temperate species, 3 in BC, feed on violets (Viola) but the northern species do not. There has been much confusion in the literature regarding larval foodplants, and we discuss only those verified by Shepard (1975) and later.
Adults of the Silver-bordered Fritillary fly from late May to early September in the Okanagan Valley. There are at least two complete broods in the south, with peak flights in mid-June and late July. A partial third brood flies in early September. At Atlin in northern BC, there is apparently only one generation per year. The larvae feed on whatever violets (Viola sp.) are available at anyone site. For one population in the West Kootenay (JHS), three species of violets are available and the larvae feed on all three. Shepard has found in mass rearings that some individual larvae from first-brood eggs take much longer to develop. This staggered larval development may be the reason for an apparent partial third generation. In years of poor summer weather and for more northern populations, these larvae may be the overwintering stage. Scudder (1889a) observed this same delayed development in the northeastern United States.
The Silver-bordered Fritillary is found throughout BC east of the Coast Range and Cascade Mountains. It is always found in sphagnum bog and fen situations in the south. In the far north it has been recorded only at bogs surrounding hot springs, such as Atlin or Liard Hot Springs. In the south various skippers are always found in the habitat along with the Silver-bordered Fritillary, for example, Polites mystic, P. peckius, Carterocephalus palaemon, and usually Oarisma garita. Also in the south, the Atlantis Fritillary is often found in the Silver-bordered Fritillary habitat. The elevational range of this habitat is 660-1,000 m.
The Silver-bordered Fritillary ranges from central AK across boreal CAN to NF. In the west it occurs south to central OR and northern NM. At the southern fringes of its western range, it is found at isolated springs or around spring-fed lakes with permanently moist meadows. In the eastern USA it is found south to latitude 40°N. The species is Holarctic, occurring in northern Europe and across southern Russia and southern Kamchatka.
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2021. E-Fauna BC:
Electronic Atlas of the Fauna of British Columbia [efauna.bc.ca]. Lab
for Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
2023-02-03 8:16:14 AM]
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