Speyeria atlantis (Edwards, 1863)

Dunford, James C., 2009, Taxonomic overview of the greater fritillary genus Speyeria Scudder and the atlantis - hesperis species complexes, with species accounts, type images, and relevant literature (Lepidoptera: Nymphalidae), Insecta Mundi 2009 (90), pp. 1-74 : 25-27

Speyeria atlantis (Edwards, 1863)

( Figure 20-24 )

Argynnis Atlantis Edwards, 1863a: 54 .

Argynnis atlantis aberrant chemo Scudder, 1889: 573.

Argynnis atlantis canadensis dos Passos, 1935: 85 .

Speyeria atlantis canadensis (dos Passos) [ dos Passos and Grey 1947] (synonymized by Scott et al. 1998) ( Figure 21 ).

Speyeria atlantis (Edwards) [ dos Passos and Grey 1945a].

Common names. Atlantis fritillary, mountain silverspot, mountain fritillary, mountain silver-spotted butterfly, Newfoundland fritillary.

Type deposited. Lectotype (male) designated by dos Passos and Grey (1947) at American Museum of Natural History ( Figure 20 ).

Type locality. Mountainous districts of the northern states and parts of British America. Defined by dos Passos (1935) based on lectotype as Hunter, Greene County, Catskill Mountains, New York. Brown (1965) noted that Holland’s 1931 image of S. atlantis is a much better match of populations that occur in the Catskill Mountains than the very dark form dos Passos and Grey designated as lectotype, but at present the specimen designated by dos Passos and Grey represents the name bearing type for S. atlantis .

Type label data. “ type Atlantis [male] Catskills; lectotype Argynnis atlantis [male], W. H. Edwards designated by dos Passos 1935 ” .

Identification, taxonomy, and variation. Speyeria atlantis forms are widespread and variable. Adult wingspan ranges from 50-69 mm. Prior to splitting the hypothetically distinct species S. hesperis from S. atlantis , there were over 25 subspecific or geographical forms associated with the atlantis complex ( Grey 1951; Moeck 1957). Scott et al. (1998) (also see Scott 1988) proposed splitting S. atlantis and S. hesperis based on wing coloration and a few larval characters. Because they behave as separate species across large parts of western North America, several works now treat S. atlantis and S. hesperis as distinct species ( Scott et al. 1998; Guppy and Shepard 2001; Opler and Warren 2002; Dunford 2005; Warren 2005); thus, there are four subspecific ‘ atlantis ’ forms recognized at present. However, some authors believe that it may still be difficult to provide a species assignment for many populations based on ventral hindwing coloration and silvering of ventral hindwing spots ( Pyle 2002), and because there are several reports of the two forms interbreeding in various parts of their range ( North American Butterfly Association 2001) (also see discussion under S. hesperis profile). The nominate, eastern S. atlantis bears black margins along the forewings and black scaling along the veins dorsally. The ventral hindwing disc is usually purplish-brown in coloration. The remaining S. atlantis forms generally bear a black outer margin dorsally and chocolate or purplish-brown hindwing discs. Ventral hindwing spots are silvered in most individuals (many S. hesperis forms are cream colored) and the submarginal band is pale and narrow. Adults may be confused with S. aphrodite in many regions (including eastern North America), but aphrodite does not have black scaling along the wing veins and usually lacks black marginal bands dorsally. Speyeria atlantis canadensis (dos Passos) , now synonymized under S. atlantis ( Scott et al. 1998) , is generally smaller in size. Holland (1969) noted that specimens taken from Hawkes Bay, Newfoundland were even smaller and redder than S. a. canadensis taken at the type locality, Doyles Station. This variability notes the probable relationship of nominate S. atlantis with S. a. canadensis and further corroborates the decision by Scott et al. (1998) to fully synonymize the smaller Canadian ‘ atlantis ’. An S. atlantis population occurring in the mountains of West Virginia may represent an undescribed subspecies ( Gatrelle 1998). Larvae of nominate S. atlantis are generally mottled black and brown with blacktipped, orange to tan spines with two cream-colored lines located dorsomedially. Larvae are somewhat variable in coloration throughout the range of S. atlantis (see Scott et al. 1998). Pupae are mottled brown and black, and the wing cases are grayish brown. Scudder (1889) and Edwards (1888a) provided a detailed description of the life stages.

Range. Widespread in Canada from the Yukon, Maritime Provinces and west to east central British Columbia; in the northeastern United States south to West Virginia, across the northern parts of the Great Lake region. Speyeria atlantis has been tentatively recorded in northeastern Illinois (Cook County) but is likely not a resident ( Irwin and Downey 1973; Bouseman and Sternberg 2001). Reportedly “accidental” in Morris County, New Jersey ( Gochfeld and Burger 1997). Disjunct populations exist in the Black Hills of South Dakota [ S. atlantis pahasapa Spomer, Scott, Kondla ] (see Grey et al. 1963; Scott et. al 1998), central Colorado [ S. atlantis sorocko Scott, Kondla, Spomer ], and northwestern Montana, northern Idaho, and Manitoba [ S. atlantis hollandi (F. H. Chermock) ]. Populations that are tentatively identified as S. a. hollandi also occur in northeastern Washington, sympatric with S. hesperis brico Kondla, Scott, Spomer.

Life history. Adapted for cooler climates, it frequents cool open woodlands near water, (i.e., bogs, river valleys), open coniferous forests, and old fields with forested borders. Scott (1988) indicated that the current distribution of wing characters suggests that the dark silvered forms of S. atlantis occupied coniferous forests in the northern U.S. and the Rocky Mountain foothills during the last ice age; they then moved higher in elevation and latitude. The unsilvered form with a reddish-brown ventral hindwing (i.e., ‘ hesperis ’ forms) occupied open forest in the southern Great Basin lowlands during the last ice age; they then spread north into the mountains, east to Wyoming and the Black Hills, and south along the Colorado mountain foothills. The mobility of western S. atlantis adults was studied by Moeck (1968) in Wyoming. He noted that tagged individuals were recaptured at least 50% of the time, indicating individuals moved very little from the study area. Eggs are laid near the base of host plant. First instar larvae typically do not feed until the following spring. Males patrol much of the day for available females. Mating behavior is described by Scott (1986b, 1988). Speyeria atlantis [as well as other Argynnini ( Sellier 1973; Magnus 1958)] adults bear scent scales that lie along the veins on the dorsal side of the forewings ( Grey et al. 1963; Scott 1986b). Males pursue females, draw their forewings forward, and flick the closed wings slightly open in quick bursts. Each burst of two to five flicks lasts less than a second, wafting pheromones up to the female’s antennae. Courting males keep their forewings in a forward position and open and close them near the resting female to waft pheromones. Unreceptive females will flutter their wings to reject males. Flight period is mid June to September.

Larval host plants. Viola septentrionalis , V. sororia affinis , V. adunca , V. canadensis ( Scott 1986b, Scott et al. 1998). Many host plant records in the literature listed for S. atlantis now pertain to members of the hesperis complex.

Adult food resources. Milkweeds, vetches, mints, mud, dung ( Scott 1986b; Douglas and Douglas 2005); especially Monarda spp. in the West (Cliff Ferris, pers. comm.).

Figures

Figure 16-20. Type images for Speyeria spp.; dorsal, ventral, and label images. 16) Speyeria callippe lectotype, described as Argynnis callippe, male, NMNH. 17) Speyeria egleis neotype, described as Argynnis egleis, female, NMNH. 18) Speyeria adiaste lectotype, described as Argynnis Adiante, female, NMNH. This specimen is not recognized as the name bearing type. 19) Speyeria adiaste lectotype, described as Argynnis Adiaste, male, CMNH. 20) Speyeria atlantis atlantis lectotype, described as Argynnis Atlantis, male, CMNH. Images 16-18 by Robert Robbins; 19-20 by James C. Dunford.

Figure 21-25. Type images for Speyeria spp.; dorsal, ventral, and label images. 21) Speyeria atlantis canadensis lectotype, described as Argynnis atlantis canadensis, male, AMNH. Now synonymized under Speyeria atlantis (Scott et al. 1998). 22) Speyeria atlantis hollandi holotype, described as Argynnis atlantis Hollandi, male, CNIC. 23) Speyeria atlantis sorocko holotype, described as Speyeria atlantis sorocko, male, AMNH. 24) Speyeria atlantis pahasapa holotype, described as Speyeria atlantis pahasapa, male, AMNH.25) Speyeria hesperis neotype, described as Argynnis Hesperis, male, CMNH. Images 21 and 23-25 by James C. Dunford; 22 by Norbert Kondla.