Speyeria idalia ( Drury, 1773 )

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 : 7-11

Speyeria idalia ( Drury, 1773)

( Figure 2-3 , 4A , 6 )

Papilio Nymphalis Phaleratus Idalia Drury, 1773: 1 ( Figure 2 )

Argynnis astarte Fisher, 1858: 179 .

Argynnis Ashtaroth Fisher, 1859: 352 .

Argynnis Idalia-Infumata Oberthür, 1912: 315 .

Argynnis idalia Drury form dolli Gunder, 1927: 286.

Argynnis idalia Drury form pallida Eisner, 1942: 124.

Speyeria idalia (Drury) [ dos Passos and Grey 1945a].

Common names. Regal fritillary, regal silverspot butterfly, regal silver-wing, ideal argynne, eastern regal fritillary, prairie regal fritillary.

Type deposited. Neotype (male) designated by dos Passos and Grey (1947) at American Museum of Natural History ( Figure 6 ).

Type locality. See Figure 2 for original description. New York. Defined by dos Passos and Grey (1947) based on neotype as New York City, New York County, New York.

Type label data. “ No. 1349, coll. J. Angus, West Farms , New York City.; NEOTYPE, Pap. Nym. Phal. Idalia Drury ” .

Identification, taxonomy, and variation. Adult wingspan ranges from 68-106 mm. The forewings in males and females are bright orange-brown with black markings. The veins in the forewing of the male are thick and dark but there is no basal suffusion. Dorsal hindwings are black with a postmedian row of white spots and submarginal row of orange (male) or white (female) spots. The ventral hindwing disc is a deep olive and the spots are large and silver. The black surface on the dorsal hindwings distinguishes S. idalia from most other Speyeria . The genitalia is similar to those in the Semnopsyche group. The male has a thick, hooked uncus ( Figure 4A ) and there is a secondary bursal sac in the female. Prior to Williams (2001a,c; 2002), there were no ‘subspecific’ taxa designated under S. idalia . Based on adult wing morphology and molecular evidence, Williams separated the western and eastern (Pennsylvania) S. idalia populations. The name Speyeria idalia occidentalis Williams (Type locality Will County, Illinois) has been given to the western populations. Eggs are pale green when newly laid, changing to tan as the larva develops inside. Larvae ( Figure 3A ) are velvety black with ochre-yellow or dull orange markings and transverse stripes. The dorsal spines are silver-white with black tips. The top half of the larval head capsule is bright red-orange. Scudder (1889) described the six larval instars in detail. Pupae ( Figure 3B ) are approximately 28 mm in length, light brown, tinged with pink, and bear black spots on the wing cases. There are also yellow transverse bands on the abdomen. Detailed egg, larval instar, and pupal descriptions are included in Edwards (1879d).

Range. Formerly known from Manitoba south through the plains states to central Colorado [likely a stray in central Colorado ( Scott 2008a p. 114)] Kansas, northeastern Oklahoma, and Missouri; in the east from New Brunswick south to northwest North Carolina. Many colonies, however, have disappeared due mostly to habitat loss. Scudder (1889) reported S. idalia as far south as northern Georgia (but see Calhoun 2007), Louisiana (but see Hovanitz 1963a), and Arkansas, and also reported it to be abundant in Connecticut and Massachusetts. Dos Passos and Grey (1947) listed the following states: Maine, Vermont, New Hampshire, Massachusetts, Connecticut, Rhode Island, New York, New Jersey, Maryland, Delaware, Pennsylvania, Virginia, West Virginia, Indiana, Ohio, Michigan, Illinois, Wisconsin, Kansas, Nebraska, Montana, South Dakota. It has been extirpated from most of New England except for a few offshore islands (but see Schweitzer 1993; Wagner 1995), and also extirpated from the mainland of New York, New Jersey, and Delaware ( Evers 1994; Gochfeld and Burger 1997). It has also been extirpated in many areas in the Great Lakes region ( Douglas and Douglas 2005) and is now rare or absent from many areas east of the Mississippi River ( Opler and Wright 1999). Adults may wander long distances, and many records represent observations of single wandering individuals ( Opler and Wright 1999). Currently, S. idalia are found in good numbers in the Great Plains states, with fragmented populations in the Midwest, and only a few known populations in the east (Pennsylvania and Virginia) ( Schweitzer 1993; Mason 2001; Williams 2001a; Mooreside et al. 2006).

Life history. Habitat includes Upper Austral to Transition Zone in wet meadows/fields, marshlands, and prairie. Open grassy areas, such as mid-grass or tall-grass prairies, are preferred habitat. Life history studies and land management issues are numerous for S. idalia ( Swengel 1993, 2004; Swengel and Swengel 2001; Wagner 1995; Glassberg 1998a,b; Debinski et al. 2000; Mason 2001; Ferster 2005; Kelly and Debinski 1998; Kopper et al. 2000; Kopper et al. 2001a,b,c; Ross 2001 ; Shepherd and Debinski 2005; Keyghobadi et al. 2006). Swengel (1997) reported S. idalia were significantly more abundant in larger Midwestern prairies with topographic diversity and management by haying or grazing. Speyeria idalia are reportedly sensitive to fire, and management activities should both address the temporal and spatial aspects of the resource needs of the butterfly ( Evers 1994; Swengel 1997; Swengel and Swengel 2001; Swengel 2004). Eggs are laid singly near host plants or on host plants ( Scudder 1889) and unfed first instar larvae hibernate. Oviposition site selection may be influenced by the presence of grass and forb overstory for protection against solar radiation and harsh overwintering conditions (Kopper et. al 2000). Females do not lay many eggs until August or early September ( Scott 1986b; Kopper et al. 2001c), and a single individual is capable of laying nearly 2,500 eggs ( Wagner 1995). Larvae have been observed feeding on violets during the day ( Kopper et al. 2001a; Mooreside et al. 2006). Flight period is from June through early September. Speyeria idalia is either listed as endangered, threatened, or are of special concern in several states ( Shuey et al. 1987; Evers 1994, Schlicht 1997; Mason 2001; Vaughan and Sheperd 2005b). Williams (1999, 2001a,b,c) suggested that the subspecific status of the eastern population of S. idalia idalia has important conservation implications and should result in federal emergency listing for this taxon. Habitat loss, due to development and agriculture, is the likely cause of the decline of S. idalia in many areas (Vaughan and Sheperd 2005b), but their decline may also be due to pesticide spraying for gypsy moths control in some regions ( Evers 1994). Larval host plant decline ( Kelly and Debinski 1998) and lack of suitable nectar sources ( Wagner 1995) may also explain the disappearance of S. idalia . Wagner (2005) reported a nuclear polyhedrosis virus in captively bred populations, and this may also be a factor in the decline of some wild populations. Small, isolated populations are vulnerable to extirpation and loss of genetic diversity unless ovipositing females can find other suitable habitats. Ries and Debinski (2001) suggested the movements of adults are influenced by the quality of habitat, and that they are less likely to exit from suitable habitat. It has also been reported that S. idalia is non-migratory and generally stay within the same local area throughout their lifetime ( Scott 1986b). Keyghobadi et al. (2006) have shown that S. idalia populations in Pennsylvania occupying three, relatively nearby meadows exhibited restricted gene flow and unique genetic signatures. This suggests there may be fine–scale genetic subdivision in areas where S. idalia populations have been largely extirpated. The results presented by Williams et al. (2002) and Williams et al. (2003) indicated that microsatellite markers have shown increased differentiation and decreased genetic diversity in the isolated, eastern S. idalia populations. Midwestern populations, which are presently experiencing the same effects of habitat fragmentation, are also more likely to experience the associated increase in extinction risk due to both genetic and demographic factors ( Williams et al. 2003).

Larval host plants. Viola pedatifida , V. papilionacea , V. lanceolata , V. pedata , V. sagittata , V. sororia ( Swengel 1997; Robinson et al. 2002; Douglas and Douglas 2005).

Adult food sources. Common milkweed, butterfly milkweed, swamp milkweed, pasture and field thistles, alfalfa, butterfly weed, black-eyed Susan, wild bergamot, blackberry, dogbanes, crown vetch, Deptford pink, spotted knapweed, ox-eye daisy, dotted blazing star, prairie blazing star, purple coneflower, black Sampson ( Shapiro and Shapiro 1973; Debinski et al. 2000; Ross 2002 ; Douglas and Douglas 2005; Ferster

2005; Shepherd and Debinski 2005; also see Kopper et al. 2001b for S. idalia and nectar source phenologies).

Figures

Figure 2. Original description and colored illustrations for ‘Idalia’ reproduced from Drury 1773.

Figure 3. Images of Speyeria idalia life stages. A) Larva. B) Pupa. C) Adult on butterflyweed, Crawford County, Wisconsin. Images A-B by David L. Wagner; C by James C. Dunford.

Figure 4. Male genitalic armature. A) Speyeria idalia (locality unknown). B) Speyeria cybele (Nebraska). C) Speyeria hesperis (aedeagus removed) (Idaho). D) Digitus located on left valva, Speyeria edwardsii (Nebraska). Images by James C. Dunford.

Figure 6-10. Type images for Speyeria spp.; dorsal, ventral, and label images. 6) Speyeria idalia neotype, described as Papilio Nymphalis Phaleratus Idalia, male, AMNH. 7) Speyeria diana holotype, described as Papilio Nymphalis Phaleratus Diana, male, BMNH. 8) Speyeria cybele neotype, described as Papilio Nymphalis Phaleratus Cybele, female, BMNH. 9) Speyeria aphrodite neotype, described as Papilio Nymphalis Phaleratus Aphrodite, male, AMNH. 10) Speyeria nokomis neotype, described as Argynnis Nokomis, male, AMNH. Images 6 and 9-10 by James C. Dunford; 7-8 by Kim Goodger Buckmaster.