Eastern persius duskywing: COSEWIC assessment and status report: chapter 5

COSEWIC Status Report
on the
Eastern Persius Duskywing
Erynnis persius persius
in Canada
2006

Species Information

Name and Classification

Scientific name:
Erynnis persius persius (Scudder, 1863)
Synonyms:
Nisionades persius, Thanaos persius
Bibliographic Citation:
Scudder, S.H. 1863. A list of the butterflies of New England. Proceedings of the Essex Institute 3: 161-179. Type Loc. = New England.
English names:
Persius Duskywing
French name:
Hespérie Persius de l’Est

The Persius Duskywing (Erynnis persius) was first described in 1863, but the original description is ambiguous, and Scudder (1863) was undoubtedly confusing E. persius with the Wild Indigo Duskywing (E. baptisiae (Forbes)) and the Columbine Duskywing (E. lucilius (Scudder and Burgess)), neither of which were described at the time. Confusion persisted in later works, such as that by Skinner (1914), which depicted male genitalia of what is considered by M. Holder to be E. baptisiae. However, Scudder and Burgess (1870) and Forbes (1936) accurately described and portrayed genitalia of E. persius. Although Forbes (1936) mentioned type material and depicted genitalia from the type specimen, Scudder (1863) did not assign types in his original description and it is unclear where the type material is deposited, if this material still exists.

Four subspecies of the Persius Duskywing have been described, three of which may occur in Canada: E. p. persius, E. p. borealis and E. p. avinoffi. The subspecies borealis was described by Cary (1907), but was originally designated a race of the Propertius Duskywing (E. propertius Scudder and Burgess). This common and widespread race is found across northern and western Canada, from James Bay in Ontario to Yukon. The known ranges of E. p. borealis and E. p. persius do not overlap, but appear disjunct by at least 1000 km (Figure 1), as judged by collection data presented by the Canadian Biodiversity Information Facility (2005), and the United States Geological Survey (2005). Erynnis (p.) avinoffi (Holland 1930) was described from a series of specimens collected in the Yukon River Valley and sites in Alaska. This subspecies’ distribution is unclear, other than the localities mentioned in the original description, and Layberry et al. (1998) do not consider the subspecies valid. A fourth subspecies, E. p. fredericki, occurs in the western United States and does not occur in Canada. Figure 1 shows the distribution of E. p. persius as well as that of the other subspecies in North America.

Further work on the taxonomy of this E. persius complex is needed to clarify spatial boundaries and distribution of its taxa. Burns (1964) did not delve into this skipper complex beyond giving a brief discussion of the problem and stating the close affinities of the four taxa. With differences in biology (different host plants and habitat requirements) and apparent differences in morphology, it may be best to consider nominate E. persius a species that is separate from the three western subspecies (see Kondla and Guppy 2001).


Figure 1: North American Range of Erynnis persius

Figure 1. North American range of Erynnis persius.

E. p. persius range is grey, other subspecies combined is black.


Description

The Eastern Persius Duskywing is a small (24-31 mm wingspan), dark skipper (Figure 2) with diffuse grey patches in the upper forewing separated by a line of four white spots; a fifth white spot may be present at the lower border of the forewing’s grey patch. Fine hair-like scales cover much of the upper surface of the forewings, a variable proportion being white. A subterminal row of grey spots borders the outer edge of the forewing, and each hindwing is solid brown with a smattering of slightly paler brown spots dotted throughout. The head, thorax and abdomen are dark brown.


Figure 2: Dorsal view of Erynnis persius persius

Figure 2. Dorsal view of Erynnis persius persius

Original drawing by Andrea Kingsley.

Despite statements to the contrary (Balogh 1981, Nielsen 1999), the pattern and shape of the forewing spots are not diagnostic (D. Lafontaine, pers. comm., 2002, D. Schweitzer, pers. comm., 2002, M. Holder, pers. obs.). An examination of series of specimens at the Royal Ontario Museum and the Canadian National Collection resulted in the conclusion that the abundance of white hair on the forewings and the arrangement of the small white forewing spots, where the basal edges of the spots align along a straight line, are indicators of the species, but exhibit such variability within E. persius and closely related E. lucilius and E. baptisiae that they are not useful for diagnosis. The different host plant associations exhibited by the three species may help with species identification in a general way: E. lucilius is associated with wild columbine (Aquilegia canadensis L.), but E. baptisiae is associated with the same host plants as E. persius, namely wild indigo (Baptisia tinctoria (L.) R. Br. ex Ait. f.) and wild lupine (Lupinus perennis L.), in addition to other species such as wild blue indigo (B. australis (L.) R. Br. ex Ait. f.) and crown vetch (Coronilla varia L.). The best method of identifying E. persius adults is through an examination of male genitalia, which are diagnostic (Figure 3). The right and left valves of E. p. persius, E. baptisiae and E. lucilius are shown for comparison (Figure 3), with arrows highlighting features on the upper and lower lobes of the valves where differences exist. Erynnis baptisiae have genitalia similar in many ways to E. lucilius, although the upper lobe of the left valve is thicker than in E. lucilius. The genitalia can only be examined with the help of a dissecting microscope after the hairs and scales that cover them are removed with a brush. Identification of females is problematic, and M. Holder does not have any useful characters for diagnosis, other than the general wing features described above.


Figure 3: Diagram Showing the Right (on right) and Left Valves of Male Genitalia

Figure 3. Diagram showing the right (on right) and left valves of male genitalia.

Valves are shown inverted, laterally viewed. Arrows point to features useful for separating the three species. I) Erynnis lucilius, II) Erynnis persius. III) Erynnis baptisiae (Original drawing by Matt Holder.).

Descriptions and illustrations of adults are found in Klots (1951), Allen (1997), Layberry et al. (1998) and Glassberg (1999). A detailed description of the adult is found in Burns (1964).

Layberry et al. (1998) state the larva is similar to that of the Afranius Duskywing (E. afranius), which is pale green striped with black and yellow along its back. Larval E. p. borealis is described as pale green with numerous white spots (Guppy and Shepard 2001). The rounded head is brown, unlike the angular black head of E. lucilius (Figure 4; Lindsey 1927, Layberry et al. 1998). The larva of E. baptisiae has not been described (Layberry et al. 1998), and may be a source of confusion.


Figure 4: Head Capsule of Fifth-instar Erynnis persius persius Larva

Figure 4: Head Capsule of Fifth-instar Erynnis persius persius Larva

Drawing by Matt Holder, based on Lindsey 1927.

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