Plebejus idas subsolanus ( Eversmann, 1851 )

Churkin, Sergei V. & Yakovlev, Roman V., 2024, New data about Plebejus idas (Linnaeus, 1761) (Lepidoptera, Lycaenidae) from Russia, with the description of the new subspecies, Ecologica Montenegrina 73, pp. 106-115 : 109-110

2. Plebejus idas subsolanus ( Eversmann, 1851) .

Lycaena subsolanus Eversmann, 1851: 620-621 . Description de quelgues nouvelles especes de Lepidopteres de la Russie. – Bull. Soc. Nat. Mosc. 24 (1): 620.

TL: “Irkutzk”.

Figures 1 (upperside) —2 (underside): 1−4.

Material: Irkutsk region: Nizhneudinsk (series), Kosaya steppe, Olkhon district (series), Kultuk (series), Marituy, outskirts of Irkutsk (several points, single specimens); Buryatia: Barguzinsky range (lower reaches of the Nesterikha Riv., 11 males and 1 female) .

Description (only taxonomically important characters).

FW length 15−17 mm (males and females) in Nizhneudinsk and Irkutsk populations, butterflies from Baikal shores and Barguzin slightly bigger (15−17.5, even 18 mm).

Male. Wings upperside violet-blue with faint shine. Wings shape slightly narrowing, like in idas . Marginal black stripe wide, about 2 mm, usually sharp – only its inner side sometimes blurred. Veins sharply highlighted in black.

Wings underside light-grey with typical pattern, spots size standard.

FW underside: submarginal pattern not complete, reduced, especially in costal area.

HW underside: basally light-grey, area behind discal band lightened, usually completely, sometimes as blurred white triangles, spots of postdiscal stripe of medium size, with non-contrasting white rings. Submarginal spots not magnified, divided or hardly touching one another (not forming one orange stripe), inner black segments of each spot not big, flattened, pattern not sharp, metallic scales developed in 1−3 spots, which is typical for this subspecies group.

Female. Brown, often with fading orange submarginal pattern on FW and HW upperside, but pattern not complete. Wing underside darker than in males, but not contrasting.

Variability. Little in Nizhneudinsk and Irkutsk populations, specimens with strong darkening of wings are quite rare, the underside sometimes is lightened (resembling cleobis , one specimen had almost white underside with extended submarginal spots without metallic scales), but light rings around spots remain. The submarginal pattern is more developed, the orange spots are well developed on FW underside, almost forming a single band on HW underside. The wing margin has a white stripe with white fringe, the inner part of this fringe bear the small dark (blackened) spots near the veins - this pattern is typical for almost all Siberian and Asian idas , often allowing to distinguish this species from females of other species of the genus.

Highly likely that the lectotype was obtained not far from Irkutsk, because it looks similar to the corresponding material (however, the available series is still too short) .

Butterflies from the shores of Baikal have a wider marginal stripe (statistically), sometimes very darkened – as a result of hybridization with the very dark obukhovi Churkin et Zhdanko, 2003 (described from Tunkinskie Goltsy) and the mentioned above ssp. kenteana . Even near Olkhon in the village Kosaya steppe the specimens with wings darkened by a third are quite common. However, in total such forms constitute up to 10−20% of the population. More important, the Baikal butterflies have slightly expanded wings, characteristic of ssp. kenteana or ssp. barabash Churkin et Zhdanko, 2003 . It should be noted that this character is related to the overall size and always appears if the FW costal edge length exceeds approximately 16 mm.

Butterflies from the Barguzinsky range have a contrasting pattern with a wide marginal black stripe; in 7 specimens out of 11 the orange spots on the underside are expanded, forming a single band; in the series there is one male indistinguishable from kenteana and one male very similar to the typical subsolanus from Nizhneudinsk.

Bionomics. Inhabits dry and wet meadows along rivers, roads, forests, base of cliffs and spurs. The food plant is not exactly known.

Distribution. Irkutsk region and the shore of Lake Baikal (except the north), including the Barguzin depression. The western distribution border unknown.

Figures

Figure 1. Adult specimens of Plebejus, upper side: 1 – Plebejus idas subsolanus, male, Russia, Siberia, Irkutsk reg., Nizhneudinsk, B. Uk r., 1.07.1999, S. Koleshichenko leg. 2 – Plebejus idas subsolanus, male, Russia, Siberia, Irkutsk reg., Ol’khon distr., Kosaya Step’, 10.07.2003, S. Koleshichenko leg. 3 – Plebejus idas subsolanus, male, Russia, Siberia, Irkutsk reg., 10 km E Kultuk v., 27.06.2003, S. Churkin leg. 4 – Plebejus idas subsolanus, female, same data as 1. 5 – Plebejus idas reshetnikovi ssp. nova, holotype, male, Russia, East Sayan, Burjatia, Oka r. valley, 20 km SW Khuzhyr v., Zham-Bolot spring, 1500 -1600m, 2.07.2023 S.Churkin leg. 6 – Plebejus idas reshetnikovi ssp. nova, paratype, male, same data as 5. 7 – Plebejus idas reshetnikovi ssp. nova, paratype, male, same data as 5. 8 – Plebejus idas reshetnikovi ssp. nova, paratype, female, same data as 5. 9 – Plebejus idas cleobis, male, North Baikal reg., Verkhnyaya Angara r., Novyi Uoyan vic., 5−7.07.2006, A. Kryukov leg. 10 – Plebejus idas cleobis, male, same data as 9. 11 – Plebejus idas cleobis, male, same data as 9. 12 – Plebejus idas cleobis, female, same data as 9. 13 – Plebejus idas cleobis, female, same data as 9 (dark form). 14 – Plebejus idas ternejana, male, Russia, Far East, Komsomolsk-on-Amur, 13.07.2005. 15 – Plebejus idas reshetnikovi ssp. nova, paratype, female (dark form), same data as 5. 16 – Plebejus idas ssp.?- male, Russia, Siberia, Irkutsk reg., Lena r., 8 km NNW Kachug v., 24.06.2023, S. Churkin leg.