On the basis of the characters of external morphology and analysis of DNA barcodes, an isolated population of the Arctic Apollo, Parnassius arcticus (Eisner, 1968) (Lepidoptera, Papilionidae), from the Momsky Range mountains (northeastern Yakutia, Russia) is described here as a new subspecies, Parnassius arcticus arbugaevi Yakovlev & Shapoval, subsp. nov. The taxonomy, distribution, ecology, and biotopical preferences of the nominotypical P. arcticus and the new subspecies are discussed.

Lepidoptera, Parnassiinae, Parnassius, DNA barcode, distribution, taxonomy

The Arctic Apollo, Parnassius arcticus was described by Eisner (1968) and was erroneously attributed to P. simo Gray, 1853 as a subspecies (Tadumia simo arctica in the original description).

Subsequently, Eisner (1976) corrected this mistake and regarded P. arcticus as a subspecies of P. tenedius (Eversmann, 1851). The description was based on the two specimens from “den Bergen östlich von Werchnosensk” [sic!] (“Werchnosensk” should refer to Verkhoyansk, Yakutia, Russia). Later, a remote population from Suntar-Khayata was discovered and described by Korshunov (1988) as a separate species P. ammosovi Korshunov, 1988 (type locality - “Russia, Yakutia, Suntar-Khayata Range, 180 km ENE from the Khandyga settlement, river Vostochnaya Khandyga upper flow, 232nd km of the road from Khandyga to Magadan”). The status of P. ammosovi appears questionable for being of specific or subspecific rank. This taxon has also been occasionally treated as a synonym of P. arcticus (Gorbunov 2001; Gorbunov and Kosterin 2003). There are no clear morphological differences that distinguish P. ammosovi from P. arcticus including any obvious biogeographical barriers that could isolate these taxa.

The Arctic Apollo is known from the following localities, according to the contemporary data (Fig. 1) (Korshunov 1988; Chichvarkhin 2004; Gorbunov 2008; Bakhaev 2017):

1. Russia, Yakutia, Verkhoyansk range, river Kele headwater, river Kokchin (L. Popova leg.) – one specimen in ISEA collection.
2. Russia, Yakutia, Suntar-Khayata Range, 180 km ENE from the Khandyga vill., river Vostochnaya Khandyga upper flow, Khandyga-Magadan road, 1400-1450 m (type locality).
3. Russia, Yakutia, Suntar-Khayata Range, ca. 95 km WSW from the Kyubeme vill., 62°45'35"N, 139°23'09"E.
4. Russia, Yakutia, Suntar-Khayata Range, 50 km S from Labynkyr lake, NE Yakutia, 62°09'00"N, 143°26'40"E, 1150-1200 m.
5. Russia, Magadan, Kolyma highlands, Yablonovy pass, Khasyn distr. [~60°25'N, 151°13'E]. A single specimen was collected by V. Baglikov (Gorbunov 2008).

It should be noted that the numerous attempts to find P. arcticus in the vicinity of Yablonovy Pass between 1995-1999 have not been successful, thus the presence of the species in Magadan Region requires confirmation.

Figure 1.

Map of collecting localities of Parnassius arcticus: blue circles – P. a. arcticus, red circle – P. a. arbugaevi ssp. n.

The biology of the P. arcticus has been described in detail by several authors (Popova 1988; Glushchenko 1996; Gorbunov and Kosterin 2003; Vinokurov and Stepanov 2007; Bakhaev 2017). This taxon inhabits scree mountain slopes of southern and south-western exposition at altitudes of 1200-1700 m, and apparently occurs in low number of individuals. Adults are feeding on Gorodkovia jacutica Botschantzev & Karavaev, 1959 (Brassicaceae) and ignore other flowering plants. Females oviposit on stones near the larval hostplant, Corydalis gorodkovii Karavaev 1957 (Papaveraceae), or at the bottom of the plant stem. The pupa is the overwintering stage. Butterflies fly from early June (rare from late May) to the beginning of July and in some years into the middle of July.

Recent phylogenetic studies revealed P. arcticus together with P. tenedius form the most basal, strongly differentiated lineage of Parnassius sensu lato, supporting its placement within the separate (sub) genus Sachaia (Michel et al. 2008; Zheng et al. 2018). It should be noted that despite dissimilarities in the sphragis and genitalia morphology as well as pronounced differences in size, wing pattern, habitat choices and food plants, these taxa appeared to be similar genetically. The phylogenetic reconstructions based on four genes (mitochondrial ND5, COI; nuclear Wingless, EF1-α) demonstrates lack of significant genetic differentiation between P. arcticus and P. tenedius (Omoto et al. 2004; Chichvarkhin et al. 2004). This fact led to the assumption on the conspecificity of this pair of taxa, but further research based on additional material is needed to fully clarify this conclusion. The phylogenetic relationships of P. arcticus and P. tenedius are not analyzed nor discussed in detail here because of a different focus of our article and the limited number of sequenced samples currently available.

During the field trip to northeastern Yakutiya taken in 2019, a remote population of P. arcticus from the Momsky Range was discovered and the analyses of DNA barcodes and morphological traits (genitalia, wing pattern) were performed. Herein we present the results of these studies, and describe a distinctive Yakutian population of Arctic Apollo as a new subspecies, P. arcticus arbugaevi ssp. n.

Sequencing of three specimens from the Suntar-Khayata Range and three samples from the Momsky Range performed in the current study did not reveal intra-population polymorphism, all of the sequenced specimens share one COI haplotype within certain population. At the same time, specimens from the Momsky Range differs from the Suntar-Khayata specimens by two fixed synonymous nucleotide substitutions (A→G) in positions 412 and 511 of the COI DNA barcode (Fig. 2). Chichvarkhin (2004) analysed P. arcticus from two remote populations at a distance of ca. 240 km of the Suntar-Khayata range. All 20 examined specimens appeared to be genetically homogenous with respect to studied mitochondrial and nuclear genes. Unfortunately, these sequences are not publicly accessible and, therefore, cannot be compared with our data.

Figure 2.

Nucleotide differences between Parnassius arcticus arcticus and P. arcticus arbugaevi ssp. n. within studied 658 bp fragment of COI gene.

Taking into account the low genetic differentiation observed between P. tenedius and P. arcticus, as well as the absence of intra-population polymorphism within P. arcticus, revealed fixed differences in the COI gene between P. a. arcticus and the newly discovered population, P. a. arbugaevi ssp.n., may reflect a relatively old isolation of the Momsky Range and the Suntar-Khayata populations due to a fragmentation of the original ancestral range of the taxon. Both subspecies have similar ecological preferences, occupying almost devoid of vegetation black aleurolite screes above 1000 m a.s.l., and being a strict host-specialists, feeding on only one Corydalis species (Fig. 6). The new subspecies also did not show significant differences in the male genitalia (Fig. 3), while differs considerably in the wing shape and wing pattern (mainly by the absence of dark spot in the forewing discal cell), which especially distinct in the females (Figs 4–5).

Figure 3.

Male genitalia of Parnassius arcticus: a – P. a. arcticus (slide coll. Yakovlev 2020#6); b – P. a. arbugaevi ssp. n. (slide coll. Yakovlev 2020#8).

Figure 4.

Wing pattern of Parnassius arcticus arbugaevi ssp. n. (a-f) and P. arcticus arcticus (g-h): a – male, holotype; b-c – males, paratypes; d-f – females, paratypes; [Russia, NE Yakutia, Momsky Range, 70 km E of Khonuu village, 1400 m, 22-24.06.2019, leg. Yu. Bakhaev]; g-h – males, [Russia, NE Yakutia, Suntar-Khayata Range, ca. 95 km WSW from the Kyubeme vill., 13.06.2017 (g), 10-15.06.2018 (h), leg. Yu. Bakhaev]. Scale bar = 1 cm.

Figure 5.

Wing pattern of Parnassius arcticus arcticus: a-d – males; e-h – females; [Russia, Yakutia, Suntar-Khayata Range, Vostochnaya Khandyga riv., Khandyga–Magadan rd., Sukhaya Rechka riv., h=1400 m, 10-20.06.1991, leg. B. Khramov]. Scale bar = 1 cm.

Figure 6.

Parnassius arcticus arbugaevi, adult specimens in nature, host plants and habitat (photo by Yu. Bakhaev): a, b − P. a. arbugaevi ssp.n. in nature, male and female; c, d − habitat of P. a. arbugaevi; e − Gorodkovia jacutica, feeding plant of adults of P. a. arbugaevi; f − Corydalis gorodkovii – larval host plant of P. a. arbugaevi. Location of eggs laid on stones near the larval hostplant indicated by an arrow.

The authors are grateful to all the colleagues whom provided assistance in preparing the article. Andrei Barabanov, Anatoly Krupitsky and Zdenek Faltynek Fric gave valuable comments, Ilya Yudakov allowed us to use P. arcticus image from his private collection, Boris Anokhin helped with images preparation. In organizing the field studies, an invaluable assistance was provided by the director of Momsky Natural Park, Mikhail Ivanov, inspector Innokentiy Fedorov, the director of ecological-ethnographic complex "Chochur Muran" German Arbugaev. The assistance in finding the comparative material and inaccessible publications was provided by Alexander Streltsov. The genital slides were made by Ksenia Proskuryakova. The financial support for this study was provided to N. Shapoval by the grant N 19-14-00202 from the Russian Science Foundation to the Zoological Institute of the Russian Academy of Sciences.

Authors contribution

R.V. Yakovlev and N.A. Shapoval contributed equally to the study design, analysis and manuscript preparation.