Plebejus nanshanicus ( Forster, 1936 )

Krupitsky, A. V. & Li, Z .., 2024, Notes on the Plebejus christophi (Staudinger, 1874) (Lepidoptera: Lycaenidae) species group of China, with a description of a new species from the Eastern Tian Shan, Russian Entomological Journal 33 (1), pp. 102-109 : 105-109

Plebejus nanshanicus ( Forster, 1936) , comb. et stat.n.

Figs 8–14 .

Lycaena christophi nanshanica Forster, 1936: 84 . Type locality: “Pass Dingtsiangmiau, Richthofengebirge, Kansu [sic] 2800 m ” [ China, Qinghai Prov., Qilianshan (= Nanshan ) Mts., Huzhu Tu Autonomous County, Datong River valley, ca. 36°55'00.0"N 102°31'00.0"E, 2800 m].

MATERIAL. 29 ♂ ♂, 26 ♀♀, CHINA, Gansu Prov., Qilianshan Mts., Sunan Yugur Autonomous County, Jingtieshan work area env., N 39°18′46″ E 97°56′29″, 2700–2750 m, 08– 11. VII.2016, A. V. Krupitsky leg.; 1 ♂, CHINA, Gansu Prov., Altyn-Tagh Mts. , Aksay Kazakh Autonomous County, 30 km S Aleteng Town, 39°24'32"N 94°17'50"E, 2800 m, 13. VII.2016, A. V. Krupitsky leg.

TAXONOMY. The taxon was originally described as a subspecies of P. christophi based on two males from the Qilianshan Mts. near the border of Qinghai and Gansu provinces, China. In the original description Forster compared it with other taxa of the P. christophi species group known at that time. The main differences mentioned in the description are the developed basal suffusion of the ventral side of the wings and the large very contrasted submarginal pattern of the ventral side of the hindwing. Since its description the taxon nanshanica has been forgotten in the taxonomic literature for nearly 90 years and, consequently, has never been considered in the genus Plebejus : before the 1940s the species currently treated in this genus were usually attributed to the genus Lycaena .

In 2016, a large series of an unusually looking Plebejus species was collected by the first author near Jingtieshan village in the western Qilianshan Mountains, Gansu Province. Examination of these specimens revealed that they correspond to the description of the obscure taxon nanshanica, which should be treated as a distinct species, P. nanshanicus , comb. et stat.n.

REDESCRIPTION. Male ( Fig 8 ). Antenna black, white-ringed at base of antennomeres, club dark. Eye brown, surrounded with white scales. Frons black, top of head dark with white hairs. Palpus: 2nd palpomere white with black scales, 3rd palpomere dark. Thorax: dark brown with bluish grey hairs dorsally, white ventrally. Legs: femur and tibia white, tarsus brown. Abdomen: dark with bluish-grey hairs dorsally, whitish ventrally. Forewing length 12.0 – 16.0 mm, wingspan 24.0–27.0 mm. Dorsal surface of forewing blue with purple tint, veins black near margin, base with light blue hairs, costal area and veins Sc– R 4+5 with suffusion of whitish scales. Margin black, thin. Fringe checkered, with blackish inner part. Ventral surface of forewing light beige with base slightly suffused with bluish scales. Discal spot large, reniform, surrounded with white scales. Postdiscal pattern well-developed, slightly curved, consisting of four large dark brown spots in spaces M1–Cu1 and two small spots in spaces R 4+5 and Cu2. Submarginal markings well-developed, consisted of black and orange elements surrounded with whitish scales. Margin dark, narrow, wavy. Fringe white, with groups of small hairs near veins. Dorsal surface of hindwing blue with purple tint, veins black near margin, base with blue hairs, space Sc+ R 1 brownish black, blue fields in spaces Rs–CuA2 with large black spots, space 2A bluish grey. Margin brownish black, narrow. Fringe checkered, white with brownish inner part. Ventral surface of hindwing light beige with bluish basal suffusion reaching basal group of spots. Basal, discal and postdiscal spots complete and well-developed. Submarginal pattern surrounded with whitish strokes reaching postdiscal row of spots, complete, each element of pattern consisting of V-shaped internal black stroke, well-developed orange lunule, and large external spot of blue metallic scales. Black margin thin, broadened near veins. Fringe checkered.

Male genitalia ( Figs 10–14 ). Labis long and thin, with pointed apex; falx rather short, stout; dorsal edge of valva with straight proximal part gradually turning into shorter straight distal part angled at about 135°, ventral edge wavy, with small rounded projection in distal portion turning into straight lower distal projection; upper distal projection of valva well-developed, with large prominent inwardly directed finely serrated appendage, lower distal projection smaller, with small claw-like pointed tooth; distal part of dorsal edge and ventral edge of valva with inner folds; juxta U-shaped, branch of juxta straight, thick, with rounded apex; aedeagus rather long, curved, with straight very stout basal part abruptly turning into distal part gradually narrowing to apex.

Individual variation.Ventral surface of hindwing of some specimens with more or less developed black submarginal lunules.

Female ( Fig. 9 ). Head, thorax and abdomen as in male. Forewing length 13.0 – 16.0 mm, wingspan 25.0 – 27.0 mm. Dorsal surface of forewing brown with violet-blue suffusion covering 2/3 of wing from base to postdiscal area, most intensive in cell and spaces Cu1–2A. Fringe checkered. Ventral surface of forewing as in male but darker, beige, orange lunules of submarginal line well-developed in all spaces. Dorsal surface of hindwing brown with strong violet-blue suffusion reaching submarginal pattern and developed in all spaces but Sc+ R 1, Rs and 2A; spaces separated by dark brown veins; submarginal lunules consisting of internal V-shaped orange stroke, large dark brown spot and whitish marginal stroke developed in spaces M1–2A. Fringe checkered. Ventral surface of hindwing as in male but darker, with less developed basal suffusion, more contrasted; orange lunules of submarginal pattern developed more strongly, with larger orange elements; metallic scales of submarginal pattern turquoise.

Female genitalia: not studied.

Individual variation. Intensity of dorsal blue suffusion slightly varies between females.

DIFFERENTIAL DIAGNOSIS. Some external characters of P. nanshanicus comb. et stat.n. resemble those of the species of the recently described Mongolian complex of the P. christophi group [ Churkin et al., 2019], P. germani , P. anikini and P. chrisreai , but generally the species in question clearly differs from the latter in the peculiar colouration and pattern of the males and females as well as in the male genitalia. The males of P. nanshanicus comb. et stat.n. differ from the males of P. germani , P. anikini and P. chrisreai in the combination of the checkered fringe and margin of the wings, well-developed dark submarginal lunules of the dorsal side of the hindwing and large metallic submarginal lunules connected by the white strokes with the postdiscal row of spots (the fringe and the margin of the wings are only slightly checkered in some specimens of all species from the Mongolian complex of the P. christophi group, dark submarginal lunules of the dorsal side of the hindwing are slightly developed in some specimens of P. germani and P. chrisreai , submarginal lunules are smaller in P. anikini and slightly connected with the postdiscal row of spots in males of P. germani ). The females of P. nanshanicus comb. et stat.n. differ from those of P. germani , P. anikini and P. chrisreai in the strong violet-blue suffusion of the dorsal side of the wings combined with well-developed orange lunules of the dorsal side of the hindwing (only basal violet-blue suffusion is developed in the females of P. germani , very light blue fields in P. chrisreai and dark lunules lacking orange scales in P. anikini ). In the pattern and colouration of the ventral side of the wing, only some females of P. chrisreai are somewhat similar to the species in question (cf. figs 11, 22, Plate 2 in Churkin et al. [2019]). In the male genitalia, P. nanshanicus comb. et stat.n. differs in the narrower valva with the rather narrow upper distal projection (broader valva with broader upper distal projection in the species from the Mongolian complex of the P. christophi group) and peculiar aedeagus with very stout base abruptly turning into distal part gradually pointed to apex (basal part of aedeagus smaller in P. germani , P. anikini and P. chrisreai ).

Additionally, P. nanshanicus comb. et stat.n. differs from P. fantomas sp.n. described above in the checkered fridge and margin of the wings, absence of extensive bluish suffusion of the ventral side of the wings in males and very well-developed white contrasted pattern of the ventral side of the hindwing.

DISTRIBUTION AND BIONOMICS. According to the known material, P. nanshanicus comb. et stat.n. inhabits the Qilianshan Mountains. Additionally, one male was collected in the Altyn-Tagh Mountains, a series of mountain ranges connecting the Kunlun Mountains and the Qilianshan Mountains. We therefore believe that it inhabits the mid-altitudes of the entire Qilianshan Mountains, Altyn-Tagh Mountains and, probably, part of the Kunlun Mountains, being isolated both from P. fantomas sp.n. and the Mongolian complex of the P. christophi group by the northwestern and northern Gobi Desert, respectively ( Fig 15 ).

Adults of this species were found in abundance on very dry rocky slopes and in bottoms of gorges covered with various xerophytic plants ( Fig. 18 ) actively flying during sunny weather and resting on stones and grasses on cloudy days ( Fig. 19 ). Imagines were associated with shrubs of Corethrodendron multijugum (Maxim.) B.H. Choi & H. Ohashi ( Fabaceae ), which may be a host plant of this species. The only observed accompanying butterfly taxa were Lasiommata deidamia kasumi Yoshino, 1995 , Patricius themis (Grum-Grshimailo, 1891) and Polyommatus sininus (Grum-Grshimailo, 1891) . Most of the collected specimens were rather fresh, so we believe that the flight period is in the first half of July.

Figures

Figs 8–9. P. nanshanicus comb. et stat.n., imago (dorsal side above, ventral side below): 8 — male; 9 — female. Рис. 8–9. P. nanshanicus comb. et stat.n., имаго (вид сверху и вид сниЗу): 8 — самец; 9 — самка.

Figs 10–14. P. nanshanicus comb. et stat.n., male genitalia: 10 — lateral view; 11 — valva, lateral view; 12 — labides and falces, ventral view; 13 — juxta; 14 — aedeagus, lateral view (above), dorsal view (below). Рис. 10–14. P. nanshanicus comb. et stat.n., гениталии самца: 10 — вид сбоку; 11 — вальва, вид сбоку; 12 — лопасти ункуса и ветви гнатоса, вид сниЗу; 13 — юкста; 14 — Эдеагус, вид сбоку и вид сверху.

Fig. 15. Distribution of some taxa of P. christophi species group in China and Mongolia based on examined specimens and published data [Forster, 1936; Churkin et al., 2019]; blank characters refer to type localities; a — P. anikini anikini, b — P. a. azhbogdo. Рис. 15. Распространение некоторых таксонов группы P. christophi в Китае и Монголии на основе исследованных ЭкЗемплЯров и данных литературы [Forster, 1936; Churkin et al., 2019]; контурные фигуры обоЗначают типовые местонахождениЯ; a — P. anikini anikini, b — P. a. azhbogdo.

Figs. 16–19. Plebejus spp., habitats of studied species and adults in nature: 16 — type locality of P. fantomas sp.n.; 17 — P. fantomas sp.n., male in nature (photo by A. Marusov); 18 — habitat of P. nanshanicus comb. et stat.n. near Jingtieshan work area; 19 — P. nanshanicus comb. et stat.n., female in nature (photo by A. Marusov). Рис. 16–19. Plebejus spp., биотопы иЗучаемых видов и имаго в природе: 16 — типовое местонахождение P. fantomas sp.n.; 17 — P. fantomas sp.n., самец в природе (фото А. Марусова); 18 — биотоп P. nanshanicus comb. et stat.n. в окрестностЯх пос. ЦЗЯньтешань; 19 — P. nanshanicus comb. et stat.n., самка в природе (фото А. Марусова).