Plebejus chrisreai Churkin, Kolesnichenko & Yakovlev, 2019

Churkin, Sergei V., Kolesnichenko, Kirill A. & Yakovlev, Roman V., 2019, Two new taxa of Plebejus Kluk, 1780 (Lepidoptera, Lycaenidae) from the Gobi desert, Mongolia, Zootaxa 4695 (1), pp. 45-58 : 47-52

Plebejus chrisreai Churkin, Kolesnichenko & Yakovlev , sp. n.

Plate 1 and 2, figs. 7 (holotype), 8–12, 21–23 (paratypes).

Holotype: ♂, SW Mongolia, Khovd aimak, Dzhungarian Gobi des., Ushig spring, 1200 m.a.s.l., 27.06.2018, 45°35’ N, 90°56’ E, S. Churkin, K. Kolesnichenko, V. Pletnev, Odbayar Tz. leg.( ZISP).

Paratypes: 172 ♂, 136 ♀, same data, S. Churkin, K. Kolesnichenko, V. Pletnev, Odbayar Tz. leg. ; 30 ♂, 20 ♀, same locality, 3.07.2015, R. Yakovlev leg. ; 1 ♂, 1 ♀, SW Mongolia, Khovd aimak, Dzhungarian Gobi des., Del Khaar Uul , 1350 m.a.s.l., water spring, 7.07.2018, 45°39’ N, 90°54’ E, S. Churkin leg.

Paratypes are deposited in private collections of S. Churkin (Reutov), V. Pletnev (Reutov), K. Kolesnichenko (Moscow), Odbayar Tz. (Ulan-Bator), P. Beda ( Ljubertzy ), G. Grieshuber ( Ortenburg ); in the Institute of General and Experimental Biology MAS and in ZISP .

Additional material: 24 ♂, 20 ♀, SW Mongolia, Khovd aimak, Dzhungarian Gobi, Olon bulak (spring), 1550 m.a.s.l., 4.07.2018, 45°10’25” N, 91°19’41” E, S. Churkin, K. Kolesnichenko, V. Pletnev, Odbayar Tz. leg. ; 5 ♂, 3 ♀, SW Mongolia, Khovd aimak, Dzhungarian Gobi , 20 km S Altai somon, water spring, 1150 m.a.s.l., 5.07.2018, 45°32’47” N, 92°10’58” E, S. Churkin leg.

Description.

Male. Holotype FW length 13 mm, paratypes 11–15 mm (average 13–14 mm, n = 40).

Fringes from the upperside white with narrow blackish inner part.

Upperside blue with light violet hue, costal side of forewing with obvious suffusion of whitish scales. Black margins thin, ends of veins blackish. Hindwing often (but not always) with submarginal black dots between veins.

Forewing underside light gray with black discal spot and s-curved postdiscal series of black spots, Cubital spot usually enlarged and shifted toward the base. Submarginal series looks erased (with rare exceptions), apical part of the spots strongly reduced, only two cubital spots more or less developed with slightly expressed orange segments.

Hindwing underside whitish-gray or light-gray with whitish marginal half of wing, Base with obvious but narrow and not dense bluish-greenish suffusion. Blackish spots normally developed, basal and postdiscal series complete (4 basal and 8 postdiscal spots), discal spot not thin. Cubital spot in postdiscal series strongly shifted toward the base. Submarginal pattern complete, each spot consists of v-shaped internal thin black segment, well-developed bright orange or reddish-orange segment and external plate of greenish-blue metallic scales. Marginal band whitish, external parts of all metallic plates also sometimes appear whitish.

Female. FW length 13–15 mm (average as in males, n=30).

Fringes whitish, with very thin dark inner part joined with blackish spots at end of veins.

Upperside whitish with blue hue of base of both wings (bluish shining is more obvious on hindwings), veins slightly blackish but do not look contrasting. Discal spot thin but often (not always) developed on both wings. Forewing with darkened submarginal band with brownish not contrasting oval spots between veins. Hindwing submarginal series complete and consists of large black spots, rarely outlined internally by reddish-orange lunules.

Forewing underside whitish or light grayish-white, pattern more developed than in males, submarginal spots often with developed orange segments, except apical and anal ones. Postdiscal spot strongly s-curved.

Hindwing underside whitish or light grayish-white/ brownish-white. Pattern as in males, bluish-green suffusion less developed. Submarginal spots with more expressed orange segments and metallic plates.

Individual variation. According to our statistics, whitish females present over 70%, but the colour varies depending on locality. Rarely females fully bluish (Pl. 1: 21), very rarely obscured and have brownish hue (but never totally brown; Pl. 1: 22). It seems that females from Olon Bulak and Altai somon (east part of the distribution area) statistically darker, but our material is mainly worn and not sufficient to confirm this observation.

Males rarely have thick black margins, while blackish ends of the veins not so prominent—but ground blue colour is light in all cases.

Male genitalia (Pl. 3: 1, Pl. 4: 1, Pl. 5: 1, 2, 5). Labis (distal parts of uncus) with moderately long and thin ends from lateral view. Valva without developed convexities, with moderately smooth outlines, upper distal projection (“upper lip”) very wide, lower distal projection (“lower lip”) also widened and massive. Juxta has straight branches which gradually move apart to ends—but the true shape nearly impossible to observe without separation.

Aedeagus thin, proximal part without large ventral inflation, and obviously but only moderately wider than distal part. Distal part with visible narrowing in middle and widened near distal end. Aedeagus curved, but curving located after joining of proximal and distal parts—so that this joining itself straight, and only distal part curved downwards. Curving usually weakly expressed, aedeagus often looks moderately straight. Distal part obviously longer than proximal part.

Diagnosis. The size of P. chrisreai is statistically smaller than that of P. germani , the latter has a forewing length of 13.5–16 mm in both sexes (average 14–15 mm: n=55 totally). Even two other taxa are also slightly larger (see below, forewing length 14–15.5 mm).

The new species differs from all other Mongolian relatives by a light colour of the upperside: P. germani and P. anikini have common dull or deep violet-blue colour. The difference is based on the pigment and not on the quantity of the white scales (that is quite obvious under magnification; P. germani has practically the same quantity of these whitish scattered scales). As a rule, the new species usually has more expressed blackish ends of the veins, but it is not such a constant feature (see Pl. 1: 23, 24, where the veins characters are changed but the ground colours are still different).

The whitish upperside of the females presents unique distinction which is not known among Plebejus spp. in East Palaearctic. Even the rare dark aberrations (Plate 1:22) cannot be confused with dark-brown females of P. anikini or P. germani .

The light underside can be easily differentiated from the dark-gray underside of the relatives. The orange lunules are bright and usually have a reddish hue, while in all other taxa these lunules are pale and yellowish, and exceptions are rare. In addition, the postdiscal row of both other species are usually moderately straight without a shifted cubital spot; the area between postdiscal and submarginal series is not contrastingly whitish compared with the colouration of P. chrisreai . These features are not consistent but easily recognizable in the series (Pl. 2: 2; the male of P. germani with a moderately curved postdiscal row on the forewing underside).

The genitalia distinctions are as follows: labis are thinner than in P. germani but similar and even wider/shorter than that in P. anikini (Pl. 3). Valva has no distinctive convexities (opposite to P. germani but similar to P. anikini ), distal lips are very wide: the upper lip is distinctively wider than in the closest P. germani , the lower lip is obviously wider than the very thin and shortened lower lip of P. anikini (Pl. 4; some details of the width of the lips are not clearly visible but the distinctions given here are consistent and useful in the comparison of the real sclerites). The juxta has a specific structure—in both other species, the branches of the sclerite are convex. The aedeagus is moderately similar to that of P. anikini , the place of curving is distally moved from the point of the joining of the proximal and distal parts. In P. germani the place of curving is situated just at the joining of the distal and proximal parts, the degree of the curving is much more expressed as a rule. In addition, the proximal part of the new species is obviously thinner (not so heavy) compared to P. anikini and especially to P. germani , the distal part is longer than the proximal part, while in both other species the character is opposite.

Bionomics (Pl. 6: 1). Bushes near the springs in the desert consist of the Tamarix sp. and food plant Halimodendron halodendron (the females laid the eggs). We anticipate that the species has several generations.

Distribution (Pl. 7). The species was numerous and collected in 4 localities—but we only included the material from Ushig springs and the closely situated spring near Del Khaar Mt in the type series. Two other localities were excluded to avoid possible future problems.

Etymology. The species is named after Christopher Anton (Chris) Rea, British rock and blues singer-songwriter and guitarist. The songs of Chris Rea accompanied us in the mountains and deserts for over two decades of expeditions and always brought us luck.