Polycaena eckweileri Krupitsky, N. Shapoval & G. Shapoval, 2024

Krupitsky, Anatoly V., Shapoval, Nazar A. & Shapoval, Galina N., 2024, Description of a new species of the genus Polycaena Staudinger, 1886 (Lepidoptera, Riodinidae) from China with designation of lectotype of Polycaena lua Grum-Grshimailo, 1891, Zootaxa 5471 (1), pp. 113-124 : 116-120

Polycaena eckweileri Krupitsky, N. Shapoval & G. Shapoval , sp. n.

( Figs 1–12 )

Material. Holotype: ♂, China, Gansu Province, Gannan Tibetan Autonomous Prefecture , Têwo County, 2800–3100 m, 21–24.VI.1988, W. Eckweiler leg., voucher number RIO112, GenBank number PP761338 . Paratypes: 1 ♂, voucher number RIO111, GenBank number PP761337, 2 ♂, same label as holotype.

Description.

Male (holotype). Head: brown, frons with long tufts of brown and whitish hairs; eye brown, densely covered with short brown setae; eye dorsally surrounded with white stripes; palpus densely covered with whitish hairs, black ventrally; antenna black dorsally, with small groups of white scales at base of each antennomere, white ventrally, club mostly black with white spots at base both dorsally and ventrally.

Thorax: dark brown with brown hairs; legs brown, densely covered with whitish scales and hairs.

Abdomen dark brown dorsally, whitish with brown medial stripe ventrally, apex covered with long whitish hairs.

Forewing length 15.0 mm; wingspan 27.0 mm. Forewing: triangular, with apex and outer margin rounded. Dorsal side brown, somewhat darker at places of localization of corresponding dark spots on ventral side, with two black and one bright orange spots in discal cell, blurred orange spot after crossvein, discal row of dark brown spots, postdiscal row of orange spots, largest in cells M 1-2 and Cu 1, and submarginal row of small orange spots; fringe long, checkered, dark brown at veins and whitish between veins. Pattern of ventral side generally corresponding to that of dorsal side; ventral side with whitish veins, motley, darkened at base, with brown stroke along Sc and whitish stroke along costa at base of wing; discal cell half-darkened, beige at half, with two dark brown spots; postdiscal, submarginal and marginal rows of dark brown spots fully developed, with orange scales between them and whitish spaces in subapical and submarginal zones. Fringe checkered, with dark areas at veins, corresponding to dark spots, and light area between veins, corresponding to light spots.

Hindwing elongated, rounded at apex, outer margin nearly straight. Dorsal side nearly uniformly dark brown, somewhat darker at places of localization of dark spots of ventral side, with poorly developed submarginal row of small blurred orange spots. Fringe as on forewing. Ventral side whitish, with fully developed pattern of dark brown spots and strikes: large triangular basal spot, medium-sized rounded discal spot at base of cell and cellular strike along stem of M 3 and Cu, large ovoid spot at crossvein, fully developed postdiscal row of ovoid and triangular spots, broad strikes in cells Cu 2 and A 2 fused with corresponding spots of postdiscal row, short narrow strike at A 3, fully developed row of black submarginal spots and marginal row of black spots separated by whitish veins and smaller whitish spots, with bright orange spots between submarginal and marginal rows in spaces between veins. Fringe checkered, with dark areas at veins, corresponding to dark spots, and light area between veins, corresponding to light spots.

Male genitalia. Uncus pointed at apex, without branches dorsally; fenestrula between tegumen and scaphium restricted to lateral sides; valva elongated, narrow, without ventral branch; ampulla of valva slightly overlapped by harpa; harpa of valva without inner process rising from sacculus, with rugouse surface; central plate (= transtilla) bifurcated posteriorly, with deep incision, each branch with two pointed processes, smaller upper and larger lower; juxta long, leaf-like anteriorly, very thin, pointed posteriorly; aedeagus simple, thin, with pointed turned-up tip and broadened rounded base lacking wings, very long, nearly two times as long as valva.

Individual variation. The development of some elements of the pattern slightly varies between the specimens. Forewing length of the paratypes 14.0–16.0 mm, wingspan 25.0–26.0 mm.

Female. Unknown.

Diagnosis. Polycaena eckweileri sp. n. externally resembles the species previously attributed to the P. lama species group: P. lama , P. kansuensis ( Nordström, 1935) , P. sakaii Sugiyama, 2015 and P. wangjiaqii Huang, 2016 . It can be readily differentiated from P. kansuensis by the large bright orange spots of the forewing dorsally combined with the orange colouration between the dark spots of the forewing ventrally (vs. the smaller whitish or light orange spots of the forewing dorsally and whitish background of the forewing in P. kansuensis ; cf. figs 1–8 in Huang & Li 2016). The new species differs from the externally similar species, P. lama , P. wangjiaqii and P. sakaii , in the reduced submarginal orange spots of the dorsal side of the forewing along with the smaller submarginal elements of the forewing ventrally (vs. the submarginal spots of the dorsal side of the forewing more developed, submarginal elements of the forewing ventrally larger in P. lama and P. wangjiaqii , cf. figs 9–14 in Huang & Li 2016, and in P. sakaii , cf. fig. 263 P 6 in Huang 2021).

The most important differences were found in the male genitalia. Surprisingly, the genitalia of the new species display a combination of the genitalic characters of several species. Polycaena eckweileri sp. n. differs from all the congeners in the combination of the elongated valva with narrow pointed ampulla, very long thin aedeagus, long bifurcate central plate with deep split between lobes, and very long juxta. The valva of the new species slightly resembles that of P. lua , P. minor Forster and P. sejila Huang, 2016 , but with the ampulla thinner and longer, pointed at the apex, projected well beyond the harpa (vs. the ampulla shorter and broader, the harpa projected beyond the ampulla in P. lua , P. minor and P. sejila , cf. figs 62–65 in Huang & Li 2016). The shape of the aedeagus, central plate and juxta are unique compared with the congeners.

Etymology. The new species is named after the collector of the type series, Wolfgang Eckweiler, the renowned German lepidopterist, expert in the Palaearctic Satyrinae and Lycaenidae .

Distribution and bionomics. The new species is known to date only from the type locality in the environments of Têwo County. According to the labels, its habitat is situated in the subalpine meadow zone at 2900–3100 m a.s.l., at the edge of the forest zone, which is the typical habitat of the species of the P. lama species group.

Phylogenetic analysis. Analysis of the DNA barcodes placed P. eckweileri sp. n. within the P. lama species group with high support, but revealed a very low level of the interspecific differentiation between the species of this group. Despite the rather high p-distances between most species involved in our analysis, the species of the P. lama species group differ only by 0.2–0.6% ( Table 2 ). Besides the clade comprising the species of the P. lama group, our analysis revealed four well-supported clades comprising P. lua + P. wangjiaqii and those corresponding to separate species, but did not reconstruct deep interspecific relationships of the Polycaena clades ( Fig. 13 ).

Discussion. Discoveries in the genus Polycaena made during the last decade ( Sugiyama 2015; Huang & Li 2016; Huang 2019, 2021) demonstrate the high rate of endemism in this group and the high degree of the external similarity between the species, which can be well differentiated on the basis of the male genitalia, such as P. lama , P. wangjiaqii , P. sakaii , P. eckweileri sp. n. and, to some extent, P. lua . Surprisingly, our molecular phylogenetic analysis revealed that the recently described species externally similar to P. lama , P. wangjiaqii , is actually the sister species to P. lua . Polycaena wangjiaqii was affiliated with the P. lama species group in the original description ( Huang & Li 2016), but, in fact, its close relationship with P. lua is confirmed also by the male genitalia characters, namely the valva with simple harpa lacking the inner process and simple central plate lacking the broadened apex. Evolution of the external and genitalic characters within the genus Polycaena might be a matter of further molecular phylogenetic researches.

Despite the striking differences both in the habitus and in the male genitalia, and despite the geographically isolated ranges, the species of the P. lama group have nearly identical COI barcodes. Such patterns were found in the family Lycaenidae , which is thought to be sister to Riodinidae according to modern reconstructions, namely in the genera Chrysoritis ( Talavera et al. 2020) , Callophrys ( ten Hagen & Miller 2010) , Tomares ( Krupitsky et al. 2022) , Lysandra ( Talavera et al. 2013) and Polyommatus ( Lukhtanov et al. 2015a) . This phenomenon can be explained by incomplete lineage sorting, interspecific hybridization leading to mitochondrial introgression or impact of the rickettsial bacterium Wolbachia Hertig, 1936 ; all these causes were hypothesized or proved to be influencing for several groups of butterflies ( Lukhtanov et al. 2015b; Bartoňová et al. 2021; Shapoval et al. 2021; Krupitsky et al. 2023).

Finally, the discovery of the new Polycaena species overlooked in the collection of such a large institute as ZISP as well as recent descriptions of new taxa ( Sugiyama 2015; Huang & Li 2016; Huang 2019, 2021) demonstrate that the diversity of the genus Polycaena remains understudied, and new discoveries are possible in remote mountain regions of China.

Figures

FIGURE 13. ML phylogenetic tree of Polycaena spp. and sister genera based on analysis of cytochrome oxidase subunit I (COI) gene fragment. Numbers at nodes indicate ultrafast bootstrap support.

FIGURES 1–12. Polycaena eckweileri sp. n., habitus (1–2, dorsal view left, ventral view right) and genitalia of holotype (3–12): 1—holotype male and its label, voucher number RIO112; 2—paratype male and its label, voucher number RIO111; 3— male genitalia, lateral view; 4—left valva, outer lateral view; 5—left valva, inner lateral view; 6—juxta, lateral view; 7—juxta, dorsal view; 8—tegumen and scaphium, dorsal view; 9—transtilla, lateral view; 10—transtilla, dorsal view; 11—aedeagus, lateral view; 12—aedeagus, dorsal view.