Ischnura elegans malikovae, Onishko & Kosterin, 2022

Onishko, Vladimir V. & Kosterin, Oleg E., 2022, Ischnura elegans malikovae subspecies nova (Odonata, Coenagrionidae) from the Far East of Eurasia, with discussion of other possible subspecies, Zootaxa 5120 (4), pp. 573-585 : 574-579

Ischnura elegans malikovae subspecies nova

( Figs 1–2 , 3a , 4 )

Type material. Holotype: ♂ ( Figs 1a , 2 , 3a ), Russia, Primorskiy Kray, Pozharskiy District, Luchegorsk Town, the Luchegorsk Reservoir bank at the outlet, 46.4625° N, 134.3009° E, 68 m a.s.l., 28 vii 2020, V. Onishko leg., deposited in RMNH . Paratypes: 2 ♀♀ ( Figs 1a , 3 ), the same data ; 4 ♂♂, Russia, Khabarovskiy Kray, Khabarovsk District, the pond in Korfovskiy Settlement , 48.2226– 48.2240° N, 135.0619– 135.0632° E, 104–106 m a.s.l., 25 vii 2020, V. Onishko and O. Kosterin leg.; deposited in RMNH and the collection by the second author .

Additional data: ♂ photographed, Russia, Primorskiy Kray, Spasskiy District, Prokhory village , the bank of a big reservoir at the dam, 44.513° N, 132.696° E, 83 m a.s.l., 31 vii 2020 .

Etymology. The subspecies is named after Dr. Elena Ivanovna Malikova, a prominent expert of Odonata of the Far East of Russia, who for the first time reported this taxon (as I. elegans ) for that territory.

Holotype. Mostly bicolorous blue and black, but head with pale greenish ground colour and the ventral part of tergites in the middle part of abdomen yellowish ( Fig. 1a ).

Head ( Fig. 2b ). Labium pale greenish. Labrum pale green with a black stripe along base with a gentle and rounded central projection. Mandibles greenish. Anteclypeus greenish. Postclypeus black. Antefrons largely pale green; postfrons black but black colour somewhat extends from the former to the latter between antennae, its border uneven. Vertex and occiput black, with two large nearly triangular (with rounded corners) azure blue postocular spots. Rear head surface pale bluish.

Thorax ( Figs 1a , 2a–b ): Most of anterior lobe of prothorax ( Fig. 2d–e ) occupied by a broad azure blue stripe. Median prothorax lobe black above, azure blue below, with black on either side making a projection at its hind margin ( Fig. 2d ). Posterior lobe azure blue laterally, black below; in dorsal view ( Fig. 2e ) has a bluntly triangular margin overlaid by a strong process protruding posteriorly. This process has a longitudinally concave surface, straight, slightly converging margins and a rounded tip bearing a large pale-blue spot with brownish margins ( Fig. 2e ). In lateral view ( Fig. 2d ) posterior lobe fore margin convex and hind margin concave, process attenuated in dorso-caudal direction. Mesostigmal plate ( Fig. 2e ) rather simple, its margin forming two gentle waves on either side. Either side of mesostigmal plate with azure blue outer half (but suture remains black), these blue stripes intruding into otherwise black pterothorax dorsum ( Fig. 2e ). Antehumeral stripes well developed, azure blue ( Figs 1a , 2a ). Black humeral stripes tapering posteriorly. Sides of pterothorax (including entire mesinfraepisternum) and coxae azure blue, with short black streak at tops of interpleural and metapleural sutures, the former very narrow, the latter expanding as a rounded diamond. ( Figs 1a , 2a ). Poststernum azure blue.

Legs ( Figs 1a , 2a ): ground colour of femora pale bluish, of tibia and tarsi yellowish-white; femora with broad black stripes along dorsal side and tibia with black stripes along ventral and posterior sides; tarsal segments pale with dark apices; all spines and claws black.

Wings hyaline; main longitudinal veins yellowish, narrow veins blackish. Ten postnodals on fore wing, eight on hind wing. Pterostigmata diamond-shaped, with slightly convex costal side, those on hindwing slightly smaller. Fore wing pterostigma tricolorous above—inner half black, outer half blue but becomes white at apex, and bicolorous below—inner ca 2/3 black, outer 1/3 pale blue; black parts with narrow paler rims; bordering veins blackish at its dark part but become yellowish at pale part. Hind wing pterostigma dark-grey inside, with whitish margins at bordering veins but blue at outer tip; bordering veins as above ( Fig. 1 ).

Abdomen ( Figs 1a , 2c ): S1 azure blue at sides, black dorsally. S2 azure blue with a large black wine-cup-shaped black dorsal spot, with a ‘base’ as dorsal trasnversal stripe at hind margin of segment. S2–S5 pale with broad dorsal black stripes, indented from anterior margin of segment, convex before their posterior margins and contacting to black stripes along the latter; ground colour changing from azure blue to bluish-yellow on S3, yellowish on S3–4 and bluish-yellow on S5. S6 ground colour azure blue, black dorsal spot broader but near posterior margin of segment on either side with roundish incisions filled with ground colour. S8 azure blue with a black streak along posterior margin going for half of its height in lateral view. S9 and S10 azure blue below and black above, with black occupying slightly less than half of S9 tergite height on S9 but about 2/3 of S10 tergite height in lateral view. S9 posterior margin with a dorsal blue dot; S10 posterior margin brownish. Secondary genitalia yellowish, hamuli with pale-brown margins, ligula brownish-black. Sternites of S1–S6 barely seen, black, of S7 bluish-yellow with a black mid-streak, on S8 pale blue with a black mid-streak, on S9–S10 pale blue, black. S10 raised dorsally towards apical tubercle, its dorsal margin in dorsal view oblique but straight. Apical tubercle has a rectangular outline with rounded corners in caudal view, its lateral margins thick and black, somewhat extending to dorsal side where they acquire brownish colour and form rounded, laterad inclined projections; tubercle inner area azure blue. In dorsal view S10 posterior margin, as well as tubercle posterior margin, shallowly incised as a blunt angle.

Cerci brown but their dorsal side and processes blackish brown; short and rounded in lateral view and nearly rectangular, disposed at a blunt angle to each other in dorsal view ( Fig. 3a ). In caudal view they are roundish, their inner processes long, blunt and deeply crossed with each other ( Fig. 3a ). Paraprocts yellowish basally but their dorsal side and protruding distal part brownish-black. They are twice as long as the cerci and twice as short than S 10 in lateral view, directed obliquely upward, the left one slightly curved, the right one very slightly so; their apices blunt; dorsal side and apices coarse because of scarcely defined blunt teeth, about three of which disposed on apex ( Fig. 3a ). In dorsal view they are very slightly diverging, almost parallel, slightly hooked at base ( Fig. 3a ). In caudal view the tips of paraprocts project onto the hind margin of S10, their inner processes yellowish with rounded tips ( Fig. 3a ).

Measurements (mm). Hindwing 18.5; abdomen without appendages 29; total length 37.

Variation in male paratypes. The angle at which the paraprocts are directed obliquely upward varies between ca 30° and 40°. In one paratype the paraprocts are slightly curved, whereas in others their shape is nearly straight. The number of irregular teeth on the apices of the paraprocts vary: in two paratypes the paraproct ends with a robust blunt tooth and a larger tubercle on dorsal surface just before it; in another paratype the left paraproct is the same while the right one ends with three irregular teeth, as in the holotype; in the fourth paratype the left paraproct also bears two and the right one five blunt teeth at apex, which is slightly expanded after a slight subapical constriction. The blue spot at the apex of the prothoracic process is as large as in the holotype in one paratype, but is reduced to occupy only its hind margin in two paratypes, and the blue colour is completely missing from the process in one paratype. The pterostigma coloration varies considerably: in one paratype the fore wing pterostigma lacks the blue colour; in two paratype it lacks the blue colour only its upper side while the black colour expands to ca 4/5 of the pterostigma or more on both sides; the hind wing pterostigma varies in the degree of darkening of its main area and the breadth of the pale rims. There are nine rather than ten postnodals in both fore wings of one paratype and in one of those in another one. Ranges of measurements (mm): hindwing 17–19; abdomen without appendages 26.5–29; total length 33–36.

Female. The two female paratypes ( Figs 1a , 4 ) resemble males in coloration; they slightly differ in size from each other; the smaller individual is illustrated in Fig 4 .

Head ( Fig. 4b ) As in male but in the smaller female the postocular spots also smaller (about twice as small with respect to area), with uneven margins.

Thorax ( Figs 1a , 4a ): Pterothorax as in male. In the larger female paratype the posterior process of its hind margin is as in the male holotype but the blue spot is larger and there is a blue dot on the left side of the median lobe. In the smaller female paratype the process is flat, slightly shorter and much broader, trapezoid with barely converging sides, almost rectangular, with rounded angles and a small and shallow incision at apex ( Fig. 4d ). In the larger female venation is dark and there is one more postnodal on each wing than in the holotype; in the smaller female venation is as in the holotype but the longitudinal veins are paler. All pterostigmata pale grey with whitish margins, three bordering veins dark but costal one pale. ( Fig. 4b ).

Abdomen ( Figs 1a , 4c ) as in male but somewhat thicker, dorsal black spot of S2 somewhat narrower, that of S7 with shallower posterior incisions and that of S9 with deeply incised margins ( Fig. 4c ) (which are straight in male). Sternite of S8 with blue spots, vulvar spine well developed ( Fig. 4c ). Ovipositor yellowish but style brownish ( Fig. 4c ). Cerci blackish, paraprocts yellowish ( Fig. 4c ).

Measurements (mm; two specimens). Hindwing 18 and 19.5; abdomen without appendages 25 and 27.5; total length 32.5 and 35.5.

Diagnosis. While currently I. elegans is considered as a monotypical species ( Boudot & Salamun 2015; Schröter et al. 2015; Schneider et al. 2018; Kosterin & Ahmadi 2018), a new subspecies described for it should be compared to the nominotypical subspecies which is to be redefined. Its type locality is Europe, from where the species was described. We find specimens of I. elegans from Europe, the Caucasus, Ural and West Siberia homogeneous with respect to the characters considered as diagnostic below, so we assume I. e. elegans to range in these territories. The new subspecies is very similar to I. e. elegans but the males strongly differ from it in their paraprocts. In dorsal view, the male paraprocts of I. e. malikovae are nearly parallel ( Fig. 3a ) while in I. e. elegans from Europe, Ural and West Siberia they are strongly divaricate and strikingly (1.5 times) longer ( Fig. 3b ). In lateral view, the male paraprocts of I. e. malikovae are directed obliquely upward ( Fig. 3a ), as in Ischnura genei (Rambur, 1842) , while in I. e. elegans they are directed strictly posteriorly ( Fig. 3b ). In specimens from Iran (Markazi Ostan), which we consider to represent the subspecies I. e. ebneri (see below), the paraprocts are scarcely or not at all divergent but of the same length as in I. e. elegans in dorsal view and strictly caudally directed in lateral view ( Fig. 3c–d ), in this view being 0.71–0.73 as long as S10 ( Fig. 3c–d ) versus ca. 0.5 in I. e. malikovae and 0.6 in I. e. elegans ( Fig. 3c–d ). The prothoracic process in males of I. e. malikovae sp. nov. is longer than broad and parallel-sided, which is, however, within the variation of I. e. elegans .

We failed to trace any diagnostic difference of females of the new subspecies from those of I. e. elegans .

From the superficially similar Ischnura senegalensis (Ris, 1916) , with which the new species co-occurs in Korea and China, I. e. malikovae differs by the presence of a strong process of the prothorax posterior lobe in both sexes, by the black dorsal spot on S 2 in males not glittering green and the ventral parts of the S7 tergite largely blue rather than black. In addition, the male paraprocts in I. senegalensis are longer, pointed and more curved towards each other in dorsal view.

One more species of Ischnura co-occurring with I. e. malikovae is Ischnura asiatica (Brauer, 1865) , which belongs to the pumilio -group and well differs by the pterostigmata substantially smaller in the hind wings than in the fore wings, S8 black but S9 pale (blue or green) in males (vice versa in I. elegans ), and smaller size.

Distribution. Ischnura e. malikovae occurs for sure in the southern Khabarovskiy Kray and Primorskiy Kray of Russia. However, based on biogeographical considerations and available illustrations in the literature (see Discussion below), it appears to enjoy a broad East Asian distribution. We believe that it likely occupies the eastern Zabaikalskiy Kray, Amur Province and Jewish Autonomous Region in Russia and broadly ranges across N and NE China, Korea, and Hokkaido and the northernmost Honshu in Japan. In Japan it seems to have been mistaken for I. elegans elegans , while specimens from China and Korea were not identified to subspecies.

Habitat. The new subspecies was found in sedge ( Carex sp. ) at the bank of a small and clear pond inside the town of Korfovskiy (southern Khabarovskiy Kray), of a large reservoir quite polluted with cattle dung inside the village of Prokhory (southern Primorskiy Kray) and of a very large, clear and warm reservoir at Luchegorsk Town (northern Primorskiy Kray). So, it inhabits a variety of lentic habitats and prefers sedge bordering open water. It is noteworthy that in the southern Far East of Russia it appears to be highly local and never so widespread and numerous as I. elegans in the West Palearctic.

Figures

FIGURE 1. Ischnura elegans malikovae. in nature: a—in copula (the holotype male and paratype female) in the type locality, the reservoir in Luchegorsk Town, Primorskiy Kray, Russia; b–c—males at the pond in Korfovskiy settlement, Khabarovskiy Kray, Russia.

FIGURE 2. Morphological details of the holotype male, of Ischnura elegans malikovae: a—head and thorax, lateral view; b— head, frontal view; c—end of abdomen, lateral view; d—prothorax, lateral view; e—prothorax, dorsal view. Scale bar 1 mm.

FIGURE 3. Male anal appendages of Ischnura elegans sspp. (left—dorsal view; middle—lateral view; right—posterior view): a—I. elegans malikovae, the holotype; b—I. elegans elegans elegans from Russia, Krasnodarskiy Kray Province, Novorossiysk Municipality, Lake Krugloe, 44.677° N 37.597° E, 10 vii 2016 (Kosterin 2017); c–d—I. elegans elegans ebneri from Iran, Markazi Province, Garehchay River at Gavigodar village 34.109° N 49.363° E, 19 v 2017 (Kosterin & Ahmadi 2018); these two specimens exhibit the extremities of the slight variation in the paraproct orientation in the same series. Scale bar 1 mm.

FIGURE 4. Morphological details of the smaller female paratype of Ischnura elegans malikovae: a—head and thorax, lateral view; b—head (dorsal view) and prothorax (lateral view); c—end of abdomen, lateral view; d—prothorax, anteriodorsal view. Scale bar 1 mm.