Leia nigricornis Van Duzee, 1928

Polevoi, Alexei & Salmela, Jukka, 2016, New data on poorly known species of the genus Leia Meigen (Diptera, Mycetophilidae) from the Palaearctic region, Zootaxa 4103 (5), pp. 487-500 : 492-495

Leia nigricornis Van Duzee, 1928 .

( Figs. 3 ; 4; 6C)

Leia nigricornis Van Duzee, 1928: 46 . Holotype: 1♂ (CAS, pinned), USA, Unalaska, Alaska, 10.9.1920, prep. by G.D. Hanna, Collector, California Academy of Sciences, Type n 2503, Leia nigricornis (handwritten), Holotype. Van Duzee (examined).

Other material examined. FINLAND: 1♂, Lkor: Sodankylä, Viiankiaapa, Kiimakuusikko E, N67.5508, E26.7701, 10.7.– 14.8.2013, Malaise trap ( ZMUT, J. Salmela leg., in alcohol); 1♂, Lkor: Sodankylä, Heinäaapa, N67.5959, E26.8845, 10.8.– 19.9.2012, Malaise trap (JES, J. Salmela leg., # MYCE-JS-2012-0021, in alcohol); 1♂, same locality and date (JES, J. Salmela leg., # MYCE-JS-2012-0029, in alcohol); 1♂, the same locality and date ( FMNH, J. Salmela leg., in alcohol); 1♀, Lkor: Sodankylä, Viiankiaapa, Kiimakuusikko E, N67.5508, E26.7701, 14.8.– 19.9.2013, Malaise trap (JES, J. Salmela leg., # DIPT-JS-2014-0171, in alcohol); 1♂, Lkor: Sodankylä, Viiankiaapa, Kiimakuusikko E, N67.5508, E26.7701, 10.7.– 14.8.2013, Malaise trap (JES, J. Salmela leg., in alcohol); 1♂, Lkoc: Kittilä, Akrahamanvuoma, N67.5933, E25.3086, 1.8.– 3.9.2007 ( ZMUT, J. Salmela leg., in alcohol); 6 ♂, 2♀ Lkoc: Kittilä, Akrahamanvuoma, N67.5933, E25.3086, 1.8.– 3.9.2007 (JES, J. Salmela leg., # DIPT-JS-2014-0213); 9♂, 1♀, Lkor: Sodankylä, Heinäaapa, N67.5959, E26.8845, 10.8.– 19.9.2012, Malaise trap (JES, J. Salmela leg., #DIPT-JS-2014-0214, in alcohol); 16♂, 3♀, Lkoc: Kittilä, Vasanvuoma, N67.5831, E25.2032, 2.8.- 2.9.2007, Malaise trap (JES, J. Salmela leg., #DIPT-JS-2014-0294, in alcohol); 1♂, Obb: Keminmaa, Kallinkangas, N65.8166, E24.5008, 28.7.– 23.9.2014, Malaise trap (JES, J. Salmela leg., #DIPT-JS- 2014-0469, in alcohol). RUSSIA: 1♂, Amur province, Klimoutsy, 40 km W of Svobodnyi, 13.9.1958 ( ZIN, Zinovjev leg., pinned); 1♂, Yakutia, Teplyi Klyuch, 70 km ENE of Handyga, 21.8.1974 ( ZIN, Gorodkov leg., pinned)

Diagnosis. A black species with almost no pale markings on thorax. Coxae yellow, hind femora with darkened apices. Wings with preapical crossband, extending from costa to cell m1 or to tip of CuA1, and a cloud behind CuA2. Male gonostylus gently curved, smooth, resembling ox horn and lacking any secondary processes.

Description. Male (n=5).

Head black with yellowish setae. Three ocelli, arranged in a row between hind margin of eyes. Lateral ocelli close to, but not touching eye margin. Central ocellus smaller than laterals. Palpus pale. Palpal segments with setae, equal in length or slightly longer than palpus width. Last segment longest, 1.60–1.81 times as long as penultimate segment. Antennae dark-brown, scape, pedicel and base of first flagellomere yellow. Scape with numerous setae, about as long as scape width, pedicel with a strong seta dorsally on apical margin, reaching the base of second flagellomere. Middle flagellomeres about 2 times longer than wide. Last flagellomere 1.27–1.53 times longer than penultimate.

Thorax black, only small yellowish spots present on anterior and posterior corners of mesoscutum (these spots are more extensive in the specimen from Amur province), and area of anterior spiracle pale. Pale setae present on mesoscutum, antepronotum, laterotergite and scutellum.

Wing ( Fig. 6 C). Wing length 4.21–4.39 mm. Wing yellowish with preapical crossband, extending from costa to cell m1 or to tip of CuA1 and a cloud behind CuA2. Darkening at base of M-fork present in some specimens. Veins pale or brown, Sc and R4 lacking setosity. Sc2 beyond the middle of Sc. Base of M-fork beyond the middle of ta. CuA1 weak, appearing interrupted at base. R1 0.39–0.63 times as long as ta, which is 0.38–0.45 times as long as R5 and 1.24–1.42 times as long as M-stem. Haltere pale yellow.

Legs. Fore and mid coxae pale yellow, bearing numerous pale setulae on anterior surface, mid coxa also with a small basal brown spot on dorsal side. Hind coxa yellow with base slightly infuscate and only a few setae both distally and proximally. Trochanters mainly yellow, with dark dots on ventral surface. Fore and mid femora yellow with a narrow, basal dark band on ventral side, bearing numerous pale brown setulae. Hind femur yellow with narrowly darkened tip, bearing numerous darkish setulae. Tibiae yellow with numerous pale to brownish setulae. Fore tibia with ca. 20 black setae, much shorter than tibial diameter, and a long black seta on apex, about as long as tibial diameter. Mid tibia with ca. 30 black setae, of which 13–15 are longer than tibial diameter. Hind tibia with ca. 30 black setae, of which 10–11 are longer than tibial diameter. Spurs yellow, with pale setulae and serrated inner side. Fore tibia with one spur, which is 2.25–2.60 times as long as apical tibial diameter. Mid and hind tibiae with two spurs. Posteroventral spur on mid tibia 1.24–1.30 times longer than anteroventral spur and posteroventral spur on hind tibia 1.30–1.53 times longer than anteroventral spur. Tarsomeres infuscate. Ratio of femur to tibia for fore, mid and hind legs: 1.04–1.15; 0.88–1.01; 0.75–0.81. Ratio of tibia to basitarsus for fore, mid and hind legs: 1.05– 1.16; 1.42–1.58; 1.91–2.09.

Abdomen predominantly dark-brown, with pale setae. Basolateral triangular pale spots present on tergites 2–5 in the specimen from Amur province. Sternites 2–4 with medial pale triangular markings, of varying size (may be confined to sternite 2 or almost totally absent). Terminalia ( Fig. 4 : A–F) brown. Gonocoxite with a ventral bifurcated medial process, ventral branch short and with several setae, dorsal branch bare and with slightly serrated margin. This medial process is surrounded by two pointed lobes (apicoventral corners of gonocoxites) with two setae on apices. Gonostylus gently curved, smooth, resembling ox horn and lacking any secondary spine like processes. Tergite 9 ovate with group of setae along caudal margin. Cerci with truncated apices, about as long as tergite 9. Aedeagus partly sclerotised, ejaculatory apodeme bilobed. Paramere evenly bowed in lateral view, about 1.5 times longer than aedeagus. Hypoproct subrectangular with 6 stout setae along caudal margin.

Female (n=5). In general, very similar to male. Antennae shorter. Wing length 4.6–4.7 mm. Terminalia as in Fig. 4 : G, H. Cercus 2-segmented, sparsely setose, basal segment about 2 times longer than apical segment. Hypoproct with about 7 long and some shorter setae laterally. Caudal margin of gonocoxite 8 with a medial Ushaped emargination.

Taxonomic remarks. Type material of L. nigricornis (holotype and a paratype) was collected from USA, Alaska, Unalaska (ca. 53.87°N, 166.52°W). According to the original description ( Van Duzee 1928) the holotype was a female and no illustrations were provided. However, the holotype ( Fig. 3 ) is a male specimen and we can state that L. nigricornis is a Holarctic species. The species is here reported for the first time from the Palaearctic region ( Finland and Russia). Leia nigricornis is rather easily separated from its congeners by the combination of spotted wings and generally black body color. Based on the male terminalia, L. nigricornis is quite similar to L. fascipennis Meigen , L. bimaculata Meigen and L. montanosylvatica Zaitzev , but can be distinguished from these due to the characteristic ventral medial process of its gonocoxite (cf. e.g. Kurina 2008, p. 282, Figs 27, 28, Zaitzev 1994, p. 269, Fig. 85: 1) and the structure of the aedeagal complex.

Biology. Finnish collecting localities are rich fens with sparse or non-existent woody vegetation. The species was quite numerous on Heinäaapa (Viiankiaapa mire conservation area), which is characterised by calcareous spring pools and lawn-level vegetation (that is, water level is somewhat below the moss carpet). Brown mosses such as Scorpidium revolvens , Campylium stellatum and Paludella squarrosa dominate in the bottom layer, and plant species such as Saxifraga hirculus , Bartsia alpina and Saussurea alpina are conspicuous in the mire. Other collecting sites, Akrahamanvuoma, Vasanvuoma (Tollovuoma-Vasanvuoma mire conservation area), Viiankiaapa and Kallinkangas (Kallinkankaanletot mire conservation area) are rich flark fens, that is, characterised by wet flarks with inundated brown mosses and narrow strings with bog vegetation. Based on its label, the male specimen from the Amur region of Russia, was collected from a Larix -Quercus forest.

Distribution. Holarctic, known from USA (Alaska), Europe ( Finland) and East Russia (Yakutia, Amur province). Finnish collecting sites, five in total, are located in Lapland, middle–north boreal ecoregions.

Figures

FIGURE 3. Leia nigricornis van Duzee, Holotype. (Photo by Mike Narahara).

FIGURE 4. Leia nigricornis van Duzee, A – F. male terminalia, G, H. female terminalia. A. ventral view. B. dorsal view. C. lateral view. D. aedeagal complex, lateral view. E. aedeagal complex, ventral view. F. hypoproct. G. lateral view. H. ventral view. Scale bars = 0.2 mm. Abbreviations: aed = aedeagus, apo = ejaculatory apodeme, cerc = cercus, gc = gonocoxite, gst = gonostylus, hyp = hypoproct, par = parameres, tg = tergite, vmpg = ventral medial process of gonocoxites, vo = ventral outgrowth of gonocoxites.

FIGURE 6. Wings of Leia males. A. Leia flavipennis. B. Leia iturupensis. C. Leia nigricornis. D. Leia rufiptera. Scale bars = 2 mm.