Hexatoma (Eriocera) pianigra Podenas, 2022

Podenas, Sigitas, Park, Sun-Jae, Byun, Hye-Woo & Podeniene, Virginija, 2022, Hexatoma crane flies (Diptera, Limoniidae) of Korea, ZooKeys 1105, pp. 165-208 : 165

Hexatoma (Eriocera) pianigra Podenas sp. nov.

Figs 33-38 , 63

Type material examined

(Fig. 63 ). Holotype, male (Fig. 33 ) (pinned), South Korea, Jeollanam-do, Gurye-gun, Toji-myeon, Naeseo-ri, Piagol valley, 35°15.95'N, 127°34.85'E, alt. 450 m, 3 June 2016 (1), S. Podenas leg. (NIBR). Paratypes: South Korea, 1 female (pinned), #25, Central National Forest 18 miles NE of Seoul, 14 August 1954, G. W. Byers leg, (USNM); 1 female (pinned), Jeollanam-do, Gurye-gun, Toji-myeon, Naeseo-ri, Piagol valley, 35°15.50'N, 127°34.93'E, alt. 310 m, 29 June 2015 (2), S. Podenas leg. (NIBR); 1 female (pinned), Jeollanam-do, Gurye-gun, Toji-myeon, Naeseo-ri, Piagol valley, 35°16.03'N, 127°34.66'E, alt. 460 m, 27 June 2019 (3), S. Podenas leg. (NIBR).

Diagnosis.

Large black species (Fig. 33 ) with body length 14.0-31.5 mm. Male antenna reaching to base of halter if bent backwards. Prescutum and presutural scutum with three distinct stripes. Wing brown with distinct stigma and darkened costal area. Cell m1 present. Legs dark brown to black. Abdomen entirely black. Epandrium of male genitalia with slightly concave posterior margin. Gonocoxite 2.6 × longer than wide. Inner gonostylus wide, slightly arched, swollen in the middle. Paramere arched. Aedeagus simple, long, narrow, straight. Ovipositor brown.

Etymology.

The species is named after the type locality, the Pia River, and for the black color of the body (= Hexatoma nigra ).

Description.

Body coloration black, semi-polished. Body length of male 14.0 mm, female 26.5-31.5 mm, wing length of male 16.3 mm, female 17.8-21.0 mm.

Head. Black, densely covered with brownish gray pruinosity and scattered short erect black setae. Eyes marginated by narrow whitish gray. Vertical tubercle large, rounded, with indistinct medial groove, concolorous with the rest of the head. Eyes widely separated in both sexes, distance between them at the base of antennae equal to length of scape. Male antenna 7-segmented, 5.2 mm long, reaching to approximately base of halter if bent backwards. Scape large, 2 × as long as wide, 4 × as long as pedicel, dark brown to blackish, sparsely dusted with brownish. Pedicel wider than long, black. Flagellum entirely black, densely covered with semi-erect black setae. Basal flagellomere longer than both basal antennomeres taken together and slightly longer than second flagellomere, third flagellomere longest, apical segment very small, button-shaped. Female antenna (Fig. 34 ) 11-segmented, 6.5-7.0 mm long, reaching wing base if bent backwards, entirely black. Rostrum dark brown, dusted with grayish. Palpus and labellum black, dusted with grayish brown pruinosity.

Thorax. Cervical sclerites dark brown dorsally, brown laterally, densely dusted with gray. Pronotum dark brown, postero-lateral angle polished rusty brown. Prescutum and presutural scutum densely dusted with orange-brownish gray, with three distinct stripes, medial stripe laterally semi-polished dark brown, divided along middle with densely dusted area, lateral stripe polished black. Tubercular pits missing, pseudosutural fovea black, semi-polished. Postsutural scutum with each lobe black, sparsely dusted. Area between lobes densely covered with pruinosity. Scutellum dark brown, densely dusted, covered with sparse short erect setae. Mediotergite dark brown densely dusted with grayish brown. Pleuron dark brown, dusted with grayish brown. Wing (Fig. 35 ) brown, dark brown along frontal margin and along cubital vein, iridescent, stigma dark brown, elongate, but not very distinct because of dark background. Veins brown to dark brown. Macrotrichiae on distal veins very scarce, nearly missing. Venation: humeral vein slightly before arculus, Sc very long, reaching wing margin distinctly beyond branching point of R2+3 and R4, sc-r at branching point of R2+3 and R4. Rs long, slightly arched at base. Free end of R1 elongate, R2 2 × its own length before apex of R1. R3 and R4 diverging, cell r3 with long stem, which is approximately as long as m-cu. Cross-vein r-m distinct, transverse, at base of discal cell. Discal cell slightly more than 2 × as long as wide. Cell m1 approximately as long as its stem or slightly shorter. Cross-vein m-cu at ~ 1/4 of discal cell length. Anal vein long, slightly sinuous, apex beyond the level of Rs base. Anal angle wide, posterior margin widely rounded. Entire halter dark brown except pale brown base of stem. Length of male halter 2.0 mm, that of female 2.0-2.2 mm. Coxa dark brown densely dusted, trochanter dark brown, femur dark brown to black with narrowly brownish base, remainder of leg dark brown to black. Tibia of fore leg with single apical spur, tibiae of middle and hind pairs of legs with two apical spurs each. Legs covered with short dense semi-erect setae. Male femur I: 9.0 mm long, II: 11.5 mm, III: 13.0 mm, tibia I: 11.7 mm, II: 10.5 mm, III: 13.7 mm, tarsus I: 11.8 mm, II: 9.2 mm, III: 8.7 mm. Female femur I: 10.0-10.5 mm long, II: 12.0-12.5 mm, III: 12.0-14.0 mm, tibia I: 11.2-11.5 mm, II: 11.0 mm, III: 10.5-15.5 mm, tarsus I: 11.5-11.7 mm, II: 8.7-9.0 mm, III: 8.4-8.5 mm. Claw rusty brown with subbasal spine.

Abdomen. Male abdomen black, semi-polished, dusted with brownish pruinosity, covered with erect sparse whitish setae, longer on sternites, shorter on tergites. Posterior margins of tergites and sternites narrowly grayish. Tergites with two pairs of transverse sutures. Female abdomen dark brown, coloration of sternites slightly varies individually from brown to dark brown, in some females basal sternites pale brown, in some seventh sternite pale brown to yellowish brown. Male terminalia (Figs 36 , 37 ) dark brown, gonocoxites rusty medially, outer gonostylus pale brown. Epandrium wider than long, posterior margin slightly concave. Gonocoxite elongate, 2.6 × longer than wide. Two pairs of long narrow gonostyli. Outer gonostylus sclerotized, point-apexed and slightly arched, apical part at right angle to longitudinal axis of gonostylus. Inner gonostylus approximately as long as outer gonostylus, wide, fleshy, and setose, slightly arched, swollen at middle. Paramere with two long and narrow arms, dorsal arm slightly arched, ventral nearly straight, longer than dorsal. Aedeagus very long, narrow, simple, straight. Anterior apodeme long and narrow, extending forward beyond lateral lobes of aedeagal sheath. Ovipositor (Fig. 38 ) brown. Tenth tergite elongate, blackish basally, brownish distally and laterally. Cercus round-apexed, distal part slightly raised upwards, brown, polished, blackened at base. Hypovalva long, parallel-sided to approximately middle, slightly swollen subapically, reaching to ~ 1/3 of cercus, pointed apex, with long setae along dorsal margin distally.

Elevation range.

300-500 m.

Period of activity.

From beginning of June through to mid-August.

Habitats.

Mountainous medium-sized rivers with sandy or fine gravel covered margins surrounded by dense mixed forests (Fig. 39 ).

Distribution.

South Korea.

Remarks.

There are a few black Eriocera species with cell m1 recorded from territories close to the Korean Peninsula, but some of them have unknown males. Among those with males described, the male terminalia are usually unstudied and separation of them is mostly based on external features such as coloration or comparative length of separate structures. Hexatoma aequinigra Alexander, 1934b is known only from the female, the size and general appearance of which is similar to that of H. pianigra sp. nov., but the species can be easily separated by leg coloration, the femur of H. pianigra sp. nov. is black with a narrowly brownish base, while that of H. aequinigra is yellow with only the tip blackened. Hexatoma atripes Alexander, 1934b is also described from the female only, the measurements of which are also close to H. pianigra sp. nov., but the halter has a yellow stem and blackened knob, while the halter of H. pianigra sp. nov. is entirely black. The male of H. issikii (Alexander, 1928) is somewhat larger than H. pianigra sp. nov., it has a yellow mesonotum, a pleuron with a broad stripe and a yellow halter with only the knob blackened. All these structures are completely black in H. pianigra sp. nov. Hexatoma lygropis (Alexander, 1920) is a somewhat larger species with a velvety black body, H. pianigra sp. nov. is semi-polished with a sparse cover of pruinosity. Hexatoma nigrotrochanterata (Alexander, 1932) is similar in size to H. pianigra sp. nov., but both species can be easily separated based on leg coloration. The femur of H. pianigra sp. nov. is black, while that of H. nigrotrochanterata is yellow with only the apical part blackened. Hexatoma pieliana Alexander, 1940 is described from the female with the male unknown, but it can be easily separated from H. pianigra sp. nov., because it has yellow legs and orange yellow abdominal sternites. Males of H. imperator Alexander, 1953b, H. jozana ( Alexander 1924), H. longeantennata (Lackschewitz, 1964), H. pallidibasis Alexander, 1953a, H. sachalinensis (Alexander, 1924), H. stricklandi (Edwards, 1921) and H. superba Savchenko, 1976 have long antennae, which are at least close to the body length, but usually a few times that. Two other similar species, H. fumidipennis (Alexander, 1927) and H. morula Alexander, 1923, are described from Sichuan, China. Hexatoma fumidipennis is dull gray and bigger than H. pianigra sp. nov. with a clear wing except a distinctly darkened costal area. Hexatoma morula generally looks more like H. pianigra sp. nov., but is much smaller with a wider wing and distinct differences in wing venation, especially the long vein Sc reaching slightly beyond R2, while it is just slightly beyond the branching point of R2+3 and R4 in H. pianigra sp. nov.

Figures

Figure 39. Type locality of Hexatoma (Eriocera) pianigra Podenas, sp. nov., Jirisan National Park, Piagol valley.

Figures 33 - 38. Hexatoma (Eriocera) pianigra Podenas, sp. nov. 33 holotype, male, lateral view 34 female antenna, paratype 35 female wing, paratype 36 male genitalia, dorsal view, holotype 37 male genitalia with ninth segment removed, dorsal view 38 ovipositor, paratype. Scale bars: 1.0 mm.

Figures 59 - 66. Sampling localities of Korean Hexatoma (Eriocera) 59 H. (E.) gifuensis Alexander, 1933 60 H. (E.) ilwola sp. nov. 61 H. (E.) masakii Alexander, 1934 62 H. (E.) pernigrina Alexander, 1938 63 H. (E.) pianigra sp. nov. 64 H. (E.) serenensis sp. nov. 65 H. (E.) stackelbergi Alexander, 1933 66 H. (E.) ussuriensis Alexander, 1934.