Empis (Xanthempis) sesquata (Ito)

Zhou, Jiale, Shamshev, Igor, Kwon, Yongjung & Yang, Ding, 2018, Species of the subgenus Empis (Xanthempis) from South Korea (Diptera, Empididae), ZooKeys 769, pp. 145-155 : 145

Empis (Xanthempis) sesquata (Ito) Figs 1-2, 3-6

Xanthempis sesquata Ito, 1961: 127, Abb. 6, 7. Type locality: Karyôsan (Aki) [now Hiroshima Prefecture], Japan ( Honsyû).

Diagnosis.

Mesoscutum with broad black median longitudinal vitta running also over scutellum and postnotum and elongate blackish spot between postpronotal lobe and suture. Occiput with contrastingly black, wedge-shaped spot including ocellar tubercle. Prothoracic spiracle yellow.

Description.

Male (Fig. 1). Body length 6.0-6.1 mm, wing length 8.5-8.6 mm. Head (Fig. 4) largely brownish yellow or yellow, faintly pale greyish pollinose; frons and face dark yellow, occiput with narrow contrastingly black, wedge-shaped spot including ocellar tubercle. Eyes dichoptic, ommatidia equally small. Frons broad, parallel-sided, with minute dark setulae laterally. Occiput (Fig. 6) with short sparse black setae arranged in two almost regular transverse rows on upper part and some pale setae behind mouth-opening. Ocellar tubercle with two short proclinate oc and some minute setulae. Antennal scape and pedicel brownish, postpedicel and stylus black; scape long, approx. five times longer than wide, with some black setulae; pedicel very short, subglobular, with circlet of black subapical setulae; postpedicel very long, narrow, subconical, approx. eight times longer than wide; stylus very short, nearly 0.3 times as long as postpedicel. Proboscis long, labrum approx. two times longer than head height; palpus yellow, with scattered blackish setulae.

Thorax largely yellow, faintly pale greyish pollinose, with greatly reduced, only black setation; mesoscutum (Fig. 3) with broad, black, distinct, median longitudinal vitta running also over scutellum and postnotum, as well as with elongate, blackish, less distinct spot between postpronotal lobe and suture on each side; antepronotum with dark spot dorsally. Prothoracic spiracle yellow. Prosternum bare. Proepisternum with 2-3 hair-like setulae on lower part. Antepronotum with several spinule-like setulae on each side. Postpronotal lobe with one short inclinate ppn and additional shorter seta anteriorly. Mesonotum with one short thin presutural sa, one long npl, one short pa (sometimes with 1-2 additional setulae), four sc (apicals short, laterals minute); acr absent; dc uniserial, 6-7 in row, situated outside black median vitta, hair-like, minute (except 1-2 prsc). Laterotergite with several black setulae of different lengths. Legs yellowish to brownish yellow, only tarsomere 5 dark brown; lacking prominent bristles (except circlets of short subapical setae on tibiae). Wing nearly hyaline; brownish yellow stigma long, narrow; veins dark brown; basal costal bristle black, very short. Calypter yellowish, blackish fringed. Halter yellow.

Abdomen extensively yellow but tergites broadly brownish dorsally forming uniform vitta, subshiny; with scattered, mostly yellowish to brownish yellow setulae longer and darker on sternite 8 posteriorly. Hypopygium (Fig. 5) large, almost entirely yellow, only cerci narrowly brownish apically. Cercus rather large, with deep excision, dorsal arm long, broad, somewhat concave apically (lateral view), ventral arm short, finger-like; covered with dark minute setulae and bearing a moderately long seta on ventral arm. Epandrial lobe rather trapezoid, with upper posterior corner broadly rounded and lower posterior corner narrowly elongated; covered with dark setae longer along upper margin and on posterior corner. Hypandrium subtriangular viewed ventrally, with two black closely set spinules apically. Phallus strongly curved, attenuated on about middle part, with dorsal projection on subapical part (lateral view), long beak-like apical opening.

Female (described for the first time, Fig. 2). Body length 7.2-7.9 mm, wing length 8.2-8.5 mm. Very similar to male, but mesonotum with somewhat long setae; scutal lateral spots less distinct and sometimes absent. Cercus long, slender, brown, clothed in minute setulae.

Material examined.

South Korea: one male, Hongcheon-gun GW, Yeongnae-ri Duchon-myeon, Mt. Baegu (37°50'39.14"N, 128°0'49.90"E), 25.V.2013, Yongjung Kwon; one male, Gangweon Prv., Mt. Obongsan (38°0'6.08"N, 127°48'22.36"E), 17.V.1981, Yongjung Kwon; one female, same locality, 19.V.1981; one female, Gangweon Prv., Mt. Seolagsan (37°50'39.14"N, 128°0'49.90"E), 19.V.1981, Yongjung Kwon.

Distribution.

Palaearctic: Japan (Hiroshima), South Korea.

Remarks.

The species has been known for a long time only from the holotype male described by Ito (1961) from Honsyû Island (Hiroshima Prefecture) of Japan. Here we record E. sesquata from South Korea for the first time, where this species was collected from a mountain area of Gangweon Province on dates ranging from the middle of May till the end of June. Empis sesquata can be readily distinguished from other species of Xanthempis known from the eastern Asia by its distinctive scutal pattern.