New species and records of Metriocnemus van der Wulp s. str. from China (Diptera, Chironomidae)

Abstract The Chinese species of Metriocnemus van der Wulp s. str., 1874 is reviewed. M. (M.) calcaneum sp. n. is described and illustrated as adult male. M. (M.) albolineatus (Meigen) is recorded from China for the first time. M. (M.) beringensis (Cranston & Oliver), M. (M.) bilobatus Makarchenko & Makarchenko, M. (M.) caudigus Sæther, M. (M.) intergerivus Sæther, M. (M.) tamaokui Sasa and M. (M.) tristellus Edwards are recorded from the Oriental Region for the first time. A key to the males of 17 Chinese Metriocnemus (Metriocnemus) species is given.


Introduction
The genus Metriocnemus van der Wulp was erected in 1874; Coquillett (1910) subsequently designated Chironomus albolineatus Meigen, 1818 as the type species. Langton and Cobo (1997) described subgenera Inermipupa based on a species with a highly aberrant pupa (Metriocnemus (Inermipupa) camencitabertarum). Subsequently Ashe and Remarks. The species differs from all other Metriocnemus species by the wing chaetotaxy, the characteristic hypopygium with very long, sharply pointed anal point and a gonostylus lacking crista dorsalis. The Chinese specimens has higher antennal ratio (AR = 1.00-1.73) than the Indian specimens (AR = 1.09). Among the specimens of China, one was identified as M. hirticollis (Staeger, 1839), which should be M. (M.) albolineatus (Meigen, 1818) after we re-examined the specimen.
Distribution. Metriocnemus (M.) aculeatus has been recorded from India (Chaudhuri et al. 1989) and the Oriental China. (Meigen) http://species-id.net/wiki/Metriocnemus_albolineatus Chironomus albolineatus Meigen, 1818:39 Chironomus atratulus Zetterstedt, 1850:3590 Metriocnemus albolineatus (Meigen); Saether (1989:399) Material examined. CHINA: Sichuan Province, Ganzi City, Yajiang County, 29°53'48"N, 103°10'19"E, 1 male, 14.vi.1986, light trap, X. Wang. Remarks. The male can be separated from other species of Metriocnemus by having a short virga (23-26 µm long), very weak inferior volsella, rounded to bluntly triangular crista dorsalis, tapering anal point with blunt apex, Sc with 10-31 setae, M with 15-32 setae, and cell m with 35-73 setae. This species is a member of the eurynotus group, but the male can be separated from other species of the group by having a shorter virga and a weaker inferior volsella. It has more setae on the wings than M. Distribution. The species is recorded from the Nearctic, Palaearctic and Oriental regions (Ashe and O'Connor 2012). In China it was collected from Sichuan Province in Oriental China for first time.
Distribution. The species is previously recorded from the Nearctic and Palaearctic regions (Ashe and O'Connor 2012 30°2'20"N, 101°50'6"E, 1 male, 15.vi.1996, water net, X. Wang. Sichuan Province, Litang County, 29°59'45"N, 100°16'11"E, 1 male, 11.vi.1996 Remarks. This species can be separated from other Metriocnemus species by having a total length of 2.18-2.42 mm, wing length of 1.85-2.25 mm, AR = 0.23-0.26, acrostichals in 2 rows, 25-37 dorsocentrals, and reduced anal lobe of the wing. The anal point is 45-48 µm long, and lacking microtrichia in distal half. Virga is 50-53 µm long and consists of a single spine. The inferior volsella is bilobate, and the length of the basal lobe is about half the length of the gonocoxite. Distribution. The species is recorded from Russian Far East (Makarchenko and Makarchenko 2004 Remarks. According to Saether (1989), the male can be separated from other members of Metriocnemus by having rounded crista dorsalis, anal point tapering to blunt apex, well sclerotized virga, comparatively sparsely haired wing with about 0-8 setae on Sc, 0-11 on M, 0-14 on PCu and 7-9 setae in cell m, and squama with 27-34 setae. The Chinese specimens have slightly more setae on wing membrane, with about 2-9 setae on Sc, 12-14 on M, 35-48 on PCu and 13-16 setae in cell m, but squama only with 15-17 setae. The species is similar to M. (M.) albilineatus (Meigen, 1818) and M. (M.) eurynotus, but has tapering anal point and rounded crista dorsalis. It has a well developed virga as in M. (M.) corticalis and differs from this species in minor details in the wing chaetotaxy and the hypopygium.
Distribution. The species is recorded from the Nearctic and Palaearctic regions (Ashe and O'Connor 2012). It was collected in both Oriental and Palaearctic China. Coloration. Head and abdomen brown, thorax and legs yellow.
Distribution. The species was described by Saether (1995) in Qinghai Province in Palaearctic China based on a single male specimen. Later two more male slides have been made which collected in the same location as the holotype.
Remarks. This species can be separated from other species of Metriocnemus by having a slender gonostylus with long, low crista dorsalis; a robust, long anal point; and an AR of 1.0-1.5. The Chinese specimen has a slightly higher 5 th /3 rd palp ratio (0.79-0.94) than the Norwegian specimens (0.70). Further, the Chinese specimen has 2 pseudospurs, 24-32 µm long, on tarsomere 1 and 1 pseudospur, 20-28µm long on tarsomere 2 of mid and hind legs, while the Norwegian specimens have 1 pseudospur, 23-38 µm long, on tarsomere 1 of mid and hind legs only.
Distribution. The species was described from Norway by Saether (1995). In China it was collected in Fujian Province in Oriental China. Remarks. The male can be recognized on the completely parallel-sided anal point with broad, rounded apex; and the sharply triangular crista dorsalis.

Metriocnemus (Metriocnemus) dentipalpus
Distribution. The species is recorded from the Nearctic, Palaearctic and Oriental regions (Ashe and O'Connor 2012). The species has been collected in both Oriental and Palaearctic China.
Distribution. The species is recorded from the Nearctic and Palaearctic regions (Ashe and O'Connor 2012). In China the species was collected in Palaearctic China. Remarks. The Chinese specimens have a low number of setae on each of subcosta (0-9, 2) and M (4-20, 12), combined with a high AR (1.89-2.90, 2.24) and LR 3 (0.44-0.50, 0.46), and a conspicuously long spur of the fore tibia (2.0-2.4 times as long as the apical width of tibia), these characters will distinguish the species from other members of Metriocnemus. Metriocnemus wittei Freeman, 1955 from Africa might be a synonym (Saether 1995).

Metriocnemus (Metriocnemus) intergerivus
Distribution. The species is recorded from the Nearctic, Palaearctic and Oriental regions (Ashe and O'Connor 2012). It has been collected in both Oriental and Palaearctic China.
Distribution. The species was described from Japan (Sasa 1983), and it is a newly recorded in China. It is known from both Oriental and Palaearctic China.

Remarks.
The species has an AR = 1.2, very low inferior volsella, and weak anal point. Basal half of the wing membrane is bare, costa is strongly produced, and the distance C-M is rather less than M-Cu. The palp is unusually short, palpomeres 3 and 4 are less than three times as long as broad, palpomere 2 is rather longer. Wang (2000) recorded M. gracei Edwards, 1929 from China, which should be M. (M.) tristellus Edwards after we re-examined the specimen.
Distribution. The species is recorded from the Nearctic and Palaearctic regions (Ashe and O'Connor 2012).The species has been collected in Oriental China for first time. Chaudhuri et al. 1989:312;Saether (1995:56) Remarks. This species can be separated from other Metriocnemus species by the following combination of characters: acrostichals 4-5, uniserial; scutellum with 12 irregularly arranged setae; squama with 7 setae; anal point narrow and pointed with 14 setae at base, and gonocoxite with a small, dorsal, flap-like setose lobe. The specimens from Tibet have a lower antennal ratio (AR = 0.66-0.88) than the Indian specimens (AR = 1.03).

Metriocnemus unilinearis Chaudhuri & Bhattacharyay in
Distribution. This species was described from India (Chaudhuri et al. 1989). It has been collected in both Oriental and Palaearctic China.