Chaetocladius ligni Cranston et Oliver

(Figs. 16–17)

Chaetocladius ligni Cranston et Oliver, 1988: 144, Figs. 1–13; Makarchenko & Makarchenko 2011: 111; Makarchenko et al. 2014: 424; Ashe & O’Connor 2012: 171.

Remarks. This species was described as adult male, female, pupa and larva from North America (Cranston & Oliver 1988), and later was recorded by us for the Russian Far East (Makarchenko & Makarchenko 2011b). The present revision of Chaetocladius s. str. from the Amur River basin indicates differences in the structure of the males from the Nearctic and East Palearctic regions. In this regard, we have found it appropriate to redescribe the adult male on the basis of our material and to present the results of DNA analysis that will allow a detailed comparing the known populations of C. ligni in the future.

Material. 3 males, Russian Far East, Jewish Autonomous Region, Obluchie District, Fedotkin Spring of Bidzhan River basin (Amur River basin), N 48°38' 409'', E 131°37' 217'', 6. IV. 2014, leg. E. Makarchenko.

Adult male (n=2–3). Total length 3.0– 3.6 mm. Wing length 2.16–2.48 mm. Total length/wing length 1.33– 1.45. Colouration brown.

Head. Eyes bare, with rounded short dorsomedian. Temporal setae include (from one side) 5–6 verticals and 5– 7 postorbitals. Clypeus with 6–14 setae. Antenna with 13 flagellomeres and well developed plume; flagellomere 13 subapical with seta; AR 0.94–1.06. Lengths of palpomeres 2–5 (in µm): 52: 160: 148: 260. Third palpomere in subapical part with 7 sensilla clavata.

Thorax. Brown, with dark brown stripes; humeral pit with light spot. Antepronotum with 9–11 lateral setae. Acrostichals 16–19; dorsocentrals 11–21 (in 1–2 rows); prealars 4–7; scutellum with 7–8 setae in 1 row.

Wing. Halteres light. R with 20–21 setae, R1 with 3–8 setae, R4+5 with 20–25 setae. Costa extension ca 60 µm. Apex of R4+5 distal of apex M3+4. Cu1 curved in apical quarter. Anal lobe developed, wide rectangular-rounded. Squama with 7–8 setae.

Legs. Spur of fore tibia 80 µm. Spurs of mid tibia 24–28 µm long, of hind tibia 84 µm and 20 µm long; ta1and ta2 of mid and hind legs with 2 pseudospurs. Hind tibial comb with 13–15 setae. Length (in µm) and proportions of leg segments as in Table 2.

continued.

Hypopygium (Figs. 16–17). Tergite IX with 18–21 long setae and long triangular anal point 56–64 µm long (n=2) (Fig. 16) and 92 µm long (n=1) (Fig. 17). Anal point in basal 1/3–1/4 with microtrichia, the remaining part naked. Laterosternite IX with 6–7 setae on each side. Transverse sternapodeme rounded, 92 µm long, with weak oral projections. Virga 56 µm long, consists of some setae. Gonocoxite 200–215 µm long; inferior volsella as in Figs. 16–17. Gonostylus 84–88 µm long, with rounded preapical crista dorsalis, megaseta 10–12 µm long.

Pupa and larva are described by Cranston & Oliver (1988), but absent in our material.

Distribution. C. ligni is known from North America (U.S.A., Oregon) and the Russian Far East.