Rheotanytarsus fundus, Wang, Xinhua & Guo, Yuhong, 2004

Wang, Xinhua & Guo, Yuhong, 2004, A review of the genus Rheotanytarsus Thienemann & Bause from China (Diptera: Chironomidae: Tanytarsini), Zootaxa 650, pp. 1-19 : 13-14

Rheotanytarsus fundus sp. n. ( Figs. 14–16 )

Type material. Holotype male (BDN No. 20226), China, Liaoning Province, Dandong Country, Caohe River. IV. 1993. J. Wang, sweep net.

Etymology. From Latin fundus , base, bottom, referring to the cluster of small setae on the base of the anal point.

Diagnosis. The species is distinguished by the tuft of setae on the basal median part of the anal point.

Male imago (n=1)

Total length 3.20 mm. Wing length 1.80 mm. Total length / wing length 1.78. Wing length / profemur length 2.14. Coloration dark brown, eyes black.

Head. Antenna with 13 flagellomeres, AR 0.91 and ultimate flagellomere 488 µm long. Temporal setae including 2 inner, 3 outer verticals and 2 postorbitals. Clypeus with 21 setae. Tentorium out of focus. Palpomere lengths (in µm): 40; 40; 140; 152; 200.

Wing ( Fig. 14 ). VR 1.41, Cu length 800 µm.

Thorax. Acrostichals 15; dorsocentrals 7; prealars 1. Scutellum damaged.

Legs. Spur of front tibia 2 0µm. Spurs of middle tibia 34 µm long and of hind tibia 36 µm long. Combs of middle leg composed of 12 and 12 free teeth, hind leg composed of 18 and 14 free teeth ( Table 7):

fe ti ta1 ta2 ta3 ta4 ta5 LR P1 840 520 928 480 400 304 120 1.78 P2 776 640 376 216 160 104 80 0.59 P3 960 860 592 360 280 180 96 0.69 Hypopygium ( Figs. 15, 16 ). Anal tergite bands of V type, widely separated medially. Tergite IX with 8 setae. Anal point 46 µm long. Setal tuft on base of anal point forms Ushaped structure. Phallapodeme 70 µm long. Transverse sternapodeme 44 µm long, straight, with pointed oral projections. Gonocoxite 140 µm long. Superior volsella 50 µm long, posterior margin hook­like produced; with 2 inner, 5–6 dorsal setae, and 1 long ventromedian seta. Inferior volsella 80 µm long. Lamellae of median volsella fused into plate. Gonostylus tapering gradually to pointed apex, 134 µm long. HR 1.04; HV 2.39.

Distribution. The species is known from Liaoning province in northern China (Palaearctic Region).

Remarks. The species is tentatively treated as a species of the pentapoda group. It differs from R. pentapodus by the median volsella not extending beyond the superior volsella, gonostylus tapering gradually to apex, and anal crests not V­shaped. All the other characters fit the pentapoda group.

Figures

FIGURES 14 – 18. Figs. 14 – 16. Rheotanytarsus fundus sp. n. Holotype, male imago: 14. Wing, 15. Hypopygium, 16. Median volsella. Figs. 17 – 18. Rheotanytarsus brevipalpus sp. n. Holotype, male imago: 17. Wing, 18. Hypopygium