Nilothauma pandum, Qi, Xin, Lin, Xiaolong, Wang, Xinhua & Shao, Qingjun, 2014

Qi, Xin, Lin, Xiaolong, Wang, Xinhua & Shao, Qingjun, 2014, A new species of Nilothauma Kieffer from China, with a key to known species of the genus (Diptera: Chironomidae), Zootaxa 3869 (5), pp. 573-578 : 574-576

Nilothauma pandum sp.n.

( Figs.1−11 )

Type materials. Holotype male, CHINA: Zhejiang Province, Quzhou City, kaihua County, Suzhuang Town, 17.iv.2011, Lin XL, sweeping method. Paratypes: 4 males, same as holotype.

Diagnostic characters. The adult male of N. pandum sp.n. can be distinguished from known species of the genus by the following combination of characters: anal point very broadly lanceolate with microtrichia in median ridge and apical margin, rounded at apex; superior volsella pad-like, expanded distally; median volsella curved, rounded at apex, with 2 long basal setae and 1 long median seta.

Etymology. The species name is from Latin “ pandum ”, means curved, referring to the shape of the median volsella.

Description. Male (n = 5). Total length 3.65−3.83 mm. Wing length 1.80−2.05 mm. Total length/wing length 1.82−2.06. Wing length/length of profemur 2.35−2.52.

Coloration. Entire body brownish-yellow.

Head ( Fig. 1 ). AR 0.15−0.28. Temporal setae 5−7. Clypeus with 17−26 setae. Tentorium 92−125 mm long, 15−20 mm wide. Stipes 123−125 µm long, 5−8 µm wide. Palpomere lengths (in mm): 30−40, 20−40, 100−120, 160−170, 190−210. Third palpomere with 3−4 sensilla clavata, longest 12 µm long. Fifth palpomere / third palpomere 1.80−1.91.

Wing ( Fig. 2 ). Wing transparent, without any pigmentation. VR 1.00−1.45. Brachiolum with 1−4 setae; R with 14−20, R1 with 17−20, R4+5 with 12−18 setae. Remaining veins and squama bare.

Thorax ( Fig. 3 ). Dorsocentrals 9−11, acrostichals 6−11, prealars 3−5. Scutellum with 1−2 setae.

Legs. Spur of front tibia 70−83 µm long,with 27−30 µm long scale ( Fig. 4 ); spur of mid tibia 23−45 µm long including 13−20 µm long comb ( Fig. 5 ); spurs of hind tibia 18−32 mm and 28−35 mm long, combs 15−20 mm long ( Fig. 6 ). Width at apex of front tibia 45−50 mm, of mid tibia 50−55 mm, of hind tibia 50−60 mm. Lengths (in mm) and proportions of legs in Table 1 .

Hypopygium ( Fig. 7 ). Tergite IX with 2 dorsal projections. Anterior projection completely divided into 2 oval lobes originating on posterior margin of anterior tergal band; each lobe 20−30 µm long, 15−20 µm wide in middle, each with 12−15 plumose setae 30−50 µm long. Posterior projection ( Fig. 8 ) 40−50 µm wide at base, 10−15 µm wide at apex, apically rounded, with 11−13 setae 20−25 µm long. Anal point very broadly lanceolate with microtrichia in median ridge and apical margin, rounded at apex, 35−45 µm long, 30−40 µm at base, 40−50 µm in middle. Posterior margin of tergite IX ( Fig. 9 ) with 10−12 long setae. Laterosternite IX with 3 setae. Phallapodeme 70−92 µm long. Transverse semi-circular, not medially widened, sternapodeme present. Gonocoxite 150−170 mm long. Superior volsella ( Fig. 10 ) pad-like, expanded distally, 50−68 µm long, 10−12 µm wide at base, 30−40 µm wide subapically, densely covered with microtrichia. Median volsella ( Fig. 11 ) curved, rounded at apex, 35−40 µm long, with 2 long basal setae and 1 long median seta. Inferior volsella 88−95 µm long, curved with pointed apex, microtrichiose, with 6−8 short, apically split setae at apex. Gonostylus 140−155 mm long, with 11−12 setae along inner margin in distal 1/3. HR 0.97−1.21, HV 1.43−2.55.

Female, pupa and larva. Unknown

Remarks. N. pandum sp.n. is similar to N. hibaratertium Sasa, 1993 , but can be separated from N. hibaratertium on the basis of the following: (1) presence of microtrichia on the anal point of N. pandus sp.n., whereas absence of microtrichia on the anal point of N. hibaratertium ; (2) the median volsella of N. pandus sp.n. curved, rounded at apex, with 2 long basal setae and 1 long median seta, whereas the median volsella of N. hibaratertium bifid, each branch with one apical seta, one branch with additional lateral seta.

Adam and Saether (1999) divided Nilothauma into four species groups, the duminola , babiyi , brayi , and pictipenne groups. The species of brayi , and pictipenne groups have 2 dorsal projections. N. pandum sp.n. is close to the species of the brayi group in having 2 dorsal projections on the tergite IX and absence of pigmentation on wings, but it differs from the members of the brayi group in the presence of microtrichia on the anal point. N. pandum sp.n. can not falls in the pictipenne group, as wings of N. pandum sp.n. lack dark pigmentation (dark pigmentation presence in members of the the pictipenne group).

Distribution. The species is known from Zhejiang Province of Oriental China.

Figures

FIGURES 1 – 11. Nilothauma pandum sp. n., male. 1. Head. 2. Wing. 3. Thorax, lateral view. 4. Front tibial apex, lateral view. 5. Mid tibial apex, lateral view. 6. Hind tibial apex, dorsal view. 7. Hypopygium. 8. Posterior projection of tergite IX. 9. Posterior margin of tergite IX. 10. Superior volsella and median volsella. 11. Median volsella.

Tables

TABLE 1. Lengths (in µm) and proportions of legs of Nilothauma pandum sp. n., male (n = 5).

	P1	P2	P3
fe	775−850	750−850	875−950
ti	575−650	600−625	900−950
ta1	875−950	725−800	475−500
ta2	475−500	325−375	250−275
ta3	350−400	120−125	250−275
ta4	175−300	70−75	175−200
ta5	125−150	50−75	75−125
LR	1.44−1.52	0.54−0.63	0.53−0.54
BV	1.49−1.98	3.78−4.24	2.79−3.00
SV	1.54−1.58	3.73−4.23	3.55−3.75