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

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Nilothauma pandum


Nilothauma pandum  sp.n.

( Figs. 1−11View FIGURES 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. 1View FIGURES 1 – 11). 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. 2View FIGURES 1 – 11). Wing transparent, without any pigmentation. VR 1.00− 1.45. Brachiolum with 1−4 setae; R with 14−20, R 1 with 17−20, R 4 + 5 with 12−18 setae. Remaining veins and squama bare.

Thorax ( Fig. 3View FIGURES 1 – 11). 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. 4View FIGURES 1 – 11); spur of mid tibia 23−45 µm long including 13−20 µm long comb ( Fig. 5View FIGURES 1 – 11); spurs of hind tibia 18−32 mm and 28−35 mm long, combs 15−20 mm long ( Fig. 6View FIGURES 1 – 11). 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. 7View FIGURES 1 – 11). 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. 8View FIGURES 1 – 11) 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. 9View FIGURES 1 – 11) 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. 10View FIGURES 1 – 11) 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. 11View FIGURES 1 – 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.

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

  1.44−1.52 0.54−0.63 0.53−0.54
    3.78−4.24 2.79−3.00
  1.54−1.58 3.73−4.23 3.55−3.75