Limnophyes subtilus Liu & Yan, 2021

Liu, Wenbin, Zhao, Cong, Kong, Fanqing, Yan, Chuncai & Wang, Xinhua, 2021, New species of Limnophyes Eaton (Diptera, Chironomidae) from China and synonymy of L. fuscipygmus Tokunaga, 1940, ZooKeys 1011, pp. 51-61 : 51

Limnophyes subtilus Liu & Yan sp. nov. Figs 5-8

Type material.

Holotype male (BDN No. 12222), China: Sichuan Province, Daocheng County, Daocheng River, 29.112°N, 100.146°E, 2492 m a.s.l., sweep net, 11.vi.1996, X. Wang. Paratype: 5 males, as holotype.

Diagnostic characters.

The new species can be separated from other members of the genus by having 9-21 lanceolate humerals, 7-9 lanceolate prescutellars, megaseta hair-like, virga very slender, and anal lobe moderately developed.

Etymology.

From the Latin, subtilus, thin, slender, referring to the shape of the virga, adjective in the nominative singular.

Description.

Male (N = 6).

Total length 2.53-2.83, 2.67 mm. Wing length 1.56-1.73, 1.63 mm. Total length / wing length 1.54-1.74, 1.64. Wing length / length of profemur 2.97-3.16, 3.05.

Coloration. Head, thorax and legs dark brown. Abdomen yellowish brown. Wing nearly transparent.

Head. Antenna with 13 flagellomeres. AR 0.76-0.88, 0.83. Ultimate flagellomere 295-330, 310 µm long. Temporal setae 5-7, 6, including 1 inner vertical, 2 outer verticals and 2-4, 3 postorbitals. Clypeus with 14-18, 16 setae. Tentorium 132-140, 136 µm long, 22 µm wide. Palpomere lengths (in µm): 25-31, 28; 40-45, 43; 79-95, 86; 78-90, 85; 120-128, 125. Length ratio of palpomeres 5/3 1.26-1.62, 1.44.

Wing (Fig. 5 ). Anal lobe moderately developed. VR 1.20-1.29, 1.26. Brachiolum with one seta. R with 5-6, 5 setae. Costal extension 22-40, 31 µm long. Squama with 6-8, 7 setae.

Thorax (Figs 6 , 7 ). Antepronotum with 3-4, 4 median and 4-6, 5 lateral setae. Humeral pit (Fig. 7 ) rounded, with sclerotized posterior margin. Dorsocentrals 43-47, 45, including 9-21, 14 lanceolate humerals, 6-10, 8 non-lanceolate humerals, 14-19, 15 other non-lanceolate dorsocentrals, and 7-9, 8 lanceolate prescutellars. Preepisternum with 2-3, 3 setae in anterior row, and posterior with 3 setae. Acrostichals 2-6, 5; prealars 4-10, 7; supraalar 1; posterior anepisternum II with 2-4, 3 setae; epimeron II with 3 setae; scutellum with 6-9, 8 setae.

Legs. Spur of fore tibia 44 µm, of mid tibia 17-19, 18 µm and 14-18, 16 µm long, of hind tibia 37-45, 41 µm and 13-22, 17 µm long. Tibial comb 42-45, 44 µm long, comb with 13 teeth. Width at apex of fore tibia 31-40, 35 µm, of mid tibia 31-33, 32 µm, of hind tibia 31-40, 35 µm. Lengths and proportions of legs in Table 2 .

Hypopygium (Fig. 8 ). "Anal point" broadly rounded, with 17-32 setae. Laterosternite IX with 3-5, 4 setae. Phallapodeme 43-62, 50 µm long; transverse sternapodeme 68-83, 77 µm long. Virga 32-35, 33 µm long, consisting of slender single spine. Gonocoxite 141-148, 144 µm long. Inferior volsella with developed digitiform dorsal lobe. Gonostylus 84-98, 91 µm long, with pointed crista dorsalis. Megaseta hair-like, 17-20, 19 µm long. HR 1.46-1.68, 1.59; HV 2.81-3.15, 2.95.

Remarks.

The characters of the new species mainly agree with L. eltoni (Edwards, 1922) ( Sæther 1990b). However, the new species differs from the latter on the basis of following characters: (1) the obvious costal extension of the new species (22-40 µm), shorter than for L. elotoni (77-94 µm); (2) "Anal point" of L. eltoni strongly projecting with apical notch, whereas in the new species it is not notched; (3) the new species has hair-like megaseta in the gonostylus, whereas the megaseta of L. eltoni is spine-like, subapically.

Distribution.

The species were collected in a subtropical mountain area in Sichuan Province in Oriental China.

Figures

Figures 5 - 8. Limnophyes subtilus Liu & Yan, sp. nov., male 5 wing 6 humeral area of the thorax 7 thorax 8 hypopygium.