Pseudorthocladius (Pseudorthocladius) binarius, Ren, Jing, Lin, Xiaolong & Wang, Xinhua, 2014

Ren, Jing, Lin, Xiaolong & Wang, Xinhua, 2014, Review of genus Pseudorthocladius Goetghebuer, 1943 (Diptera, Chironomidae) from China, ZooKeys 387, pp. 51-72 : 52-54

Pseudorthocladius (Pseudorthocladius) binarius sp. n. Figures 1-7

Diagnosis.

The male imago can be distinguished from the known species of the genus by the following combination of characters: low AR (0.29); squama with few setae; anal lobe reduced; inferior volsella has two sub–lobes; virga absent.

Description.

Adult male (n = 4). Total length 1.50-1.80, 1.63 mm. Wing length 0.81-0.97, 0.89 mm. Total length/wing length 1.83-1.86, 1.84. Wing length/length of profemur 2.26-2.43 (3).

Coloration. Head, abdomen, legs brown; thorax with yellow ground with brown postnotum and preepisternum.

Head. Antenna with 13 flagellomeres. Terminal flagellomere length 95-108, 105 μm. AR 0.28-0.33, 0.29. Temporal setae 8 (2), including 2 (2) inner verticals, 3-4 (3) outer verticals, and 2 (2) postorbitals. Clypeus with 6-10, 8 setae. Tentorium 86-96, 92 μm long, 14-19, 15 μm wide. Palpomere lengths (in μm): 19-24, 22; 26-29, 28; 55-62, 59; 84-91, 86; 98-120, 110. L: 5th/3rd 1.77-2.10, 1.86.

Wing (Figure 1). VR 1.25-1.29 (3). Anal lobe reduced. Brachiolum with 1 seta; R with 9-15, 13 setae; R1 with 1-4, 2 setae; R4+5 9-11, 10 setae; M with 0-1, 1 seta. Squama with 1-2, 1 seta. Costal extension 70 μm long. Cu1 slightly curved.

Thorax (Figure 2). Antepronotum with 3-6, 5 lateral setae, dorsocentrals 13-15, 13, acrostichals 3-7, 5, prealars 4-6, 5. Scutellum with 6-8, 7 setae.

Legs. Pulvilli present. Spur of fore tibia 29 (3) μm long, spurs of mid tibia 22-24, 23 μm and 16-19, 18 μm long; hind tibia with a long spur 40-43, 42 μm long, a short spur 14-17, 16 μm long and comb composed of 10-12, 11 spines. Width at apex of fore tibia 24-28, 26 μm, of mid tibia 20-26, 24 μm, of hind tibia 31-36, 33 μm. Lengths (in μm) and proportions of legs as in Table 1.

Hypopygium (Figures 3-7). Laterosternite IX with 4-6, 5 setae. Anal point (Figure 5) subtriangular with rounded apex, 24-26, 25 μm long, with 13-15, 14 strong setae. Phallapodeme 22-24, 24 μm long. Transverse sternapodeme 44-50, 48 μm long. Virga absent. Gonocoxite 110-122, 118 μm long. Inferior volsella (Figure 6) with two sub–lobes, the dorsal lobe with concave inner margin and 4-5, 5 marginal setae, the ventral lobe semi–rounded with 3-4, 3 marginal setae. Gonostylus (Figure 7) 60-67, 64 μm long, narrowed at base. Megaseta 9-10, 10 μm long. HR 1.82-1.92, 1.85. HV 2.43-2.48, 2.45.

Female, pupa and larva unknown.

Type materials.

Holotype: ♂ (BDN No.20200), China, Fujian, Quanzhou City, Dehua County, Daiyun Mountain, 25°40'N, 118°11'E, 13.ix.2002, Zheng Liu, sweep net. Paratypes: 3 ♂♂, as holotype.

Etymology.

The specific name is from Latin, binarius, meaning "of two", referring to the inferior volsella has two sub–lobes.

Remarks.

The new species resembles Pseudorthocladius (Pseudorthocladius) tusimoquereus Sasa & Suzuki (1999) in the structure of hypopygium, but can be separated from the latter on the following points: (1) Pseudorthocladius (Pseudorthocladius) binarius sp. n. has small body size (1.63 mm) and low AR (0.29); (2) wing anal lobe reduced and squama with few setae; (3) inferior volsella with two sub–lobes; (4) virga absent.

Distribution.

The new species is collected in a subtropical mountain area in Fujian Province (Oriental China).