Stenochironomus brevissimus, Qi, Xin, Lin, Xiaolong, Liu, Yuedan & Wang, Xinhua, 2015

Qi, Xin, Lin, Xiaolong, Liu, Yuedan & Wang, Xinhua, 2015, Two new species of Stenochironomus Kieffer (Diptera, Chironomidae) from Zhejiang, China, ZooKeys 479, pp. 109-119 : 111

Taxon classification Animalia Diptera Chironomidae

Stenochironomus brevissimus sp. n. Figs 1-10

Diagnosis.

The adult male of Stenochironomus brevissimus sp. n. can be distinguished from all other species of Stenochironomus by the following combination of characters: superior volsella very short and small, spatulate, with 2 long setae, elongated inferior volsella with 6 long setae, posterior margin of tergite IX with 20−22 setae and 8 spines.

Description.

Male imago (n = 3). Total length 4.3−4.6 mm. Wing length 2.2−2.5 mm. Total length / wing length 1.8−1.9. Wing length / length of profemur 1.7−1.8.

Coloration. Head yellow, antenna brown. Thorax light yellow, postnotum and scutum with brown spots. Wings transparent, without any pigmentation. Abdomen and hypopygium yellow, anal point brown. Fore legs yellow with femur apically brown. Mid legs with apex and posterior basal region of femur with dark brown stripes, tibia brown, tarsomeres 1-5 yellow. Hind legs brown with femur yellow with dark brown stripes at apex.

Head (Fig. 1). AR 1.80−1.92. Temporal with 10−12 setae. Clypeus with 20−22 setae. Tentorium 173−176 mm long, 43−46 mm wide. Stipes 140−145 µm long, 10−13 µm wide. Palpomere lengths (in mm): 60−63, 60−65, 210−230, 140−150, 260−300. Palpomere ratio (5th/3rd) 1.2−1.3.

Wings (Fig. 2). VR 1.08−1.15. Brachiolum with 3−4 setae; R with 25−32 setae, R1 with 27−30 setae, R4+5 with 41−42 setae. Squama with 8−10 setae.

Thorax (Fig. 3). Dorsocentrals 12−14, acrostichals 14−16, prealars 4−5. Scutellum with 6−7 setae.

Legs (Fig. 4). Fore leg: width at apex of tibia 60−65 mm, tibia with scale 53−56 µm long, with 2−4 strong setae (Fig. 5). Mid leg: width at apex of tibia 80−83 mm, tibia with two apical spurs 40−50, 43-53 μm long. Hind leg: width at apex of tibia 70−80 mm, tibia with two apical spurs 40−50, 40-55 μm long. Mid and hind tibiae with fused combs (Figs 6-7), each comb 36−50 µm long. Lengths (in mm) and proportions of legs in Table 1.

Hypopygium (Fig. 8). Anal point 113−120 mm long, 15−20 µm wide at base, 13−15 µm wide at apex, parallel-sided, slender, apically rounded. Tergite IX with 16−17 long setae medially, posterior margin of tergite IX with 20−22 setae and 8 spines (Fig. 9). Phallapodeme 120−123 mm long; transverse sternapodeme 30−50 mm long. Gonocoxite 200−230 mm long. Superior volsella short, small and spatulate, 16−18 mm long, 20−22 mm wide, with 2 long setae (Fig. 10). Inferior volsella elongated, 190−200 mm long, with 6 long setae. Gonostylus 210−230 mm long, with 4 long setae along inner margin in distal 1/3. HR 0.95−1.00, HV 1.89−2.04.

Female, pupa and larva.

Unknown.

Type material.

Holotype: Male, CHINA, Zhejiang, Quzhou City, Hunan County, 19.iv.2012, leg. XL Lin, sweep net. 2 Paratypes: 2 males, same data as holotype.

Etymology.

The specific epithet is a Latin adjective “brevissimus”, meaning the shortest, and refers to the superior volsella, which is the shortest in the genus.

Remarks.

Stenochironomus brevissimus sp. n. is similar to Stenochironomus hainanus Qi, Shi & Wang, 2008 and Stenochironomus okialbus Sasa, 1990 in having short and small superior volsella, but can separated from these species by the differences given in Table 2.

Distribution.

The species is currently known only from Zhejiang Province of Oriental China.