Research Article |
Corresponding author: Xin Qi ( qixin1981@hotmail.com ) Academic editor: Vladimir Blagoderov
© 2015 Xin Qi, Xiaolong Lin, Yuedan Liu, Xinhua Wang.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Qi X, Lin X, Liu Y, Wang X (2015) Two new species of Stenochironomus Kieffer (Diptera, Chironomidae) from Zhejiang, China. ZooKeys 479: 109-119. https://doi.org/10.3897/zookeys.479.8364
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Two new species of Stenochironomus Kieffer (Diptera: Chironomidae: Chironominae), S. brevissimus sp. n. and S. linanensis sp. n., are described from China and the male imagines are illustrated. S. brevissimus sp. n. can be separated from the so far known species by having very short and small, spatulate superior volsella with two long setae, whereas S. linanensis sp. n. is easily separated from the other species of Stenochironomus by the following characters: wings transparent, body yellow, superior volsella finger-like, with nine long setae, elongated inferior volsella with four long setae and one well developed terminal spine; tergite IX with 10−15 long setae medially. A key to the males of Stenochironomus occurring in China is given.
Stenochironomus , new species, key, China
Stenochironomus Kieffer, 1919 is a species-rich genus with worldwide distribution, occurring in all biogeographical regions except in Antarctica (
Zhejiang Province is located in the Chinese central subtropical region, which has a humid monsoon climate. In Zhejiang, three species of Stenochironomus [S. koreanus Borkent, 1984, S. nubilipennis Yamamoto, 1981 and S. satorui (Tokunaga & Kuroda, 1936)] have been recorded (
The morphological nomenclature follows
Abbreviations of parts measured are as follows:
AR Antennal ration, length of 13th / length of flagellomeres 1–12
Palpomere ratio (5th/3rd) Length of the 5th Palpomere / length of the 3rd Palpomere
VR Venarum ration, length of Cubitus (Cu) / length of Media (M)
BV Length of (femur + tibia + ta1) / length of (ta2 + ta3 + ta4 + ta5)
LR Leg ration, length of ta1 / length of tibia
SV Length of (femur + tibia) / length of ta1
HR Hypopygium ration, length of gonocoxite / length of gonostylus
HV Hypopygium value, total length / length of gonostylus times ten
p1 Fore leg
p2 Mid leg
p3 Hind leg
fe femur
ti tibia
ta1…tan tarsus1…tarsusn
R Radius
R1 Radius 1 vein
R4+5 Radius 4+5 vein
The adult male of S. 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.
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.
Stenochironomus brevissimus sp. n., male. 1 head 2 wing 3 thorax, lateral view 4 legs coloration (a. fore leg; b. mid leg; c. hind leg) 5 fore tibial apex, ventral view 6 mid tibial apex, lateral view 7 hind tibial apex, lateral view 8 hypopygium 9 spines on posterior margin of tergite IX, ventral view 10 superior volsella.
Wings (Fig.
Thorax (Fig.
Legs (Fig.
Lengths (in µm) and proportions of leg segments in Stenochironomus brevissimus sp. n. (n = 3).
p1 | p2 | p3 | |
---|---|---|---|
Fe | 1300−1400 | 1125−1200 | 1325−1525 |
Ti | 1300−1500 | 1000−1125 | 1275−1400 |
ta1 | 1500−1600 | 725−800 | 950−1100 |
ta2 | 775−875 | 375−450 | 525−625 |
ta3 | 675−750 | 340−410 | 440−500 |
ta4 | 525−600 | 200−290 | 260−360 |
ta5 | 250−300 | 90−110 | 110−130 |
LR | 1.07−1.15 | 0.71−0.73 | 0.74−0.79 |
BV | 1.78−1.84 | 2.48−2.83 | 2.49−2.66 |
SV | 1.73−1.81 | 2.91−2.95 | 2.66−2.74 |
Hypopygium (Fig.
Unknown.
Holotype: Male, CHINA, Zhejiang, Quzhou City, Hunan County, 19.iv.2012, leg. XL Lin, sweep net. 2 Paratypes: 2 males, same data as holotype.
The specific epithet is a Latin adjective “brevissimus”, meaning the shortest, and refers to the superior volsella, which is the shortest in the genus.
S. brevissimus sp. n. is similar to S. hainanus Qi, Shi & Wang, 2008 and S. okialbus Sasa, 1990 in having short and small superior volsella, but can separated from these species by the differences given in Table
Main differences between S. brevissimus sp. n., S. hainanus and S. okialbus.
S. brevissimus | S. hainanus | S. okialbus | |
---|---|---|---|
Wing | transparent, without any pigmentation | transparent, without any pigmentation | with dark bands across the middle and posterior area |
Coloration | thorax light yellow, postnotum and scutum with brown spots; 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 | whole body yellow, without dark pigmentation | thorax yellow; fore legs yellow with femur apically brown, apex and basal region of tibia with dark brown stripes; mid legs yellow with femur apically brown; hind legs yellow with femur apically brown |
Superior volsella | with 2 setae | with 3 setae | with 4 setae |
Inferior volsella | with 6 setae | with 3 setae | with 4 setae and a strong terminal spine |
Posterior margin of tergite IX | with 20−22 setae and 8 spines | with 16 setae | with 8 setae and 8 spines |
The species is currently known only from Zhejiang Province of Oriental China.
The adult male of S. linanensis sp. n. can be distinguished from all other species of Stenochironomus by the following combination of characters: wings transparent, body yellow, superior volsella finger-like, with 9 long setae, elongated inferior volsella with 4 long setae and one well-developed terminal spine, tergite IX with 10−15 long setae medially.
Male imago (n = 5). Total length 2.9−3.8 mm. Wing length 1.4−1.5 mm. Total length / wing length 1.98−2.41. Wing length / length of profemur 1.30−1.57.
Coloration. Head yellow. Thorax greenish yellow. Wings transparent, without any pigmentation. Abdomen yellow, hypopygium brown. Legs pale yellow.
Head (Fig.
Wings (Fig.
Thorax (Fig.
Legs. Fore leg: width at apex of tibia 33−47 mm, tibia with scale 33−46 µm long, with 2−3 strong setae (Fig.
Lengths (in µm) and proportions of leg segments in Stenochironomus linanensis sp. n.
p1 | p2 | p3 | |
---|---|---|---|
fe | 925−1075 | 625−700 | 650−725 |
ti | 700−875 | 650−725 | 750−900 |
ta1 | 925−1100 | 475−550 | 780−950 |
ta2 | 500−725 | 200−260 | 400−600 |
ta3 | 400−500 | 210−300 | 300−350 |
ta4 | 320−400 | 130−200 | 240−300 |
ta5 | 140−200 | 70−80 | 100−120 |
LR | 1.25−1.32 | 0.73−0.75 | 1.04−1.06 |
BV | 1.67−1.88 | 2.35−2.87 | 1.88−2.10 |
SV | 1.76−1.83 | 2.60−2.68 | 1.71−1.79 |
Hypopygium (Fig.
Unknown.
Holotype: Male, CHINA, Zhejiang, Linan City, Qingliangfeng Mountain, 16.v.2012, leg. XL Lin, sweep net. 4 Paratypes: 4 males, same data as holotype.
The specific epithet is an adjective referring to the type locality, Linan City.
S. linanensis sp. n. is similar to S. macateei (Malloch, 1905), S. maculatus Borkent, 1984 and S. recticaudatus Borkent, 1984 in the structure of the hypopygium and the inferior volsella with a strong terminal spine, but can be separated from these species by the differences given in Table
Main differences between S. linanese sp. n., S. macateei, S. maculatus and S. recticaudatus.
S. linanese | S. macateei | S. maculatus | S. recticaudatus | |
---|---|---|---|---|
Wing | transparent | transparent | entire wing with pigmentation | transparent |
Median setae of tergite IX | 10−15 | 35−37 | 25−28 | 35−37 |
posterior margin of tergite IX | with 12−14 setae and 4 spines | with 8 setae and 6 spines | with 8 setae and 4 spines | with 14 setae and 8 spines |
Anal point | apex of anal point slightly swollen and rounded | parallel-sided | apex of anal point slightly swollen and rounded | apex of anal point slightly swollen and rounded |
Superior volsella | with 9 setae | with 4−5 setae | with 4−6 setae | with 6 setae |
Coloration | whole body yellow, without dark pigmentation | whole body yellow, without dark pigmentation | postnotum, scutum and scutellum with dark pigmentation; other parts of body yellow | dark pigmentation entirely absent except on tarsomeres 3−5 of all legs |
The species is known from Zhejiang Province of Oriental China.
1 | Inferior volsella with a well-developed terminal spine | 2 |
– | Inferior volsella without a well-developed terminal spine | 7 |
2 | Wing membranes with dark pigmentation | 3 |
– | Wing membranes without any pigmentation | 4 |
3 | Legs almost entire brown, posterior area smoky area between veins C and M pale | S. gibbus (Fabricius, 1805) |
– | Legs yellow; entire wing smoky gray | S. maculatus Borkent, 1984 |
4 | Apex of anal point swollen and rounded | 5 |
– | Apex of anal point not swollen and rounded | 6 |
5 | Superior volsella with 9 setae; posterior margin of tergite IX with 12−14 setae and 4 spines | S. linanensis sp. n. |
– | Superior volsella with 4 setae; posterior margin of tergite IX with 14−16 setae | S. koreanus Borkent, 1984 |
6 | Posterior edge of tergite IX with 8 long setae and 6 spines; anal point parallel-sided | S. macateei (Malloch, 1915) |
– | Posterior edge of tergite IX with 14 long setae, without any spine; anal point roughly triangular, apically pointed | S. mucronatus Qi, Shi & Wang, 2008 |
7 | Wing membranes with dark pigmentation | 8 |
– | Wings without any pigmentation or with narrow pigment areas around RM and along veins M3+4 and Cu1 | 10 |
8 | Abdomen and hypopygium light yellow | S. inalemeus Sasa, 2001 |
– | Abdominal tergites I−IV light yellow, tergites V−VIII light brown, hypopygium dark brown | 9 |
9 | Preepisternum with brown spots; anal point slender and parallel-sided, apically rounded | S. nubilipennis Yamamoto, 1981 |
– | Preepisternum without any pigmentation; anal point slender and parallel-sided, apically pointed | S. satorui (Tokunaga & Kuroda, 1936) |
10 | Posterior margin of tergite IX with spines | S. brevissimus sp. n. |
– | Posterior margin of tergite IX without spines | 11 |
11 | Entire body yellow, without dark pigmentation; wings transparent, without any pigmentation; inferior volsella with 3 long setae | S. hainanus Qi, Shi & Wang, 2008 |
– | Body yellow, with brown spots on thorax, abdomen, hypopygium and legs; wings with narrow pigment areas around RM and along veins M3+4 and Cu1; inferior volsella with 6 long setae | S. totifuscus Sublette, 1960 |
Financial support from the National Natural Science Foundation of China (NSFC, grant No. 31301908, 31272284) and the Zhejiang Provincial Natural Science Foundation of China (grant No. Y3100486) are acknowledged with thanks.