Research Article |
Corresponding author: Wenbin Liu ( skyliuwenbin@163.com ) Academic editor: Fabio Laurindo da Silva
© 2018 Chuncai Yan, Ting Liu, Wei Cao, Guangjun Zhao, Wenbin Liu.
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:
Yan C, Liu T, Cao W, Zhao G, Liu W (2018) A review of the Japanese Cryptochironomus Kieffer, 1918 (Diptera, Chironomidae). ZooKeys 771: 139-155. https://doi.org/10.3897/zookeys.771.24220
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The genus Cryptochironomus Kieffer, 1918 from Japan is reviewed based on material composed of male adults. New combinations of three species are established and they are re-described based on male adult of: C. misumaiprimus (Sasa & Suzuki, 1998), comb. n., C. tokaraefeus (Sasa & Suzuki, 1995), comb. n. and C. tonewabeus (Sasa & Tanaka, 2002), comb. n. Additional taxonomic notes are also provided: C. albofasciatus (Staeger, 1839), which is a senior synonym of Parachironomus inafegeus Sasa, Kitami & Suzuki, 2001 and C. rostratus (Kieffer, 1921) as the senior synonym of Paracladopelma inaheia Sasa, Kitami & Suzuki, 2001. A key to the known adult males of the genus from Japan is given.
Cryptochironomus , Japan, key, new combination, synonymy, taxonomy
Cryptochironomus is a diverse genus and widely distributed worldwide.
Eight Cryptochironomus species were reported from Japan by
In this paper, the genus Cryptochironomus is reviewed from Japan. Three new combinations and two synonyms are established and re-described. A key to the known adult males of the genus from Japan is presented.
A large amount of material composed of adult males belonging to the genus Cryptochironomus was examined based on slide-mounted following the procedures outlined by
Abbreviations used in text as follows:
AR antennal ratio = length of ultimate fagellomere: combined lengths of fagellomeres one to penultimate;
fe femur;
HR hypopygium ratio = gonocoxite length: gonostylus length;
HV hypopygium value = body length: gonostylus length × 10;
LR leg ratio: tarsomere length: tibia length;
LR1 tarsomere I length: tibia length;
p1–3 Legs (1–fore, 2–mid, 3–hind);
R Radius; R1, Radius 1; R4+5, Radius four and five;
Ta1–5 tarsomeres 1–5;
Ti tibia;
VR ratio of length of Cu: length of M.
Chironomus
albofasciatus
Chironomus (Cryptochironomus) albofasciatus
Staeger.
Cryptochironomus
albofasciatus
(Staeger).
Parachironomus inafegeus Sasa, Kitami & Suzuki, 2001: 6 (syn. n.).
China. ♂ (No. 05227) Fujian Province, Longyan City, Shanghang county, 3.v.1993, light trap, X. Wang. The type specimen of Parachironomus inafegeus Sasa, Kitami & Suzuki. Holotype, ♂ (No. 398: 65), on the shore of lake Inawashiro, insect net, 8.vi.2000.
Thorax yellowish brown with white stripes; anal point parallel-sided, slender; anal tergite bands “V”-shaped, not fused in the middle; superior volsella crescent-like; inferior volsella tuberculate with two small protuberances, bearing two strong apical setae, free of microtrichia.
China (Fujian Province); Russian Far East; Japan; Europe.
The holotype specimen of Parachironomus inafegeus Sasa, Kitami & Suzuki, 2001 mainly agrees with the description of Cryptochironomus albofasciatus (Staeger, 1839) by Goetghebuer (1937–195: 38, fig. 116), especially the characters of anal point, superior and inferior volsella, and gonostylus. Consequently, it must be considered a junior synonym of Cryptochironomus albofasciatus (Staeger, 1839). See also the species illustration in
Cryptochironomus
hentonensis
Hasegawa & Sasa, 1987: 290;
Japan. The type specimen of Cryptochironomus hentonensis Hasegawa & Sasa. Holotype, ♂ (No. 64: 91), on the bank of Eel pond at Hentona, Okinawa, in the Ryukyu Islands, southern Japan. 2.xii.1982.
AR 3.03; frontal tubercles present; anal point long and tapering, lateral setae and microtrichia absent; superior volsella thumb-like, inferior volsella finger-shaped.
Japan; Russian Far East.
Cryptochironomus
javae
Kieffer, 1924: 264;
According to
Japan; Indonesia.
Cryptochironomus jokaprimus Sasa & Ogata, 1999: 86; Sasa and Suzuki 2001: 2.
Japan. Holotype, ♂ (No. 321: 37), at the side of a stream discharging water (the Kurobe Municipal Sewage Treatment Plant (Kurobe Joka Center)), in urban areas of Japan, 27.viii.1996, light trap.
Frontal tubercles prominent, roughly conical. Tergite IX rounded at the posterior margin. Anal point concave in its median portion, and parallel-sided to the apex, apically rounded. Superior volsella narrow at base and strongly expanded distally, bearing five strong setae, inferior volsella semicircular, gonostylus with small protrusion at apex.
Japan.
Paracladopelma misumaiprima Sasa & Suzuki, 1998: 18.
Japan. Holotype, ♂ (No. 348: 30), at Misumai, Hokkaido, 6. ix. 1997, sweep net.
AR 2.84. LR1 1.48. Anal point linear and distinctly parallel-sided, slender. Anal tergite bands “wide Y”-shaped. Superior volsella broadly semicircular; inferior volsella finger-shaped, slender at base, swelling at apex, bearing two setae, free microtrichia. Gonostylus tapering to the apex.
Male imago (n = 1).
Total length 5.45 mm; wing length 2.60 mm; total length / wing length 2.10; wing length / length of profemur 2.08.
Coloration. Thorax yellow-white, with yellow-brown spots. Femora of front legs yellow-brown, tibia and tarsi dark brown; femora, tibiae and tarsi I of mid and hind legs yellow-brown, tarsi II–V dark brown. Abdomen yellow-brown, hypopygium dark brown.
Head.AR: 2.84. Ultimate flagellomere 1080 μm; frontal tubercles present but unclear. Temporal setae 24, including ten inner verticals, six outer verticals, and eight postorbitals. Clypeus with 16 setae; palpomere lengths (µm): 48; 63; 245; 208; 260. Palp segment 5th/3rd: 1.06.
Thorax. Antepronotals unclear; acrostichals nine; dorsocentrals 16; prealars six. Scutellum with 24 setae.
Wing. VR: 1.10. R with 22 setae. R1 with 21 setae. R4+5 with 37 setae. Brachiolum with three setae. Squama with nine setae.
Legs. Front tibia with three subapical setae, 185 μm and 188 μm, the other lost. Mid legs with two spurs, 30 mm and 33 mm; tibial comb with 52 teeth, 14 mm long. Spurs of hind tibia 30 mm and 33 mm long, tibial comb with 62 teeth, 15 mm long. The sensilla chaetica of tarsus I of mid leg and metapedes were not distinguishable. Lengths (in µm) and proportions of thoracic legs as in Table
Male adult of Cryptochironomus misumaiprimus (Sasa & Suzuki, 1998), comb. n. Length (µm) and proportions of legs.
fe | ti | ta1 | ta2 | ta3 | ta4 | ta5 | LR | |
---|---|---|---|---|---|---|---|---|
p1 | 1250 | 1000 | 1475 | 710 0 |
630 | 540 | 230 | 1. 48 |
p2 | 1150 | 1025 | 700 | 310 | 250 | 140 | 100 | 0. 68 |
p3 | 1250 | 1375 | 920 | 460 | 370 | 220 | 120 | 0. 67 |
Hypopygium (Fig.
Japan.
The characters of frontal tubercles, superior and inferior volsella, and gonostylus of this species followed the generic character of the genus Cryptochironomus emended by
Chironomus rostratus Kieffer, 1921: 67.
Chironomus (Chironomus) rostratus
:
Chironomus (Cryptochironomus) rostratus
:
Cryptochironomus
rostratus
:
Paracladopelma inaheia Sasa, Kitami & Suzuki, 2001: 7 (syn. n.).
Japan: the type specimen of Paracladopelma inaheia Sasa, Kitami & Suzuki, Holotype, ♂ (No. 402: 17), shore of Lake Inawashiro, Japan, 21.viii.2000, light trap.
Thorax with dark brown spots; the posterior margin of tergite IX shoulder-like or slightly cone-like; anal point slender, tapering distally or parallel-sided. Superior volsella crescent-like; inferior volsella tuberculate, bearing 1-3 stout setae, free microtrichia. Anal tergite bands “V” shaped, the junction of gonostylus and gonocoxite distinctly concaved, curved at 1/3 distance from base, apex with a small protrusion, bent inwards and bearing one seta.
Male imago (n = 1).
Total length 5.45 mm; wing length 2.30 mm, total length/wing length 2.37; wing length / length of profemur 2.17.
Coloration. Thorax yellow-white, with yellow-brown spots. Femora of front legs yellow-brown, tibiae and tarsomeres dark brown; femora and tibiae of mid and hind legs yellow-brown, tarsi I yellow-brown except for dark yellow-brown at ends, tarsi II–V dark yellow brown. Abdomen yellow-brown, hypopygium dark brown.
Head. AR: 2.89. Ultimate flagellomere 1010 μm; little and semi-circular frontal tubercles, diameter 7 μm. Temporal setae 25, including six inner verticals, 12 outer verticals, and seven postorbitals. Clypeus with 17 setae. Palpomere lengths (µm): 45; 65; 220; 212; 230. Palp segment 5th/3rd. 1.05.
Thorax. Antepronotals bare; acrostichals ten; dorsocentrals 14; prealars eight. Scutellum with 32 setae.
Wing. VR: 1.12. R with 24 microtrichia. R1 with 23. R4+5 with 22 setae. Brachiolum with three strong setae. Squama with 17 fringed setae.
Legs. Front tibia with three subapical setae, 165μm and 168μm, the other lost. Mid legs with two spurs, 30 mm and 35 mm, tibial comb with 44 teeth, 15 mm long. Spurs of hind tibia 35 mm and 37 mm long, tibial comb with 60 teeth, 15 mm long. Tarsus I of mid leg with nine sensilla chaetica, Tarsus I of metapedes leg with six sensilla chaetica. Lengths (in µm) and proportions of thoracic legs as in Table
Male adult of Cryptochironomus rostratus (Kieffer, 1921). Lengths (µm) and proportions of legs.
fe | ti | ta1 | ta2 | ta3 | ta4 | ta5 | LR | |
---|---|---|---|---|---|---|---|---|
p1 | 1060 | 825 | 1500 | 650 0 |
540 | 440 | 200 | 1.82 |
p2 | 1020 | 910 | 630 | 300 | 220 | 120 | 100 | 0.69 |
p3 | 1110 | 1200 | 860 | 450 | 350 | 190 | 120 | 0.72 |
Hypopygium (Fig.
China (Zhejiang, Fujian, Jiangxi, Guangxi, Hainan, Sichuan, Guizhou, Tibet, Taiwan); South Korea; Japan; India; Bangladesh; Lebanon; Turkey; Europe (Germany, UK, Holland, Belgium).
The holotype of Paracladopelma inaheia belongs to the well-known European Cryptochironomus rostratus based on morphological characters of the hypopygium and metric measurements (
Cryptochironomus sp. “hentona” Sasa & Ichimori, 1983: 103.
Cryptochironomus
tamaichimori
Sasa in
Frontal tubercles and the posterior margin of tergite IX are highly variable in this species. The main distinguishing features are as follows: superior volsella bulbous to globular, both sides of the inferior volsella stretching upward at base, formed into flank-shaped, free microtrichia, bearing two long apical setae at apex. The junction of gonostylus and gonocoxite concaved obviously, gonostylus abruptly narrowed near apex and apically pointed, bearing one seta at apex.
China (Hebei, Zhejiang, Fujian, Hubei, Guangdong, Hainan, Sichuan); Japan; Russian Far East.
Cryptochironomus
tamayoroi
Sasa & Ichimori, 1983: 102;
Japan. Holotype, ♂ (No. 74: 01), Tama River, at the Yoroi Bridge, at Yoroi-bashi, Japan. 11. iii. 1982.
AR 2.56. Frontal tubercles present; tergite IX bearing three setae, posterior margin tapering. Anal point parallel-sided. Anal tergite bands “V”-shaped. Superior volsella about twice as long as wide, with four long setae; inferior volsella extending well beyond posterior margin of superior volsella. Gonostylus wider at base and tapering towards apex, with one single apical seta.
Japan.
Cryptochironomus tokaracedeus Sasa & Suzuki, 1995: 260.
Japan. ♂ (No. 286: 21), edge of rice paddies, Tokara Islands, Kagoshima, Japan. 18–19. v. 1994, sweep net, Coll. H. Suzuki.
Frontal tubercles present. The tibia of front leg with one subapical seta. The posterior margin of tergite IX shoulder-like. Anal point tapering to the apex, lateral setae and microtrichia absent. Anal tergite bands “H”-shaped. Superior volsella small, thumb-like, almost entirely covered by microtrichia; inferior volsella bearing three apical setae at apex, free microtrichia.
Japan.
Paracladopelma tokaraefea Sasa & Suzuki, 1995: 262.
Japan. Holotype specimen of Paracladopelma tokaraefea Sasa & Suzuki, 1995. ♂ (No. 287: 19), at the edge of a rice paddy, on Kuchinoshima Island, on the Tokara Islands Kagoshima, Japan. 19.v.1994, insect net, Coll. H. Suzuki.
Anal point almost parallel-sided. Anal tergite bands H-shaped. Superior volsella bulbous to spherical; inferior volsella square-shaped, and width is equal to half of superior volsella, bearing three long setae at apex, free microtrichia.
(n = 1). Total length 5.23 mm; wing length 2.20 mm; total length / wing length 2.38; wing length / length of profemur 2.26.
Coloration. Thorax yellow-white, with yellow-brown spots; femora, tibiae and tarsi I of mid and hind legs yellow-brown; tarsi II-V dark yellow-brown. Abdomen yellow brown; hypopygium dark brown.
Head. Antenna damaged; frontal tubercles unrecognizable. Temporal area damaged. Clypeus with 15 setae. Palpomere lengths (µm): 48; 52; 200; 180; 228. Palp segment 5th/3rd: 1.14.
Thorax. Antepronotals bare; acrostichals eight; dorsocentrals 13; prealars five. Scutellum with 28 setae.
Wing. VR: 1.08. R with 24 microtrichia. R1 with 19. R4+5 with 28 setae. Brachiolum with three strong setae. Squama with at least ten fringed setae.
Legs. Front tibia with two subapical setae, 150 μm and 155 μm. Mid legs with two spurs, 13 mm and 22 mm, tibial comb with 50 teeth, 10 mm long. Spurs of hind tibia 14 mm and 25 mm long, tibial comb with 66 teeth, 10 mm long. Tarsus I of mid and hind leg were not distinguishable. Lengths (in µm) and proportions of thoracic legs as in Table
Male adult of Cryptochironomus tokaraefeus (Sasa & Suzuki, 1995), comb. n. Length (µm) and proportions of legs.
fe | ti | ta1 | ta2 | ta3 | ta4 | ta5 | LR | |
---|---|---|---|---|---|---|---|---|
p1 | 975 | 800 | 1325 | 550 0 |
500 | 400 | 180 | 1.66 |
p2 | 960 | 890 | 560 | 270 | 200 | 120 | 100 | 0.63 |
p3 | 1050 | 1115 | 810 | 400 | 300 | 270 | 120 | 0.73 |
Hypopygium (Fig.
Japan.
The characters of frontal tubercles, superior volsella and inferior volsella, and gonostylus followed the generic character of the genus Cryptochironomus by
Paracladopelma tonewabea Sasa & Tanaka, 2002: 30.
Japan. Holotype specimen of Paracladopelma tonewabea Sasa & Tanaka, 2002. ♂ (No. 405: 51), Tone River at Taisho Bridge, Gunma Prefecture, Japan. 19. xii. 2000, reared from bottom sample, coll. N. Tanaka.
AR 2.53, frontal tubercles cylindrical. Tergite IX broadly semi-circular, with 16 setae (eight on each side of base of anal point). Anal point wide at base, parallel-sided medially and distally, rounded apically. Anal tergite bands “wide V”-shaped, not fused in the middle, and abruptly interrupted at the end. Superior volsella peanut-like, concave midially. Inferior volsella thumb-like, with slender extension at the base. Gonostylus and gonocoxite fused completely. Gonostylus wider at base, tapering to the apex.
Coloration. Thorax light yellow-brown, with yellow-brown spots, Femora of front legs yellow-brown, tibia and tarsomeres dark brown; femora, tibiae and tarsi I of mid and hind legs brown; tarsi II-V dark yellow-brown, hypopygium dark brown.
Head. AR: 2.53, Ultimate flagellomere 1010 μm; frontal tubercles tapering, 20 μm high, 13 μm width at base. Temporal setae 23, including seven inner verticals, nine outer verticals, and seven postorbitals. Clypeus with 20 setae. Palpomere lengths (µm): 60; 75; 290; 120; 330. Palp segment 5th/3rd: 1.14.
Thorax. Antepronotals bare; acrostichals ten; dorsocentrals ten; prealars six. Scutellum with 25 setae.
Wing. VR: 1.15. R with 22 microtrichia. R1 with 19. R4+5 with 28 setae. Brachiolum and squama were broken.
Legs. Front tibia with three subapical setae, 175 μm, 180 μm, 193 μm. Mid legs with three spurs, 28 μm, 30 μm; tibial comb with 48 teeth, 12 μm long. Spurs of hind tibia 30 μm and 37 μm long, tibial comb with 64 teeth, 13 μm long. Tarsus I of mid leg with three sensilla chaetica; tarsus I of metapedes leg with two sensilla chaetica. Lengths (in µm) and proportions of thoracic legs as in Table
Male adult of Cryptochironomus tonewabeus (Sasa & Tanaka, 2002), comb. n. Length (µm) and proportions of legs.
fe | ti | ta1 | ta2 | ta3 | ta4 | ta5 | LR | |
---|---|---|---|---|---|---|---|---|
p1 | 1300 | 950 | 1700 | 780 0 |
650 | 600 | 225 | 1. 79 |
p2 | 1125 | 1030 | 690 | 320 | 240 | 140 | 100 | 0. 67 |
p3 | 1275 | 1330 | 920 | 450 | 380 | 210 | 110 | 0. 69 |
Hypopygium (Fig.
Japan.
Frontal tubercles cylindrical, superior volsella peanut-like, and concave medially combined with a thumb-like inferior volsella, bearing four long setae at apex, and free microtrichia followed the generic characters of
1 | Superior volsella spherical to bulbous | 2 |
– | Superior volsella not as above | 7 |
2 | Junction of gonostylus and gonocoxite distinctly compacted | 3 |
– | Junction of gonostylus and gonocoxite compacted slightly or not at all | 6 |
3 | Inferior volsella with microtrichia | C. tamayoroi Sasa & Ichimori, 1983 |
– | Inferior volsella bare | 4 |
4 | Anal point tapering to the apex | 5 |
– | Anal point nearly parallel-sided | C. rostratus (Kieffer, 1921) |
5 | Tibia and tarsi of front legs dark brown, tibia with 3 subapical setae | C. tamaichimori Sasa & Kawai, 1987 |
– | Tibia and tarsi of front legs light brown, tibia with 1 subapical seta | C. tokaracedeus Sasa & Suzuki, 1995 |
6 | Anal tergite bands “wide Y”-shaped | C. misumaiprimus (Sasa & Suzuki, 1998), comb. n. |
– | Anal tergite bands “H”-shaped | C. tokaraefeus (Sasa & Suzuki, 1995), comb. n. |
7 | The posterior margin of tergite IX tapered | 8 |
– | The posterior margin of tergite IX arced | 9 |
8 | Frontal tubercles low and broad, width is at least two times longer than height | C. albofasciatus (Staeger, 1839) |
– | Frontal tubercles tapering, width nearly equal to height | C. hentonensis Hasegawa & Sasa, 1987 |
9 | Anal point wide and short, gonostylus blunt and rounded apex | C. javae Kieffer, 1924 |
– | Anal point slender and short, gonostylus tapering to the apex | 10 |
10 | Superior volsella spherical, slightly compacted at base | C. jokaprimus Sasa & Ogata, 1999 |
– | Superior volsella peanut-like, distinctly compacted at distal 1/3 | C. tonewabeus (Sasa & Tanaka, 2002), comb. n. |
We are grateful to Dr A. Shinohara (Department of Zoology, National Science Museum, Tokyo, Japan), who kindly enabled us to examine Sasa’s type specimens. Dr Alexander Egan (University of Minnesota, USA) also provided valuable comments on a previous version of this manuscript. Financial support from the National Natural Science Foundation of China (grant Nos. 31672324, 31672264, 31460572). Science and Technology project of Tianjin (17KPXMSF00040, 14JCQNJC14600), 18JCQNJC14700, Tianjin City High School Science & Technology Fund Planning Project (20090608), and the Tianjin Normal University Foundation (5RL104, 043135202-XB1715, 135305JF79; 043135202-XK1706) are acknowledged with thanks.