Cryptochironomus rostratus (Kieffer, 1921)

Yan, Chuncai, Liu, Ting, Cao, Wei, Zhao, Guangjun & Liu, Wenbin, 2018, A review of the Japanese Cryptochironomus Kieffer, 1918 (Diptera, Chironomidae), ZooKeys 771, pp. 139-155 : 141-144

Cryptochironomus rostratus (Kieffer, 1921) Figure 2

Chironomus rostratus Kieffer, 1921: 67.

Chironomus (Chironomus) rostratus : Edwards 1929: 390.

Chironomus (Cryptochironomus) rostratus : Goetghebuer 1928: 84; Kruseman 1933: 187.

Cryptochironomus rostratus : Pinder 1978: 116; Ree and Kim 1981: 143; Cranston and Judd 1989: 252; Chaudhuri and Chattopadhyay 1990: 157; Dutta et al. 1996: 269; Wang 2000: 643.

Paracladopelma inaheia Sasa, Kitami & Suzuki, 2001: 7 (syn. n.).

Material examined.

Japan: the type specimen of Paracladopelma inaheia Sasa, Kitami & Suzuki, Holotype, ♂ (No. 402: 17), shore of Lake Inawashiro, Japan, 21.viii.2000, light trap.

Diagnostic characters.

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.

Description.

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 2.

Hypopygium (Fig. 2). Tergite IX broad with cone-like posterior margin, bearing approximately 30 setae located dorsally and ventrally near the base of anal point. Laterosternite IX with six lateral setae. Anal point 88 mm long, slightly wider at base, almost parallel-sided, apically rounded, lateral setae and microtrichia absent. Anal tergite bands “V” -shaped. Phallapodeme 135 mm long. Transverse sternapodeme 75 mm long. Superior volsella spherical to bulb-like, covered with microtrichia, bearing six strong setae at apex. Inferior volsella tuberculate, bearing three setae at apex, free microtrichia. Gonocoxite 138 mm long, with six stout setae placed along inner margin. Gonostylus 170 mm long, base widest, slightly curved in the middle, tapered to the apex, bearing seven short setae along inner margin and one stronger seta at apex. HR: 0.81; HV: 3.21.

Distribution.

China (Zhejiang, Fujian, Jiangxi, Guangxi, Hainan, Sichuan, Guizhou, Tibet, Taiwan); South Korea; Japan; India; Bangladesh; Lebanon; Turkey; Europe (Germany, UK, Holland, Belgium).

Remarks.

The holotype of Paracladopelma inaheia belongs to the well-known European Cryptochironomus rostratus based on morphological characters of the hypopygium and metric measurements ( Kieffer 1921; Pinder 1978: fig. 147B). Populations of C. rostratus from both Japan and other European areas key close together despite some minor morphological differences mainly related to geographical variation, especially the general shape of tergite IX, anal point, superior volsella, inferior volsella, and gonostylus. Thus, Paracladopelma inaheia can be considered as a junior synonym of Cryptochironomus rostratus (Kieffer, 1921).