Cryptochironomus tonewabeus (Sasa & Tanaka, 2002)

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: 146-149

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Cryptochironomus tonewabeus (Sasa & Tanaka, 2002)

comb. n.

Cryptochironomus tonewabeus (Sasa & Tanaka, 2002)  comb. n. Figure 4

Paracladopelma tonewabea  Sasa & Tanaka, 2002: 30.

Material examined.

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.

Diagnostic characters.

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 vol sella 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 4.

Hypopygium (Fig. 4 A–B). Tergite IX shoulder-shaped at the posterior margin, bearing 16 setae. Laterosternite IX with six lateral setae. Anal point 77 μm long, wider at base, parallel-sided with rounded apex, lacking dorsal and lateral setae, microtrichia absent. Anal tergite bands “V” -shaped, not fused in the middle. Phallapodeme 90 μm long. Transverse sternapodeme 80 μm long. Superior volsella peanut-like, concave medially, bearing six strong setae. Inferior volsella thumb-like, with slender extension at the base, bearing four long setae at apex, free microtrichia. Gonocoxite 158 μm long, bearing eight strong setae along inner margin; Gonostylus 164 μm long, with seven short inner setae and one single seta. HR: 0.78; HV: 3. 25.




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 Cranston et al. (1989). The “V” shaped anal tergite bands, not fused medially, are similar to Cryptochironomus albofasciatus  (Staeger, 1839), but C. tonewabeus  can be differentiated by the frontal tubercles, superior volsella and inferior volsella.