Chaoborus flavicans (Meigen, 1830)

Bang, Woo Jun & Shin, Seunggwan, 2023, A new species of the Chaoborus flavicans complex (Diptera, Chaoboridae) in South Korea, Zootaxa 5360 (1), pp. 57-81 : 63-65

Key to species of Chaoborus flavicans complex (based on Salmela et al. 2021b)

Adult male

1. Gonostylus rather short, length/width 9.43 (7.9–10.7); paramere dark, apical claw relatively long......... C. posio Salmela

- Gonostylus rather narrow and long, length/width 12.6–13.7 (10.2–16.2); paramere light brown to brown, unicolorous or bicolorous, apical claw relatively short ( Fig. 3a )............................................................. 2

2. Paramere bicolorous, apical claw relatively narrow and gently curved or straight................... C. flavicans (Meigen)

- Paramere unicolorous, apical claw relatively stout and curved.................................................. 3

3. Paramere medially bent and constricted ( Fig. 3b–c ).......................... C. pseudoflavicans sp. nov. Bang & Shin

- Paramere almost straight or slightly curved........................................... C. albipes ( Johannsen, 1903)

Pupae

* Pond-dwelling specimens are hard to distinguish due to intraspecific variation.

1. Respiratory organ club-shaped, subapical constriction absent, relatively short 844 (770–930)............ C. posio Salmela

- Respiratory organ slender or voluminous form, subapical constriction present..................................... 2

2. Length of respiratory organ> 1000 μm (920–1360), slender form in ponds ( Fig. 4e ); voluminous form in lakes............................................ C. flavicans (Meigen) / C. pseudoflavicans sp. nov. Bang & Shin (only slender form)

- Length of respiratory organ mostly <1000 (690–1050), slender form...................... C. albipes ( Johannsen, 1903)

IV instar larvae

* Serration of labral blades are mostly varied in all complex species.

1. Mandibular lateral teeth inconspicuous, first lateral tooth shorter or smaller than mandibular tooth 3 (subordinate tooth)........................................................................................ C. flavicans (Meigen)

- Mandibular lateral teeth conspicuous, first lateral tooth about as long as mandibular tooth 3 (subordinate tooth)........... 2

2. Number of mandibular fan bristles <14 (usually 10–13), average number of lateral teeth almost <4 (3–4) ( Fig. 4c )........................................................................... C. pseudoflavicans sp. nov. Bang & Shin

- Number of mandibular fan bristles> 20, average number of lateral teeth> 5 (5–8).................................. 3

3. Number of mandibular fan bristles usually> 22, (up to 29); labral blade almost serrated, rather wide–length/width 3.7 (3–5)....................................................................................... C. posio Salmela

- Number of mandibular fan bristles usually 15–21, (up to 25); labral blade almost smooth, rather narrow–length/width 5.6 (4.4–6.9)...................................................................... C. albipes ( Johannsen, 1903)

Figures

FIGURE 3. Chaoborus pseudoflavicans sp. nov., hypopygium, (a) dorsal view (scale bar 200 μm), (b) parameres viewed in different positions (scale bar 50 μm). gst = gonostylus, pm = paramere, gx = gonocoxite, ac = apical claw.

FIGURE 4. Chaoborus pseudoflavicans sp. nov., immature stages, (a) larva, habitus in lateral view (scale bar 1.0 mm), (b) pupa, habitus in lateral view (scale bar 1.0 mm), (c) larval mandibles (scale bar 50 μm), (d) larval blades (scale bar 50 μm), (e) respiratory organ (scale bar 500 μm). lb = larval blade, ant = antenna, md = mandible, ans = anal fan setae, ro = respiratory organ, tp = terminal process, Lt = lateral teeth, I–IV = mandibular teeth, III being the subordinate tooth.