Cryptochironomus Kieffer

Saether, Ole A., 2009, Cryptochironomus Kieffer from Lake Winnipeg, Canada, with a review of Nearctic species (Diptera: Chironomidae), Zootaxa 2208, pp. 1-24 : 3-4

Key to Nearctic males of Cryptochironomus Kieffer

1. Anal point broad and flat ............................................................................................................................................. 2

- Anal point narrow ........................................................................................................................................................ 3

2. Mesal apical margin of gonostylus emarginate .................................... C. scimitarus Townes (Townes 1945 fig. 110).

- Mesal apical margin of gonostylus straight or nearly straight ..................... C. sorex Townes (Townes 1945 fig. 109)

3. Mesal apical margin of gonostylus emarginate ................................... C. argus Roback (Roback 1957: 106, fig. 557).

- Mesal apical margin of gonostylus not emarginate .................................................................................................... 4

4. Gonostylus about 4.0 times as long as wide, AR about 3.7, Wing length 3.1–3.4 mm .................................................. ................................................................................................................... C. blarina Townes (Townes 1945 fig. 112).

- Gonostylus 2.0–3.7 times as long as wide; when AR higher than 3.6, Wing length higher than 3.4 mm or lower than 3.1 mm ........................................................................................................................................................................ 5

5. Gonostylus widened towards apex; frontal tubercles present; AR 3.5–5.1; LR1 1.12–1.39 (1.5 in Townes), 9–24 sen- silla chaeticae on p2 ....................................................................................................................................................... 6

- Gonostylus not distinctly widened towards apex; frontal tubercles mostly absent, when present AR 2.5–3.8, LR1

1.45–2.02 and mostly 1–6 sensilla chaeticae on p2; when AR higher than 3.5, LR1 higher than 1.59 ......................... 7 6. AR 4.35–5.12, LR1 1.12–1.21, gonostylus strongly widened towards apex .................................................................. ............................................. C. stylifera (Johannsen) ( Fig. 2 A, B; Townes 1945 fig. 114 as C. psittacinus (Meigen) .

- AR 3.54–4.03, LR1 1.23–1.39, gonostylus slightly widened towards apex.................................................................... .............................................................................................................. C. digitatus (Malloch) ( Townes 1945, fig 113)

7. LR1 1.31–1.67, frontal tubercles absent ....................................................................................................................... 8

- LR1 1.45–2.02, when lower than 1.7 frontal tubercles present................................................................................... 10

8. Wing length 4.99–5.78 mm; LR1 1.48–1.67 ................................................. C. eminentia Mason (Mason 1985 fig. 3)

- Wing length 2.30–4.75 mm; LR1 1.31–1.55 ................................................................................................................ 9

9. Wing length 3.01–4.75 mm, AR 2.64–3.40, LR1 1.34–1.55 ............... C. ramus Mason ( Fig. 4 A; Mason 1985 fig. 4)

- Wing length 2.30–2.80, AR 2.52–2.82, LR1 1.31–1.45 ............................................................................ C. ramus var.

10. Wing length 1.8 mm, gonostylus only about twice as long as wide, frontal tubercles present ...................................... .......................................................................................... C. parafulvus Beck et Beck (Beck and Beck1964 Fig. 1 A).

- Wing length 1.9–5.6 mm, gonostylus at least 2.5 times as long as wide, frontal tubercles present or absent ........... 11

11. Gonostylus about 2.8–3.2 times as long as wide, anal point slightly spatulate apically, frontal tubercles absent ........ .......................................................................................................... C. ponderosus ( Sublette) (Sublette 1964 fig. 56).

- Gonostylus about 2.2–2.7 times as long as wide, anal point tapering parallel-sided or slightly spatulate, frontal tuber- cles present or absent ................................................................................................................................................. 12

12. Frontal tubercles absent; wing length 2.5–5.6 mm ......................................................................................................... ......................................................................... C. curryi Mason (Mason 1985 fig. 2; Darby 1962 fig. 49 as C. fulvus )

- Frontal tubercles present; wing length 1.9–3.2 mm or 5.1–5.3 mm .......................................................................... 13

13. Wing length 5.1–5.3 mm; AR 2.5–2.6 ................................................................. C. conus Mason (Mason 1985 fig. 1)

- Wing length 1.8–3.2 mm; AR 2.5–3.4........................................................................................................................ 14

14. LR1 1.56–1.73, mean 1.64; anal point slightly spatulate apically ...................................... C. imitans sp. n. ( Fig. 4 C).

- LR1 1.60–2.02, mean 1.78 ( Sublette 1964: 132), anal point parallel-sided .................................................................... ......................................................................................................... C. fulvus (Johannsen) ( Sublette 1964 fig. 72–75).

Figures

FIGURE 1. Map of Lake Winnipeg showing sampling stations and the larval distribution of the four most common species of Cryptochironomus Kieffer in the lake.

FIGURES 2. Cryptochironomus stylifera (Johannsen), male (A, B) and larva (C – G). A — frontal tubercles; B — hypopygium; C - antenna; D — labrum and epipharynx; E — premandible; F — mandible; G — mentum.

FIGURE 4. Cryptochironomus ramus Mason (A) and Cryptochironomus imitans sp. n. (B – D), imagines. A, C — male hypopygium; B — frontal tubercles; D — female genitalia.