Xestochironomus Sublette et Wirth, 1972

Pinho, Luiz Carlos & Souza, João Francisco, 2013, New species of Xestochironomus Sublette et Wirth, 1972 (Diptera: Chironomidae) from Atlantic Forest, Brazil, Zootaxa 3652 (5), pp. 595-600 : 598

Key to adult males of Xestochironomus Sublette et Wirth, 1972

1. Gonostylus with simple, tapering apex.................................................................... 2

- Gonostylus forked, at least with low mesial lobe............................................................ 11

2. Abdominal segments uniformly pale, straw yellow or brown, without contrasting darker crossbands.................... 3

- Abdominal segments pale to yellow, with brown crossbands on tergites II–V, sometimes I–VII........................ 8

3. Posnotum with no pigmentation......................................................................... 4

- Posnotum with pigmentation, at least pale brown............................................................ 5

4. Anal point moderately bulbous, apex about 1.5x wider than base. AR 0.79.................................................................................................... Xestochironomus ankylis Sublette et Sasa (1994: 51)

- Anal point markedly bulbous, apex about 3x wider than base. AR 1.25–1.53........................................................................................................ Xestochironomus subletti Borkent (1984: 25)

5. Lateral vittae light to medium brown, contrasting with predominantly pale remaining areas of thorax................... 6

- Thorax entirely pale (except for postnotum), or entirely brown................................................ 7

6. AR lower than 0.90..................................... Xestochironomus dominicanus Sublette et Wirth (1972: 10)

- AR 1.20–1.45................................... Xestochironomus aisenensis Andersen et Kristoffersen (1998: 296)

7. Body pale, except for posnotum very pale brown.......................... Xestochironomus gilvus Borkent (1984: 27)

- Body completely brown............................................. Xestochironomus virgoferreae sp. n. ( Fig. 2 )

8. Anal point bulbous.................................................................................... 9

- Anal point parallel-sided.............................................................................. 10

9. Lateral vittae and ventral portion of preepisternum brown. Hind tibia pale brown................................................................................................... Xestochironomus brunneus Borkent (1984: 28)

- Lateral vittae and ventral portion of preepisternum with no pigmentation. Hind tibia darker brown...................................................................................... Xestochironomus latilobus Borkent (1984: 29)

10. Superior volsella with swollen apex.................................. Xestochironomus bulbosus Borkent (1984: 27)

- Superior volsella with slender apex............................. Xestochironomus comptus Sublette et Wirth (1972: 9)

11. Apex of gonostylus markedly forked, with deep concavity between thumb-like lobes.............................. 12

- Apex of gonostylus slightly forked, with low concavity between not thumb-like lobes.............................. 14

12. Abdomen yellowish, without dark crossbands.............................................................. 13

- Abdomen with dark crossbands................. Xestochironomus furcatus (Johannsen) , see Sublette & Wirth (1972: 12)

13. Thorax brownish yellow, legs yellowish..................... Xestochironomus luteifurcatus Sublette et Wirth (1972: 14)

- Thorax yellow, legs uniformly brown............................. Xestochironomus flinti Sublette et Wirth (1972: 10)

14. Abdomen yellowish, without dark crossbands.............................................................. 15

- Abdomen with dark crossbands......................................................................... 16

15. Anal point slender, parallel sided; superior volsella curved; gonostylus gradually broadened distally, with low, rounded mesial lobe subapically............................................. Xestochironomus hobbsi Sublette et Wirth (1972: 13)

- Anal point spatulate; superior volsella hooked; gonostylus slender, pointed, with low, triangular mesial lobe subapically................................................... Xestochironomus laselvensis Andersen et Kristoffersen (1998: 301)

16. Lateral lobe of gonostylus overreaching mesial lobe.................................................................................................................. Xestochironomus nebulosus Sublette et Wirth (1972: 15)

- Lateral lobe of gonostylus not overreaching mesial lobe.......................................................................................................................... Xestochironomus dickinsoni sp. n. ( Fig. 1 )

Figures

FIGURE 1. Xestochironomus dickinsoni sp. n., male: A, Wing; B, Anal point and tergite IX and dorsal aspect of left gonocoxite and gonostylus; C, Left inferior volsella, dorsal view; D, Hypopygium with anal point and tergite IX removed, left dorsal aspect, right ventral aspect.

FIGURE 2. Xestochironomus virgoferreae sp. n., male: A, Wing; B, Anal point and tergite IX and dorsal aspect of left gonocoxite and gonostylus; C, Hypopygium with anal point and tergite IX removed, left dorsal aspect, right ventral aspect.