Dexia, Meigen, 1826

Zhang, Chun-Tian, Shima, Hiroshi & Chen, Xiao-Lin, 2010, A review of the genus Dexia Meigen in the Palearctic and Oriental Regions (Diptera: Tachinidae) 2705, Zootaxa 2705, pp. 1-81 : 8-10

Key to species of Dexia of the Palearctic and Oriental Regions

1. Costal spine absent or very small, if present then less than 1/3 length of r-m crossvein; thoracic scutum usually with 2 broad longitudinal black vittae................................................................................................................................... 2

- Costal spine usually more than twice as long as costal setae, rarely short, but distinct and more than 1/2 length of rm crossvein; thoracic scutum usually with 2 outer and 2 inner longitudinal black vittae, inner and outer vittae sometimes merged on postsutural scutum ............................................................................................................................. 8

2. Three katepisternal setae; abdominal tergites 4 and 5 with median discal setae in male .............................................3

- Two katepisternal setae; abdominal tergites with or without discal setae.................................................................... 5

3. Proepisternum bare; prementum more than 3/5 as long as eye height; base of vibrissa with or without sparse pruinosity; legs black; abdomen reddish yellow, with a narrow mid-dorsal longitudinal black vitta ......................... 4

- Proepisternum haired; prementum about 1/2 as long as eye height; base of vibrissa with pruinosity; legs yellow; abdomen broadly translucent reddish yellow with a broad mid-dorsal longitudinal black vitta and faint brownish markings on sides of each tergite ................................................................................................... D. caldwelli Curran

4. Wing tinged with pale brown basally and dark brown medialy; lower calypter with short fringe................................. ........................................................................................................................................................ D. fusiformis Walker

- Wing weakly tinged with yellow basally, pale brown anteriorly and medially; lower calypter with long fringe .......... ................................................................................................................................................... D. bivittata (Townsend)

5. Abdomen with median discal setae on tergites 3 to 5 in male, broadly translucent yellow with broad longitudinal black vitta and faint pale brownish spot on posterolateral portion of each tergite; legs reddish yellow except tarsi and claws, at most narrowly darkened on apices of femora and very weakly on tibiae; lower calypter with short fringe. 6

- Abdominal tergites without median discal setae, yellow, more or less dark brown on posterior margin of each tergite and mid dorsal longitudinal portion; legs with distal portion of femora and basal and distal portions of tibiae more or less darkened; lower calypter with long or short fringe................................................................................................ 7

6. Scutellum with a pair of fine discal setae; abdominal tergites 4 and 5 wholly covered with grayish white pruinosity; proepisternum bare or hairy; palpus shorter than 1st flagellomere ............................................. D. montana (Baranov)

- Scutellum without discal setae; abdominal tergites 4 and 5 covered with very thin silvery white pruinosity on dorsum, dense on sides of tergite 5; proepisternum with a few black hairs; palpus at least as long as 1st flagellomere ......................................................................................................................................................... D. vittata (Baranov)

7. Thoracic pleura with pale hairs at least on lower portion of katepisternum and anepimeron; 3 supra-alar setae, anterior seta shifted outward; palpus slightly longer than pedicel and 1st flagellomere combined; distal portion of femora and basal and distal portions of tibiae darkened; longitudinal black vitta on thoracic scutum usually separated into broad outer and narrow inner vittae on presutural area; lower calypter with short fringe on outer margin ................... ......................................................................................................................................................... D. major (Malloch)

- Thoracic hairs all black; 2 supra-alar setae, if 3, then anterior seta only slightly shifted outward; palpus shorter than combined length of pedicel and 1st flagellomere; femora mostly reddish yellow, distal portion weakly darkened, tibiae weakly darkened; thoracic scutum with 2 broad longitudinal black vittae; lower calypter with long fringe ........... ....................................................................................................................................................... D. extendens Walker

8. Femora dark brown to black; lower calypter usually with short fringe; thoracic scutum with 4 dark longitudinal vittae, though sometimes darkened on area between inner and outer vittae .................................................................... 9

- Femora yellow to reddish brown, if darkened then lower calypter with long fringe.................................................. 17

9. Three katepisternal setae; wing at most evenly and rather weakly tinged with pale brown ...................................... 10

- Two katepisternal setae; wing with distinct markings on anterior portion ................................................................ 13

10. Prementum about 6 times as long as wide; wing at most evenly and rather weakly tinged with pale brown; syntergite 1+2 with 1 pair of median marginal setae................................................................................................................... 11

- Prementum 3−4 times as long as wide; wing with distinct markings on anterior portion; syntergite 1+2 without median marginal setae................................................................................................................................................. 12

11. Thoracic pleura, abdominal sternite 1 and mid ventral portion of syntergite 1+2 with yellowish white hairs; 2 presutural dorsocentral setae; costal spine shorter than 1/2 length of crossvein r-m; abdomen with narrow mid dorsal longitudinal black vittta ........................................................................................................... D. longipes (Townsend)

- Thorax and abdomen with black hairs; 3 presutural dorsocentral setae; costal spine about as long as crossvein r-m; abdomen with a dark triangular marking on posteromedian portion of each tergite ...................................................... .......................................................................................................................... D. kurahashii Zhang et Shima sp. nov.

12. Antenna dark brown except reddish yellow on basal 1/2−1/3 of 1st flagellomere; 3 supra-alar setae, 1st seta fine and shifted outward .......................................................................................................... D. chaoi Zhang et Shima sp. nov.

- 1st flagellomere reddish yellow, pedicel reddish brown; 2 supra-alar setae......... D. chinensis Zhang et Chen sp. nov.

13. Thoracic scutum with 2 broad black vittae; wing pale yellowish basally and dark brownish anteriorly and medially ..................................................................................................................................................................................... 14

- Thoracic scutum with 2 narrow inner and 2 broad outer vittae, inner and outer vittae sometimes merged on median portion; wing only weakly and evenly tinged with pale brown.................................................................................. 16

14. Proepisternum bare ..................................................................................................................................................... 15

- Proepisternum hairy ..................................................................................................................... Dexia vicina (Mesnil)

15. Scutellum with silvery white pruinosity; alula and lower calypter white; frons about 1/5 head width in male, 2/ 7 in female ......................................................................................................................................... Dexia veltina (Mesnil)

- Scutellum with pale yellowish white pruinosity; alula and lower calypter pale yellowish; frons about 1/7 head width in male, slightly more than 1/ 4 in female ............................................................................... Dexia atripes (Malloch)

16. Costal spine short, about 1/2 as long as r-m crossvein; frons 0.17−0.20 times as wide as head width in male, 0.33 times in female; male abdomen with 2 pairs of median discal setae on tergites 3 and 4; usually 1 presutural and 1−2 postsutural acrostichal setae ........................................................................................................ Dexia fulvifera Röder

- Costal spine strong, at least as long as r-m crossvein; frons 0.13−0.2 times as wide as head width in male, 0.31−0.34 times in female; abdominal tergites 3 and 4 of male each with 1 pair of median discal setae; usually 0 presutural and 1 postsutural acrostichal setae ....................................................................................... Dexia sumatrensis (Townsend)

17. Lower calypter with short fringe on outer margin; usually 3 katepisternal setae ........................................................ 18

- Lower calypter with long fringe on outer margin; 2 katepisternal setae.................................................................... 22

18. Two katepisternal setae; 2 presutural dorsocentral setae; abdominal sternite 1 with pale yellowish hairs .................... ........................................................................................................................................................... D. basifera Walker

- Three katepisternal setae; 2−3 presutural dorsocentral setae; abdominal sternite 1 with black hairs ........................ 19

19. Two presutural dorsocentral setae; abdominal syntergite 1+2 without median marginal setae.................................. 20

- Three presutural dorsocentral setae; abdominal syntergite 1+2 with or without 2 median marginal setae…………………………………………………………………………………………...21

20. Thoracic scutum with 4 longitudinal black vittae, inner vittae almost subequal on postsutural scutum; abdomen dark brown on mid dorsal longitudinal portion of syntergite 1+2 to tergite 5, posterior 1/4 of tergite 3 and 1/3 of tergite 4, with dense pale yellowish pruinosity on anterior 1/5 of tergite 3 and entire tergites 4 and 5......................................... ......................................................................................................................................... D. fraseri (Malloch) (female)

- Thoracic scutum with 4 narrow longitudinal vittae, 2 black inner vittae merged and forming a dark transverse band on anterior 2/5 of postsutural scutum; abdomen almost without pruinosity, tergite 3 with a large triangular black marking extending to lateral margins on posterior portion, tergites 4 and 5 each with a dark median longitudinal stripe and 2 brown lateral spots .................................................................................................. D. flavida (Townsend)

21. 1st flagellomere about twice as long as pedicel; abdominal syntergite 1+2 without median marginal setae; body with dense yellowish pruinosity .......................................................................................................... D. rustica (Fabricius)

- 1st flagellomere about 4 times as long as pedicel; abdominal syntergite 1+2 with 1 pair of median marginal setae; tergites 4 and 5 with thin grayish white pruinosity on entire dorsum ........... D. tenuiforceps Zhang et Shima sp. nov.

22. Two presutural and 3 postsutural dorsocentral setae................................................................................................... 23

- Three presutural and 3−4 postsutural dorsocentral setae ............................................................................................ 24

23. Postpronotal lobe reddish in ground color; thorax with yellowish pruinosity; scutellum reddish yellow except dark brown on basal 1/3; abdominal tergites 3 and 4 each with one pair of median discal setae in male, female without discal setae ......................................................................................................................... D. longipennis (Townsend)

- Postpronotal lobe black; thoracic scutum and pleura with grayish white pruinosity; scutellum dark brown; abdominal tergites 3 and 4 each with 2 pairs of discal setae in male, female without discal setae ........... D. monticola (Malloch)

24. Four postsutural dorsocentral setae; abdominal tergite 3 with a complete row of marginal setae; gena about 0.47 times as wide as eye height in male; postpronotal lobe black ........................................................ D. seticincta Mesnil

- Three postsutural dorsocentral setae; abdominal tergite 3 usually with 1 pair of median marginal and 1−2 lateral marginal setae ............................................................................................................................................................. 25

25. Prosternum narrow, 3−4 times as long as wide....................................................................... D. violovitshi Kolomiets

- Prosternum 2−2.5 times as long as wide..................................................................................................................... 26

26. Antenna wholly reddish yellow ..................................................................................................................................27

- 1st flagellomere blackish brown on apical half, reddish yellow on basal half ..... D. alticola Zhang et Shima sp. nov.

27. Abdominal tergite 3 without median discal setae in both sexes, tergite 4 rarely with short and fine discal setae; abdomen with dense yellowish white pruinosity on anterior 1/5 of tergite 3, 2/5 of tergite 4 and 1/2 of tergite 5 ........ ............................................................................................................................................... D. luzonensis (Townsend)

- Either or both abdominal tergites 3 and 4 with median discal setae in both sexes, if female lacking discal setae, then abdomen more or less with pruinosity on narrow anterior portion of tergites 3 or 4 and anterior portion of tergite 5 .. ..................................................................................................................................................................................... 28

28. Abdomen with dense yellowish pruinosity at least on anterior 1/4 of tergite 3, 1/2 of tergite 4; tegula reddish to brown, sometimes dark ............................................................................................................................................... 29

- Abdomen with thin yellowish pruinosity only on narrow anterior margin of tergites 3 and 4; tegula usually black or dark brown .................................................................................................................................................................. 32

29. Palpus shorter than 1st flagellomere ........................................................................................................................... 30

- Palpus subequal in length to, or longer than 1st flagellomere .................................................................................... 31

30. Frontal vitta wider than or subequal in width to fronto-orbital plate at middle; black inner vitta of thoracic scutum 1/ 2−1/3 as wide as pruinose portion between inner and outer vittae; head and thorax with dense yellowish pruinosity; tegula reddish to brown; abdomen with dense yellowish pruinosity on anterior 1/3 of abdominal tergite 3, 1/2 of tergite 4 and 4/5 of tergite 5 .................................................................................................................. D. gilva Mesnil

- Frontal vitta narrower than fronto-orbital plate at middle; black inner longitudinal vitta of thoracic scutum 1/3−1/4 as wide as pruinosity portion between inner and outer vittae; head and thorax with dense pale yellowish white pruinosity; tergula reddish yellow; abdominal tergites 3 to 5 each with rather thin yellowish white pruinosity on anterior 1/3−1/5 ......................................................................................................................................... D. flavipes Coquillett

31. Thoracic scutum with 4 very narrow dark longitudinal vittae; scutellum with sparse pruinosity; tegula yellowish brown, basicosta brown.............................................................................................. D. maritima Kolomiets (female)

- Thoracic scutum with 4 wider dark longitudinal vittae; scutellum with dense grayish yellow pruinosity; tegula reddish yellow or reddish brown on basal half and dark brown on apical half .............................................................. 32

32. Gena 0.45−0.49 times as wide as eye height in male, 0.59 in female; tegula reddish yellow to dark brown; abdomen of male at most with rather dense yellowish pruinosity on anterior 1/2 of each tergite; palpus subequal in length to pedicel and 1st flagellomere combined ........................................................................................... D. ventralis Aldrich

- Gena about 0.4 times as wide as eye height in male, 0.52 in female; tegula usually reddish yellow; abdominal dorsum almost entirely with grayish white pruinosity in male, sometimes broadly bare on posterior sides of tergite 3 and narrow posterior margins of tergites 3 and 4, about anterior 1/2 or more of each tergite in female; palpus about as long as 1st flagellomere ...................................................................................................................... D. vacua (Fallén)

33. Abdominal syntergite 1+2 with 1 pair of median marginal setae in male; tergite 5 with grayish white pruinosity on anterior 1/4, 1/2 on side; 1 presutural and 2 postsutural acrostichal setae .................................. D. lepida Wiedemann

- Abdominal syntergite 1+2 without median marginal seta in male; grayish white pruinosity on anterior 1/3 of tergite 5 ..................................................................................................................................................................................... 34

34. Tibiae brown; abdominal tergite 5 brown or dark brown; female with 1 pair of median discal setae only on abdominal tergite 3 .................................................................................................................................. D. subnuda (Malloch)

- Tibiae reddish yellow; female with 1 pair of median discal setae on abdominal tergites 3 and 4; tergite 5 broadly reddish yellow in male, darkened at most on basal 1/ 2 in female, with whitish pruinosity on anterior 1/3...................35

35. Abdominal tergite 3 with 1 pair of marginal and 1−2 lateral marginal setae in both sexes; an inner vitta of thoracic scutum about 1/2 as wide as pruinose portion between inner and outer vittae; tegula dark brown, sometimes reddish brown, broadly pale yellowish on basal 1/2 .................................................................................. D. divergens Walker

- Abdominal tergite 3 with a complete row of marginal setae in both sexes; an inner vitta of thoracic scutum 1/3−1/4 pruinose portion between inner and outer vittae; tegula wholly dark brown ............................... D. hainanensis Zhang