Mesembrinella aeneiventris (Wiedemann, 1830)

Whitworth, Terry L. & Yusseff-Vanegas, Sohath, 2019, A revision of the genera and species of the Neotropical family Mesembrinellidae (Diptera: Oestroidea), Zootaxa 4659 (1), pp. 1-146 : 68

Key to the species of the M. aeneiventris species-group

1 Postpronotal lobe with 3 setae........................................................................... 2

- Postpronotal lobe with 2 setae........................................................................... 7

2 Subcostal sclerite setose ( Fig. 490); body color orange to reddish-brown; kat 1:1; T1+2 yellowish..................... 3

- Subcostal sclerite bare or pubescent; body color blue-black; kat usually 2:1; T1+2 black to blue-black.................. 4

3 Apices of mid and hind femora orange; ac 1:1; male frons narrow, about 0.02 of head width at narrowest; epandrium, cerci and surstyli as in Figs 53–54; female terminalia as in Fig. 300, T 6 without median suture; [known only from Colombia and Venezuela]...................................................................................... M. vogelsangi

- Apices of mid and hind femora black; ac 2:1; male frons much broader, 0.09 of head width at narrowest; epandrium, cerci and surstyli as in Figs 55–56; female terminalia as in Fig. 301, T 6 with median suture; [known only from Costa Rica]........................................................................................... M. zurquiensis sp. nov.

4 Femora pale; male frons 0.07 of head width at narrowest; male surstylus long and slender, parallel-sided in lateral view ( Fig. 39); cerci in posterior view long with a broad base ( Fig. 40); female T6 broadly divided midway anteriorly ( Fig. 293); [known only from Colombia and Venezuela]............................................................. M. decrepita

- Femora dark; male frons width variable; male surstylus variable in lateral view; cerci in posterior view either broad at base and short, or narrow at base and longer; female T6 not divided midway.............................................. 5

5 Anterior and posterior thoracic spiracles pale yellow; male frons 0.14 of head width at narrowest; cercus exceptionally short and broad ( Fig. 50); female T6 of OU shape; T7 narrowed midway ( Fig. 298); [known only from Costa Rica and Mexico].............................................................................................. M. uniseta

- Anterior thoracic spiracle yellow-brown to black, posterior thoracic spiracle brown to black; other characters variable..... 6

6 Acrostichal setae 0:1, outer posthumeral seta present; anterior thoracic spiracle black; legs black; male frons 0.06 of head width at narrowest; cerci slender ( Wolff et al. 2017: figs 9–10); [known only from Colombia]...................... M. obscura

- Acrostichal setae 2:1, outer posthumeral seta absent; anterior thoracic spiracle yellow-brown; legs reddish-brown; [known only from Mexico; male unknown].............................................................. M. xanthorrhina

7 Subcostal sclerite setose (as in Fig. 490); thoracic chaetotaxy with ac 0:1 and dc 2:2; coxae, trochanters and femora orange with reddish-brown apices; male frons narrow, 0.015 of head width; [for epandrium, cerci and surstyli and other characters, see Wolff et al. (2017: figs 12–18); known only from Colombia]......................................... M. cordillera

- Subcostal sclerite bare; other characters variable............................................................. 8

8 Outer posthumeral seta present.......................................................................... 9

- Outer posthumeral seta absent.......................................................................... 11

9 Pleural area of thorax and legs blue-black; ac 0:0; male frons 0.07 of head width at narrowest; epandrium, cerci and surstyli as in Figs 41–42; female terminalia as in Fig. 294......................................................... M . lara

- Pleural area of thorax and femora yellow-orange, tibiae and tarsi brown; usually ac 1:1 or 1:2 (in M. aeneiventris sometimes missing on one or both sides)........................................................................... 10

10 Acrostichals 1:2 (but sometimes missing on one or both sides); male frons broad, 0.07–0.08 of head width at narrowest; male with ST5 very broad and wing-like ( Fig. 249); epandrium, cerci and surstyli as in Figs 35–36; female terminalia as in Fig. 292; [known from Brazil, Colombia, Costa Rica, Ecuador, Panama and Peru].............................. M. aeneiventris

- Acrostichals 1:1; male frons narrower, 0.03–0.05 of head width at narrowest; ST5 normal ( Fig. 252); epandrium, cerci and surstyli as in Figs 43–44; female terminalia as in Fig. 295; [known only from Costa Rica]........ M. nigrocoerulea sp. nov.

11 Wing with well-defined infuscation along costa; thorax reddish-brown to blackish; ac 0:1; male with surstylus long and slender in left lateral view, arching inward in posterior view ( Figs 45–46); female terminalia as in Fig. 296; [known from Peru, Ecuador and Brazil]................................................................................ M. purpurata

- Wing hyaline or only faintly infuscated; surstylus not as long and slender; other characters variable................... 12

12 T1+2 and anterior 1/3 or more of T3 yellow-orange, varying dorsally, always yellow laterally; ac 0:1; other characters variable............................................................................................... 13

- T1+2, T3 blue-black; ac 1:1; male frons 0.02 of head width at narrowest; epandrium, cerci and surstyli as in Figs 51–52; female terminalia as in Fig. 299; [known only from Costa Rica]....................................... M. violacea sp. nov.

13 Femora brown to black; scutellum lacking discal setae [NB: discal setae present on T5]; [known only from Peru; male unknown].................................................................................... M. bequaerti

- Femora orange; scutellum with discal setae; male frons 0.05 of head width at narrowest; T3 of abdomen with dark, inverted V shape mid-dorsally in male; epandrium, cerci and surstyli as in Figs 47–48; female terminalia as in Fig. 297; [known only from Costa Rica]................................................................................ M. semiflava