Mesembrinella, Giglio-Tos, 1893

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 : 48

Key to species-groups of Mesembrinella

1 Anterior thoracic spiracle with a broad oval opening above ( Fig. 5); discal scutellar setae usually present (as in Fig. 194); disc of T5 with or without a row of discal setae ( Fig. 8 shows T5 with row of discal setae) (not to be confused with discal setae on the scutellum); most species with 3x 3 postpronotal setae...................................................... 2

- Anterior thoracic spiracle with a long, narrow opening gradually widening above ( Fig. 6); discal scutellar setae absent; disc of T5 without row of stout setae; with 2x 2 postpronotal setae........... M. bolivar group [four species; formerly Giovanella ]

2 Male with epandrium large and elongate, broadly divided dorsally over its full length (as in Figs 104, 491), with surstyli and cerci tiny and at posterior end ( Figs 27, 29); sternites much wider than long (ST4 about 4x wider than long), posterior edge of ST5 with pair of posteriorly-pointed projections midway [ Fig 12 (see arrow), Figs. 245–246]; sternites shorter and partially hidden in M. mexicana sp. nov. ( Fig. 245) [for lone females, terminalia should be dissected and examined; two species, M. mexicana sp. nov. and M. spicata , are similar ( Figs 289–290), the other, M. guaramacalensis sp. nov., is as in Fig. 288]............................................................. M. spicata group [three species; formerly Henriquella ]

- Male with epandrium smaller, surstyli and cerci more typical, as in Figs 35–98, except M. anomala ( Figs 99–100); sternites much narrower, often longer than wide, ST1–4 never more than 2x wider than long ( Figs 247–279); posterior edge of ST5 without projections.................................................................................... 3

3 Disc of T5 with horizontal row of stout setae ( Fig. 8), rest of T5 with fine setulae. Male: surstylus usually more or less straight, parallel-sided; cercus curved anteriorly (as in Fig. 39); phallus usually significantly narrowed just anterior to hypophallic lobe (as in Fig. 130)...................................... M. aeneiventris group [13 species; formerly Huascaromusca ]

- Disc of T5 without horizontal row of stout setae midway, with short- to medium-length fine setae and setulae over whole surface, dense in most species but sparser in a few species; surstylus and cercus usually curving toward each other in lateral view (as in Fig. 63); phallus usually not significantly narrowed anterior to hypophallic lobe ( Fig. 148)...................... 4

4 Stem vein setose ( Fig. 489); wing with dark infuscation along costa from subcosta-costa junction to R 2+3 -costa junction, including all of r 1 cell; section IV of wing 0.30 (0.27–0.33/5) of section III; male frons broad, 0.20 of head width at narrowest; cerci in posterior view right-angled midway ( Fig. 26); female terminalia as in Fig. 287; [known only from Brazil]..................................................................... M. latifrons group [1 species; formerly Albuquerquea ].

- Stem vein usually bare; if setose, then other combination of characters different.................................... 5

5 Male: T5 1.5– 2x as long as T4 (as in Fig. 496); terminalia very unusual, with surstylus short and broad and cercus small and slender ( Figs 99–100). Female T6 of FU shape with broad division midway ( M. anomala , Fig. 324; condition unknown in M. andina )................................................. M. anomala group [2 species; formerly Thompsoniella ]

- Male: T4 and T5 of equal length; terminalia unlike those in Figs 99–100. Female T6 without a broad division (except in M. decrepita )................................................................... M. bicolor group [22 species].