Key to known males of Tabanus trivittatus species-group. Adapted from Fairchild (1976)

1 Ventral half (inflated portion) of subcallus wholly bare and shiny (Figs. 6C, 8C).................................... 2

- At least ventral half of subcallus pruinescent (Figs. 2C, 20C, 26C, 28C).......................................... 5

2 Middorsal abdominal stripe very broad (Fig. 6A). Dorsolateral barely visible......................... T. argentivittatus

- Middorsal abdominal stripe not so broad. Dorsolateral obviously evident.......................................... 3

3 All femora black, strongly contrasting with yellow tibiae (Fig. 8B)...................................... T. callosus

- At least mid and hind femora yellow, not contrasting with the yellow and yellow haired tibiae......................... 4

4 Dorsolateral abdominal stripes a series of oval patches................................................. T. schadei

- Dorsolateral abdominal stripes continuous...................................................... T. restrepoensis

5 Area of large facets of the eye distinctly pilose.............................................................. 6

- Area of large facets of the eye bare........................................................................ 7

6 Postpedicel long and slender (Fig. 26D). Abdomen banded ventrally.................................... T. trivittatus

- Postpedicel short and broad. Abdomen unbanded ventrally............................................. T. palpalis

7 Subcallus with a dorsal triangular shiny area (Fig. 2C)........................................ T. albocapillus sp.n.

- Subcallus entirely pruinescent, without shiny area (Figs. 20C, 28C).............................................. 8

8 Middorsal abdominal stripe broad and even, dorsolateral stripes faint or absent. Occipital band of small facets very narrow............................................................................................. T. unistriatus

- Middorsal abdominal stripe narrower than the well-marked dorsolateral stripes. Occipital band of small facets wide.................................................................................................. T. rhizonshine