Key to the species of Onchopelma Hesse
1. Males; eyes holoptic; mesonotum and scutellum almost entirely black to brown........ 2
Females; eyes dichoptic; mesonotum and scutellum with yellow; mesonotum with conspicuous patterning.................................................................................................. 3
2. Hind basitarsus with basal hook; abdominal tergites black with yellow fasciae posteriorly ........................................................................................................... pulchellum Hesse
Hind basitarsus without basal hook; abdominal tergites IVVII with black restricted to medial and lateral spots (Fig. 1)................................. brevifasciatum Evenhuis, sp. n.
3. Mesonotum without admedian pale vittae (Fig. 6); occiput with small white spot immediately posterior to ocellar tubercle (Fig. 6)................. nitidum Evenhuis, sp. n.
Mesonotum with admedian vittae ..................... .......................................................... 4
4. Coxae black; black color of occiput extending laterally only slightly beyond with of median mesonotal vitta (Fig. 8); first antennal flagellomere subequal in length to scape and pedicel........................................................................................ trilineatum Hesse
Coxae yellow; black color of occiput extending laterally well beyond width of mesonotalmedianvitta;firstantennalflagellomerelongerthanscapeandpedicelcombined ..................................................................................................................................... 5
5. Scutellum black on apical margin (Fig. 7) ...................................... pulchellum Hesse
Scutellum all yellow, without black apically (some black may be present ventrolaterally in irwini, sp.n.) ..................................................................................................... 6
6. Mesonotal pattern with teardrop shaped supra alar dark spot (Figs. 2, 3, 5)............... 7
Mesonotum without supra alar spot (Fig. 4) .................................... karooanum Hesse
7. Frons black on upper half or more ................................................................................ 8
Frons all yellow, black color extending from occiput ends at ocellar triangle (Fig. 5)... ................................................................................................... majus Evenhuis, sp.n.
8. Mesonotum with admedian dark vittae confluent with median vittae posteriorly (Fig. 3); abdominal terga with black transverse bands on segments 17, segment 8 yellow (Fig. 3); scutellum with small spot of black color ventrolaterally .................................. ................................................................................................... irwini Evenhuis, sp.n.
Mesonotum with admedian dark vittae separate from median vittae posteriorly (Fig. 2); abdominal terga with black transverse bands on segments 13, black on remaining segments as medial spots and lateral black spots (Fig. 2); scutellum completely yellow to white...................................................................... brevifasciatum Evenhuis, sp. n.