Keys out to Chyliza in MND's psilid key (1) and to C. apicalis in Melander's key (2). I've been unable to find a newer key than Melander's.

Character states from the Melander key:
1) dorsum of thorax yellow (vs. mostly black)
2) pleurae more or less yellow (vs. black)
3) "Upper half of pleurae with black vitta; apex of wings clouded" (vs. entirely yellow and wings hyaline)
4) "Apical cloud of wings following the margin, not widened behind, veins two, three and four ending in the cloud; pleurae marked with only the vitta." (vs. a Mexican species with "Apical cloud widening behind, apex of veins two, three and four not clouded.")

MND says Chyliza should have 3 pairs of scutellar bristles with the basal pair possibly weak; Melander says there should be 2 pairs. This fly appears to have split the difference – I see 5 scutellar bristles although one may be hidden (see the last photo).