Key to world species of Hylophasma

1. Occipital carina ventrally interrupted, its lower end projecting into a small but distinct tooth. Hind wing with posterior section of AA (brachiella) present. Head predominantly white with occiput, frons and vertex black. Mesoscutum with mark centrally and lateral margins posteriorly white.Antenna of both sexes with white ring occupying at least five flagellomeres. The cavigena species-group. Mexico ................................................................................. 2

- Occipital carina complete, joining to hypostomal carina ventrally. Hind wing with posterior section of AA (brachiella) usually absent. Head black, clypeus sometimes pale. Mesoscutum usually completely black, without white spot centrally, sometimes with reddish markings. Antenna of both sexes with white ring occupying at most five flagellomeres. The debilis species-group.............................................................................................. 3

2. Gena ventrally with a deep concavity just behind the lower corner of the mandible................................................................................................... 3. H. cavigena Kasparyan & Ruíz-Cancino

- Gena ventrally evenly rounded between lower corner of mandible and hypostomal carina, without concavity.............................................................................. 1. H. altacima Kasparyan & Ruíz-Cancino

3. Mesosoma predominantly black except for rufous collar, tegulae, small whitish marks in hind corner of pronotum and sometimes at apex of scutellum................................................................................... 4

- Mesosoma predominantly black with metapleuron and propodeum reddish; in H. nigriceps speculum and scutellum sometimes white.............................................................................................. 5

4. Hind wing with posterior section of AA (brachiella) distinct. Abdomen of female fulvoferruginous, tergites more or less in basal half brownish. In male tergites dark brown, first five tergites in their apical 0.5± brownish fulvous; tergites 6 and 7 entirely dark brown. USA ....................................................................... H. debils Townes, 1970

- Hind wing without posterior section of AA (brachiella). Abdomen of female blackish with hind margin of tergites 2–7 in apical 0.2–0.35 pale brownish (Fig. 12). In male tergites dark brown with rather narrow pale rufous apical band widened in middle part anteriorly; tergite 7 pale rufous with brownish its basal 0.4 (Fig. 16). Mexico ................ 2. H. aterrima sp. nov.

5. Pronotum entirely black. [Mesopleuron black except for reddish lower posterior corner of mesepimeron. Antenna black with flagellomeres 7–10 white ventrally and two basal ones reddish dorsally; scape reddish. Body black with metapleuron, propodeum completely and hind half metasomal tergites 1–3 reddish; legs reddish with fore and mid coxae and trochanters white, and hind tibia and all tarsus brownish. Brachiella absent.] China ..................... H. luica Sheng et al., 2019

- Pronotum partly or entirely white. Mexico ................................................................. 6

6. Pronotum completely white. Mesopleuron pale reddish with speculum white.... 4. H. nigriceps Kasparyan & Ruíz-Cancino

- Pronotum partly black, with front margin entirely white. Mesopleuron black except for pale subtegular ridge and mesepimeron....................................................... 5. H. pulchra Kasparyan & Ruíz-Cancino