Key to the Central American Mesoconius species.

1 Head with inner vertical, outer vertical and postocellar bristles. Katatergite slightly convex, not conspicuously prominent. Head and anterior thorax entirely black but posterior 3/4 of thorax and entire abdomen orange (Fig. 4)..................................................................................................... M. nigrihumeralis n. sp.

- Head with outer vertical and sometimes postocellar bristles absent. Katatergite conspicuously convex, sometimes with a pointed or nipple–like apex. Never with head and anterior thorax black and balance of thorax and abdomen orange........ 2

2 Postocellar and outer vertical bristles absent but inner vertical present (Fig 5G). Katatergite convex but rounded, without a point or nipple–like apex (Fig. 5F). Thoracic pleuron yellow with vertical black stripes (Fig. 5A). Distal distiphallus shorter than basal distiphallus (Fig. 5E). Paired spermathecal duct uniform in texture until point of separation into two ducts............................................................................................... M. tigrinus n. sp.

- Postocellar bristles present. Katatergite with a pointed or nipple-like apex (Fig. 3B). Thoracic pleuron various, but lacking vertical black stripes. Distal distiphallus of known males longer than basal distiphallus (Fig. 3C). Paired spermathecal duct with a basal striate section and a distal smooth section (Fig. 3D)...................................................... 3

3 Thorax entirely black or dark brown (Fig. 6B). Mid and hind femora black on basal 2/3, orange on distal third (Fig. 6B)............................................................................................. M. zadbi n. sp.

- Thorax with at least ventral part of thoracic pleuron yellow or orange (Figs 3A, 1C), sometimes entirely orange (Fig 2A). Mid and hind femora at least partly orange in basal 2/3............................................................ 4

4 Thorax and abdomen, including abdominal pleuron, orange or reddish orange (Fig. 2A); scutum uniformly microsetulose with uniform rows of dorsocentral setulae but without acrostichal setulae between dorsocentral rows. Top of head entirely smooth and shining, with no trace of striations....................................................... M. dianthus n. sp.

- Thorax mostly black or dark brown, all or part of pleuron paler. Abdominal pleuron at least partly white or black. Scutum irregularly microsetulose, with patches of dense, long microsetulae creating broad silvery patches or strips; acrostichal setulae present. Top of head with microscopic longitudinal striations.................................................. 5

5 Thorax dark dorsally, almost all yellow laterally. Postsutural silvery patch on scutum without a central dark gap. Abdomen of

female conspicuously marked with ventrally tapered black pleural bands (Fig. 3A); abdominal tergites of both sexes black. Mid and hind femora with mixed black and yellow pigmentation on basal 3/4, usually more yellow ventrally and more black dorsally (Figs. 3F,G)................................................................... M. hemithorax Frey - Thorax mostly dark dorsally and laterally, orange only on ventral third of pleuron (Fig. 1B, C). Postsutural silvery patch on scutum broken by a dark, oval central area (Fig. 1G). Abdomen with tergites mostly orange and sharply contrasting with darker thorax, apex of oviscape black (Fig. 1 H); pleuron not conspicuously marked. Mid and hind femora almost entirely yellow to orange, with only indistinct preapical and apical dark rings (Fig. 1G)................................ M. bicolor n. sp.