Key to the adult species of Arthropeina

1. Body predominantly pale yellow to reddish yellow (e.g., Fig. 78); postpronotal lobes and notopleural strip slightly contrasting with scutum color (e.g., Fig. 60........................................................................... 2

-. Body predominantly black (Figs. 82, 88); postpronotal lobes and notopleural strip white, strongly contrasting with scutum color (Fig. 64) (Brazil, Ecuador and Peru)............................................. A. melanochroma, sp. nov.

2. Scutum and scutellum with no black markings or bands (e.g., Fig. 60)............................................ 3

-. Scutum and scutellum with black markings or bands (e.g., Fig. 62).............................................. 4

3. Hind coxa predominantly dark brown to black (Fig. 84); projection of posterior margin of genital fork short (e.g., Fig. 15); spermathecal capsule helicoid, with two coils (Fig. 18) (Brazil, States of Mato Grosso, Minas Gerais, Rio de Janeiro, Santa Catarina and São Paulo).................................................................... A. fulva Lindner

-. Hind coxa yellow (Fig. 89); projection of posterior margin of genital fork nearly indistinguishable (e.g., Fig. 52); spermatheca capsule helicoid with three coils (Fig. 53) (Brazil, State of Rondônia; Bolivia)................... A. pseudofulva, sp. nov.

4. Length of flagellomere 8 more than three times length of flagellomere 7 (e.g., Figs. 4); scutum with distinct black markings (e.g., Fig. 62); anepisternum anteriorly with black markings (e.g., Figs. 86)........................................ 5

-. Length of flagellomere 8 twice length of flagellomere 7 (Fig. 3); scutum with black markings only laterally (Fig. 61); anepisternum anteriorly without markings (Fig. 85) (Colombia).................................... A. colombiana, sp. nov.

5. Medial band of scutum wide, nearly parallel-sided anteriorly, extending from prescutum to scutellum (Fig. 62); laterotergite with or without black maculae; projection of posterior margin of genital fork very long and acuminate (e.g., Fig. 27) (Brazil)................................................................................. A. diadelothorax, sp. nov.

-. Medial band of scutum very slender anteriorly, nearly absent at anterior margin, widening abruptly in posterior half (Fig. 63); laterotergite without black maculae; projection of posterior margin of genital fork long, rounded (e.g., Fig. 34) (Brazil, Guyana)................................................................................ A. lindneri, sp. nov.