Costatrichia Mosely, 1937 is a Neotropical genus included in the subfamily Leucotrichiinae. Previously, this genus included 14 described species, two from Brazil and eight from Costa Rica. Based on recent specimens collected with light traps in the Brazilian Amazon and Costa Rica, we describe two new species: Costatrichia ipixuna sp. nov. from the state of Amazonas, Brazil (C. lodora group) and C. falsa sp. nov. from Puntarenas, Costa Rica (C. simplex group). Costatrichia ipixuna sp. nov. is most similar to C. noite Angrisano, 1995, but can be distinguished by the shallower U-shaped incision on posterior margin of sternum VIII, by the absence of the lateral projection of the same segment bearing very long setae, and by the phallus with a pair of spine-like sclerotized processes apically. Costatrichia falsa sp. nov. is most similar to C. zopilote Harris & Holzenthal, 1999, but differs from it by the median pair of spines of segment VIII, directed mesad and curved posteriorly crossing over each other; by the irregular posterior margin of segment VIII, in ventral view; by the segment X without short lateral paired spines; and by the flange-like apical processes on phallus. In addition, we provide the first record of C. noite Angrisano, 1995 from Brazil (state of Amazonas).
Amazon Forest; Costa Rica; Costatrichia ipixuna sp. nov.; Costatrichia falsa sp. nov.; microcaddisflies
