Four species of Procyrnea were collected in birds from the Area de Conservacion Guanacaste, Costa Rica. Procyrnea brevicaudata n. sp. in Crypturellus cinnamomeus resembles P. ficheuri, P. murrayi, P. ameerae, P. dollfusi, and P. aptera in lacking lateral alae but differs from all these species in having 2 longitudinal ridges on the left side of the body, in having a sinistral rather than ventral vulvar opening, and in having dorsally bent rather than straight female tails. Procyrnea mawsonae n. sp., in Buteo magnirostris, is similar to P. strialata in body size and in having 2 transverse striated lateral alae, but differs by having longer and differently shaped spicules, and by lacking a single preanal sessile papilla. Procyrnea mclennanae n. sp., in Heliomaster constantii, is similar to P. strialata (Zhang, 1991) and P. mawsonae n. sp. in having 2 transverse striated lateral alae, but it can be distinguished from P. strialata and P. mawsonae in having 4 rather than 3 small teeth on the interior border of the pseudolabia, in having unequal rather than equal lateral alae, and in having longer spicules. Procyrnea sp., on the basis of a single adult male in Campephilus guatemalensis, resembles P. suraiyae, P. tulostoma, and P. unilateralis in possessing a single and long lateral ala, but can be distinguished from P. suraiyae and P. tulostoma in the length of the left spicule, in the left spicule having a bifid distal end, the right spicule having a rounded distal end rather than both spicules having pointed distal ends, and in having the lateral ala beginning at the lip region instead of posterior to the cervical papillae. It differs from P. uncinipenis in having a spicule ratio of 1:3.5 rather than 1:2.5, in the left spicule having a bifid rather than alate distal end, and in the absence of a single preanal papilla.