ABSTRACT Four new sympatric species of Cosmetus Perty, 1833 are described from "Reserva Natural Privada Burbayar, Provinciar Panamá, Panamá" (male holotypes deposited in MIUP). Cosmetus balboa sp. nov. can be distinguished by the combinations of following features: smooth ocularium, larger distal tubercle on pedipalpal femur, coxa I with large ventral tubercle directed upwards, coxa IV with one large dorsoproximal tubercle, two geminate (from base) dorsoapical tubercles with blunt apex. Cosmetus burbayar sp. nov., can be distinguished from other species of the genus by the irregular and discontinuous shape of its yellow spot, extending from lateral anterior to posterior margins and invading prosoma, areas I-III and free tergites. Cosmetus pollera sp. nov. can be distinguished from congeners by two small yellow and two large pairs of spots on prosoma and two other spots on posterior margin of dorsal scutum. Cosmetus tamboritos sp. nov. is distinguished from other species of the genus by the following combinations of characters: having two retrolateral apical tubercles on bulla, one being double size of other; coxa IV lacks patches of a cluster of four tubercles on dorsolateral proximal region and two pointed tubercles fused at their apices; and femur IV with bifid retrolateral apical tubercle. The penis of Cosmetus arietinus (Mello-Leitão, 1940) and C. variolosus Mello-Leitão, 1942 are described for the first time. A table with the main diagnostic features of Cosmetus species is given. We suggest that the spine of area III, sexually dimorphic chelicerae and posterior legs, and pigmentation of dorsal scutum are good diagnosti c features at species level.

A new species of Stygnidae Simon, 1879, Imeri ajuba sp. nov., is described based on males and females from Coari, Amazonas, Brazil. The new species, differs from the only other species of the genus, Imerilomanhungae Pinto-da-Rocha & Tourinho, 2012, in having the following characteristics: three white marks on posterior margin of dorsal scutum, one white mark on free tergite I, three pairs of tubercles on area I, one pair of tubercles on area II, femur IV with ventromesal row of five tubercles, truncus of penis with six pairs of setae on lateral and ventral sides and ventral plate with two pairs of distal setae on dorsal portion.