Two new species of Goniosomatinae (Opiliones: Gonyleptidae) narrowly endemic to the Atlantic Forest of Brazil.

In the present work, two new species are described for the subfamily Goniosomatinae. Goniosoma bragagnolo sp. nov. is described from the seasonal semideciduous forests of Minas Gerais state and is distinguished from other species in the genus by a unique combination of features: a pair of small tubercles on the ocularium and on area III of the dorsal scutum, a complex dry mark on the dorsal scutum and the presence of a ventral process with a flabellum on the penis. Serracutisoma hara sp. nov. inhabits a cave in dense ombrophilous forests in Santa Catarina state and is considered to be part of a group of species related to Serracutisoma inerme (i.e., the S. inerme group), set apart from other species by the armature of femur III with spines close to each other and the armature of row 2 of femur IV with spines only in the medial-apical portion. For the first time, terminology for the penis macrosetae is discussed for the subfamily. Additionally, the study discusses the phylogenetic implications and biogeographic aspects of the new species. Goniosomatinae species tend to be narrowly endemic in the Atlantic Forest, which is confirmed by these new species ranges, although S. hara is only known by one specimen.