Description of Mitogoniella mucuri sp. nov. (Opiliones: Gonyleptidae) and considerations on polymorphic traits in the genus and Gonyleptidae.

Mitogoniella mucuri sp. nov. is described for some caves in Minas Gerais, Brazil. This species differs from other Mitogoniella species by large tubercles on the ocularium that have fused bases and free apices (or almost fully fused tubercles with bifurcated apices), and by a large dry-mark between tubercles on the longitudinal groove of area III. Mitogoniella species are hard to recognize: their males lack any armature on leg IV (normally an important diagnostic character among gonyleptid species), and they also present many polymorphisms in coloration (dry-mark), male secondary sex characters, the number of dorsal scutal granules, and the shapes of tubercles on the ocularium. The patterns of these polymorphisms are discussed for the genus and for the family. The present work also presents new occurrences for all the species of the genus, and their biogeography is discussed.