The tarantula genus Tmesiphantes Simon, 1892 includes 20 valid species
distributed in Argentina and Brazil. These spiders are distinguished from other
Theraphosinae genera by the presence of an incrassate femur III, more evident in
males, urticating hair types III and IV on the abdominal dorsum, few cuspules on the
labium (0 to 30), maxillae with a maximum of 200 cuspules and sternum rounded. From
recent examination of material from Peru, we discovered specimens that share all the
morphological characters of Tmesiphantes, but did not fi t with any known species. In
the present study T. intiyaykuy sp. nov. is diagnosed, described, and illustrated. This
new species resembles T. caymmii in the circular patch with stiff setae on midventral
abdomen but can be distinguished by the shape of the palpal bulb and spermathecae.
Also, we performed a phylogenetic analysis using morphological characters to infer the
taxonomic placement of the new species. The analysis included 26 terminal species and
36 characters. Representatives of Tmesiphantes formed a monophyletic group and T.
intiyaykuy sp. nov. is close related with T. caymmii. A dichotomous identifi cation key and
a geographic distribution map were constructed for recognized species of Tmesiphantes.
Anais da Academia Brasileira de Ciências 94(4, e20200702): 1-17