The troglomorphic scorpion genus Troglotayosicus Lourenço, 1981, occurs in hypogean and epigean habitats in the Andean and Amazonian rainforests of Colombia and Ecuador. The phylogenetic relationships among the species of Troglotayosicus are currently unknown. In the present contribution, a new species, Troglotayosicus akaido, sp. nov., is described from specimens collected in the leaf litter of a primary rainforest in the Colombian Amazon, near the border with Peru, raising the number of species in the genus to seven. The new species represents the easternmost record of the genus and further extends its distribution into the Amazon. Its phylogenetic position was tested in an analysis of all species of the genus and two outgroup taxa, scored for 131 morphological characters (16 new and 115 legacy; 104 binary and 27 multistate) analyzed with maximum likelihood under the MK model. Troglotayosicus was recovered as monophyletic and composed of two main clades. The morphological survey revealed that the ventral macrosetae of the leg telotarsi of the type species, Troglotayosicus vachoni Lourenço, 1981, are simple, subspiniform macrosetae, irregularly distributed, but not arranged into clusters nor forming elongated clusters of setae/spinules, as previously suggested. A distribution map and key to the identification of the species of Troglotayosicus are provided. Further research, incorporating molecular data, is needed to understand the evolution and biogeographical history of this enigmatic scorpion genus.