The Cyphophthalmi genus Troglosiro (the only genus of the family Troglosironidae) is endemic to New Caledonia, representing one of the oldest lineages of this emerged part of Zealandia. Its species are short-range endemics, many known from single localities. Here we examined the phylogenetic relationships of Troglosironidae using standard Sanger-sequenced markers (nuclear 18S rRNA, 28S rRNA, and mitochondrial 16S rRNA and cytochrome c oxidase subunit I) and a combination of phylogenetic methods, including parsimony under Direct Optimization and maximum likelihood with static homology. We also applied a diversity of species delimitation methods, including distance-based, topology-based and unsupervised machine learning to evaluate previous species designations. Finally, we used a combination of genetic and morphological information to describe four new species – T. dogny sp. nov., T. pin sp. nov., T. pseudojuberthiei sp. nov. and T. sharmai sp. nov. – and discuss them in the broader context of the phylogeny and biogeographic history of the family. A key to the species of Troglosiro is also provided.