Integrated taxonomy of three new species of Glyphiulus from Laos

Three new species of the millipede genus Glyphiulus Gervais, 1847 are described and illustrated based on specimens collected from caves in Laos, namely G. pseudocostulifer, new species, from Oudomxay Province, G. steineri, new species, from Khammouan Province, and G. houaphanhensis, new species, from Houaphan Province. All of them belong to the javanicus-group, which share the unique structure of the first pair of legs in males and the carinotaxic formula of midbody rings. However, they differ from each other in the number of ommatidia, body colouration, the carinotaxic formula of the collum, as well as anterior and posterior gonopod structures. Mitochondrial COI sequences were used as DNA barcodes for species delineation, and were successfully obtained for two of the new species (G. pseudocostulifer, new species, and G. steineri, new species). Phylogenetic analyses revealed strong support for all examined Glyphiulus species, even for a pair of species which exhibited high morphological similarity, with mean uncorrected COI p-distances between Glyphiulus species ranging from 15–22%. Two additional Glyphiulus species are listed, but not described, as male material is lacking. One of them occurs in direct sympatry with G. houaphanhensis, new species. An identification key to the species of Glyphiulus so far recorded from Laos and a distribution map are also presented.