Review of the millipede genus Bollman, 1893 (Diplopoda, Polydesmida, Paradoxosomatidae) in Vietnam, with several new records and descriptions of two new species.

The genus is shown to currently be represented in Vietnam by ten species or varieties, including new records of (Attems, 1937), (de Saussure, 1860), (Attems, 1937) and Jeekel, 1964, and two new species, and A key to all eight species and two varieties known to occur in Vietnam is provided. Although the morphological characters that have been traditionally used for taxonomy are here considered superior to molecular ones, molecular-based phylogenetic relationships and taxon assignments within the tribe Orthomorphini are provisionally analyzed using fragments of the cytochrome c oxidase subunit I (COI) mitochondrial gene. The preferred phylograms, both rooted and unrooted, demonstrate the monophyly of the tribe Orthomorphini, but due to the special, uncertain or even controversial position of , which occurs closer to the genera and , the genus in current usage appears to be polyphyletic. However, if is to be treated within the monotypic genus , the monophyly of becomes manifest. On the other hand, a cautious approach is followed to avoid descriptions of suspicious new taxa/species. Thus, solely because the average genetic distance between and , as well as that between and , are both found to be negligibly small, the statuses of the sympatric and closest yet morphologically different varieties are treated only as such, i.e., infrasubspecific categories. The apparent discord observed between morphological and molecular data is obviously due to only partial and single-gene topologies used, possibly also to hybridization already known to occur in some closely related and sympatric paradoxosomatid species or even genera.