Two new species of Parobisium (Pseudoscorpiones: Neobisiidae) Chamberlin, 1930 from South Korea, with a preliminary phylogeny of the genus

Poorly dispersing pseudoscorpions (Arachnida: Pseudoscorpiones) are often considered suitable models for biogeography studies. Several lineages show interesting distribution patterns, such as the genus Parobisium Chamberlin, 1930 that occurs in the western U.S.A. and eastern Asia but is absent in Europe and central Asia. Here we review the pseudoscorpion genus Parobisium using an integrative taxonomic approach and describe two new species from South Korea based on morphological and molecular data: Parobisium namkungi sp. nov. and P. troglophilum sp. nov. Phylogenetic analyses using three genetic markers, cytochrome c oxidase subunit I (COI), histone H3A, and 28S ribosomal DNA also reveal that two former subspecies, P. magnum ohuyeanum (Morikawa, 1952) and P. magnum chejuense (Morikawa, 1970), are genetically distinct enough to recognize them as separate species, P. ohuyeanum stat nov. and. P. chejuense stat. nov. The phylogenetic data show that there is an old split between the East Asian and North American lineages that is indicative of ancient vicariance rather than recent dispersal. Similar biogeographic patterns have been reported in other poorly dispersing invertebrate taxa, such as Grylloblattidae and flightless beetles, which also show deep genetic divergences across these landmasses. We hypothesize that Parobisium may once have been widespread in Holarctic but subsequently became restricted to isolated fragments in East Asia and North America.