Leaf domatia in Korean plants: floristics, frequency, and biogeography

Abstract

Leaf domatia, specialized structures on the undersides of leaves, appear to promote mutualism between plants and those mites that protect leaves from pathogenic fungi and small herbivorous arthropods. Their occurrence was surveyed on 425 plant species (368 native species and 57 species introduced from other regions of northeastern Asia), comprising 177 genera and 59 families of woody Dicotyledonae in the Korean flora. Domatia, primarily of tuft or pocket forms (84% of species), were present in vein axils on leaves of 152 species (36%) within 66 genera (37%) and 39 families (66%). Overall, we report leaf domatia in nine new families and 25 additional genera. Mites, primarily from families or suborders (e.g., Acaridida, Phytoseiidae, Tydeidae) in which arboreal representatives are primarily fungivorous or predaceous, were found in domatia on leaves of 78% of all species sampled. Domatia frequency depended upon both growth form and habit of species. They were especially common among tree species (55%), but less so on shrubs (20%) and woody vines (22%). Domatia were much more frequent on species of deciduous plants (40% of those sampled) than on evergreen species, of which only 10% had leaf domatia. This difference was consistent across a number of local deciduous and broadleaf evergreen forests in South Korea. The high frequency of leaf domatia in this survey indicates that plant-mite mutualism may be widespread in Korean plant communities. The floristic affinities of plants with domatia in Korea to those in other regions of East Asia, eastern North America, and Europe suggest that these plant-mite associations characterize the temperate broadleaf deciduous forest biome in the Northern Hemisphere.