Morphological characterisation and molecular phylogeny of several species of Criconematina (Nematoda: Tylenchida) associated with turfgrass in Korea, as inferred from ribosomal and mitochondrial DNA

Six species belonging to the Criconematina, including a morphologically cryptic population within the Mesocriconema curvatum-group, are characterised based on integrative taxonomy based on morphological and molecular phylogenetic inferences from analyses of the 28S-rRNA, ITS-rRNA and COI gene sequences. Mesocriconema sp. 1 is morphologically similar to M. nebraskense and M. curvatum, differing from M. curvatum by the occasional presence of 1-2 anastomoses and a relatively higher R value, and from M. nebraskense by only a narrowed first lip annulus. However, based on COI gene sequence analysis, significant differences among the three species are evident. The sequence information in the COI gene among Mesocriconema spp. continues to reveal the existence of cryptic species within well-established species designations, and the concept of Molecular Operational Taxonomic Units might be helpful in grouping the different lineages according to sequence identities. Mesocriconema nebraskense is detailed herein for the first time outside the USA. DNA sequences of Hemicycliophora labiata were similar to those in GenBank while the existence in Korea of M. curvatum, Hemicriconemoides brachyurus and Paratylenchus nanus is molecularly confirmed.