Family Tylenchidae (Nematoda): an overview and perspectives

Nematodes in the Tylenchidae family are one of the most important soil-inhabiting species, yet little is known about this intriguing group. The present review examines newly collected samples of Tylenchidae from worldwide sources as well as slides from museum collections. Together with all available literature, detailed morphology among genera are summarized and compared, allowing us to explore the importance of each morphological character in a phylogenetic framework. An updated phylogeny inferred from concatenated 18S and 28S ribosomal RNA dataset is reconstructed; the results suggest that not all didelphic genera may be included in Tylenchidae. In fact, our analyses suggest Tylenchidae should be split into several families, although their phylogeny has not yet fully been resolved. Currently, the Tylenchidae family comprises 44 genera and 412 nominal species; however, diversity estimations for the group ranged from 2000 to 10,000 species, meaning that 75–95% of the species remains undiscovered. This is partially because the biased sampling in agro-ecosystems with most Tylenchidae may present in neglected habitats. Finally, we discussed current difficulties in morphology, taxonomy, and molecular phylogeny research of Tylenchidae and the need for multi-gene phylogeny or phylogenomic approaches to resolve the deep phylogeny in Tylenchidae.