Unexpected rDNA divergence between two morphologically minimalistic nematodes with description of a new species (Tylenchomorpha: Tylenchidae)

Abstract

Summary Species of the family Tylenchidae are encountered in large numbers in soils. The genus Labrys was recently described characterised by a remarkable lip pattern that differs from all other known Tylenchidae genera. Here we describe a curious new species, Labrys fujianensis sp. n., that morphologically fits the genus Labrys but which is genetically divergent. The phylogeny was inferred based on 18S and 28S rDNA and light and scanning electron microscopy were used to extract detailed morphologies. The phylogenetic position of this species and its phenotypic convergence are discussed. The possibility of a long-branch attraction artefact was inspected both by removal of variable nucleotide sites and monophyletic testing of topologies. The results confirmed the divergent positioning of the presented species and it is demonstrated that the genetic diversity in Tylenchidae may be much higher than expected due to morphological homoplasy.