Morphological and molecular characterisation of one new and several known species of the reniform nematode, Rotylenchulus Linford & Oliveira, 1940 (Hoplolaimidae: Rotylenchulinae), and a phylogeny of the genus

Abstract

The reniform nematodes of the genusRotylenchulusare semi-endoparasites of numerous herbaceous and woody plant roots and are mainly distributed in tropical and subtropical regions. In this study, we provide morphological and molecular characterisation of six out of ten presently known valid species ofRotylenchulus:R. clavicaudatus,R. leptus,R. macrodoratus,R. macrosoma,R. reniformisandR. saccharifrom South Africa, USA, Italy and Spain.Rotylenchulus parvuswas only studied morphologically. A new species,R. macrosomoidessp. n., isolated from soil and roots of sugarcane in South Africa, is described. The phylogeny ofRotylenchulus, as inferred from the analyses of D2-D3 of 28S rRNA, ITS rRNA,coxImtDNA andhsp90gene sequences, is presented. The study revealed thatR. reniformisandR. macrosomahave a sister relationship, but that relationships between otherRotylenchulusspecies remain unresolved. The phylogenetic analysis also confirmed the hypothesis that this genus originated from the Afrotropical zoogeographical region. Our study revealed thatR. reniformisandR. macrosomoidessp. n. have two distinct rRNA gene types andR. macrosomahave three rRNA gene types in their genomes. PCR with species-specific primers was developed for rapid diagnostics ofR. reniformis.