Morphological and molecular characterisation of some Hemicriconemoides species (Nematoda: Criconematidae) together with a phylogeny of the genus

Abstract

Sheathoid nematodes of the genus Hemicriconemoides are migratory root-ectoparasites of many plants including various agricultural crops and fruit trees. They are generally found inhabiting warm areas of the world and presently consist of 52 valid species. In this study we provide morphological and molecular characterisation of 12 species of this genus viz.: H. alexis, H. brachyurus, H. californianus, H. chitwoodi, H. macrodorus, H. minutus, H. ortonwilliamsi, H. promissus, H. silvaticus, H. strictathecatus, H. wessoni and Hemicriconemoides sp. originating from China, Greece, Japan, Myanmar, Spain, South Africa and the USA. Morphological descriptions, measurements, light and scanning electron microscopic observations and drawings are given for several species. Phylogenetic relationships within Hemicriconemoides, as inferred from the analyses of the D2-D3 of 28S rRNA and ITS-rRNA gene sequences, resulted in trees with three major clades that corresponded with species groupings based on morphology of the lip pattern and vulval flap. PCR with species-specific primers were developed for H. californianus, H. chitwoodi and H. strictathecatus.