Characterization of Hoplolaimus seinhorsti and Hoplolaimus pararobustus (Tylenchina: Hoplolaimidae) from banana, with phylogeny and species delineation in the genus Hoplolaimus

The morphological and molecular characterisations of two lance nematode species isolated from the rhizosphere of banana, and , are provided based on an integrative study that includes light and scanning electron microscopy, phylogenetic analysis and two tree-based molecular species delimitation methods (GMYC and bPTP). Nineteen new sequences were obtained, including 5 partial 18S rRNA, 6 D2-D3 of 28S rRNA, 1 ITS rRNA and 7 mtDNA (the first sequences of and ), and an updated morphological character comparison of 37 species is presented. The tree-based molecular species-delimitation approaches employed gave markedly differing results, and also showed remarkable discrepancies among the investigated genes, although the bPTP output was found to agree well with established morphological species delimitations. Both species-delimitation approaches did, however, provide the same output for the mtDNA sequences, and the mtDNA gene sequence was also found to correspond better to established morphological species. It is therefore recommended by this paper as representing the most suitable barcode marker for species identification. This integrative study also resulted in the corrective reassignment of 17 gene sequences that were previously unidentified or incorrectly classified, as well as concluding that consists of two cryptic species.