Decrypting species in the Nacobbus aberrans (Nematoda: Pratylenchidae) complex using integrative taxonomy

The plant-parasitic nematode Nacobbus aberrans s.l. is a major agricultural pest of quarantine importance worldwide and is one of the top 10 nematodes in plant pathology because it causes significant losses in several crops. There are evidences of the existence of a species complex, with species being difficult to discriminate using only morphological characters. In this study, we aimed at resolving the taxonomic situation from a multi-disciplinary approach, based on morphometric data and molecular analyses. The results supported the identification of three nominal species in the complex: N. aberrans s.s., N. bolivianus and a new taxon, Nacobbus celatus sp. n. This new species, described based on the revision of published and new data, is widely distributed in the lowlands of Argentina. Our results also evidence the possible existence of a new taxon native to the Andean region of the same country. For the first time, the utility of cytochrome oxidase c subunit 1 barcoding for Nacobbus species identification is corroborated. This study also includes the estimation of divergence time among Nacobbus spp.; the possible geographical origin of the genus and colonization pattern are discussed. The present work shows the usefulness of an integrated approach to the resolution of systematic problems.