Integrative taxonomy unravels cryptic diversity in the Paratrichodorus hispanus-group complex to resolve two new species of the genus and the molecular phylogeny of the family (Nematoda: Trichodoridae)

Abstract

The genus Paratrichodorus currently comprises 26 species of polyphagous ectoparasitic plant nematodes that are distributed worldwide and include a few tobravirus vector species. Paratrichodorus is one of the most difficult genera for species identification because it is phenotypically conserved, with morphometric characters that often overlap between species. From 2003 to 2016, nematode surveys were conducted in southern Spain, and the present study addresses 22 nematode populations of the Paratrichodorus hispanus group. Among them, two new species, Paratrichodorus almadenensis sp. nov. and Paratrichodorus ramblensis sp. nov., are described here morphologically and molecularly and compared with topotype specimens of Paratrichodorus hispanus. Furthermore, this analysis was complemented with the first molecular data for this species complex and for the genus Monotrichodorus. The phylogeny of family Trichodoridae showed the relationship of Monotrichodorus with Trichodorus, both of which are phylogenetically associated with the P. hispanus species group, including the two newly described species. Several phylogenetic hypotheses about the monophyly of the genera with molecular data composing the family Trichodoridae were tested using ShimodairaHasegawa and approximately unbiased tests. This work also includes the first observations of copulatory plugs in Paratrichodorus, which clearly differ from the different types of mating plugs described in Trichodorus species.