Pratylenchus speijeri n. sp (Nematoda: Pratylenchidae), a new root-lesion nematode pest of plantain in West Africa

摘要

A new root-lesion nematode, particularly pathogenic to Musa spp. and causing important plantain losses in Ghana, is described and named Pratylenchus speijeri n. sp. The cryptic status of this species within the P coffeae species complex has been assessed and confirmed in this study. An extensive comparison of the morphological and molecular characteristics of this new species with those of R coffeae and other related amphimictic species did not result in an unambiguous separation of this species from P coffeae because only a few morphological features of diagnostic value were found. Sequence and phylogenetic analyses of the D2-D3 expansion segments of the 28S rRNA gene, the ITS rRNA gene and a portion of the hsp90 gene of P speijeri n. sp. and P coffeae species complex populations from different sources generated majority consensus BI trees with three major clades: P. speijeri n. sp. from Musa spp. roots in Ghana; unidentified or putative new Pratylenchus sp. C 1 from Colocasia esculenta roots in Japan and R coffeae with non-homogeneous relationships from different hosts and distant geographical areas. These results confirmed the validity of P speijeri n. sp. as a new taxon and indicated that P coffeae populations from Colocasia in Japan also need to be considered as a new species. Sequence differences in the ITS were used to design group- and species-specific primers to detect P speijeri n. sp. and other species of coffeae species complex. The use of these species-specific primers for the separation of P speijeri n. sp., Pratylenchus sp. Cl and R coffeae has important practical application in breeding programmes for agriculture in West Africa.