A revision of the taxonomy of Aphelenchoides stammeri Körner, 1954 (Rhabditida: Aphelenchoididae) and proposal for a new genus

Abstract

Summary During the present study, Aphelenchoides stammeri was recovered from pine packaging wood imported from Spain to China (isolate 3334), and was also later found in China (isolate CN24). The first population (3334) was characterised by 912-1075 μm long females and 803-983 μm long males, a rounded elevated and offset lip region separated from the rest of the body by a sharp constriction having fine annuli in scanning electron microscopic (SEM) images, 14.0-19.3 μm long well-sclerotised stylet with a wide lumen (especially in the shaft) and small basal swellings, its conus forming ca 40% of the total length, the metacorpus with well-sclerotised and large central or slightly postcentral valve plates, vulva with no flap, functional rectum and anus, dorsally convex, ventrally bent conical tail (c’ = 3.3-4.3), males common with aphelenchoidid-type spicules having an elongate condylus with wide bluntly rounded end, a blunt rostrum and simple end, and seven precloacal + cloacal + caudal papillae. The SEM data of the studied Spanish population, the detailed light microscopic (LM) observations on previously reported populations and detailed studies of a cultured population from Germany, yielded new observations, supporting the status of this species as an independent genus. The phylogeny of the new genus was investigated using four markers, viz., small and large (SSU, LSU D2-D3), internal transcribed spacer1 (ITS) rDNA, and mitochondrial cytochrome c oxidase 1 (COI mtDNA) genes. Potensaphelenchus n. gen. is proposed for the species and it is placed under the Parasitaphelenchinae based upon its morphological characters and phylogenetic affinities. The diagnostics of the new genus and its relationships with similar aphelenchoidid genera are discussed. Seinura lii is proposed as new junior synonym of Potensaphelenchus stammeri n. gen., n. comb.