Tylaphelenchus jiaae n. sp and Aphelenchoides varicaudatus (Nematoda: Aphelenchoidinae) from Simao pine in Yunnan Province, China

摘要

Two aphelenchoidid nematodes, Nxy17 and Nxy22, isolated from Simao pine in Yunnan Province, China, were cultured on Botrytis cinerea. Identification, based on morphology, showed that the parthenogenetic population Nxy17 was Aphelenchoides varicaudatus but that the amphimictic population Nxy22 was an undescribed species belonging to Tylaphelenchus, herein described as T jiaae n. sp. The new species is characterised by small female and male bodies (401-603 and 309-450 mu m, respectively), weakly offset cephalic region, slender stylet (10-12 mu m long) with small basal knobs or bipartite thickenings, well-developed post-uterine sac (ca 2/5-2/3 of vulva-anus distance), a narrow lateral field (1.4-1.9 mu m wide) set off by two prominent lines, sometimes with a crack-like line in the middle, conoid female tail tapering to a mucronate pointed end, three pairs of subventral papillae on the male tail region, thorn-like spicule strongly arcuate to a pointed end, and male tail blunt with smooth terminus. Males were less abundant, 1:4.7 to females in fungal culture. The ribosomal DNA genes of the near-full-length small subunit, internal transcribed spacer 1, 5.8S, partial ITS2 and large subunit expansion segments of D2/D3 were performed for these two species to examine the phylogenetic relationships with other aphelenchoidids. DNA sequence data revealed that T jiaae n. sp. had closest phylogenetic affinity with the recently described Pseudaphelenchus yukiae and P vindai. Unfortunately, no DNA sequences of other Tylaphelenchus species or A. varicaudatus population were available in GenBank to confirm the taxonomic status of either species.