Cactodera guizhouensis n. sp. (Nematoda: Heteroderinae), a new species of cyst-forming nematode from roots and surrounding soil of potato in Guizhou, China

A new cyst-forming nematode, Cactodera guizhouensis n. sp., isolated from roots and surrounding soil of potato in Guizhou, China, was the first species of genus Cactodera found from the potato rhizosphere. The new species was characterized by its L/W ratio of cyst is 1.4±0.1 (1.3-1.8), while fenestral diam. is 17.7-28.7×12.3-23.4 μm and absent vulval denticlest; its stylet length of second stage juveniles is 26.5±1.2 (24.1-29.0) μm, while tail is 53.4±3.9 (45.0-61.9) μm and hyaline tail is 25.7±2.4 (21.6-29.8) μm, as well as lateral field with four incisures and areolation; its eggshell with punctations. The internal transcribed spacer sequences of ribosomal RNA (ITS-rRNA), the sequences of the D2-D3 region of 28S ribosomal RNA (28S-rRNA) from the new species were amplified and sequenced. The phylogenetic tree based on sequences of ITS-rRNA and 28S-rRNA D2-D3 region showed that the new species clustered into a separate clade and could be distinguished from other species in genus Cactodera. A key to the species of Cactodera is also provided in this study.