A new cyst-forming nematode, Cactodera tianzhuensis n. sp. (Nematoda:Heteroderinae) from Polygonum viviparum in China with a key to the Genus Cactodera.

Wenhao Li,Huixia Li,Chunhui Ni,Yiwen Zhang,Deliang Peng,Mingming Shi,Xuejuan Wei,Yonggang Liu

doi:10.21307/jofnem-2021-029

Abstract

A new cyst-forming nematode, Cactodera tianzhuensis n. sp. was isolated from the rhizosphere soil of Polygonum viviparum L. in Tianzhu county, China. Morphologically, the new species is characterized by lemon-shaped or rounded cysts that have protruding necks and vulval cones. The vulval cone of the new species appeared to be circumfenestrate without bullae and underbridge, vulval denticle present and anus distinct. Second-stage juveniles are vermiform, stylet well-developed with the rounded stylet knobs to slightly concave anteriorly. Lateral field with four incisures. Tail gradually tapering to a finely rounded terminus with a length of ca 54 (47–59) µm, outline of hyaline portion is V-shaped or U-shaped. Egg shells without visible markings or punctations. The phylogenetic analyses based on ITS-rDNA, D2-D3 of 28S-rDNA clearly revealed that the new species formed a separate clade from other Cactodera species, which further support the unique status of C. tianzhuensis n. sp. Therefore, it is described herein as a new species of the genus Cactodera.

Highlights

Cactodera is a cyst-forming nematode genus of the Heteroderidae erected by Krall and Krall (1978) and the type species is cactus cyst nematode, Cactodera cacti (Filipjev and Schuurmans Stekhoven, 1941) Krall and Krall, 1978, which is distributed worldwide and mainly damaged plants of the family Cactaceae grown in glasshouse as ornamental (Skantar et al, 2019)
Very little is known about the occurrence and distribution of Cactodera nematode and only three species of Cactodera have been reported in China: C. cacti (Filipjev and Schuurmans Stekhoven, 1941) Krall and Krall, 1978 parasitizing the roots of Opuntia dillenii (Pan et al, 1997) and Hylocereus undatu (Duan et al, 2012) in Fujian and Liaoning province, respectively; C. thornei (Golden and Raski, 1977) Mulvey and Golden, 1983 was found in cereal fields in Qinghai province (Peng and Vovlas, 1994); C. chenopodiae Feng et al, 2018 was described as a new cyst-forming nematode in the genus Cactodera parasitizing on Chenopodium album in Liaoning province (Feng et al, 2018)
Krall and Krall (1978) proposed the genus Cactodera from the type species name and several Heterodera species added in this genus

Summary

Introduction

Cactodera is a cyst-forming nematode genus of the Heteroderidae erected by Krall and Krall (1978) and the type species is cactus cyst nematode, Cactodera cacti (Filipjev and Schuurmans Stekhoven, 1941) Krall and Krall, 1978, which is distributed worldwide and mainly damaged plants of the family Cactaceae grown in glasshouse as ornamental (Skantar et al, 2019). Traditional identification of cyst forming nematode based on morphology is imprecise and time-consuming to separate the related species. Its characters were compared with all the related species of the genus Cactodera. This population is described as Cactodera tianzhuensis n. To help identify the species in the genus Cactodera, a key to Cactodera species is presented

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Conclusion