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

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.

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

“…sp., Cactodera sp. (GenBank) and C. tianzhuensis (Li et al, 2021a) were clustered a clade and revealed the new species might be sisters or same species of Cactodera sp.. However, this new species could be distinguished from C. tianzhuensis in morphological characteristic by vulval denticles absent, eggshell with punctations.…”

“…Subbotin et al (2010) provided the key to species of genus Catodera, with 13 species. Since then, four new species have been described (Cid Del Prado and Subbotin, 2014;Feng et al, 2018;Escobar-Avila et al, 2020;Li et al, 2021a). Morphological identification of Cactodera species was mainly based on its L/W ratio, fenestral diam., and vulval denticles present or absent in cyst; the length of stylet, tail, and hyaline region in second stage juveniles (J2); and eggshell surface smooth or punctate (Graney and Bird, 1990;Subbotin et al, 2010;Li et al, 2021a).…”

“…Morphological identification of Cactodera species was mainly based on its L/W ratio, fenestral diam., and vulval denticles present or absent in cyst; the length of stylet, tail, and hyaline region in second stage juveniles (J2); and eggshell surface smooth or punctate (Graney and Bird, 1990;Subbotin et al, 2010;Li et al, 2021a). In Heteroderinae, due to the overlap of morphological measurements between species makes, it is difficult to distinguish the approximate species (Cid Del Prado and Subbotin, 2014;Feng et al, 2018;Handoo et al, 2021;Li et al, 2021a). At present, the molecular characteristics such as sequences of ITS-rRNA gene, D2-D3 region of the 28S-rRNA gene provide a new reference for accurate identification of species in Heteroderinae.…”

“…Since then, four new species have been described (Cid Del Prado and Subbotin, 2014;Feng et al, 2018;Escobar-Avila et al, 2020;Li et al, 2021a). Morphological identification of Cactodera species was mainly based on its L/W ratio, fenestral diam., and vulval denticles present or absent in cyst; the length of stylet, tail, and hyaline region in second stage juveniles (J2); and eggshell surface smooth or punctate (Graney and Bird, 1990;Subbotin et al, 2010;Li et al, 2021a). In Heteroderinae, due to the overlap of morphological measurements between species makes, it is difficult to distinguish the approximate species (Cid Del Prado and Subbotin, 2014;Feng et al, 2018;Handoo et al, 2021;Li et al, 2021a).…”

Molecular and morphological characterization of a first report of Cactodera torreyanae Cid del Prado Vera & Subbotin, 2014 (Nematoda: Heteroderidae) from Minnesota, the United States of America

“…The newly obtained sequences of the D2-D3 of 28S rRNA, ITS rRNA, COI genes were aligned using ClustalX 1.83 with corresponding published gene sequences ( Cid del Prado Vera and Subbotin, 2014 ; Escobar-Avila et al, 2021 ; Li et al, 2021 ; Skantar et al, 2021 ). Sequence alignment was analyzed with Bayesian inference (BI) using MrBayes 3.1.2 ( Ronquist and Huelsenbeck, 2003 ) under the GTR + G + I model and with PAUP* 4b10 ( Swofford, 2002 ) as described by Subbotin (2021b) .…”