Heterodera amaranthusiae n. sp. (Nematoda: Heteroderidae), a new cyst nematode parasitising Amaranthus retroflexus L. in China

Abstract

Summary A new species of cyst-forming nematode, Heterodera amaranthusiae n. sp., is described and illustrated from the weed, Amaranthus retroflexus, in a potato field in Yunnan Province, China. It is characterised by having canary to russet-brown and asymmetric lemon-shaped cyst, distinct neck, bifenestrate vulval cone, relatively short vulval slit of 29 (28-32) μm, bullae absent and underbridge absent or weak if present. Second-stage juveniles are characterised by a well-developed stylet of 23 (22-25) μm with robust shaft and basal knobs concave anteriorly, tail conoid, 51 (48-58) μm long and hyaline region comprising 48 (41-53)% of its length. Morphologically and morphometrically it most resembles H. vallicola in the Humuli group. The ITS, 28S and COI gene sequences of H. amaranthusiae n. sp. clearly differentiate it from other Heterodera species. For diagnostic purposes, restriction enzyme analysis of the ITS region and three restriction enzymes, AluI, BsuRI (HaeIII) and CfoI (HhaI), were selected, clearly distinguishing H. amaranthusiae n. sp. from representative species in the Humuli group. Phylogenetic relationships with other species of the genus, inferred from two ribosomal regions and the cytochrome oxidase c subunit 1 region, based on Bayesian analysis, consistently showed that H. amaranthusiae n. sp. clustered with high support with other Humuli group species but with separate species status.

Reliability and Utility of Standard Gene Sequence Barcodes for the Identification and Differentiation of Cyst Nematodes of the Genus Heterodera

“…Lastly, it is important to keep in mind that no one technique is likely to be a panacea for the identification of species of Heterodera. New species are being described at a fairly steady rate (e.g., Li et al, 2020;Phougeishangbam et al, 2020;Jiang et al, 2022), and sequence data continue to accumulate and provide further insight into the population Utility of Heterodera barcode data: Huston et al…”

Morphological and molecular characterization of Heterodera ripae, a new record cyst nematode in the rhizosphere soil of Fagopyrum esculentum

“…However, current taxonomic evaluations recognize 82 nominal species, clustered into nine distinct subgroups—Afenestrata, Avenae, Bifenestra, Cardiolata, Cyperi, Goettingiana, Humuli, Sacchari, and Schachtii—based on morphological traits 2 , 3 . Recent years have also seen the identification of new species such as H. dunensis , H. microulae and H. amaranthusiae 4 – 6 . Some Heterodera species rank among the world's most damaging plant pests, second only to root-knot nematodes 7 .…”