Punctodera achalensis n. sp. (Nematoda: Punctoderidae), a new cyst nematode from Argentina

Abstract

A new cyst nematode, Punctodera achalensis n. sp., was collected from the rhizosphere soil and roots of an endemic grass, Poa stuckertii (Poaceae), in high-elevation grasslands in Pampa de Achala area (Córdoba province, Argentina). The new species is characterised by having brown spherical or subspherical cysts and subcuticular punctations over the entire body, circular vulval and anal fenestrae of similar size, and small and scattered bullae in the terminal area. Second-stage juvenile (J2) is filiform, with a well-developed stylet, anteriorly slightly concave basal knobs, pharynx occupying about 39% of total body length, tail tapering to a pointed terminus, and hyaline portion about 63% of the tail length. Morphology of P. achalensis n. sp. resembles the five known species of the genus. It differs from the other species by having a shorter J2 mean stylet length (22 μm vs. 24–28 μm) and tail length (57 μm vs. 62–88 μm). Phylogenetic relationships, inferred from ITS and 28S rDNA sequences using Bayesian Inference method, showed that P. achalensis n. sp. occupies a basal position within Punctodera species. An identification key to the six nominal species is included. This is the first record of the genus in South America, even in the Southern Hemisphere.