Description of a new species of seed-gall nematode, Anguina obesa n. sp. (Nematoda: Anguinidae) from northern Iran, and its phylogenetic relations with other species and genera

Abstract

Anguina obesa n. sp., a new species of the genus, causing small seed galls inside the ovaries of foxtail weed plants (Alopecurus mysuroides Huds.) is described and illustrated based on its morphological and molecular characters. The new species is characterized by its 1516–2564 μm long obese females irregularly ventrally curved after fixation, having six lines in lateral fields, 6–9 μm long stylet with well-developed rounded knobs, constriction at junction of isthmus with the pharyngeal bulb, monodelphic-prodelphic female reproductive system, and conical, 60–80 μm long tail. Males of the new species are characterized with their slender 936–1420 μm long body, 25–30 μm long tylenchoid spicules, and bursa not reaching tail tip. Second stage juveniles of the new species were also common inside the galls and also recovered from soil in type locality. The new species is morphologically close to Anguina agropyronifloris, A. amsinckiae, A. paludicola and A. tumefaciens, but is more closely related to A. paludicola, from which it can be separated based on differences in morphological characters and internal transcribed spacer sequence. In Bayesian inference using sequences of the aforementioned genomic fragment, the new species formed a clade with A. agrostis, A. funesta, A. graminis, A. phalaridis and some unidentified isolates, with robust Bayesian posterior probability (BPP). The morphologically closest species, A. paludicola, occupied a separate position, outside of the clade containing the new species. The sequences of two other genomic fragments, 18S and 28S rDNA (D2/D3 region) were also made available for the new species. Morphological comparisons of the new species with the related species are discussed.