Description of Pauronemoides siddiqii n. gen., n. sp. (Tylenchomorpha, Paurodontidae), a morphological and molecular phylogenetic study

Summary Three populations of Pauronemoides siddiqii n. gen., n. sp. were recovered from three different locations in northwestern and northern Iran from bark and soil samples. The new genus was described and illustrated based upon morphological and molecular characteristics. Pauronemoides n. gen. belongs to the family Paurodontidae and is characterised by the medium-sized body, asymmetrical knobs in stylet base, stem-like extension into intestine, post-vulval uterine sac (PUS) absent or rudimentary, different tail tip shape between sexes, and bursa enveloping tail or reaching to the tail end. The type species, Pauronemoides siddiqii n. gen., n. sp., is mainly characterised by 752-1281 μm body length in females and 660-1085 μm in males, six equally-sized lips, stylet 9-11 μm long with asymmetrical knobs, six incisures in lateral fields forming five bands, three of which (two outers and one central) are wider, and variably lengthened stem-like extension projecting into the intestine. Vulva situated posteriorly (V = 87.7-91.7%), PUS absent. Conical tail with widely rounded end, having a small mucron at tip in females, males with conical tail ending to a narrower tip and bursa enveloping tail completely. The type species of the new genus was compared with all known species of the genera Prothallonema, Paurodontus, Paurodontoides and Paurodontella. Pauronemoides siddiqii n. gen., n. sp. resembles Prothallonema macrocellum and P. mucronatum by having the bulb extension penetrating into the intestine, dimorphism in tail shape of both sexes and bursa enveloping tail, and Paurodontella iranica by tail shape dimorphism between sexes and bursa ending near tail tip. Therefore, the above-mentioned species are transferred to the new genus as Pauronemoides macrocellus n. gen., n. comb. (= Prothallonema macrocellum), P. mucronatus n. gen., n. comb. (= Prothallonema mucronatum) and P. iranicus n. gen., n. comb. (= Paurodontella iranica). In addition to morphological comparisons, molecular phylogenetic analyses were performed using two sequences of small subunit (SSU), and three partial sequences of D2-D3 expansion segments of the large subunit (LSU) rDNA, and the resulting topologies were discussed.