Axonchoides smokyensis sp n. (Dorylaimida: Belondiridae) from the Great Smoky Mountains National Park: the second species of a very rare genus

Abstract

Axonchoides smokyensis sp. n., collected from a natural forest area in Tennessee, USA, is described and illustrated, including LM and SEM pictures as well as molecular (rRNA SSU-ITS1 and LSU D2/D3) sequences. The new species is characterised by its body length of 2.56-3.18 mm, lip region continuous and 10-12 mu m wide, odontostyle 10-13 mu m long, neck 662-789 mu m long, anterior portion of pharynx enlarging gradually, pharyngeal expansion 407-548 mu m long or 60-70% of the total neck length and surrounded by a strong muscular sheath with nearly longitudinal bands, female genital system pseudodidelphic-monodelphic with anterior branch lacking a functional ovary and posterior one bearing a long and tripartite uterus, V = 42-46, female tail slightly clavate (27-34 mu m, c = 84-105, c' = 0.8-1.0), male tail short and rounded (34-38 mu m, c = 87-113, c' = 0.7-0.9), spicules 49-53 mu m long, and five or six widely spaced ventromedian supplements outside the range of the spicules. The taxonomy of Axonchoides is discussed on the base of morphological and molecular evidence, and an emended diagnosis proposed. It was easily differentiated from other sequenced dorylaimid taxa, but phylogenetic analysis from SSU and LSU failed satisfactorily to resolve its placement in Dorylaimina.