Morphological and molecular characterisation of Hoplolaimus smokyensis n. sp. (Nematoda: Hoplolaimidae), a lance nematode from Great Smoky Mountains National Park, USA

Abstract

Summary Hoplolaimus smokyensis n. sp. is a new species of lance nematode collected in Great Smoky Mountains National Park, USA. Females of H. smokyensis n. sp. have a labial region characterised by six, occasionally five, annules. The basal lip annule is subdivided by about 24 longitudinal striae. The stylet averages 47 μm long with robust, tulip-shaped stylet knobs bearing anterior projections. The hemizonid is ca 4 μm anterior to the excretory pore. The lateral field is incompletely areolated and has four continuous incisures from the metacorpus region to the tail region. There are three pharyngeal gland nuclei. Vulval epiptygma are absent. The scutellate phasmids are located one anterior and one posterior to the vulva. The male is shorter than the female and the head region is higher and more rounded than that of the female. The bursa extends to the tail tip and the gubernaculum is large and protrusible and has titillae and a capitulum. Morphologically, H. smokyensis n. sp. is most similar to H. galeatus and H. stephanus, but can be distinguished by differences such as the number of annules and longitudinal striae on the lip region and morphometric values. Hoplolaimus smokyensis n. sp. is also genetically distinct from other species according to comparisons of ribosomal and mitochondrial DNA sequences. Phylogenetic analyses based on ribosomal and mitochondrial gene sequences suggest that H. smokyensis n. sp. is a lineage distinct from related Hoplolaimus species.