New morphological observations on Neolobocriconema serratum (Khan & Siddiqi, 1963) Mehta & Raski, 1971 (Rhabditida: Criconematidae)

Abstract

Summary A population of Neolobocriconema serratum was recovered from the rhizosphere of Hosta sp., northern Iran, for the first time. It was studied using morphological and molecular data and new morphological observations were made. The Iranian population is characterised by females having 37-43 body annuli, their outer margin ornamented with 12-14 small lobe-like outgrowths under light microscopy, anastomoses occur sparsely in some females and the succeeding annulus is usually anteriorly bent opposite to the vulva. The cephalic region has a single smooth wavy annulus with grooves and is separated from the first, wider body annulus by a very short neck. Four prominent discoid submedian lobes and two lateral pseudolips present, appearing two layered (i.e., one above the other) in scanning electron microscopy (SEM). Body 487-607 μm long, stylet 85-93 μm long with rounded to anchor-shaped knobs, ovary very long, vulva generally closed, but open in some specimens under SEM. Tail conoid with bluntly rounded end and males absent. The recovered population agreed well with the type population based upon the morphometric data and female morphology. In having an almost identical morphology and morphometrics, N. allantoideum is proposed as a junior synonym of N. serratum. The molecular phylogenetic analyses were done by using near-full-length sequences of the small subunit ribosomal DNA (SSU rDNA), the internal transcribed spacer 1 (ITS1 rDNA) and the mitochondrial cytochrome c oxidase subunit I (COI mtDNA). The Iranian population of this species formed a clade with three other populations of the species in the SSU rDNA, and with one population in both the ITS1 rDNA and the COI mtDNA trees using Bayesian inference.