Morphological and molecular characterisation of Chitwoodius coffeae sp. n. (Dorylaimida: Tylencholaimidae) from Vietnam, with a revised taxonomy of the genus

Abstract

SummaryChitwoodius coffeae sp. n. is described, including SEM observations and molecular (D2-D3 expansion segment of the rDNA 28S) analysis, from a coffee plantation in the Central Highlands of Vietnam. The new species is characterised by its 1.69-2.01 mm long body in females and 1.29-1.51 mm in males, lip region offset by deep constriction and 15-17 μm broad, odontostyle 27-30 μm long, neck 340-473 μm long, pharyngeal expansion occupying 52-54% of total neck length, uterus a simple tube-like structure 68-106 μm long, vulva longitudinal (V = 54-59), tail short and rounded conoid (20-28 μm, c = 54-88, c′ = 0.6-0.8) with a nearly terminal projection of inner cuticle layer, spicules 60-64 μm long, and 7-10 spaced ventromedian supplements without hiatus. SEM pictures, available for the first time for a representative of the genus, show a hexagonal (nearly hexastellate) oral field divided into six sectors by the existence of six deep incisures. Molecular analyses, also presented for the first time for a representative of the genus, results in a narrow evolutionary relationship among Chitwoodius and Tylencholaimus, and supports the monophyly of the Tylencholaimidae. This is the first record of Chitwoodius in Asian Far East territories. Chitwoodius ahmadi sp. n. is proposed for a misattributed population of C. seshadrii.