The root-knot nematode speciesMeloidogyne daklakensisn. sp. was discovered on the roots of Robusta coffee (Coffea canephoraPierre ex A. Froehner) in Dak Lak Province, Vietnam. This species is characterized by the females having rounded or oval perineal patterns, smooth, regular, continuous striae, and reduced lateral lines. The dorsal arch is low, rounded and encloses a quite distinct vulva and tail tip. The stylet is normally straight with well-developed and posteriorly sloped knobs. The males have a rounded cap that extends posteriorly into the lip region. The procorpus is outlined distinctly, and is three times longer than the metacorpus. The metacorpus is ovoid, with a strong valve apparatus. The species closely resemblesM. marylandi,M. naasi, M. ovalis, M. panyuensis, M. lopezi, M. maliandM. baeticain the perineal pattern of the females, and the morphology of the males and the second-stage juveniles. Nonetheless, it can be differentiated from other species by a combination of morphometric, morphological and molecular characteristics. Phylogenetic analysis was conducted based on the internal transcribed spacer (ITS) and 28S rDNA as well as the region between the cytochromecoxidase I (COI) and cytochromecoxidase II (COII) mitochondrial genes. Herein, this nematode is described, illustrated, and designated as a new species,Meloidogyne daklakensissp. n., based on morphometric, morphological and molecular analyses.

Bursaphelenchus chengi sp. n. is described and illustrated. Dauer juveniles were isolated from imported wood packaging materials from Taiwan to Nanjing Port, China. Bursaphelenchus chengi sp. n. was reared and maintained on Petri dish cultures of the fungus Botrytis cinerea. The new species is characterised by the medium body size in both sexes, the presence of only two incisures in the lateral field and the robust and strongly curved spicules. The spicule lamina is angular distally, the rostrum digitate and the condylus rounded. The tail is arcuate with a pointed terminus. The bursa is usually truncate with the posterior margin indented in some specimens or rounded with a fine axial point. Females have a small vulval flap formed by a short extension of the cuticle of the anterior lip, and a conical tail that gradually tapers to an almost straight or slightly recurved, pointed or rounded terminus. Because of the presence of two lateral lines, similar spicule shape, tapering female tail and the presence of a small vulval flap, B. chengi sp. n. should be grouped in the abietinus-group sensu Braasch. together with B. abietinus, B. antoniae, B. hellenicus, B. hylobianum and B. rainulfi. ITS-RFLP profiles support the proposal of the new species, and phylogenetic analysis of the 28S rDNA D2/D3 domain sequence places it close to B. antoniae and other species of the abietinus-group.

Summary: Root-lesion nematodes, Pratylenchus spp., are one of the most important nematode groups in economic terms. The combination of morphological analyses and molecular analyses based on D2-D3 of 28S rDNA, ITS rDNA, and COI mtDNA regions supported the establishment of a new Pratylenchus species, making a total of 103 valid Pratylenchus species. The females of P. horti n. sp. are characterised by the following traits: low labial region with two annuli continuous to the body, en face form belonging to group II sensu Corbett & Clark (1983) with submedian triangular-shaped segments fused with the oral disc and separated from the lateral segments, lateral field with four incisures at vulval level and lacking areolation, robust stylet 15-17 μm long with rounded knobs, and subcylindrical tail with smooth tail tip. The males are largely similar to the females but differ from the females by the partially areolated lateral field, slightly ventrally arcuate and weakly cephalated spicules (15-19 μm), and ventrally curved elongate conical tail with a poorly protruding, crenate bursa. The new species was recovered from soil and root samples from the rhizosphere of Hedychium greenii growing in the Botanical Garden, Ghent University, Belgium.

The family Criconematidae is a remarkable group of nematodes, containing roughly 600 nominal root-ectoparasitic species, of which many species are known to be significant agricultural pests. Strikingly, our phylogenetic analyses based on 18S, D2-D3 of 28S rRNA, and COI mtDNA sequences of criconematid species, supported by tree topology tests (SH and AU tests), revealed that almost all studied genera, including Criconema, Ogma, Crossonema, Discocriconema, Hemicriconemoides, Criconemoides, Mesocriconema, and Lobocriconema, are not monophyletic groups, a finding that is partly contrary to those of previous studies on these groups. Our results suggest that key morphological characters used in the classification of Criconematidae are the consequence of convergent evolution. It is clear from our studies that the species status of at least 40 sequences of criconematid species from GenBank must be either revised or reconsidered, with analyses based on a polyphasic approach that includes different tree- and distance-based molecular species-delimitation methods (bPTP, GMYC, ABGD1, and ABGD2). Our studies found the ABGD2 output of the automatic barcode method to agree remarkably well with established species delimitations, while in general, the four species-delimitation results corresponding to three barcode regions forwarded significantly more putative species compared to those originally considered. This study also characterised for the first time the populations of Criconemoides myungsugae and Discocriconemella hensungica associated with Vietnamese ginseng, one of the most precious and rare ginseng varieties in the world. Although these populations are morphologically in agreement with the original descriptions of C. myungsugae and D. hengsungica, their molecular data display notable variations compared to the sequences deposited in GenBank. These species demonstrate clearly the immense molecular variations that can be observed in several species of the family Criconematidae.