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Caenorhabditis auriculariae, which was morphologically described in 1999, was re-isolated from a Platydema mushroom-associated beetle. Based on the re-isolated materials, some morphological characteristics were re-examined and ascribed to the species. In addition, to clarify phylogenetic relationships with other Caenorhabditis species and biological features of the nematode, the whole genome was sequenced and assembled into 109.5 Mb with 16,279 predicted protein-coding genes. Molecular phylogenetic analyses based on ribosomal RNA and 269 single-copy genes revealed the species is closely related to C. sonorae and C. monodelphis placing them at the most basal clade of the genus. C. auriculariae has morphological characteristics clearly differed from those two species and harbours a number of species-specific gene families, indicating its usefulness as a new outgroup species for Caenorhabditis evolutionary studies. A comparison of carbohydrate-active enzyme (CAZy) repertoires in genomes, which we found useful to speculate about the lifestyle of Caenorhabditis nematodes, suggested that C. auriculariae likely has a life-cycle with tight-association with insects. [ABSTRACT FROM AUTHOR]

Ribosomal RNA genes have long been a favoured locus in phylogenetic and metabarcoding studies. Within a genome, rRNA loci are organized as tandem repeated arrays and the copies are homogenized through the process of concerted evolution. However, some level of rRNA variation (intragenomic polymorphism) is known to persist and be maintained in the genomes of many species. In nematode worms, the extent of rRNA polymorphism (RP) across species and the evolutionary and life history factors that contribute to the maintenance of intragenomic RP is largely unknown. Here, we present an extensive analysis across 30 terrestrial nematode species representing a range of free‐living and parasitic taxa isolated worldwide. Our results indicate that RP is common and widespread, ribosome function appears to be maintained despite mutational changes, and intragenomic variants are stable in the genome and neutrally evolving. However, levels of variation were varied widely across rRNA locus and species, with some taxa observed to lack RP entirely. Higher levels of RP were significantly correlated with shorter generation time and high reproductive rates, and population‐level factors may play a role in the geographic and phylogenetic structuring of rRNA variants observed in genera such as Rotylenchulus and Pratylenchus. Although RP did not dramatically impact the clustering and recovery of taxa in mock metabarcoding analyses, the present study has significant implications for global biodiversity estimates of nematode species derived from environmental rRNA amplicon studies, as well as our understanding of the evolutionary and ecological factors shaping genetic diversity across the nematode Tree of Life. [ABSTRACT FROM AUTHOR]

This contribution provides new insights in the phylogeny and taxonomy of the nematode genus Sectonema with an integrative approach. A brief historical outline of the matter is presented. Then, the morphological pattern of the genus is revised and illustrated, the nature of its stomatal protruding structure, either a reduced odontostyle or a mural tooth, being its most relevant diagnostic feature. The existence of cilia‐ or seta‐like structures in the perioral area and/or at the anterior part of cheilostom of some species is evidenced by SEM observations for the first time. Available molecular data (D2–D3 LSU‐rRNA gene) are analysed, including two new sequences of S. septentrionale from Spain. The monophyly of the genus is confirmed, and two species groups with geographical projection are tentatively identified. A close relationship with Metaporcelaimus is also demonstrated as both taxa constitute a highly supported clade. A likely polyphyly of the family Aporcelaimidae is once more demonstrated. Finally, an updated taxonomy of the genus is proposed, including revised diagnosis, list of species, identification key and a compendium of their main morphometrics. [ABSTRACT FROM AUTHOR]

Abstract Intermediate filaments (IF) belong to major cytoskeletal components of metazoan cells. We have previously determined a tissue specific expression and assembly properties of all eleven cytoplasmic IFs (IFA-1 - IFA-4, IFB-1, IFB-2, IFC-1, IFC-2, IFD-1, IFD-2, IFP-1) in C. elegans and reported an essential function for four (IFA-1, IFA-2, IFA-3 and IFB-1) of them. In this study we continued the characterisation of the IF proteins in C. elegans by searching for in vivo polymerisation partners of the IFA proteins. Using the murine IFA-1 to IFA-3-specific monoclonal Ab MH4 and the immunoprecipitation assay as a tool, we identified the heteropolymeric IFA-1/IFB-1 complexes in the whole nematode protein extract, confirming their existence also in vivo. Moreover, in the present study we also analysed evolutionary aspects of the IF proteins in C. elegans and in nematodes. We found 106 C. elegans IF homologs in different nematode clades. Phylogenetic analyses suggest that all nematode IFs (including the three newly identified IF sequences IFA-5, IFCDP-1 and IFCDP-2) might arose from a AB-type IF ancestor through repeated gene duplications and sequence divergence. Interestingly, the C. elegans IF proteins IFA-1 and IFB-1 represent a heteropolymeric IF cytoskeleton in all investigated nematode clades, in contrast to other sequences restricted to the clade III-V (IFA-2, IFA-4), III (IFA-5) and V (IFB-2, IFCDP) taxa, or even to the Caenorhabditis genus (IFA-3, IFC-1 to IFP-1). These analyses provide an insight into the origin of the multiple IFs in nematodes and also represent a basis for further studies of these sequences in nematodes. Highlights • Two essential proteins IFA-1/IFB-1 form a heteropolymeric IF system in the C. elegans tissue. • All nematode IFs might arose from a AB-type IF ancestor. • IF complexity differs significantly between the Caenorhabditis genus and the other here investigated nematodes. [ABSTRACT FROM AUTHOR]

The authors describe five new species of Pristionchus from Japan and Hongkong. Scarab beetle samplings in Hongkong identified P. hongkongensis sp. n. and P. neolucani sp. n., representing the first beetle-associated Pristionchus species from China. Surprisingly, samplings of millipedes in Japan revealed a previously unknown association of Pristionchus nematodes with these arthropods. Specifically, the authors found three previously known Pristionchus species, P. arcanus, P. entomophagus, and P. fukushimae on Japanese millipedes. In addition, the authors found three new Pristionchus species on millipedes, which are described as P. riukiariae sp. n., P. degawai sp. n., and P. laevicollis, sp. n., the latter of which was also found on stag beetles. These species are most closely related to P. maxplancki, P. japonicus, and P. quartusdecimus and belong to the pacificus species-complex. The authors describe all species based on morphology, morphometrics, and genome-wide sequence analysis. Mating experiments indicated that all species are reproductively isolated from each other and in contrast to the species of the “pacificus species-complex sensu stricto" they do not form F1 hybrids. [ABSTRACT FROM AUTHOR]

The 18S small subunit (SSU) ribosomal DNA sequence is one of the most useful molecular loci for identification and phylogeny reconstruction of agriculturally important nematodes. Various pairs of universal primers have been developed in the past to amplify short and long nematode sequences. However, certain nematode taxa were not readily amplified and/or sequenced with the existing primer tools. Frequently, the center region of a roughly 1,000 nucleotide segment would be lost. Therefore new primers were developed based on a very large 276 taxon alignment of 124 agriculturally important nematode species, and tested on problematic nematode taxa such as Aphelenchoides, Bursaphelenchus, Ditylenchus, and Panagrolaimus. New primers and protocols are provided for successful generation of sequences useful in future investigations of nematode systematics. [ABSTRACT FROM AUTHOR]

Gracilacus paralatescens n. sp., isolated in Anji County, Zhejiang Province, China from the rhizospheric soil of bamboo. The new species can be characterized by the female lateral field with three incisures, stylet 71.5 to 78.8 μm long, lip region truncated, excretory pore located anterior to basal knobs. Vulval lips non-protruding and without vulval flap, spermatheca large, elongated squarish shaped filled with sperms. Tail slender, relatively straight having wedge shape terminus. The spicule slender, slightly curved and 17.5 to 18.9 μm long. In the phylogenetic analysis based on 18S, D2-D3 of 28S and ITS regions of rDNA, the new species is clustered with Paratylenchid species having longer stylet length. Morphologically, the new species belongs to Group 9 of Paratylenchus sensu lato and is most similar to G. latescens. [ABSTRACT FROM AUTHOR]

Millipedes may cause unexpected damage when they are introduced to new locations, becoming invaders that leave behind their old parasites and predators. Therefore, it was interesting to find numerous rhabditid nematodes within the gut of the invasive phytophagous millipede Chamberlinius hualienensis Wang, 1956 (Diplopoda, Paradoxosomatidae) from Hachijojima (Japan) in November, 2014. This millipede originated in Taiwan but was discovered in Japan in 1986. The nematodes were identified as juvenile Oscheius rugaoensis (Zhang et al., 2012) Darsouei et al., 2014 (Rhabditidae), and juvenile and adult Mononchoides sp. (Diplogastridae) based on images, morphometrics, and sequences of 18S and 28S rDNA. A novel short 28S sequence of a separate population of Oscheius necromenus SB218 from Australian millipedes was also included in a phylogenetic comparison of what can now be characterized as a species complex of millipede-associated Oscheius. The only other nematode associates of millipedes belong to Rhigonematomorpha and Oxyuridomorpha, two strictly parasitic superorders of nematodes. These nematode identifications represent new geographic and host associations. [ABSTRACT FROM AUTHOR]

Tripylella jianjuni sp. n. (Tripylidae) is described from New Zealand. Females are characterised by a relatively long body (1743 (1675-1860) μm in the female and 1747 (1576-1979) μm in the male), outer labial setae (8-9 μm long) and cephalic setae (4-5 μm long) in a single circle, two large subventral teeth in two adjacent stomatal chambers, relatively short pharynx (b = 5.5 (5.4-5.6) in the female and 5.7 (5.3-6.1) in the male), vulva located slightly anterior to mid-body (V = 44 (43-46)), protuberant lips, and long filiform tail (461 (398-531) μm, c = 3.8 (3.3-4.2) and c' = 23.2 (18-29) in the female, and 450 (362-511) μm, c = 3.9 (3.6-4.4) and c' = 19.0 (16.0-20.8) in the male), tail with three ventromedian caudal setae. Males have arcuate spicules 37 (35-41) μm long, gubernaculum straight, 14 (12-16) μm long, three ventromedian supplementary papillae located anterior to the cloacal aperture, and a single plus four pairs of subventral caudal setae located posterior to the cloacal aperture on the tail. Preliminary analyses of phylogenetic relationships within the Triplonchida were done using the SSU and D2-D3 region of LSU DNA sequences. [ABSTRACT FROM AUTHOR]

As a result of the scarcity of informative morphological and anatomical characters, nematode systematics have always been volatile. Differences in the appreciation of these characters have resulted in numerous classifications and this greatly confuses scientific communication. An advantage of the use of molecular data is that it allows for an enormous expansion of the number of characters. Here we present a phylogenetic tree based on 1215 small subunit ribosomal DNA sequences (ca 1700 bp each) covering a wide range of nematode taxa. Of the 19 nematode orders mentioned by De Ley et al. (2006) 15 are represented here. Compared with Holterman et al. (2006) the number of taxa analysed has been tripled. This did not result in major changes in the clade subdivision of the phylum, although a decrease in the number of well supported nodes was observed. Especially at the family level and below we observed a considerable congruence between morphology and ribosomal DNA-based nematode systematics and, in case of discrepancies, morphological or anatomical support could be found for the alternative grouping in most instances. The extensiveness of convergent evolution is one of the most striking phenomena observed in the phylogenetic tree presented here - it is hard to find a morphological, ecological or biological characteristic that has not arisen at least twice during nematode evolution. Convergent evolution appears to be an important additional explanation for the seemingly persistent volatility of nematode systematics. [ABSTRACT FROM AUTHOR]

The first integrative approach using sequences of two genes (18S and 28S rRNA) plus morphological and life history traits, was explored in Pharyngodonidae nematodes parasitic in reptiles. Additionally, first genetic characterization of Parapharyngodon bainae and new data on its morphology are given. This approach evaluated the phylogenetic relationships among genera within Pharyngodonidae, as well as the importance of their diagnostic morphological features. Specimens of P. bainae were collected from faecal pellets of the lizard Tropidurus torquatus in the State of Minas Gerais, Brazil. Nematodes were fixed for scanning electron microscopy and molecular procedures. Morphological observations revealed the accurate structures of cephalic end, of cloacal region in males, of vulva and eggs. Phylogenetic reconstructions were based upon four datasets: aligned sequences of the 18S, of the 28S, of both concatenated genes and of combined morphological and molecular datasets. Bayesian inference and maximum likelihood were performed to infer the phylogenies of molecular datasets and maximum parsimony to infer that of all-combined data. Pharyngodonid parasites of reptiles seem to configure two general monophyletic lineages, as previously assertions. Results also showed the monophyly of Spauligodon, Skrjabinodon and Parapharyngodon, as well as the clear separation between the latter and Thelandros. Combination of datasets improved nodal supports. Analysis of the all-combined datasets revealed the importance of vulval position and egg morphology as phylogenetic informative traits. However, characters of male caudal morphology appear as are highly homoplastic, and seem to be product of convergent evolution or multiple losses of ancestral traits. The closely-related Thelandros and Parapharyngodon are kept valid and their diagnosis should be based upon the position of the operculum in eggs (terminal or subterminal, respectively). Some inconsistencies in the scarce molecular and morphological databases were noted. Thus, new genetic data is required for further conclusions and current database must be evaluated with attention. [ABSTRACT FROM AUTHOR]

Labrys filiformis n. sp., the second species of the rare genus Labrys, was recovered from natural forests of Gilan province and is described based upon morphological and molecular characters. The new species is characterized by its smooth cuticle under light microscopy, lateral field with two incisures forming a single plain band, lip region continuous with body contour, dorso-ventrally flattened and forming four poorly prominent lobes, having a dorso-ventrally narrower protuberant labial plate laterally extended to the amphidial margins, oral area (oral plate) dorso-ventrally elongated and embedded in the labial plate with six small labial sensilla surrounding the slightly prominent oral aperture, amphidial apertures as longitudinally lemniscatic slits bordered by the labial plate extensions which are overlapped at the middle length of amphids, stylet delicate, 6 to 7 μm long, elongate weakly developed fusiform median bulb with weak valve, wide excretory pore with long and heavily sclerotized duct, offset spermatheca filled with small spheroid sperm cells, 106 to 127 μm long elongate-conoid tail with filiform distal region and finely rounded tip. Molecular phylogenetic analyses were performed using a near-full length fragment of the 18S rDNA and the D2-D3 expansion segments of the 28S rDNA using Bayesian inference and maximum likelihood methods. In the inferred phylogenetic tree with 18S rDNA, the new species has a close affinity with several isolates of the type species, Labrys chinensis. The reconstructed phylogenetic tree using partial 28S rDNA, revealed the new species is nested inside the putative monophyletic group of several populations of L. chinensis. [ABSTRACT FROM AUTHOR]

Xiphinema parachambersi n. sp. recovered in Ningbo, China, from the rhizosphere of ornamental plants (Gardenia jasminoides and Euonymus hamiltonianus) imported from Japan is described. The new species is characterized by a long female body 1,830 to 2,109 μm long, odontostyle 105 to 116 μm long, reproductive system monoopisthodelphic, vulva located anteriorly at 25.2 to 27.7% of total body, long ovary 119 to 292 μm with simple uterus and Z-organ absent, female tail elongated conoid with a rounded terminus. Only two juvenile stages were available to study and no male was found. The polytomous identification codes for this new species are A1, B4, C2, D23, E1, F2, G2, H2, I2, J2, K?, L1 and it belongs to the morphospecies group 1. Phylogenetic analysis based on the 18S, ITS1 and 28S D2/D3 sequences of the new species showed close relationships with X. chambersi. Morphologically, the new species is similar to X. chambersi, X. hangzhouense, and X. winotoi but can be differentiated by morphological characters and DNA sequences. To help identify the species, a diagnostic key to the group 1 species is presented. [ABSTRACT FROM AUTHOR]

Pristionchus pacificus Sommer, Carta, Kim, and Sternberg, 1996 is an important model organism in evolutionary biology that aims to integrate developmental biology and evo-devo with population genetics and ecology. Functional studies in P. pacificus are supported by a well-established phylogenetic framework of around 30 species of the genus Pristionchus that have been described in the last decade based on their entomophilic and necromenic association with scarab beetles. Biogeographically, East Asia has emerged as a hotspot of Pristionchus speciation and recent samplings have therefore focused on Islands and mainland settings in East Asia. Here, we describe in a series of three publications the results of our sampling efforts in Taiwan, Japan, and Hongkong in 2016 and 2017. We describe a total of nine new species that cover different phylogenetic speciescomplexes of the Pristionchus genus. In this first publication, we describe two new species, Pristionchus sikae sp. n. and Pristionchus kurosawai sp. n. that are closely related to P. pacificus. Together with five previously described species they form the "pacificus speciescomplex sensu stricto" that is characterized by all species forming viable, but sterile F1 hybrids indicating reproductive isolation. P. sikae sp. n. and P. kurosawai sp. n. have a gonochorist mode of reproduction and they are described using morphology, morphometrics, mating experiments, and genome-wide sequence analysis. We discuss the extreme diversification in the pacificus species-complex sensu stricto in East Asia and its potential power to study speciation processes. [ABSTRACT FROM AUTHOR]

Longidorids are economically important plant-parasitic nematodes because several species are virus vectors. Populations of Paralongidorus sali and Longidorus jonesi, isolated from woody perennials of Hangzhou, Zhejiang, China, were characterized molecularly and morphologically. The morphometric data of the Chinese populations of both species were compared with other populations. The present study provided a first record of the occurrence of Paralongidorus in China coupled with description of the first-stage juvenile and male of L. jonesi. Phylogenetic analysis based on 18S and D2-D3 expansion segments of 28S gene indicated that L. jonesi clustered with L. jonesi reported from Japan and P. sali grouped with P. bikanerensis from Iran. Considering the pathological and economic importance of this group of nematodes, the study emphasized the need of updated descriptions from accurately identified specimens, isolation of sufficient material for examination, and molecular and phylogenetic analysis for a better understanding and diagnostics of Longidorid nematodes. [ABSTRACT FROM AUTHOR]

The placement of the rare deep-sea nematode order Rhaptothyreida remains unclear due to the unique morphology of this group, an unknown life cycle with morphologically distinct juvenile stages which may or may not be parasitic, and lack of molecular sequences. Here, we investigate the phylogenetic placement and status of the Rhaptothyreida based on SSU and D2-D3 of LSU rDNA sequences of Rhaptothyerus typicus specimens obtained from the continental slope of New Zealand. Molecular sequences of three adults and a late stage juvenile were identical, confirming that they belong to the same species despite pronounced morphological differences. We observed the presence of the rare nucleotide transition A → G and transversion G → Y in the loops of Hairpin 35 and 48 regions, which is consistent with the placement of R. typicus within the order Enoplida. Rhaptothyreus typicus was consistently recovered as a long branch clade in SSU and D2-D3 of LSU analyses, which can have a destabilising effect on tree topology. After Gblocks were used to remove sites of questionable alignment, R. typicus was placed in a clade comprising Trissonchulus , Dolicholaimus and Ironus sequences (family Ironidae, order Enoplida) in both Bayesian and Maximum Likelihood SSU topologies. Depending on which alignment algorithm was used, analyses of LSU sequences focusing on enoplid taxa either suggested a relationship between R. typicus and Halalaimus (family Oxystominidae) or did not identify any clear relationships. Overall, our results provide strong evidence for placing R. typicus and the family Rhaptothyreidae within the order Enoplida, although further work is required to clarify relationships between rhaptothyreids and other enoplid taxa. A parasitic lifestyle could explain the unique morphology of this group, their highly divergent SSU and LSU rDNA molecular sequences, and the marked morphological differences between late juveniles and adults. Further molecular investigations targeting both free-living and parasitic early juvenile life stages in potential deep-sea hosts are needed to better understand the evolution of this unusual nematode taxon. [ABSTRACT FROM AUTHOR]

The phylogenetic position of Paramicrolaimidae Lorenzen, 1981, a rare group of marine free-living nematodes, has been the subject of debate due to the unique morphology of the buccal cavity, an unusual combination of other morphological traits, and lack of molecular sequences. Here, Paramicrolaimus hohonucola sp. nov. is described from the continental slope of New Zealand, and the position of the family Paramicrolaimidae is investigated based on analyses of the small subunit (SSU) and D2–D3 region of large subunit (LSU) rDNA genes. This is the first record of Paramicrolaimidae from the Southwest Pacific, and the deepest record of the family to date (347–1514 m depth). Observations using scanning electron microscopy revealed the presence of a transverse mouth opening formed by the fusion of the two ventrosublateral lip lobes and enlarged dorsal lip lobe, resulting in partial dorsoventral symmetry, which is an unusual feature within the phylum. Phylogenetic analyses suggest a close relationship between the Paramicrolaimidae and the family Selachinematidae Cobb, 1915 (order Chromadorida Chitwood, 1933). The Paramicrolaimidae lack cuticle punctations, a key morphological trait of all families currently classified within the Chromadorida; however, in the absence of any clear morphological affinities with other chromadorean orders, we propose that Paramicrolaimidae be placed within Chromadorida based on evidence for a close relationship with Selachinematidae as shown by SSU and LSU phylogenies. Our SSU phylogeny supports the results of previously published analyses showing a close relationship between Molgolaimus Ditlevsen, 1921 and the Microlaimidae Micoletzky, 1922. We therefore propose that Molgolaimus be removed from Desmodoroidea where it is currently classified and instead placed within Microlaimoidea. We also propose that the family Molgolaimidae Jensen, 1978 be reinstated and moved to accommodate Molgolaimus within Microlaimoidea. As in previous SSU phylogenies, our analyses provide no evidence for a close relationship between Desmodoroidea and Microlaimoidea, which currently comprise Desmodorida. Based on this molecular evidence, the clear morphological differences between Microlaimoidea and the closely related Chromadorida, and the lack of a synapomorphy linking Desmodoroidea and Microlaimoidea, we propose the order Microlaimida ord. nov. to accommodate the superfamily Microlaimoidea. [ABSTRACT FROM AUTHOR]

The northern root-knot nematode, Meloidogyne hapla, is one of the most important nematode pathogens occurring in cold regions. It is a sedentary, biotrophic parasites of plants and overwinter in the soil or in diseased roots. This study showed that the cold tolerance for the second-stage juveniles (J2) of M. hapla was moderate with the 50% survival temperature (S50) of -2.22°C and the fatal temperature was -6°C when cooling at 0.5°C min-1. Cryoprotective dehydration significantly enhance cold tolerance of M. hapla J2 with the lowest S50 of -3.28°C after held being at -1°C for 6 h. Moreover, cold shock and cold acclimation had significant effects on the freezing survival of M. hapla J2. The lethal temperature of eggs was -18°C. Therefore, the cold tolerance of M. hapla is sufficiently favorable to withstand winters in cold temperature environments. [ABSTRACT FROM AUTHOR]

Unidentified cestodes and 14 species of nematode and larvae that could not be placed to family level, were collected from the digestive tracts of 27 individuals of Paramelomys lorentzii, four of Mammelomys lanosus and a single M. rattoides from Papua New Guinea and Papua Indonesia. Of these three were new species. Hughjonestrongylus woolleyae sp. nov. can be distinguished from its congeners in having up to 26 ridges in the synlophe and a dissymmetric dorsal ray. Parvinema bafunminensis gen. nov., sp. nov. can be distinguished from all other genera in the family by the combination of features in the synlophe; with a carene, up to 17 ridges, and the pattern of ridge sizes. Parvinema helgeni sp. nov. differs from P. bafunminensis in the length of the spicule and the number of eggs in the uterus. The nematode assemblage of P. lorentzii had similar species richness to, and was also dominated by heligmonellids, as that of Paramelomys rubex, although the two assemblages differed in species composition. [ABSTRACT FROM AUTHOR]

Potato cyst nematodes PCNs are the most economically damaging pest of potato crop worldwide. During 2013, a survey was carried out in Ain Defla region of Algeria. 81 soil samples collected from potato fields of 14 localities were submitted to nematological analysis which revealed the presence of these nematodes in 22.22% of the prospected fields. Sixteen PCN populations from five localities were characterized by combination of features the perineal regions of cysts and those of second stage juveniles. The morphological identification has been confirmed by the analysis of the ITS-RFLP profiles, sequencing and phylogenetic analysis of the ITS region. The results revealed that the two species Globodera rostochiensis and G. pallida are present in this region occurring separately or in mixed populations. However, we noted a dominance of G. pallida since only 12.25% of the populations have been identified like G. rostochiensis whereas 31.5% were G. pallida and 56, 25% of the populations were constituted of a mixture of the two species and among these mixed populations, 77.77% presented a dominance of G. pallida. The predominance of G. pallida has been noted in the sites of Ain Defla, El Amra, Mekhatria and Arib. G. rostochiensis was dominant in Rouina. Intraspecific variation was noted between populations of G. rostochiensis and G. pallida. Because of the high divergence among Algerian populations of G. pallida and G. rostochiensis it can be assumed that they were multi-introduced in Algeria. The most divergent population of G. pallida, that formed a well separated group with some populations from Chile and Peru, suggests a later or independent introduction of this population in Algeria. [ABSTRACT FROM AUTHOR]

Haemonchus contortus is a major parasite of small ruminants and its blood-feeding behaviour causes effects ranging from mild anaemia to death. Knowledge of the genetic variation within and among H. contortus populations can provide the foundation for understanding transmission patterns and aid in the control of haemonchosis. Adult male H. contortus were collected from three geographical regions in Egypt. The second internal transcribed spacer (ITS2) of nuclear ribosomal DNA was amplified using the polymerase chain reaction (PCR) and sequenced directly. The population genetic diversity and sequence variations were determined. Nucleotide sequence analyses revealed one genotype (ITS2) in all worms, without genetic differentiation. The similarity in population genetic diversity and genetic patterns observed among the three geographical regions could be attributed to possible movement between the sites. This is the first study of genetic variation in H. contortus in Egypt. The present results could have implications for the rapid characterization of H. contortus and other trichostrongyloid nematodes, and evaluation of the epidemiology of H. contortus in Egypt. [ABSTRACT FROM PUBLISHER]

The family Tylenchidae is phylogenetically important to understanding early-branching Tylenchomorpha and to assess soil ecosystems. In this study, we focus on Malenchus and Filenchus as representatives of the Tylenchidae. Samples collected worldwide result in 58 new sequences, and light microscopy and transmission electron microscopy provide details on morphological features. For the first time, comprehensive morphological data are evaluated in the context of a molecular framework, thus highlighting the phylogenetic and evolutionary complexity of this structurally minimalistic group. Results show that the genus Filenchus is polyphyletic in both the 18S and 28S rDNA phylogeny, while Malenchus is polyphyletic and monophyletic in the 28S rDNA and the 18S rDNA, respectively. Ultrastructural study demonstrates specific aspects of lateral cuticular incisures, cuticular layering and the amphideal fovea are surprisingly congruent with the obtained molecular phylogenies, while classical characteristics such as cuticle annulations are evolutionary highly plastic and mosaic in distribution. The study also reveals the shortage of D2/D3 domain in 28S rDNA as a phylogenetic marker for early-branching Tylenchomorpha. [ABSTRACT FROM AUTHOR]

The phylogenetic analysis of partial SSU, LSU (rDNA) and COI (mtDNA) sequences was performed for the quimperiid nematode Ichtyobronema hamulatum, a common parasite of the burbot Lota lota. The study of SSU (for 2007 bp long alignment) has shown that in all kinds of analyses I. hamulatum cluster with Paraquimperia africana (Quimperiidae), while another quimperiid, Paraseuratum sp., unites in a separate clade with Spectatus spectatus (Kathlaniidae). Both groups do not form direct phylogenetic links with the rest of seuratoid nematodes (i.e. Cucullanidae and Seuratidae). Obtained data (for 1080 bp long alignment) exhibit the phylogenetic affi nity of I. hamulatum and P. africana with kathlaniids of the genus Falcaustra. The analysis of LSU sequences has revealed that I. hamulatum occupies the basal position in relation to all other members of Spirurina and Rhabditina. [ABSTRACT FROM AUTHOR]

A new cyst nematode, herein described as Globodera sandveldensis n. sp., was found in the Sandveld, Western Cape Province, South Africa. As the host plant of G. sandveldensis n. sp. is currently unknown, the species is represented by cysts and second-stage juveniles (J2) only. The J2 are characterised by a well developed stylet of 26.4 (24.8-28.5) µm with rounded to anteriorly flattened knobs. The distance from the dorsal pharyngeal gland outlet to the stylet knobs is 4.5 (2.4-7.2) µm. The tail is 64 (56-77) µm long and the length of the hyaline region is 33 (22-39) µm. The cysts are characterised by their ovate to spherical shape, short neck, and the presence of subcuticular punctations and bullae or vulval bodies. Six to 14 cuticular ridges/lines are present on the outer surface of the cyst between the anus and vulval basin. Granek's ratio is 1.7 (0.9-3.0), the vulval basin diam. is 20.4 (13.1-34.6) µm and the distance between vulval basin and anus is 33.5 (19.7-54.0) µm. Phylogenetic relationships with other species of the genus, inferred from ITS-rDNA sequences, indicate that G. sandveldensis n. sp. is included in the clade of Globodera sp. that parasitise non-solanaceous plants and is closely related to unidentified Globodera spp. from Portugal, G. millefolii, and G. artemisiae. [ABSTRACT FROM AUTHOR]

The yam nematode, Scutellonema bradys, is a major threat to yam (Dioscorea spp.) production across yam-growing regions. In West Africa, this species cohabits with many morphologically similar congeners and, consequently, its accurate diagnosis is essential for control and for monitoring its movement. In the present study, 46 Scutellonema populations collected from yam rhizosphere and yam tubers in different agro-ecological zones in Ghana and Nigeria were characterised by their morphological features and by sequencing of the D2-D3 region of the 28S rDNA gene and the mitochondrial COI genes. Molecular phylogeny, molecular species delimitation and morphology revealed S. bradys, S. cavenessi, S. clathricaudatum and three undescribed species from yam rhizosphere. Only S. bradys was identified from yam tuber tissue, however. For barcoding and identifying Scutellonema spp., the most suitable marker used was the COI gene. Additionally, 99 new Scutellonema sequences were generated using populations obtained also from banana, carrot, maize and tomato, including the first for S. paralabiatum and S. clathricaudatum, enabling the development of a dichotomous key for identification of Scutellonema spp. The implications of these results are discussed. [ABSTRACT FROM AUTHOR]

The type population of Meloidogyne brasiliensis is synonymised under M. ethiopica based on morphological and morphometric similarities, as well as through biochemical, molecular and phylogenetic studies. Meloidogyne ethiopica was first described in 1968 in Tanzania using specimens from a single egg mass culture on tomato and re-described in 2004 using an isolate from Brazil. Meloidogyne brasiliensis was described in 2002 in Brazil based on specimens collected from tomato (type population) and pea. Morphological and morphometric studies of their descriptions showed important similarities in major characters as well as some general variability in others. Characterisation of esterase isozyme phenotypes of three populations of M. ethiopica from Brazil, Chile and Kenya, and two M. brasiliensis populations, resulted in only one esterase pattern (E3), a phenotype already known for M. ethiopica. In PCR assays, the species-specific 350 bp SCAR marker developed for M. ethiopica was amplified from the M. brasiliensis populations tested. In phylogenetic analyses based either on sequences of the ITS1-5.8S-ITS2 and D2-D3 (28S) rRNA regions or on RAPD and AFLP data, the populations of both species clustered together with a strong bootstrap support. Altogether, these results provide congruent evidence that M. brasiliensis is not a valid species but rather a junior synonym of M. ethiopica. [ABSTRACT FROM AUTHOR]

Paralongidorus francolambertii sp. n., a bisexual species found in the rhizosphere of silver lime (Tilia tomentosa) and common juniper (Juniperus communis), is described. The species is characterised by its medium to large size (L = 5.86-8.29 mm) and slender body (a = 143-197), a lip region flattened with rounded profile, clearly offset from the body by a deep constriction, a narrow neck between the head and body, a shoulder-like body posterior to the neck, a stirrup-shaped amphidial fovea, with conspicuous slit-like aperture, lying on the lateral cuticular collar, a moderately long odontostyle ca 140 µm long, a guide ring located at ca 28 µm from anterior end, a tail terminus with thickened outer cuticular layer in both sexes, and males with spicules ca 52 µm long. The D2-D3 expansion domains of the 28S rRNA gene and the ITS-containing region of P. francolambertii sp. n. were amplified and sequenced. Phylogenetic analyses by using the Maximum Likelihood method showed that P. francolambertii sp. n. had a sister relationship with P. rex and that all Paralongidorus species formed a well-supported group. [ABSTRACT FROM AUTHOR]

Background: Steinernematid nematodes form obligate symbioses with bacteria from the genus Xenorhabdus. Together Steinernema nematodes and their bacterial symbionts successfully infect, kill, utilize, and exit their insect hosts. During this process the nematodes and bacteria disassociate requiring them to re-associate before emerging from the host. This interaction can be complicated when two different nematodes co-infect an insect host. Results: Non-cognate nematode-bacteria pairings result in reductions for multiple measures of success, including total progeny production and virulence. Additionally, nematode infective juveniles carry fewer bacterial cells when colonized by a non-cognate symbiont. Finally, we show that Steinernema nematodes can distinguish heterospecific and some conspecific non-cognate symbionts in behavioral choice assays. Conclusions: Steinernema-Xenorhabdus symbioses are tightly governed by partner recognition and fidelity. Association with non-cognates resulted in decreased fitness, virulence, and bacterial carriage of the nematode-bacterial pairings. Entomopathogenic nematodes and their bacterial symbionts are a useful, tractable, and reliable model for testing hypotheses regarding the evolution, maintenance, persistence, and fate of mutualisms. [ABSTRACT FROM AUTHOR]

Longidorus piceicola, a new geographical and host record from Romania, was described and illustrated on the basis of two populations originating from a coniferous and a deciduous forest. The main morphological characters of specimens from Romania correspond very well with the type material collected from the soil around Picea abies L. (Slovakia) except for the shorter body and tail. The D2-D3 fragment of 28S rDNA from both populations was amplified and sequenced, and the sequences were identical to L. piceicola sequence from Slovakia. The partial 18S-ITS1-5.8S-ITS2 rDNA regions from one of the populations were sequenced for the first time. The evolutionary relationships between L. piceicola and the closest species L. intermedius based on D2-sequence divergence and single-nucleotide polymorphisms are discussed. Although having very low sequence dissimilarity (0.3–0.9 %) both species have distinct morphology and biology. Longidorus piceicola differs from L. intermedius in having a much longer odontostyle, body, distance anterior end - guide ring, a wider lip region, more ventromedian supplements (11 vs 5–7) in the male, and develops through four rather than three juvenile stages. Furthermore, L. piceicola occurs more frequently in association with conifers, while L. intermedius is found mainly in oak forests. [ABSTRACT FROM AUTHOR]

Aphelenchoides macrospica n. sp. is described and illustrated from theWest Azerbayjan province, northwestern Iran. The new species is characterized by its body length of 807 to 963 mm (males) and 792 to 1,094 mm (females), offset cephalic region, lateral fields with four incisures, long stylet with 15 to 16 mm length, and excretory pore situated opposite or behind the nerve ring. Pharyngeal glands overlapping intestine dorsally and extending for 90 to 121 mm, tail terminus mucronate in both sexes. Vagina directed anteriad, and spicules are relatively large (27-32 mm) with well-developed broadly rounded apex and condylus. The new species comes close to seven known species of the genus namely A. arcticus, A. blastophthorus, A. haguei, A. huntensis, A. lucknowensis, A. parasaprophilus, andA. xui, but it differs from them by the body size, stylet length, size of spicules, and length of postvulval uterine sac. The results of phylogenetic analyses based on sequences of D2-D3 expansion region of 28S and 18S rDNA, confirmed its status as a new species. [ABSTRACT FROM AUTHOR]

Nematode surveys of North American grasslands conducted from 2010 to 2015 frequently recovered a species of criconematid nematode morphologically resembling Mesocriconema curvatum. These specimens were recovered from remnant native prairies in the central tallgrass ecoregion of North America, and not from surrounding agroecosystems. Historical records indicate that M. curvatum is a cosmopolitan species feeding on a wide range of agronomic and native plants. DNA barcoding indicates North American grasslands contain at least 10 phylogenetically distinct lineages of Mesocriconema that resemble, but are not, M. curvatum. Analysis of the two most common lineages reveals two distinctly different population structures. The variation in population structure suggests unique evolutionary histories associated with their diversification. These two major lineages share a sympatric distribution and their slight morphological differences contrast with a high level of genetic separation. Based on their genetic divergence, fixed diagnostic nucleotides, population structure, species delimitation metrics, and a sympatric distribution, we believe that one of these distinct lineages warrants formal nomenclatural recognition. Herein, we provide formal recognition for Mesocriconema nebraskense n. sp. and discuss its relationship to other Mesocriconema lineages discovered in native North American grasslands. [ABSTRACT FROM AUTHOR]

A new species of Paurodontella, P. persica n. sp., collected from the Alborz rangelands of Iran, is described and illustrated. The new species is characterised by its body length of 506 (416-599) µm and 424 (388-461) µm in female and male, respectively, four incisures in lateral field, lip region annulated and continuous with body contour, total stylet 6.2 (5.5-7.0) µm long. Basal pharyngeal bulb with small posterior extension projecting reaching to the intestine. Excretory pore situated at the level of basal pharyngeal bulb region. Post-uterine sac short, 4.5 (3.0-6.0) µm long and uterus with an offset diverticulum. Tail of both sexes similar, conoid pointed, terminus tapering into a long pointed mucron. Male with adanal bursa and spicules 16.5 (16.0-17.0) µm long. The new species comes close in morphology and morphometrics to four known species of the genus, namely P. auriculata, P. myceliophaga, P. minuta and P. niger. Molecular analyses of the partial small subunit rDNA gene (SSU), D2-D3 expansion segments of the large subunit rDNA gene (LSU) and internal transcribed spacer (ITS) revealed this to be a new species. [ABSTRACT FROM AUTHOR]

The genus Xiphinema includes a remarkable group of invertebrates of the phylum Nematoda comprising ectoparasitic animals of many wild and cultivated plants. Damage is caused by direct feeding on root cells and by vectoring nepoviruses that cause diseases on several crops. Precise identification of Xiphinema species is critical for launching appropriate control measures. We make available the first detailed information on the diversity and distribution of Xiphinema species infesting wild and cultivated olive in a wide-region in southern Spain that included 211 locations from which 453 sampling sites were analyzed. The present study identified thirty-two Xiphinema spp. in the rhizosphere of olive trees, ten species belonging to Xiphinema americanum-group, whereas twenty-two were attributed to Xiphinema non-americanum-group. These results increase our current knowledge on the biodiversity of Xiphinema species identified in olives and include the description of four new species (Xiphinema andalusiense sp. nov., Xiphinema celtiense sp. nov., Xiphinema iznajarense sp. nov., and Xiphinema mengibarense sp. nov.), and two new records for cultivate olives (X. cadavalense and X. conurum). We also found evidence of remarkable prevalence of Xiphinema spp. in olive trees, viz. 85.0% (385 out of 453 sampling sites), and they were widely distributed in both wild and cultivated olives, with 26 and 17 Xiphinema spp., respectively. Diversity indexes (Richness, Hill´s diversity, Hill´s reciprocal of D and Hill´s evenness) were significantly affected by olive type. We also developed a comparative morphological and morphometrical study together with molecular data from three nuclear ribosomal RNA genes (D2-D3 expansion segments of 28S, ITS1, and partial 18S). Molecular characterization and phylogenetic analyses allowed the delimitation and discrimination of four new species of the genus described herein and three known species. Phylogenetic analyses of Xiphinema spp. resulted in a general consensus of these species groups. This study is the most complete phylogenetic analysis for Xiphinema non-americanum-group species to date. [ABSTRACT FROM AUTHOR]

During the last decade, many morphotypes of larval forms of Hysterothylacium have been proposed; however, their boundaries are taxonomically unclear. We compare newly collected material with data available for Hysterothylacium larvae, based on genetics and morphology, in order to evaluate their relationships and simplify their classification. The previously described Hysterothylacium larval type IV, type V, and type X were found in several marine fishes from Brazil. A new Hysterothylacium larval type XV, parasitic in Elops saurus from State of Sergipe, north-eastern Brazil, was proposed based on its genetic singularity and the presence of numerous spines throughout the body. Based upon phylogenetic reconstruction using the ribosomal DNA (rDNA) ITS2 sequences along with morphological traits, the following third stage larvae were considered valid (synonyms are inside parenthesis) type III (= types VII and VIII), type V (= types VI, XII, and XIII), and type X (= type XIV). Despite the lack of molecular data, Hysterothylacium larval type II is considered as synonym of type I because of their identical morphology. The morphometry of Hysterothylacium third stage larvae proved to be weak as a diagnostic tool due to its high rates of variation. Phylogenetic reconstruction using the concatenated sequences of rDNA ITS1-5.8S-ITS2 and the mitochondrion DNA (mtDNA) cox2 revealed that the sampled Hysterothylacium larval types V may represent three different species and H. deardorffovestreetorum may represent two different taxa. Furthermore, H. deardorffovestreetorum is considered species inquirenda due to its problematic description and diagnosis which are based only on larvae. A key to Hysterothylacium larvae from marine fishes is provided. [ABSTRACT FROM AUTHOR]

Ektaphelenchus berbericus n. sp. was recovered from soil samples collected in eastern Iran and is described and illustrated based on morphological, morphometric and molecular data. The new species is characterised by having female body 512-691 μm long, lip region separated from rest of body by a shallow depression, lips separated and equally sized, 19-22 μm long stylet with wide lumen and lacking knobs or swellings at its base, cuticle with fine, but distinct transverse annuli and three lines in lateral field, excretory pore located at base of metacorpus (with slight variation in position), reproductive system monodelphic-prodelphic with spheroid and fine sperm cells inside spermatheca in some individuals and short post-vulval uterine sac (PUS), rectum and anus vestigial (invisible in few individuals), conical posterior body end (tail), narrowing at mid-point between anus and rounded tail tip, and males lacking. The new species is typologically similar to species belonging to four genera: Devibursaphelenchus, Ektaphelenchoides, Ektaphelenchus and Seinura, by a combination of morphological characters, e.g., gross morphology of stylet (lacking knobs or swellings at base), morphology of posterior body end (having short conical tail), PUS length, and having a vestigial anus and rectum in most individuals. In molecular phylogenetic analyses using sequences of the partial small subunit of the ribosomal RNA gene (SSU) and the D2-D3 expansion segments of the large subunit (LSU) ribosomal RNA gene, the new species is close to the Ektaphelenchoides/Cryptaphelenchus clade in an inferred SSU tree, and formed a clade with Ektaphelenchoides and Devibursaphelenchus spp. in a D2-D3 LSU tree. Further phylogenetic analyses using full length sequences of the internal transcribed spacer region (ITS) (= ITS1 + 5.8S + ITS2) corroborated results from the SSU and D2-D3 LSU trees, and the multilocus analyses using the combined SSU and LSU data placed the new species in a robustly supported clade with Ektaphelenchoides poinari and Devibursaphelenchus lini. [ABSTRACT FROM AUTHOR]

A new nematode species belonging to the family Rhabditidae, genus Phasmarhabditis, was isolated in the city of Bari (strain BAR) and near the village Gravina (strain GRA) in Apulia, Italy, and is described herein as Phasmarhabditis apuliae n. sp. The original hosts were Milax sowerbyi and M. gagates. Females are 2623 (2262-2848) μm long with a long tapering tail. Prominent papilla-like phasmids are present. Males are 2096 (1898-2363) μm long. They have a peloderan bursa with nine pairs of rays arranged as 1 + 1 + 1 + 2 + 1 + 3. Each ray bears a single papilla. A non-paired papilla is located near the ventral appendage anterior to the cloacal aperture. Prominent papilla-like phasmids are situated close to the tail tip. Dauer juveniles have lateral fields formed from two prominent wide ridges and have three incisures. Phasmarhabditis apuliae n. sp. seems to be a facultative mollusc-parasitic nematode that is capable, in a similar manner to P. hermaphrodita, of long-term survival in the saprophytic phase on decaying organic matter. Ecology, morphology and phylogenetic relationships of Phasmarhabditis nematodes are discussed. [ABSTRACT FROM AUTHOR]

DNA sequence analysis was carried out on Strongyloides spp. larvae obtained from fecal samples of local humans, a wild western lowland gorilla ( Gorilla gorilla gorilla ) and a central chimpanzee ( Pan troglodytes troglodytes ) inhabiting Dzanga-Sangha Protected Areas (DSPA), Central African Republic, and eastern chimpanzees ( Pan troglodytes schweinfurthii ) living in degraded forest fragments on farmland in Bulindi, Uganda. From humans, both Strongyloides fuelleborni and Strongyloides stercoralis were recorded, though the former was predominant. Only S. fuelleborni was present in the great apes in both areas. Phylogenetic analysis of partial mtDNA cytochrome c oxidase subunit 1 gene ( Cox1 ) and comparison of 18S rDNA hyper variable region IV (HVR-IV) sequences implied that in DSPA S. fuelleborni populations in humans differ from those in the nonhuman great apes. [ABSTRACT FROM AUTHOR]

Nematode parasites of the cardiopulmonary system of livestock and pet animals have been receiving attention due to the pathogenic effects they produce in the course of the infection. However, parasitism in wild animals by metastrongilid nematodes has been neglected, resulting in potential risk to wildlife. Heterostrongylus heterostrongylus is the etiological agent of bronchial pneumonia in the black-eared opossum, Didelphis aurita , a widely distributed marsupial frequently reported to inhabit areas from wild environments to peri-urban spaces. In this study, we reassessed the taxonomy of H. heterostrongylus , describing and comparing morphology of L 1 and L 3 larvae and adult worms with closely related angiostrongilids, and inferring phylogenetic affinities within the family Angiostrongylidae; we also detailed histopathological reactions under natural infection. Ultrastructural morphology and light microscopy confirmed cephalic structures with well-developed trilobed lips, patterns of caudal bursa rays, spicules shape, terminal anal aperture and presence of the ventral protuberance in L 3 larvae, characteristics present for the family Angiostrongylidae. Our molecular phylogenetic analyses, based on the partial small subunit (SSU) 18S rRNA gene, suggested that H . heterostrongylus and Didelphostrongylus hayesi are closely related. Pathological analyses agreed with previous findings, showing that cardiopulmonary parasitism provokes verminous pneumonia and mucous bronchiolitis with hypertrophy of the smooth bronchiolar muscle. These data confirmed that H. heterostrongylus represents a pulmonary pathogen in D. aurita , produces severe pathological effects, and may represent risk to domestic and wild animals. [ABSTRACT FROM AUTHOR]

Using ribosomal (18S, ITS1, ITS2, D2-D3 expansion segments of 28S rDNA) and mitochondrial (partial cox1 and nad4) DNA markers in a study of several populations of Xiphinema americanum-group from Europe and Morocco, two cryptic species X. browni sp. n. (formerly reported as X. pachtaicum) and X. penevi sp. n. were revealed. The species are described, illustrated and their phylogenetic relationships discussed. The first species is most similar to X. parasimile and is a member of X. simile species complex. The phylogenetic reconstructions inferred from three molecular markers (18S, D2-D3 28S rDNA and cox1) showed that X. penevi sp. n. is part of X. pachtaicum-subgroup and is closely related to X. incertum, X. pachtaicum, X. parapachydermum, X. plesiopachtaicum, X. astaregiense and X. pachydermum. Also, a separate "X. similesubgroup", outside the X. pachtaicum-subgroup and so far consisting only of the parthenogenetic species X. simile, X. parasimile, X. browni sp. n. and probably X. vallense was formed. New primers for amplification and sequencing of part of the nad4 mitochondrial gene were designed and used. [ABSTRACT FROM AUTHOR]

Three nematode species of the superfamily Desmodoroidea Filipjev, 1922, were isolated from beach sediments in Wellington, New Zealand, for morphological and molecular analyses. Two of these species, D esmodorella verscheldei sp. nov. and D racograllus ngakei sp. nov., were new to science and are described herein. E psilonema rugatum Lorenzen, 1973, comb. nov., which was originally described from New Zealand material as a subspecies of E psilonema dentatum from Chile, is redescribed and elevated to the rank of species based on cuticular ornamentation. The phylogenetic relationships amongst the three Desmodoroidea families are investigated based on new and existing sequences of the D2 and D3 expansions segments of large subunit ( LSU) 28S rRNA gene and small subunit ( SSU) of 18S r DNA gene. Our analyses suggest that the Draconematidae is a sister taxon to the Desmodorinae and Spiriniinae, with the Draconematidae forming a monophyletic crown group and the Desmodorinae and Spiriniinae forming a paraphyletic stem group. Phylogenetic relationships between the Epsilonematidae and Stilbonematinae, however, could not be determined with certainty. The SSU and D2- D3 of LSU consensus trees indicate that the morphological resemblance between the Draconematidae and Epsilonematidae, which are both characterized by swollen pharyngeal body regions and mid-posterior body regions with specialized setae, reflects distinct and independently evolved adaptations to their unusual mode of locomotion, with differences in the structure and distribution of specialized setae between the two families also consistent with convergent evolution. We show that the family Desmodoridae and superfamily Desmodoroidea as currently defined are not monophyletic. It was not possible to determine whether the Prodesmodorinae are more closely related to the Desmodoroidea or Microlaimoidea, although it is clear that they do not belong to the Desmodoridae. The single Molgolaiminae sequence available formed a distinct clade together with the superfamily Microlaimoidea, and should therefore be placed with the latter. Clarifying the phylogenetic relationships within the Desmodoroidea will require greater focus on the Pseudonchinae, Molgolaiminae, and Epsilonematidae, for which no or very few sequences are available at present. © 2016 The Linnean Society of London [ABSTRACT FROM AUTHOR]

The genus Ditylenchus has been divided into 2 groups: the D. triformis-group, and the D. dipsaci-group based on morphological and biological characters. A total of 18 populations belong to 5 species of Ditylenchus was studied: D. africanus, D. destructor, D. myceliophagus and dipsaci, D. weischeri, the first 3 belong to the D. triformis-group, the last 2 the D. dipsaci-group. The species of D. triformis-group were cultured on fungi, while the species from D. dispaci-group cultured on excised roots of plant hosts in petri dish. DNA sequences of regions of the nuclear ribosomal first internal transcribed spacer (ITS1) and the small subunit 18S were PCR amplified, sequenced and the phylogenetic analyses also including the sequences of the closely related species from the GenBank. The randomly amplified polymorphisms of genomic DNA (RAPD) were also generated. Two clusters or clades corresponding to the 2 groups were consistently observed with significant statistical support from the 3 datasets. The phylogenetic analysis also revealed that the genus is paraphyletic, separating the 2 groups by species of Anguina and Subanguina. [ABSTRACT FROM AUTHOR]

The genus Longidorus includes a remarkable group of invertebrate animals of the phylum Nematoda comprising polyphagous root-ectoparasites of numerous plants including several agricultural crops and trees. Damage is caused by direct feeding on root cells as well as by transmitting nepoviruses that cause disease on those crops. Thus, correct identification of Longidorus species is essential to establish appropriate control measures. We provide the first detailed information on the diversity and distribution of Longidorus species infesting wild and cultivated olive soils in a wide-region in southern Spain that included 159 locations from which 449 sampling sites were analyzed. The present study doubles the known biodiversity of Longidorus species identified in olives by including six new species (Longidorus indalus sp. nov., Longidorus macrodorus sp. nov., Longidorus onubensis sp. nov., Longidorus silvestris sp. nov., Longidorus vallensis sp. nov., and Longidorus wicuolea sp. nov.), two new records for wild and cultivate olives (L. alvegus and L. vineacola), and two additional new records for wild olive (L. intermedius and L. lusitanicus). We also found evidence of some geographic species associations to western (viz. L. alvegus, L. intermedius, L. lusitanicus, L. onubensis sp. nov., L. vineacola, L. vinearum, L. wicuolea sp. nov.) and eastern distributions (viz. L. indalus sp. nov.), while only L. magnus was detected in both areas. We developed a comparative study by considering morphological and morphometrical features together with molecular data from nuclear ribosomal RNA genes (D2–D3 expansion segments of 28S, ITS1, and partial 18S). Results of molecular and phylogenetic analyses confirmed the morphological hypotheses and allowed the delimitation and discrimination of six new species of the genus described herein and four known species. Phylogenetic analyses of Longidorus spp. based on three molecular markers resulted in a general consensus of these species groups, since lineages were maintained for the majority of species. This study represents the most complete phylogenetic analysis for Longidorus species to date. [ABSTRACT FROM AUTHOR]

The genus Phasmarhabditis is an economically important group of rhabditid nematodes, to which the well-known slug-parasite P. hermaphrodita belongs. Despite the commercial use of Phasmarhabditis species as an attractive and promising approach for pest control, the taxonomy and systematics of this group of rhabditids are poorly understood, largely because of the lack of diagnostic morphological features and DNA sequences for distinguishing species or inferring phylogenetic relationship. During a nematode sampling effort for identifying free-living relatives of Caenorhabditis elegans in Huizhou City, Guangdong, China, a novel species belonging to the genus Phasmarhabditis was isolated from rotting leaves. Detailed morphology of the gonochoristic P. huizhouensis sp. nov. was described and illustrated. The adult female has a robust body, a relatively short and wide buccal capsule conjoined by a rhabditiform pharynx. Females are characterized by a short cupola-shaped tail end bearing a slender pointed tip, with the junction flanked by a pair of ‘rod-like’ phasmids. Males have an open peloderan bursa that is supported by 9 pairs of genital papillae and 1 terminal pair of phasmids. P. huizhouensis sp. nov. is morphologically very similar to the type species Phasmarhabditis papillosa but is distinguishable by its male caudal traits. The new species is readily differentiated from other taxa in the genus by its female tail shape. Molecular phylogenetic inferences based on small subunit (SSU) and the D2-D3 domain of large subunit (LSU) ribosomal DNA genes reveal that P. huizhouensis sp. nov. forms a unique branch in both phylogenies which is genetically related to P. hermaphrodita and other parasites such as Angiostoma spp. The host associations of P. huizhouensis sp. nov. and its ability to parasitize slugs are unknown. [ABSTRACT FROM AUTHOR]

The roundworms of genus Strongylus are the common parasitic nematodes in the large intestine of equine, causing significant economic losses to the livestock industries. In spite of its importance, the genetic data and epidemiology of this parasite are not entirely understood. In the present study, the complete S. equinus mitochondrial (mt) genome was determined. The length of S. equinus mt genome DNA sequence is 14,545 bp, containing 36 genes, of which 12 code for protein, 22 for transfer RNA, and two for ribosomal RNA, but lacks atp 8 gene. All 36 genes are encoded in the same direction which is consistent with all other Chromadorea nematode mtDNAs published to date. Phylogenetic analysis based on concatenated amino acid sequence data of all 12 protein-coding genes showed that there were two large branches in the Strongyloidea nematodes, and S. equinus is genetically closer to S. vulgaris than to Cylicocyclus insignis in Strongylidae. This new mt genome provides a source of genetic markers for the molecular phylogeny and population genetics of equine strongyles. [ABSTRACT FROM AUTHOR]

The equine pinworm Oxyuris equi (Nematoda: Oxyuridomorpha) is the most common horse nematode, has a worldwide distribution, and causes major economic losses. In the present study, the complete O. equi mitochondrial (mt) genome was sequenced, and the mt genome structure and organization were compared with those of other closely related pinworm species, Enterobius vermicularis and Wellcomia siamensis . The O. equi mt genome is a 13,641-bp circular DNA molecule that encodes 36 genes (12 protein-coding genes, 22 tRNAs, and two rRNAs) and one non-coding region, which is slightly shorter than that of E. vermicularis and W. siamensis . The O. equi mt gene arrangement was consistent with that of GA13-type E. vermicularis but it differs from GA12-type W. siamensis . Phylogenetic analyses using concatenated amino acid sequences of the 12 protein-coding genes with three different computational algorithms (maximum parsimony, maximum likelihood, and Bayesian inference) revealed that there were two distinct clades in Chromadorea nematodes that reflected infraorder. Spiruromorpha formed one clade, whereas Rhabditomorpha, Ascaridomorpha, and Oxyuridomorpha formed another clade. O. equi , E. vermicularis , and W. siamensis represent distinct but closely related species, which indicated that Oxyuridomorpha is paraphyletic. Sequencing the O. equi mt genome provides novel genetic markers for studying the molecular epidemiology and population genetics of pinworms. [ABSTRACT FROM AUTHOR]

Mononchida is an order of predatory nematodes and includes the suborders Bathyodontina and Mononchina. In this survey, sequences of the 18S rDNA were amplified and used to reconstruct the phylogeny of the Mononchina. Phylogenetic analyses using Neighbour Joining (NJ) and Maximum Likelihood (ML) were employed with five outgroup taxa and 65 mononch sequences including 14 new sequences from Iran. Both analyses indicated that the Anatonchus is monophyletic. Actus was placed as the sister group of Mylonchulus with weak and strong support, respectively, from the ML and NJ analyses. In both phylogenetic analyses, trees obtained from SSU rDNA alignments were subdivided into five highly- or moderately-supported clades, designated Clade I: Mylonchulus spp., Clade II: Actus salvadoricus, Clade III: Anatonchus spp., a group comprising the genera Clarkus, Coomansus, Miconchus and Prionchulus, Clade IV: Mononchus spp., and Clade V: Granonchulus sp. The 18S rDNA analysis demonstrated that this region of the nuclear genome can be used to resolve the relationships of members of this suborder. [ABSTRACT FROM AUTHOR]

Diploscapteroides persicus n. sp. is described and illustrated based on morphological, morphometric and molecular data. The new species is mainly characterised by female body length of 469-673 μm, female tail length of 51-99 μm, shape of gubernaculum and spicules and arrangement of male genital papillae. Also, the arrangement of male genital papillae of the new species shows the presence of precloacal papillae, a feature that has not been previously described for the genus. The new species is comparable with all valid species of the genus, namely D. boettgeri, D. brevicauda, D. chitinolabiatus, D. coroniger, D. dacchensis and D. flexuosus, from which the morphological comparisons of the new species with aforementioned species are discussed. Phylogenetic analyses using partial sequences of SSU and LSU rRNA genes were performed for the new species, being the first representative of the genus to be phylogenetically studied using both Bayesian inference (BI) and maximum likelihood (ML) methods, and revealed that D. persicus n. sp. formed a clade with a species of Cephaloboides. [ABSTRACT FROM AUTHOR]

This study surveyed the genetic differences among Angiostrongylus cantonensis (A. cantonensis) using the mitochondrial cytochrome b (cytb) gene. Partial cytb sequences were determined for 91 worms from eight locations in Thailand. Using morphological techniques, the nematodes were found to be A. cantonensis. Phylogenetic analysis found two main clades, which were subdivided into four subclades (clusters). Haplotype network analysis showed that 11 distinct cytb haplotypes were also present in four groups of A. cantonensis. There was no observable relationship between the genetic differentiation of gene flow and geographical distance. This low genetic variation and geographical distribution of A. cantonensis in each location indicates a founder effect, which may have resulted from multiple independent origins, and suggests that haplotypes migrated from endemic areas via human-related activities. [ABSTRACT FROM AUTHOR]

Three species of the family Tylenchidae, including one new and two known species, are described and illustrated. Atetylenchus minor n. sp. is characterised by its short body length of 633 (558-691) µm, MB = 45 (41-46), lateral field with four crenate incisures, stylet 12.0 (11.5-12.5) µm long, without distinct basal knobs but with swollen arms of the shaft at its base, V = 56.3 (53.7-59.3), absence of lateral vulval membranes, and conical tail 57 (51-62) µm long with a rounded tip. Morphological differences of the new species with four known species of the genus, namely A. abulbosus, A. graminus, A. amiri and A. metaporus, are discussed. Molecular phylogenetic studies of the new species using 1089 bp partial sequences of 18S rDNA revealed that the new species formed a clade with an unpublished species assigned to Psilenchus in Bayesian inference (BI) with low Bayesian posterior probability (BPP). This clade forms a sister clade to a major clade containing two species of Psilenchus and several belonolaim species and genera. The same result was achieved using maximum likelihood (ML) analysis. Morphological and molecular phylogenetic studies were also performed on two other species, Malenchus labiatus and Neothada cancellata, using 28S rDNA D2-D3 sequences. In the inferred Bayesian tree, M. labiatus formed a clade with other species of Malenchus with 28S information with maximal support (1.00 BPP), while N. cancellata formed a clade with Boleodorinae, again with maximal (1.00) BPP. [ABSTRACT FROM AUTHOR]