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Marek Renčo, Franciszek Wojciech Kornobis, Krzysztof Domaradzki, Anna Jakubska-Busse, Jana Jurová and Zuzana Homolová

Summary

We analysed the effect of the invasive perennial plant Heracleum sosnowskyi on soil nematode communities and diversity, and plant species composition, by comparing invaded and non-invaded (control) areas in natural conditions. Invasion of H. sosnowskyi caused significant shifts in plant species composition, which subsequently modified nematode assemblages. Stress-sensitive omnivores, fungivores and root-biomass-dependent obligate plant parasites best reflected changes in soil nematode communities under the influence of H. sosnowskyi invasion. The negative effect of H. sosnowskyi was most evident on Aphelenchus, Tylencholaimus, Geocenamus, Helicotylenchus, Pratylenchus, Tylenchorhynchus and Aporcelaimellus. Our results indicate that significant changes in the herbaceous layer after H. sosnowskyi invasion in ecosystems where H. sosnowskyi eventually became dominant impacted soil nematode communities but did not affect nematode diversity. This was in contrast to the habitats where a solitary plant of H. sosnowskyi grew and no significant changes in nematode communities were observed.

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Natsumi Kanzaki, Yu Ichihara, Takuya Aikawa, Taisuke Ekino and Hayato Masuya

Summary

Litylenchus crenatae n. sp., isolated from leaf galls of Fagus crenata from Japan, is described and figured. The new species is characterised by its dimorphism in adult females, six (or more) lateral lines, a more or less pointed tail tip in both sexes, male bursa arising posteriorly and reaching to near tail tip, presence of a quadricolumella and a post-uterine sac in females. Litylenchus crenatae n. sp. is distinguished from its only congener, L. coprosma, by the number of lateral lines, six or more vs four; the lip morphology, offset with very shallow constriction or dome-shaped without clear constriction vs clearly offset; tail tip morphology, more or less pointed vs blunt; and structure of the median bulb, weakly muscular with a clear valve vs not muscular with an obscure valve. The molecular phylogenetic analysis confirms that the new species is close to, but clearly different from, L. coprosma.

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Farzad Aliramaji, Esmaeil Miraeiz, Ebrahim Pourjam and Ramin Heydari

Summary

Cryptaphelenchus baujardi n. sp. is described and illustrated based on two populations from Golestan province, northern Iran. The new species is characterised by female and male body length of 224 (190-261) and 215 (195-229) μm, respectively, offset cephalic region with a shallow constriction, delicate stylet 6.6 (6.0-7.0) μm long, four incisures in the lateral field, presence of a rudimentary post-uterine sac in the female gonoduct, elongate-conoid female tail ending in an acute to finely rounded terminus, male tail conical, male with seven caudal papillae and delicate spicules. The new species shows a strong resemblance to C. varicaudatus and C. iranicus, but has a sclerotised mass near the tip of the spicule and an indistinct spermatheca. Phylogenetic analyses based on both partial SSU and LSU rDNA sequences confirm its status as a new taxon.

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Daniel Leduc and Zeng Qi Zhao

Summary

Spirinia parasitifera is a common nematode species recorded from coastal habitats of the White, North and Barents Seas, the Northwest Atlantic, the Maldives and Australia, and exhibits a high degree of variability in some morphological characters. For these reasons it has been suggested that S. parasitifera is a species complex comprised of several distinct but potentially cryptic species. However, no study has yet combined molecular and morphological approaches to verify this assertion. Here, we describe S. antipodea n. sp., a species morphologically very similar to S. parasitifera, from the coast of New Zealand. Spirinia antipodea n. sp. differs from the original description of S. parasitifera as well as subsequent descriptions by other authors in at least one body dimension, but no single trait differs consistently between the New Zealand specimens and all descriptions of S. parasitifera. Phylogenetic analyses showed that the new species is distinct from other species of the genus, including S. parasitifera specimens sampled near the type locality. The S. antipodea n. sp. SSU sequence differed from other Spirinia sequence by 2.1-5.3%, whilst D2-D3 of LSU sequences differed by 12.5-18.9%. The consensus SSU tree also recovered three distinct S. parasitifera clades, which provides support for the existence of a species complex. Because it is not possible to determine whether the variability in morphological characters observed among descriptions of S. parasitifera is intra- or interspecific, and therefore to determine which trait can reliably be used to differentiate between S. antipodea n. sp. and S. parasitifera, the new species is best differentiated from S. parasitifera and other closely related species based on SSU sequences rather than morphological characters.

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Robbie Rae

Summary

The terrestrial gastropod parasitic nematode Phasmarhabditis hermaphrodita is the only nematode that evolved to infect and kill slugs and snails. Because of this ability it has been formulated into a biological control agent for gardeners. In this Forum article, the author outlines several reasons why P. hemaphrodita is a nematode that is worth studying, including its ability to control the behaviour and kill slug hosts. The author discusses how P. hemaphrodita is being developed as a model nematode to be used to study the genetic evolution of parasitism, as well as potential research ideas for the future.

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Reyes Peña-Santiago

Summary

Labronema ferox is redescribed on the basis of two females and four males from the USA. It is characterised by its 2.90-4.45 mm long body, lip region offset by deep constriction, 31-39 μm broad and slightly sucker-like with distinctly protruding perioral liplets, odontostyle 34-37 μm long with aperture occupying 37-42% its length, neck 673-883 μm long, pharyngeal expansion occupying 48-52% of total neck length, female genital system didelphic-amphidelphic, uterus long and complex, including an intermediate pars musculosa, vulva longitudinal (V = 51-54), caudal region short and rounded (27-39 μm, c = 93-135, c=0.6-0.8), spicules 76-89 μm long, and 20-25 nearly contiguous ventromedian supplements with an hiatus. Previous information about the species is analysed and discussed in the light of the present redescription. A new name, Labronemella zullinii sp. n., is proposed for the two females from Nepal described by Zullini in 1973. This new characterisation of L. ferox lays the foundations to study the taxonomy of the genus in more detail.

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Kaikai Qiao, Mengxin Bai, Qiu Wang, Xiangyu Hou, Jingwei Chen, Shun Xiao, Guokun Liu, Wim Bert and Xue Qing

Summary

Species of the family Tylenchidae are encountered in large numbers in soils. The genus Labrys was recently described characterised by a remarkable lip pattern that differs from all other known Tylenchidae genera. Here we describe a curious new species, Labrys fujianensis sp. n., that morphologically fits the genus Labrys but which is genetically divergent. The phylogeny was inferred based on 18S and 28S rDNA and light and scanning electron microscopy were used to extract detailed morphologies. The phylogenetic position of this species and its phenotypic convergence are discussed. The possibility of a long-branch attraction artefact was inspected both by removal of variable nucleotide sites and monophyletic testing of topologies. The results confirmed the divergent positioning of the presented species and it is demonstrated that the genetic diversity in Tylenchidae may be much higher than expected due to morphological homoplasy.

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Chau N. Nguyen, Anh T. Do, Phap Q. Trinh and Phuc K. Hoang

Summary

The virulence and efficacy of two species of entomopathogenic nematodes, Steinernema sp. (strain PQ16) and Heterorhabditis indica (strain KT3987), against nymphs of the coffee cicada, Dundubia nagarasingna, was evaluated under laboratory and glasshouse conditions. The highest mortality rates of coffee cicada nymphs caused by these two nematode strains were 93.5 and 100%, respectively, at an inoculation dose of 600 infective juveniles (IJ) nymph−1. The virulence (LC50) was established as 137.5 IJ and 149.1 IJ for strains S-PQ16 and H-KT3987, respectively. The highest IJ yields of these nematode strains were 66 × 103 IJ (for S-PQ16) and 134.4 × 103 IJ (for H-KT3987) at a dose of 500 IJ nymph−1. The efficacies of the two nematode strains to coffee cicadas at treated dose of 60 × 103 IJ pot−1 were 84.4 and 88.9% after 30 days, higher than the efficacies at treated dose of 40 × 103 IJ pot−1. The number of IJ in 250 ml of soil at 10, 20 and 30 days after treatment, increased from 0.38 × 103 to 4.80 × 103 IJ in soil treated with a dose of 40 × 103 IJ and from 0.66 × 103 to 5.02 × 103 IJ in soil treated with a dose of 60 × 103 IJ (for S-PQ16). Similarly, for H-KT3987 the number of IJ increased from 0.43 × 103 to 8.99 × 103 IJ and from 0.62 × 103 to 9.64 × 103 IJ, at the respective doses. Based on results of a pot trial from glasshouse modelling, an IJ application dosage for biological control of coffee cicada nymphs in coffee plantations was proposed.

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Natsumi Kanzaki and Robin M. Giblin-Davis

Summary

A new Acrostichus species is described based upon molecular sequence profiles and hybridisation testing. The new species, A. palmarum n. sp., had been previously described as local isolates (strains) of A. rhynchophori, i.e., an isolate recovered from Rhynchophorus cruentatus from South Florida (culture code RGD193) was designated as the type strain of A. rhynchophori, and other Central and South American strains (RGD194-196), recovered from R. palmarum were considered as conspecific regional isolates. However, additional sequencing of ribosomal DNA loci (near full-length of small subunit, full length of internal transcribed spacer and D2-D3 expansion segments of large subunit) and partial mitochondrial cytochrome oxidase subunit I gene and hybridisation testing suggested the independent species status of RGD194-196. Furthermore, two strains of A. palmarum n. sp., RGD194 and RGD195, showed partial reproductive isolation from each other, i.e., the fecundity of F1 progeny was obviously low, suggesting that geographical isolation within a widely-distributed species is occurring.

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Jessica M.S. Monteiro, Vanessa S. Mattos, Marcilene F.A. Santos, Ana C.M.M. Gomes, Valdir R. Correa, Daniela A. Sousa, Juvenil E. Cares, Jadir B. Pinheiro and Regina M.D.G. Carneiro

Summary

The type population of Meloidogyne polycephannulata is synonymised with M. incognita based on morphological and morphometric characters, as well as biochemical, molecular and phylogenetic studies. Morphological variability and a wide host range were reported for M. incognita during its first description and later re-description. Meloidogyne polycephannulata was described in Brazil from specimens collected in a carrot field (type population). The esterase phenotype (Est) characterised for this species was identical to the phenotype Est I2 of M. incognita, the most ubiquitous phenotype used for diagnostics. Morphological and morphometric characters of the descriptions of the two nominal species showed major similarities, as well as variability within the range of variation detected in M. incognita. In PCR assays, three SCAR markers species-specific for M. incognita (incK14 F/R, Mi/FR and incB06 F/R) amplified the same fragments of 399 bp, 955 bp and 1200 bp, respectively, for populations in both species. In phylogenetic studies based either on concatenated sequences of ITS1-5.8S-ITS2, D2-D3 rRNA, mitochondrial COII regions or on RAPD and AFLP data, the populations of both species grouped in the same clade with high bootstrap support. Altogether, these results provide congruent evidence that the M. polycephannulata type isolate deposited at the Embrapa Cryopreserved National Collection of Root-knot Nematodes is not a valid species but rather a junior synonym of M. incognita.