Identification and Biological Characterization of a New Cyst Nematode, Heterodera glycines sbsp.n. tabacum, Parasitizing Tobacco in China

In an investigation of diseases from plant-parasitizing nematodes in Henan Province, a cyst nematode was found on tobacco roots and in rhizosphere soil. We identified this strain as a new cyst nematode subspecies, Heterodera glycines sbsp.n. tabacum. The cysts and second-stage juveniles (J2s) parasitizing Henan tobacco were larger than those of H. glycines. A single 345-bp fragment was amplified from H. glycines sbsp.n. tabacum, whereas the 345- and 181-bp fragments were amplified from the soybean cyst nematode. Thus, H. glycines sbsp.n. tabacum was distinct from H. glycines. There were base transversions at 504 sites and base transitions at 560, 858, 920, and 921 sites in the rDNA-ITS sequences of H. glycines sbsp.n. tabacum compared with H. glycines, and there were base transitions at 41, 275, 278, and 380 sites in the mtDNA-COI sequences. In the phylogenetic tree based on the rDNA-ITS and mtDNA-COI regions, H. glycines sbsp.n. tabacum was clustered on a single branch. Based on the randomly amplified polymorphic DNA (RAPD) technique, sequence characterized amplified region (SCAR)-PCR primers were designed. A single 1,113-bp fragment was amplified by specific primers (HtF1/HtR1) from H. glycines sbsp.n. tabacum, while no fragments were obtained from H. glycines. The H. glycines sbsp.n. tabacum can infect soybean plants but cannot complete its life cycle on soybean. Eleven tested tobacco cultivars were infected, with an average reproduction factor (Rf) of 9.74 and a maximum of 64.2 in 'K326'. The cumulative egg hatching rate of H. glycines sbsp.n. tabacum in the presence of tobacco root exudates was 42.6% at 32 days posthatching, which was significantly greater than that in the presence of soybean root exudates (30.3%) or sterile water (33.1%). In summary, the cyst nematode population parasitizing Henan tobacco was identified as a new subspecies, H. glycines sbsp.n. tabacum.

Effect of Temperature on the Embryogenesis of Three Geographically Distinct Populations of Meloidogyne incognita Is Driven by Intrinsic Thermal Acclimation Reaction

Research interest in the mechanisms enabling plant-parasitic nematodes to adjust their physiological performance and cope with changing temperatures has intensified in light of global warming. Here, we show that geographically distinct populations of the root-knot nematode Meloidogyne incognita, which is prevalent in the three main pepper-growing regions in Israel-Carmel Valley (Carmel), Jordan Valley (JV), and Arava Rift (Arava)-possess persistent differences in their thermal acclimation capacity, which affect pre- and postembryonic development. The optimal temperature for embryonic growth completion was 25°C for the Carmel population; 25 and 30°C for the JV population; and 30°C for the Arava population. Cumulative hatching percentages showed variations among populations; relative to hatching at 25°C, the Carmel population experienced hatching reduction at the higher studied temperatures 30 and 33°C, while the JV and Arava populations exhibited an increase in hatching at 30 and 33°C, respectively. Juvenile survival indicates that at the lowest temperature (20°C), the Carmel population gained the highest survival rates throughout the experimental duration, while at the same duration at 33°C, the Arava population gained the highest survival rate. Infective juveniles of the Carmel population demonstrated increased penetration of tomato roots at 25°C compared to the JV and Arava populations. Inversely, at 33°C, increased penetration was observed for the Arava compared to the Carmel and JV populations. Altogether, the Arava population's performance at 33°C might incur distinct fitness costs, resulting in consistent attenuation compared to the Carmel population at 25°C. Precisely defining a population's thermal acclimation response might provide essential information for models that predict the impact of future climate change on these populations.

The Root-Lesion Nematode, Pratylenchus penetrans, Affects Early Growth and Physiology of Grafted M.9, G.41, and G.935 Apple Rootstocks Similarly Under Field Microplot Conditions

The root-lesion nematode, Pratylenchus penetrans, is a ubiquitous parasite of roots of temperate fruit trees. It affects early growth of trees replanted into former orchard sites where populations have built up and may contribute to decline complexes of older trees. Most British Columbia, Canada, apple acreage is planted with M.9 rootstock, but growers are increasingly considering Geneva-series rootstocks such as G.41 and G.935. Among these rootstocks, responses to P. penetrans, specifically, are poorly known. To compare the resistance and tolerance to P. penetrans of G.41, G.935, and M.9 rootstocks ('Ambrosia' scion), a field microplot experiment was established in spring of 2020 at the Summerland Research and Development Centre. The experimental design was a two by three factorial combination of: P. penetrans inoculation (+/-) and rootstock (G.41, G.935, and M.9), with 20 replicate microplots of each of the six treatment combinations arranged in a randomized complete block design. The P. penetrans inoculum was 5,400 nematodes per microplot (54 P. penetrans liter-1 soil), which is below commonly accepted damage thresholds. Though P. penetrans population densities were lower for the G.41 rootstock by the end of the 2021 growing season, the effects of P. penetrans were similar among rootstocks. In the establishment year (2020), P. penetrans caused significant reductions in aboveground growth. In 2021, shoot growth and root weight were reduced by P. penetrans. The nematode also reduced rates of leaf gas exchange and stem water potential. These data suggest that while G.41 and G.935 may have other horticultural benefits over M.9, they are equally susceptible to P. penetrans at the early stages of tree growth.

Discovery and Characterization of Four Aphelenchid Species from Cultivated Regions of Southern Alberta, Canada

The nematode family Aphelenchoididiae is considered fungal-feeding, predatory, or root hair feeders. Some members of this family are universally present in agricultural landscapes and are an integral part of soil health and conservation studies. In the present soil nematode biodiversity survey, we detected four species of the genera Aphelenchus, Aphelenchoides, and Robustodorus. Because fungal-feeding nematodes from southern Alberta have not previously been reported, we conducted a detailed morphological and molecular investigation, identifying these species as Aphelenchus avenae, Aphelenchoides limberi, Aphelenchoides prairiensis n. sp. and Robustodorus paramegadorus n. sp. The first two species we document as new records from southern Alberta, whereas A. prairiensis n. sp. and R. paramegadorus n. sp. we describe in detail as new taxa. Briefly, A. prairiensis n. sp. is an amphimictic species having 4 lateral lines; hemispherical anteriorly flattened lip region; delicate stylet and swelling-like stylet knobs; excretory pore at the posterior edge of nerve ring. Female tail conical, gradually tapering towards a truncated end with single mucro. Spicule 23.0 (20.0-25.0) µm long having elongated rounded condylus, small, blunt conical rostrum, and lamina that gradually tapers towards the rounded distal end; three pairs of caudal papillae were present on the male tail. Robustodorus paramegadorus n. sp., is a parthenogenetic species with 3 lines in the lateral fields; lip region rounded, anteriorly flattened; stylet robust, with knobs rounded to bean-shaped; excretory pore located posterior to nerve ring; reproductive components were quite indiscernible with a short 24.0 (18.0-27.0) µm post-vulval uterine sac; tail conical, ending with pointed to wedge-shaped tip. We performed molecular characterizations for each species and constructed phylogenetic trees to study the phylogenetic relationship of these aphelenchid species. The discovery of A. prairiensis n. sp. and R. paramegadorus n. sp. indicates that soil nematode diversity is relatively unexplored in southern Alberta. The findings of this study will significantly enhance the identification processes and may contribute towards future soil health and biodiversity efforts.

Morphological and Molecular Characterization of a New Root-Knot Nematode, Meloidogyne limonae n. sp. (Nematoda: Meloidogynidae), Parasitizing Lemon in China

Root-knot nematodes of the genus Meloidogyne parasitize the roots of thousands of plants and can cause severe damage and yield losses. Here, we report a new root-knot nematode, Meloidogyne limonae n. sp., parasitizing "lemon" (Citrus limon) in Hainan Province, South China. Lemon trees infected by the root-knot nematode showed poor-quality lemons, chlorosis of foliage, weak growth, and numerous root galls with white females and egg masses protruding outside. Phylogenetic trees of sequences within the ribosomal and mitochondrial DNA demonstrated that this species differs clearly from other previously described root-knot nematodes. Morphologically, the new species is characterized by an oval-shaped perineal pattern and the lateral field marked by a ridge of cuticle on one or both sides; the dorsal arch is low, with fine to coarse, smooth cuticle striae; the vulva slit is centrally located at the unstriated area; the spicules of males are arcuate and curved ventrally; the gubernaculum is distinct and curved; the labial disc of second-stage juveniles is prominent and dumbbell shaped; stylet knobs are oval and sloping backwardly; pharyngeal glands are not filling the body cavity and overlapping the intestine ventrally; and the conical tail is gradually tapering. Phylogenetic trees based on the ITS1-5.8S-ITS2, D2-D3 of the 28S rDNA, and COI and COII-16S rRNA genes of the mtDNA showed that M. limonae n. sp. belongs to an undescribed root-knot nematode lineage that is separated from other species with the resemblance in morphology, such as M. floridensis, M. hispanica, M. acronea, and M. paranaensis.

The more we search, the more we find: discovering and expanding the biodiversity in the ring nematode genus Xenocriconemella De Grisse and Loof, 1965 (Nematoda: Criconematidae)

The ring nematode genus Xenocriconemella De Grisse and Loof, 1965 comprises only one nominal species, Xenocriconemella macrodora (Taylor, 1936) De Grisse and Loof, 1965. The initial objective of the present study was to investigate the morphological-morphometric and molecular diversity of 28 X. macrodora populations in the Iberian Peninsula associated with tree forests (mainly Quercus spp.). However, a detailed integrative taxonomic analysis (morphological-morphometric and molecular data) from each population and analysis of this data using principal component analysis (PCA) for morphometric data (including these 28 populations and other 25 X. macrodora populations around the world) and molecular and phylogenetic species delimitation methods revealed that X. macrodora forms a species complex. This species complex is composed by species that are morphometricly and morphologically similar, but clearly different at the molecular level. Three new species are described applying integrative taxonomy, namely as Xenocriconemella iberica sp. nov., Xenocriconemella paraiberica sp. nov. and Xenocriconemella pradense sp. nov. However, the molecular diversity of this species in USA and Italy confirmed that additional species are likely present in this species complex, and the diversity of this group may be higher than expected. The study of X. macrodora topotypes can clarify the position of this species using molecular markers under an integrative approach.

Description and molecular characterization of Trachactinolaimus persicus sp. n. from Iran (Nematoda, Dorylaimida, Actinolaimidae), with new insights into the taxonomy and evolutionary relationships of the genus

A new species of the free-living nematode genus Trachactinolaimus, collected in natural habitats of northern Iran, is described, including morphological and molecular (28S-rDNA) data. Trachactinolaimus persicus sp. n. is characterized by its 1.95-2.44 mm long body, lip region weakly offset by depression and 18-20 μm wide, odontostyle 25-27 μm long, neck 540-636 μm long, pharyngeal expansion occupying one-half of the total neck length, bipartite uterus 2.6-3.9 body diameters long, vulva (V = 49-53) pore-like, tail long and filiform in both sexes (174-223 μm, c = 10.0-13.4, c' = 5.9-7.0 in females, 165-196 μm, c = 10.7-13.8, c' = 4.6-5.8 in males), spicules 68-75 μm long, and 12-14 almost contiguous ventromedian supplements with hiatus. Molecular data supports the monophyly of the genus and the hypothesis that Dorylaimidae are the sister group of actinolaims. The taxonomy of Trachactinolaimus is updated, including diagnosis, list of species, key to their identification, and a compendium of their main morphometrics. Dominiactinolaimus is regarded as its junior synonym.

Description of Acromoldavicus xerophilus n. sp. (Nematoda, Rhabditida, Elaphonematidae) from the southern Iberian Peninsula, including a key to species of the genus

A new species of the genus Acromoldavicus is described from coastal sand dunes and sandy soil in the southeast of the Iberian Peninsula. Acromoldavicus xerophilus n. sp. is characterized by its 557-700 μm body length, cuticle tessellated, lip region with three pairs of expanded lips bearing a large labial expansion, primary axils bearing guard processes with two different morphology, secondary axils lacking guard processes, stoma short and tubular with prostegostom bearing prominent rhabdia directed towards the stoma lumen, female reproductive system monodelphic-prodelphic, post-vulval sac 0.6-0.9 times body diameter, rectum very large, female tail short with biacute terminus and males unknown. The description, light micrographs, scanning electron microscope images, illustrations, and molecular analyses are provided. Molecular analyses (based on 18S and 28S rDNA) revealed its relationship with some species of the genera Cephalobus (18S tree), Nothacrobeles, Paracrobeles, and Spinocephalus (28S tree). Keys to species identification of this genus are also included.

Integrative taxonomy of Metastrongylus spp. in wild boars from Brazil

BACKGROUND

Wild boars (Sus scrofa) may cause substantial damage to crops and can spread zoonotic parasites to domestic animals, posing a risk to health and animal production. Metastrongylus spp. can negatively affect the wild boar population, increasing piglet mortality. In addition to that, studies with Metastrongylus genetic characterization are still scarce in Brazil. The present study aims to characterize Metastrongylus spp. from wild boars hunted in the states of São Paulo, Paraná, and Rio Grande do Sul, Brazil, using traditional morphological description and DNA sequences in an integrative taxonomic approach.

METHODS

After nematode collection from 58 wild boars, the parasites were morphologically identified and genetically characterized by the amplification of 18S ribosomal DNA (rDNA), 28S rDNA, internal transcribed spacer (ITS) region, and cox-1 mitochondrial DNA (mtDNA). Descriptors of infection were determined and Pearson's Chi-square test was applied to compare the prevalence of infections among the identified parasite species, host age group (juveniles and adults), and sex. The Mann-Whitney U test was performed to compare the mean intensity between the age groups and sex.

RESULTS

Metastrongylus salmi, Metastrongylus apri, and Metastrongylus pudendotectus were identified in 77.6% (45/58) of the necropsied wild boars. Metastrongylus salmi was the most prevalent and abundant species (70.7%, 11.1), followed by M. pudendotectus (18.9%, 4.3) and M. apri (17.2%, 2.2). Metastrongylus pudendotectus showed the highest mean intensity and range (25.2, 1-93), followed by M. salmi (15.7, 1-58) and M. apri (12.6, 3-27). We found a significantly higher prevalence of Metastrongylus spp. and M. salmi in adult wild boars, probably associated with a more prolonged time of exposure to intermediate host species. The phylogenetic analysis revealed that ITS2 region and cox-1 mtDNA are the most suitable genetic markers for Metastrongylus species characterization. Genetic variability between M. apri and M. salmi isolates was verified.

CONCLUSIONS

We expand the knowledge about the Metastrongylus community in the non-captive wild boar population from Brazil as well as the importance of this exotic species in the maintenance of Metastrongylus spp. in its areas of occurrence. The novel genetic sequences obtained may help further studies to understand the genetic diversity in other nematode populations from Brazil and other countries.

Bursaphelenchus mucronatus (Nematoda: Parasitaphelenchidae) associated with Monochamus galloprovincialis from Bosnia and Herzegovina and Georgia

Bursaphelenchus mucronatus was detected in association with the pine sawyer beetle (Monochamus galloprovincialis) during the implementation and testing of cross traps with insect attractants as an efficient tool for detection survey for pine wood nematode (Bursaphelenchus xylophilus) in Bosnia and Herzegovina and Georgia in 2017 and 2018, respectively. This nematode was characterized by morphological, morphometric and molecular features. This is the first report of B. mucronatus in association with a M. galloprovincialis in Bosnia and Herzegovina and in Georgia.

Morphological and Molecular note on the identity of Mylonchulus sigmaturus Cobb, 1917 (Nematoda: Mylonchulidae) from Pakistan

A species of predatory nematode, Mylonchulus sigmaturus Cobb, 1917, was recovered around the soil and roots of banana plants (Musa paradisiaca) from four different localities of Pakistan. The male of this species represents a new record from Pakistan. Morphological and morphometric data of the species have been contributed along with the molecular study. The phylogenetic analysis using 18S rDNA placed the Pakistani populations of M. sigmaturus with the same species in a clade with 100 posterior probabilities. The first input of 28S rDNA data placed Pakistani M. sigmaturus in a separate clade with 100 posterior probability support, however close with Prionchulus punctatus (Cobb, 1917) Andrássy, 1958 and Clarkus papillatus (Bastian, 1865) Jairajpuri, 1970.

Morphological and Molecular Characterization, Including Parasitic and Pathogenic Studies of a New Spherical Cyst Nematode Species, Globodera vulgaris n. sp. (Nematoda: Heteroderidae), Associated with Potatoes in China

In this study, a new spherical cyst nematode belonging to the genus Globodera, herein described as Globodera vulgaris n. sp., was extracted from the roots and rhizosphere soil of potato and circumjacent weeds belonging to different families in three provinces in southwest China. The new species was characterized by 8 to 24 ridges between the anus and fenestra and an average Granek's ratio of 2.8 to 3.8 in cysts, a head with three to four annules, a dorsal knob anteriorly projected, ventral knobs round or anteriorly projected in second stage juveniles, a head with three to five annules, a short spicule with an average length of less than 30.0 μm, and a developed velum in males. Pathogenicity tests showed that G. vulgaris n. sp. infected potato but did not damage or affect the potato yield compared with the control, and it parasitized tomato with a low reproduction rate (RF < 1) while it did not parasitize tobacco (RF = 0). The new species was closely related to G. rostochiensis, based on molecular diagnostic marker sequences and constructed phylogenetic analysis, based on internal transcribed spacers of ribosomal DNA, large-subunit rDNA, and small-subunit rDNA. However, the new species exhibited differences from G. rostochiensis in terms of morphological characteristics, a wide host preference, lack of damage to hosts, and an egg-hatching rate induced by hatching factors.

Transcriptomics of Cruznema velatum (Nematoda: Rhabditidae) with a redescription of the species

Cruznema velatum isolated from soil in a chestnut orchard located at Guangdong province, China, is redescribed with morphology, molecular barcoding sequences, and transcriptome data. The morphological comparison for C. velatum and six other valid species is provided. Phylogeny analysis suggests genus Cruznema is monophyletic. The species is amphimix, can be cultured with Escherichia coli in 7-9 days from egg to egg-laying adult, and has a lifespan of 11 to 14 days at 20°C. The transcription data generated 45,366 unigenes; 29.9%, 31.3%, 24.8%, and 18.6% of unigenes were annotated in KOG, SwissProt, GO, and KEGG, respectively. Further gene function analysis demonstrated that C. velatum share the same riboflavin, lipoic acid, and vitamin B6 metabolic pathways with Caenorhabditis elegans and Pristionchus pacificus.

A Blind-Identification Test on Criconema annuliferum (de Man, 1921) Micoletzky, 1925 Species Complex Corroborate the Hyper-Cryptic Species Diversity Using Integrative Taxonomy

Ring nematodes are obligate ectoparasites on crops and natural herbaceous and woody plants, and some species are of economic importance and cause damage to roots of several crops. Recent integrative taxonomical analyses recognized the existence of two cryptic species within the Criconema annuliferum morphotype in Spain. In this study, we corroborated that morphometric, morphological and a multi-locus analysis (including the ribosomal markers D2-D3 expansion segments of 28S rRNA, ITS rRNA, 18S RNA, and the mitochondrial DNA cytochrome oxidase I gene) identified a new lineage clearly separated from C. annuliferum, C. paraannuliferum and C. plesioannuliferum. The new lineage was described herein as Criconema pseudoannuliferum sp. nov., confirming that C. annuliferum species complex species complex comprises a hyper-cryptic species complex. This research analysed soil samples from the rhizosphere of maritime pine (Pinus pinaster Ait.) forests in Bermeja-Crestellina Mountain, located at the western part of Málaga province, southern Spain. The integrative taxonomical analyses revealed the occurrence of a new cryptic species identified using females, males and juveniles with detailed morphology, morphometry and molecular markers, described herein as Criconema pseudoannuliferum sp. nov. All molecular markers (D2-D3, ITS, 18S and COI) were obtained from the same individual that was also used for morphological and morphometric analyses. This research demonstrated the hidden diversity within the C. annuliferum species complex species complex can reach to four lineages under ribosomal and mitochondrial gene markers for one morphospecies group, which includes four species, viz. C. annuliferum, C. paraannuliferum, C. plesioannuliferum, and C. pseudoannuliferum sp. nov. Criconema pseudoannuliferum sp. nov. was detected in moderate soil density in two maritime pine forests (5 and 25 nematodes/500 cm³ of soil) suggesting that does not cause damage to maritime pine.

New Records of Ditylenchus Species from Southern Alberta, Canada

The presence of plant-parasitic nematodes (PPNs) in cultivated areas is a limiting factor in achieving marketable crop yield. To control and alleviate the effects of these nematodes and determine appropriate management strategies, species-level identification is crucial. Therefore, we conducted a nematode diversity survey, which resulted in the detection of four Ditylenchus species in cultivated areas of southern Alberta, Canada. The recovered species had six lines in the lateral field, delicate stylets (>10 µm long), distinct postvulval uterine sacs, and pointed to rounded tail tips. The morphological and molecular characterization of these nematodes revealed their identity as D. anchilisposomus, D. clarus, D. tenuidens and D. valveus, all of which are members of the D. triformis group. All of the identified species were found to be new records in Canada except for D. valveus. Accurate Ditylenchus species identification is crucial because false-positive identification can result in the implementation of quarantine measures over the detected area. Our current study not only documented the presence of Ditylenchus species from southern Alberta, but also described their morpho-molecular characteristics and subsequent phylogenetic relationships with related species. The results of our study will aid in the decision on whether these species should become a part of nematode management programs since nontarget species can become pests due to changes in cropping patterns or climate.

Meloidogyne paramali n. sp. (Nematoda: Meloidogyninae) and First Report of M. marylandi in maple and yacca tree from Japan

Meloidogyne paramali n. sp. was detected from Japanese maple trees (Acer palmatum) from Chiba, Japan during quarantine inspections in China. This species is characterized by second-stage juveniles (J2) with short tail length 32.2 (24-36.8) μm, finely rounded to broadly pointed tail terminus with extremely short hyaline tail terminus 4.3 (3.0-4.9) μm; perineal patterns of females characterized by an oval or irregular appearance, with round and low dorsal arch, and fine and smooth striae. M. paramali n. sp. is very similar to M. mali in that the perineal pattern has fine, smooth striae and both J2 have a short tail, but it can be distinguished from the latter by perineal pattern of the female (lateral field distinct vs. indistinct), shorter J2 hyaline tail terminus (4.3 [3.0-4.9] μm vs. 8.2 [4.8-12.7] μm, and by J2 tail with finely rounded to broadly pointed tail terminus, never sharply pointed vs. finely rounded and almost pointed. The polytomous key codes of the new species are as follows: Female: A21, B2, C32, D4; Male: A21, B3, C2, D1, E2, F2; J2: A2, B23, C43, D34, E12, F34. Detailed phylogenetic analysis based on partial 18S, ITS, D2-D3 28S, and partial mtCOI sequences also confirmed it as a new species, which is very close to M. mali and M. vitis and forms molecular group VIII. M. marylandi and other Meloidogyne species detected from plants from Japan in China are also discussed.

Epidemiology and Integrative Taxonomy of Helminths of Invasive Wild Boars, Brazil

Wild boars (Sus scrofa) are a significant invasive species in Brazil. We evaluated the helminth diversity of 96 wild boars in São Paulo state. Helminth infection descriptors were calculated, the species were identified and their 18S, 28S rDNA and internal transcribed spacer (ITS) regions were amplified for phylogenetic analyses. Ascarops strongylina, Strongyloides ransomi, Globocephalus urosubulatus, Oesophagostomum dentatum, Trichuris suis, Metastrongylus salmi, Metastrongylus pudendotecus, Ascaris suum and Stephanurus dentatus and Macracanthorhynchus hirudinaceus were identified. Globocephalus urosubulatus had the highest prevalence and mean abundance, and most animals had mixed infections with three parasite species. There was no association between parasite intensity and prevalence and host sex and body condition index (p > 0.05). Novel DNA sequences were obtained from G. urosubulatus, A. strongylina, and S. dentatus. This is the first study on the helmint diversity of non-captive wild boars in Brazil, and the first report of the occurrence of M. hirudinaceus, G. urosubulatus and S. dentatus in Brazilian wild boars. Non-captive wild boars of São Paulo State did not act as capture hosts for native helminth species but maintained their typical parasites, common to domestic pigs. They may act as parasite dispersers for low-tech subsistence pig farming and for native Tayassuidae.

Pratylenchus Araucensis (Rhabditida: Pratylenchidae) a Widely Distributed Nematode in Musa Spp. from Colombia

Pratylenchus is one of the most limiting nematodes of Musaceae production in the world. Knowledge of the nematode species is one of the requirements for its management in the field. This study aimed to identify up to the species level Pratylenchus populations associated with plantain and banana crops in the states of Caldas, Quindío, and Valle del Cauca in Colombia. In these regions, Pratylenchus has been reported to affect these crops in the past, but with records of the nematode only up to the genus level. For this purpose, five populations of Pratylenchus extracted from samples composed of roots and rhizospheric soil, four from plantain and one from banana, were identified through morphological, morphometric, and molecular analysis (sequencing of the D2-D3 of rRNA and cytochrome oxidase subunit I of mtDNA). All populations were identified as P. araucensis, a species reported previously in eastern Colombia, and one that the present study found in the center and southwest of the country, indicating that this species of nematode is widely distributed in the Musaceae-producing areas of Colombia. The present study reports the first COI mtDNA sequences for this species of nematode.

Description of Xiphinema pupureum n. sp. (Nematoda: Longidoridae), a new Xiphinema americanum group species detected from the rhizosphere of Ilex purpurea from Japan

A new species of Xiphinema americanum group was recovered in the rhizosphere of holly (Ilex purpurea) imported from Japan. It is described and illustrated in the present study as X. purpureum n. sp. The new species is characterised by moderately long females 2267 (2115-2550) μm, round lip region slightly offset from the rest of the body, 103.5 (98.5-109.0) μm long odontostyle, genital branches without discernible endosymbiotic bacteria, vulva located at 54.1 (51.6-57.1)% of the body, tail 30 (24.3-33.4) μm long with a broadly rounded terminus, male absent and four juvenile developmental stages. The polytomous codes of the new species are as follows: A4/5, B2/3, C1/2, D2/3, E3, F1, G1, H2, I1/2/3. The new species was molecularly characterised using near full length 18S, ITS1, and 28S D2-D3 regions of rRNA, and mitochondrial cytochrome c oxidase subunit I gene sequences. The phylogenetic analyses placed X. purpureum n. sp. with X. americanum group species, particularly with X. brevicolle complex species. This is the third X. americanum group species described from Japan.

Comparative morphological and molecular analyses of Acrobeloides bodenheimeri and A. tricornis Cobb, 1924 (Rhabditida, Cephalobidae) from Tunisia

Four populations of Acrobeloides nematodes were isolated from Tunisian soils. Based on morphological and morphometric data, two populations, TC9 and HWO, were identified as A. tricornis and the other two, TC7 and K18g, as A. bodenheimeri. Acrobeloides tricornis is distinguished from its closely related species by its high labial probolae with arcuate termini, inconspicuous post-uterine sac, and five lateral incisures, while A. bodenheimeri is distinguished from other acrobeloids by having a low and rounded labial probolae, distinct post-uterine sac, five lateral incisures, and vulva frequently with vaginal plug. The A. tricornis and A. bodenheimeri reported in this study are distinguished by the shape of labial probolae (high with acute distal part vs low and rounded), post-uterine sac (inconspicuous vs distinct), position of the reproductive system with respect to the intestine (sinistral vs dextral), vulva with vaginal plug (present vs absent) and some morphometric characters (such as body length). Further, these species were also molecularly characterised using the sequences of the D2-D3 region of the 28S rRNA gene, the 18S rRNA gene, the ITS rRNA gene, and of the mitochondrial cytochrome c oxidase subunit I (mtCO1) gene. Phylogenetic trees using ribosomal RNA gene sequences clearly separate species of the ‘Maximus’ group, but these sequences appear to be identical in several other Acrobeloides species, and thus are unlikely to be useful as molecular markers for species-level molecular identification in the genus Acrobeloides. The mtCO1 gene sequences of two A. tricornis populations differ in 58 and 64 nucleotide bases from A. varius and A. nanus, respectively, indicating that the mtCO1 gene sequences have greater phylogenetic resolving power than nuclear rRNA gene sequences, and that this gene marker can differentiate closely related species in the genus Acrobeloides.

Description of Hemicycliophora geraerti n. sp. (Tylenchida: Hemicycliophoridae) associated with Prunus persica L. from China

Hemicycliophora species are migratory root ectoparasites of higher plants, commonly known as sheath nematodes. The present study describes a new species, Hemicycliophora geraerti n. sp., recovered from the rhizosphere of peach tree (Prunus persica) in Zhejiang Province, China. This species is characterised by a cuticular sheath loosely fitting to the body, a lip region slightly set-off with body contour bearing 3-4 annuli, oral plate narrow, ovate, and non-protruding, amphidial apertures plugged, dorsoventrally flanked in the first lip annulus, stylet 110 (103-116) μm long and flexible, excretory pore located 4-7 annuli posterior to the base of the pharyngeal bulb; vulval lips modified with a small vulval sleeve, anus located 16 (13-21) annuli posterior to vulva, tail elongated, having a narrowly rounded slightly offset spike. The molecular characterisation and phylogenetic analyses based on D2-D3 expansion segments of the 28S rRNA, ITS rRNA, and COI mtDNA gene indicated the unique status and support the novelty of this population of Hemicycliophora, therefore herein described as H. geraerti n. sp.

First Report of Tripylina Zhejiangensis Associated with Grassland in South Africa

Specimens of Tripylina zhejiangensis, collected from natural grass in the Free State Province of South Africa, were identified morphologically and molecularly. This species characterizes by body length (1037 - 1128 μm), a = 27.3 - 35.3, b = 5.1 - 5.6, c = 16.1 - 19.8, c' = 2.5 - 3.4, V = 62 - 65. Molecular analysis was also undertaken, based on the 28S rDNA regions, and confirmed this population as T. zhejiangensis. Phylogenetic analysis using the Bayesian inference method, places this population in a clade close to T. zhejiangensis with a 1.00 posterior probability value. According to the knowledge, this is the first report of the genus Tripylina and its species from South Africa. Besides, this is the second report of T. zhejiangensis worldwide after the original description from China.

DNA Barcoding and Morphometry Reveal Further Cryptic Bio-Diversity within the Pin Nematode Genus Paratylenchus (Nematoda: Tylenchulidae)

Paratylenchus species are obligate ectoparasitic nematodes on cultivated and wild herbaceous and woody plants occupying numerous soil categories. Several species may cause damage to several crops (viz. P. dianthus, P. enigmaticus, P. microdorus, P. hamatus and P. epacris on carnation, lettuce, rose and walnut, respectively). This investigation proves and emphasizes the relevance of applying integrative taxonomy for the accurate detection of Paratylenchus species in mountainous wild environments in the Malaga province, Southern Spain. This research analyzed 45 soil samples of maritimus pine and one of green heather in southern Spain and identified fourteen Paratylenchus species, two of them are described herein as new species (P. paraaonli sp. nov., P. plesiostraeleni sp. nov.), six of them were first reports for Spain (P. canchicus, P. nainianus, P. neonanus, P. salubris, Paratylenchus sp. 2 SAS, and P. wuae), and six species (P. caravaquenus, P. microdorus, P. nanus, P. neoamblycephalus, P. sheri, and P. variabilis) have been already reported in Spain. Accordingly, these data increase the biodiversity of pin nematodes in Spain comprising a total of 47 species (33.1% out of 142 total species of this genus). Phylogenetic analyses based on ribosomal and mitochondrial markers (D2-D3, ITS, and partial COI) resulted in a consistent position for the newly described Paratylenchus species in this study (P. plesiostraeleni sp. nov., P. paraaonli sp. nov.). Paratylenchus plesiostraeleni sp. nov. grouped in a separated subclade as unequivocal species from the P. straeleni-complex species (including P. straeleni and P. parastraeleni), and P. paraaonli sp. nov. clustered with P. vitecus, but clearly separate from this species. This study indicates that Paratylenchus species diversity in natural environments may be higher than expected, and this study may help in accurate identifications.

Identification and a culture method for a Helicotylenchus microlobus from tomato in China

Background

The nematodes of the genus Helicotylenchus are root parasites of a wide variety of plants, and certain species can cause serious damage to their hosts. During a survey of the plant-parasitic nematode associated with tomato, a population of Helicotylenchus was collected from tomato roots and soil samples. Thus, one of the objectives of the study was to confirm the specie of Helicotylenchus obtained from the tomato samples based on morphological and molecular characteristics. In addition, a mass pure culture of plant-parasitic nematodes is key to pathogenicity studies and many other biological studies. However, a successful mass rearing method for Helicotylenchus has not been reported. Thus, the other objective of the study was to establish a method of culturing Helicotylenchus.

Results

Based on both the morphological characteristics and molecular analysis of the internal transcribed spacer (ITS) and D2-D3 expansion region of 28S ribosomal RNA (rRNA) sequences the specimens were identified as Helicotylenchus microlobus. Phylogenetic analysis with the rRNA sequences of the ITS and 28S D2-D3 regions was consistent with molecular identification, suggesting this population formed a highly supported clade with other H. microlobus populations. Additionally, a method for culture of H. microlobus on carrot disks was established, and the effect of temperature on the reproduction rate (Rr) of H. microlobus was investigated. The optimum temperature for culturing H. microlobus on carrot disks was 27.5 °C and, after inoculation with 30 females of H. microlobus at 27.5 °C for 90 days, Rr reached 406.

Conclusions

To our knowledge, this is the first detailed description of H. microlobus from tomato in China. This study also demonstrated that the carrot disk method is suitable for the culture of H. microlobus. This study lays a foundation for other related research on H. microlobus, and has significance for the study of Helicotylenchus.

Phylogenetic position of Ptychaphelenchus eucalypticola Hodda, 2009 within the Aphelenchoidoidea Skarbilovich, 1947 (Siddiqi, 1980) inferred from partial 18S and 28S rDNA gene sequences

At the time of description, the morphology of Ptychaphelenchus eucalypticola Hodda, 2009 indicated it could be assigned to either the Aphelenchoididae Skarbilovich, 1947 (Paramonov, 1953) or the Parasitaphelenchidae Ruehm, 1956 (Siddiqi, 1980) within the Aphelenchoidoidea Skarbilovich, 1947 (Siddiqi, 1980). Although P. eucalypticola was, tentatively, and remains assigned to the Aphelenchoididae, its relationships with other aphelenchoids have not been reassessed, and no molecular data were previously available for this species. We re-collected P. eucalypticola from its type host and locality, Eucalyptus macrorhyncha F. Muell. ex Benth., from Mount Ainslie, ACT, Australia. We performed Bayesian inference and maximum likelihood analyses of a concatenated 18S + 28S rDNA gene sequence dataset to determine the position of P. eucalypticola within the Aphelenchoidoidea, followed by 18S and 28S single-gene analyses to further assess relationships between this species and an expanded set of close relatives. All analyses indicated P. eucalypticola is correctly assigned to the Aphelenchoididae, in a clade comprising all species of Ficophagus Davies & Bartholomaeus, 2015 and some species presently assigned to Aphelenchoides Fisher, 1894, sister to Martininema Davies & Bartholomaeus, 2015 and additional species of Aphelenchoides. Our 18S single-gene analyses did not resolve the position of P. eucalypticola relative to Aphelenchoides and Ficophagus; however, our 28S single-gene analyses indicated a sister relationship between P. eucalypticola and Ficophagus. This sister relationship is plausible as the former species shares many characteristics with species of the latter genus; however, there are sufficient morphological differences to consider P. eucalypticola as representative of a distinct lineage within the Aphelenchoidoidea.

Morphological and molecular characterisation of Talanema ibericum sp. n. (Dorylaimida, Qudsianematidae) from southern Iberian Peninsula

A new species of the genus Talanema, T. ibericum sp. n., collected in natural areas of southeastern Iberian Peninsula, is characterised, including morphological description, line, LM and SEM illustrations, and molecular (18S, D2-D3 28S rDNA sequences) study. The new species is distinguished by its 1.27-1.59 mm long body, lip region offset by constriction and 14-16.5 μm wide with perioral liplets, odontostyle 16.5-19.5 μm long, neck 285-359 μm long, pharyngeal expansion occupying 42-48% of the total neck length, uterus tripartite and 147-228 μm long or 2.6-4.0 body diam., vulva transverse (V = 53-59), presence of cuticular irregularities at both sides of vulva, female tail conical with a dorsal concavity (27-40 μm, c = 36-54, c′ = 1.0-1.3), male tail short and rounded conoid (24 μm, c = 66, c′ = 0.8), spicules 58 μm long, and 17 almost contiguous ventromedian supplements with hiatus. Morphological and molecular data reveal that the new species is similar to (but easily separable from) T. baqrii, with which it is compared. Present results support the monophyly of the genus Talanema.

First Report of Root-knot Nematode, Meloidogyne Graminicola on Brassica Juncea in China

In southern China, the staple food rice (Oryza sativa) field is commonly rotated with brown mustard Brassica juncea. Root-knot nematodes (RKNs) are a major threat to rice production. From 2019 to 2021, B. juncea in 56 fields from 26 counties in Guangxi Province were observed with symptoms of leaf yellowing, stunting, and several hook-shaped galls on the roots. Females and egg masses of Meloidogyne sp. were found within the galls. The females, males, and second-stage juveniles (J2s) were collected, and identified with morphological and molecular characteristics and female perineal patterns. Brassica juncea was transplanted in pots and a pathogenicity test was conducted to confirm the species as Meloidogyne graminicola. In China, this is the first record of a natural infection of mustard with M. graminicola, and this finding has great importance for Chinese mustard production, since this nematode may damage mustard plants and become an additional problem for this crop.

Distribution, Ecological Factors, Molecular Diversity, and Specific PCR for Major Species of Pin Nematodes (Paratylenchus spp.) in Prunus Plantations in Spain

This study aimed to evaluate the prevalence and distribution of Paratylenchus species in the main areas of Prunus spp. production in Spain, their ecological constraints, and new molecular tools for the specific identification of major species. Pin nematodes are recognized as plant-parasitic nematodes with a wide host range and global distribution. Therefore, understanding the environmental and agronomic factors involved in their distribution is critical to design environmental and sustainable management strategies to reduce plant damage. A total of 219 sampling sites were surveyed and 12 Paratylenchus species were identified based on an integrative taxonomic approach (P. baldaccii, P. enigmaticus, P. goodeyi, P. hamatus, P. holdemani, P. indalus, P. israelensis, P. pedrami, P. tateae, P. tenuicaudatus, P. veruculatus, and P. zurgenerus). The most common pin nematode was P. hamatus, followed by P. tenuicaudatus. Nematode abundance was influenced by climatic characteristics, soil chemical properties, and agronomic management practices. Nine explanatory variables were selected as the most strongly associated with Paratylenchus distribution. Specifically, P. tenuicaudatus was significantly correlated with soil chemical characteristics, such as pH and carbon, sulfur, and sodium content, whereas P. goodeyi was closely related to fields with <10 years of almond cultivation. Species-specific PCRs were developed for P. hamatus and P. tenuicaudatus and their validity was evaluated studying the molecular variability of these species and against other Paratylenchus species.

First report of Longidorus leptocephalus Hooper, 1961 (Nematoda: Longidoridae) from Greece

Longidorid nematodes comprise more than 500 species, and Longidorus and Xiphinema are the most diversified, prevalent, and cosmopolitan genera within plant-parasitic nematodes. The genus Longidorus comprise a group of species, some of which are vectors of plant viruses. New sampling for needle nematodes was carried out in a grapevine area in Thessaloniki, northern Greece, and one nematode species of Longidorus (L. leptocephalus) was recovered. Nematodes were extracted from soil samples by modified sieving and a decanting method. Extracted specimens were processed using glycerol, mounted on permanent slides, and subsequently identified morphologically. Nematode DNA was extracted from individual, live specimens, and PCR (Polymerase Chain Reaction) assays were performed for D2-D3 expansion segments of 28S rRNA, ITS1 rRNA, and partial mitochondrial COI regions. Morphology and morphometric data obtained from this population were consistent with the original description and reported populations of L. leptocephalus. To our knowledge, this is the first report of L. leptocephalus in Greece and the second in the Mediterranean Basin after the record of the species from Slovenia, extending the geographical distribution of this species in Europe.

A Proposed New Species Complex within the Cosmopolitan Ring Nematode Criconema annuliferum (de Man, 1921) Micoletzky, 1925

Ring nematodes are obligate ectoparasites on cultivated and wild herbaceous and woody plants, inhabiting many types of soil, but particularly sandy soils. This study explored the morphometrical and molecular diversity of ring nematodes resembling Criconema annuliferum in 222 soil samples from fruit crops in Spain, including almond, apricot, peach and plum, as well as populations from cultivated and wild olives, and common yew. Ring nematodes of the genus Criconema were detected in 12 samples from under Prunus spp. (5.5%), showing a low to moderate nematode soil densities in several localities from southeastern and northeastern Spain. The soil population densities of Criconema associated with Prunus spp. ranged from 1 nematode/500 cm³ of soil in apricot at Sástago (Zaragoza province) to 7950 and 42,491 nematodes/500 cm³ of soil in peach at Ricla and Calasparra (Murcia province), respectively. The integrative taxonomical analyses reveal the presence of two cryptic species identified using females, males (when available), and juveniles with detailed morphology, morphometry, and molecular markers (D2-D3, ITS, 18S, and COI), described herein as Criconema paraannuliferum sp. nov. and Criconema plesioannuliferum sp. nov. All molecular markers from each species were obtained from the same individuals, and these individuals were also used for morphological and morphometric analyses. Criconema paraannuliferum sp. nov. was found in a high soil density in two peach fields (7950 and 42,491 nematodes/500 cm³ of soil) showing the possibility of being pathogenic in some circumstances.

Bursaphelenchus taedae sp. n. (Tylenchina: Aphelenchoididae) – a new species of the eggersi-group in Loblolly pine logs from the USA

Bursaphelenchus taedae sp. n. of the eggersi-group was detected in loblolly pine logs from the USA together with B. antoniae. It is characterised by a relatively small stylet with basal swellings, a lateral field with three lines, and the excretory pore located at the level of the nerve ring. The female has a very small extension of the anterior vulval lip over the vulva (= a ‘vulval flap’), a long PUS extending for 40.1-67.8% of vulva to anus distance, and hook-like tail conical, gradually tapering to a finely rounded or broadly rounded terminus. The male spicules are 17-22 μm long in chord, only slightly ventrally curved, condylus short, truncate, slightly dorsally bent to dorsally hooked, rostrum ca 3-4 μm long, close to the proximal spicule end, without cucullus. Seven genital papillae present. Bursaphelenchus taedae sp. n. can be distinguished from other species of the eggersi-group by morphological and molecular characters.

Description of Rotylenchus zhongshanensis sp. nov. (Tylenchomorpha: Hoplolaimidae) and discovery of its endosymbiont Cardinium

A new bisexual species of Rotylenchus is described and illustrated based on morphological, morphometric and molecular characterizations. Rotylenchus zhongshanensis sp. nov. is characterized by having a conoid lip region complying with the basic pattern for Hoplolaimidae, but with pharyngeal glands slightly overlapping intestine dorsally and cuticle thickened abnormally in female tail terminus. Females have robust stylet (30.1-33.8 μm). The pharyngeal gland has short dorsal (11.2-16.8 μm) overlap on the intestine. The vulva is located at 48.0-56.5% of body length, and phasmids are pore-like, 4-6 annuli posterior to the anus. For males, phasmids are pore-like, 11-17 annuli posterior to cloaca. The spicules are ventrally arcuate (21.0-28.5 μm) with gubernaculum in 5-8 μm length. The rRNA and mitochondrial COI genes were successfully sequenced from the assembled whole-genome sequences of the new species, and were used for reconstructing the phylogenetic relationships of the new species. A new strain of cyto-endosymbiont Cardinium was also discovered from the genome sequences of R. zhongshanensis sp. nov. The 16S rRNA phylogeny analyses revealed that this new bacterial strain is closed to that from cyst and root-lesion nematodes.

Multigene phylogenetic analysis reveals non-monophyly of Anisakis s.l. and Pseudoterranova (Nematoda: Anisakidae)

The nematode genera Anisakis s.l. and Pseudoterranova (Anisakidae) include causative agents of anisakiasis and pseudoterranovosis, parasitic diseases resulting from eating undercooked or raw fish or squid. Species in both genera have thus attracted considerable attention especially in public health and taxonomic studies. The phylogenetic relationships of these genera within the subfamily Anisakinae, however, remain to be investigated with dense taxonomic sampling. In this study, we collected an anisakid third-stage larva, and identified it morphologically and molecularly as Pseudoterranova ceticola. Phylogeny of 15 anisakine species, including the newly collected specimen of Ps. ceticola, was reconstructed based on sequences of three mitochondrial (cox1, cox2, and 12S rRNA) and two nuclear (ITS and 28S rRNA) regions. The obtained tree suggested the non-monophyly of Anisakis s.l. and Pseudoterranova. Anisakis s.l. was divided into two groups, which are distinguished from each other by the shape of the ventriculus. Based on phylogenetic relationships and morphology, three species with a shorter ventriculus ("A." brevispiculata, "A." paggiae, and "A." physeteris) were assigned to the genus Skrjabinisakis, as recently proposed. Pseudoterranova ceticola was distantly related to the monophyletic Ps. decipiens species complex. Although the phylogenetic position of the type species Ps. kogiae has not been investigated due to a lack of sequence data, this species may morphologically and ecologically resemble Ps. ceticola, inferring a close kinship between the two species.

First Report of the Root-Knot Nematode Meloidogyne enterolobii infecting Acalypha australis in China

Copperleaf (Acalypha australis; Euphorbiaceae), widely cultivated in China, is a traditional Chinese herbal medicine that is used for clearing heat and detoxifying, astringency and hemostasis (Zhang and Zhang 1994). In September 2021, wild Asian copperleaf plants showed leaf yellowing in a corner outside a greenhouse (22°50' N; 108°17' E), Guangxi Province, China. Galls and egg masses were observed on the plant roots on approximately 60% of plants. Females and second-stage juveniles (J2) were dissected and extracted from roots with galls. The perineal pattern of females was dorsal-ventrally oval with low and round dorsal arches, lacking clear lateral lines. Morphological measurements of females (n=20; mean ± standard error) were body length (BL) 697.7 ± 17.3 μm, maximum body width (BW) 521.5 ± 18.3 μm, stylet length 14.8 ± 0.3 μm, and dorsal pharyngeal gland orifice to stylet base (DGO) 5.1 ± 0.2μm. J2s (n = 20) were vermiform, had a slender tail, with a tapering to rounded tip with distinct hyaline region at the tail terminus and had the following morphological measurements: BL 475.5 ± 32.7 μm, BW 16.7 ± 0.6 μm, stylet length 14.4 ± 1.4 μm, DGO 3.9 ± 0.1 μm, hyaline tail length 18.0 ± 0.6 μm, and tail length 50.1 ± 1.2 μm. These morphological characteristics fit the description for Meloidogyne enterolobii (Yang and Eisenback 1983). In order to confirm species identification, genomic DNA was extracted from 12 single J2 (Luo et al. 2020). Species identity was further explored by the rDNA-internal transcribed spacer (ITS) region using primers V5367/26S (Vrain et al. 1992), and the D2-D3 fragment of the 28S ribosomal RNA gene using primers D2A/D3B (De Ley et al. 1999). The sequences for the target genes were 733 bp (GenBank accession no. OM168996) and 734 bp (GenBank accession no. OM177195), respectively. Homologies were 99 to 100% identical with those in GenBank for known sequences of M. enterolobii. Furthermore, species identification was confirmed using PCR to amplify a portion of the rDNA-IGS2 with M. enterolobii-specific primers Me-F/Me-R (Long et al. 2006). Koch's postulates was tested in a greenhouse at 25 to 28˚C temperature. Eggs were multiplied on tomato in the greenhouse using a single egg mass hand-picked from originally natural infected A. australis roots. Fifteen A. australis seedlings maintained in 14.5-cm diameter and 10-cm high pots containing autoclaved sandy soil (sand/soil = 3:1), one seedling/pot, inoculated with 5,000 eggs/plant, and five noninoculated seedlings were used as controls. After 60 days, all inoculated plants showed galling root symptoms and the control plants displayed no symptoms. The reproduction factor (Rutter et al. 2021) on A. australis was 4.3. Furthermore, the morphological and molecular characterization of the nematode was identical to the original samples. To our knowledge, this is the first report of M. enterolobii infecting Asian copperleaf that is cultivated in 29 provinces/regions of China. The growers should be aware of this nematode and take measures to avoid spread and serious economic losses.

First report of Xiphinema ifacolum Luc, 1961 (Dorylaimida: Longidoridae) from Nigeria

A population of a species of dagger nematode (Xiphinema) belonging to the non-americanum group was recovered from the fields of kola nut (Cola sp.) in southern Nigeria. The morphological and morphometric data obtained from this population were consistent with the characteristics of the species Xiphinema ifacolum. In addition, molecular identification based on D2-D3 expansion segments of 28S rRNA and partial mitochondrial COI gene regions confirmed its identity. According to our knowledge, this is the first report of the species from Nigeria, and the second report from Africa, after the original description from Foulaya, Guinea.

Detection and identification of Ektaphelenchoides diversislocis sp. n. isolated from Pinus woodlands of China and Japan

Understanding the occurrence and distribution of parasitic nematodes is crucial – some are economic pests, and some are important predators of their insect associates. In our recent nematode inventory survey, two populations of an ektaphelechid nematode were detected in the branches of Pinus trees; later the same nematode population was detected in plant quarantine examinations of wood packaging material imported from Japan. The species was processed and identified as Ektaphelenchoides diversislocis sp. n. The new species can be characterised by having three lateral lines, stylet long and tripartite, excretory pore at the level of nerve ring, comparatively longer post-vulval uterine sac, indistinct rectum and anus. Female posterior body region conical, gradually narrowing, like a mucron or filiform. Male spicule with well-developed condylus, triangular rostrum, and cucullus absent. The species is morphologically and molecularly close to E. compsi. The new species was characterised with near full-length 18S, 28S D2-D3 regions, and internal transcribed spacer (ITS) rRNA genes and mitochondrial cytochrome oxidase I (COI) gene sequences. The species within the Ektaphelenchoides genus are considered to have predatory roles against insect associates; therefore, the discovery of E. diversislocis sp. n. from local and foreign woodlands warrants increased sampling and research attention.

A new needle nematode, Longidorus maginicus n. sp. (Nematoda: Longidoridae) from southern Spain

During nematode surveys in natural vegetation in Sierra Mágina, Jaén province, southern Spain, a Longidorus species closely resembling Longidorus carpetanensis was found, but application of integrative taxonomic approaches clearly demonstrated that it is a new species described herein as Longidorus maginicus n. sp. The new species is amphimictic, characterized by a moderately long body (4.2-5.2 mm); lip region anteriorly flattened, slightly separated from the rest of body by a depression, 9.0-11.0 μm wide and 3.5-6.0 μm high; amphidial fovea not lobed; relatively short odontostyle (61.0-70.5 μm); guiding ring located 23.5-27.0 μm from anterior end; vulva located at 42.0%-51.3% of body length; female tail 39.0-61.0 μm long, conoid, dorsally convex with rounded terminus (c' = 1.3-2.1), with two or three pairs of caudal pores; and males common (1:2 ratio males:females), with moderately long spicules (39.0-48.5 μm) and 1 + 6-9 ventromedian supplements and three juvenile developmental stages. According to the polytomous key, codes for the new species are (codes in parentheses are exceptions): A2-B1-C2-D2-E1-F2(3)-G2-H5(4)-I2-J1-K6. The results of molecular analysis of D2-D3 28S, internal transcribed spacer region, partial 18S rDNA, and cytochrome oxidase c subunit 1 (coxI) gene sequences further characterized the new species status, and separated it from L. carpetanensis and other related species.

Morpho-Molecular and Ultrastructural Characterization of Discocriconemella parasinensis n. sp. from Zhejiang Province, China

During a recent inventory survey of the nematofauna of tea plantation at Zhejiang Province, China, Discocriconemella parasinensis n. sp. was detected in the rhizosphere of Camellia sinensis. The new species can be characterized by having the uninterrupted rounded labial disc, en face view showing rectangular-rounded labial plate without submedian lobes, R = 82.6 (80–86), Rex = 22 (21–23), stylet length of 68.3 (59–76) μm, excretory pore located 1–2 annuli posterior to the esophageal bulb, vulva open, postvulval body elongated conoid, and tail conoid with bilobed terminus. Morphologically, the species shares the same lip-type with D. discolabia, D. mauritiensis, D. mineira, D. perseae, and D. sinensis. Phylogenetic relationships of the new species based on D2–D3 expansion segments of 28S, ITS, and 18S rRNA genes revealed that D. parasinensis n. sp. formed a separated clade from other criconematid species, thereby supporting its status as a new species of the genus. The new species showed close phylogenetic relationships with Criconemoides geraerti.

Redescription of Diastolaimus grossus (Truskova & Eroshenko, 1977) Andrássy, 1984 (Rhabditida, Chambersiellidae) from Europe and comments on its phylogenetic position

Two populations of the species Diastolaimus grossus have been obtained from bark of trees in Bosnia and Herzegovina and the Czech Republic. The species is described and characterized in detail using morphological techniques (light and electron scanning microscopy) and morphometrical (Gower General Similarity coefficient of morphological characters) and molecular analyses, including phylogenetic analysis of all related and already sequenced species of the family Chambersiellidae. Morphological and molecular analyses, based on 18S and 28S ribosomal DNA sequences, show that the family Chambersiellidae is polyphyletic, being the subfamily Chambersiellinae related with Cephalobomorpha and Tylenchomorpha, and the subfamily Macrolaiminae is located into Panagrolaimomorpha. The genus Diastolaimus, previously belonging to Macrolaiminae, is transferred to Chambersiellinae. Diastolaimus mexicanus is proposed as a junior synonym of D. grossus.

Comparative study of three cryptic species of the genus Eucephalobus Steiner, 1936 with conoid-elongate tail and its relationship with the genus Pseudacrobeles Steiner, 1938 (Rhabditida, Cephalobidae)

Three cryptic species of the genus Eucephalobus, collected from coastal dunes of Spain and wet areas of California and Vietnam, are studied. The objective of this study is the differentiation of those species of the genus Eucephalobus with a long tail, which can be confused with each other and especially with Eucephalobus oxyuroides. These species are E. compsus, E. hooperi and E. panaxi. Furthermore, Pseudacrobeles unguicolis, which is also confused with these species, has been studied. This study provides detailed morphological and morphometrical characterisation for the three species of Eucephalobus, including light and scanning electron microscopy illustrations. Molecular characterisation of E. hooperi, E. mucronatus, E. striatus and Pseudacrobeles unguicolis is also presented.

Occurrence and Geographic Distribution of Plant-Parasitic Nematodes Associated with Citrus in Morocco and Their Interaction with Soil Patterns

Plant-parasitic nematodes (PPNs) are found in citrus plantations throughout the world, but they are considered to be the most problematic pest in Morocco. Citrus fruit quality and yield have been adversely affected by PPNs. Due to data unavailability of nematodes associated with citrus, a detailed survey was conducted in the main citrus-growing regions of Morocco during 2020–2021 to assess the occurrence, distribution, and diversity of PPNs associated with rhizospheres of citrus trees. In addition, some soil properties have also been assessed for their impact on soil properties. Plant-parasitic nematode diversity was calculated using two ecological indexes, the Shannon diversity index (H′) and the Evenness index (E). The collected soil and root samples were analyzed, and eleven genera and ten species of plant-parasitic nematodes were identified. The results show that the most predominant PPN species were Tylenchulus semipenetrans (88%), Helicotylenchus spp. (75%), Pratylenchus spp. (47%), Tylenchus spp. (51%), and Xiphinema spp. (31%). The results showed that PPN distributions were correlated with soil physicochemical properties such as soil texture, pH levels, and mineral content. Based on the obtained result, it was concluded that besides the direct effects of the host plant, physicochemical factors of the soil could greatly affect PPN communities in citrus growing orchards.

Phylum Nematoda: trends in species descriptions, the documentation of diversity, systematics, and the species concept

This paper summarizes the trends in nematode species description and systematics emerging from a comparison of the latest comprehensive classification and census of Phylum Nematoda (Hodda 2022a, b) with earlier classifications (listed in Hodda 2007).   It also offers some general observations on trends in nematode systematics emerging from the review of the voluminous literature used to produce the classification.   The trends in nematodes can be compared with developments in the systematics of other organisms to shed light on many of the general issues confronting systematists now and into the future.