Figure 4 - uploaded by Pablo Castillo
Content may be subject to copyright.
Scanning electron microscope photographs of Ditylenchus gigas n. sp. female (a–f) and male (g–i). (a) Anterior end; (b) en face view; (c) excretory pore; (d) vulva in ventral view; (e) female (left) and male (right) tails (anus opening arrowed); (f,i) lateral fields, showing four incisures; (g,h) anterior end in different views. Scale bars: a,b,f–h = 5 μm; c = 10 μm; d,e, i = 20 μm.
Source publication
Morphologial, biochemical, molecular and karyological analyses of different populations and races of the stem and bulb nematode Ditylenchus dipsaci have suggested that it represents a species complex, of which only D. dipsaci sensu stricto and its morphologically larger variant, known as the giant race of the stem and bulb nematode, are plant paras...
Contexts in source publication
Context 1
... rest of the body by a slight constriction. Under the light micro- scope, the lip region contour appears smooth in two-thirds anterior and with a basal annulus in the third posterior (Fig. 2h). In SEM view, labial area with quadrangular outline, showing incisures like incomplete annuli in submedial and subdorsal sectors of the first lip annulus (Fig. 4b), giving the appearance of a lip region composed of three to four annuli. Stoma opening pore- like, in the middle of a slightly raised, small and circular oral disc. Amphidial apertures often partially covered by debris, and therefore difficult to detect. Stylet delicate, conus 5AE5 ± 0AE2 (5-6) lm long, knobs distinctly sloping ...
Context 2
... ± 1AE3 (17AE5-21AE0) 18AE8 ± 0AE6 (18AE2-19AE6) 18AE6 ± 0AE7 (18AE0-19AE4) c' 5AE1 ± 0AE5 (4AE8-5AE4) 4AE6 ± 0AE3 (4AE1-4AE8) 5AE0 ± 0AE5 (4AE4-5AE6) a All measurements are in lm unless otherwise stated. b All other abbreviations used are defined by Siddiqi (2000). lines (Figs 2e and 3h), the inner two appearing sometimes faint and indistinct (Fig. 4f). Ovary mono-prodelphic, outstretched, 1084 ± 120 (868-1265) lm long, 63 ± 6AE6 (50-72) % of body length, with the apex of germinal zone sometimes reaching to middle of pharyngeal bulb. Spermatheca strongly elongated, 127 ± 22AE9 (98- 176) lm long, with its posterior end distant 174 ± 35AE6 (131-223) lm from vagina, usually filled with ...
Context 3
... 6AE6 (50-72) % of body length, with the apex of germinal zone sometimes reaching to middle of pharyngeal bulb. Spermatheca strongly elongated, 127 ± 22AE9 (98- 176) lm long, with its posterior end distant 174 ± 35AE6 (131-223) lm from vagina, usually filled with round sperm. Uterus with a quadricolumella, comprised of four rows of four cells each (Fig. 4e), followed by a proper uterus which swells near the vagina. Post-vulval uterine sac well developed, 2AE0 ± 0AE3 (1AE7-2AE5) times the vulva- anus distance. Tail elongate conoid, tapering posteriorly to a finely rounded terminus. Phasmids were seen in two specimens only, located at 63 and 76 lm from the tail ...
Context 4
... incisures similar to those of female were present in the first lip annulus (Fig. 4g,h). Lip region mostly smooth, with a barely distinct basal annulus. Sty- let delicate, conus 5AE2 ± 0AE3 (4AE7-5AE7) lm long; knobs small but distinct, 2AE8 ± 0AE3 (2AE3-3AE3) lm across. DGO 1AE5 ± 0AE3 (1AE3-2AE0) lm, 13AE2 ± 2AE3 (11-18) % of stylet length. Median bulb oval, measuring 17AE8 ± 2AE3 (12- 21) lm and 10AE7 ± 1AE5 (6AE5-13) ...
Context 5
... (11-18) % of stylet length. Median bulb oval, measuring 17AE8 ± 2AE3 (12- 21) lm and 10AE7 ± 1AE5 (6AE5-13) lm in longitudinal and cross diameter, respectively. Isthmus slender, 58AE5 ± 15AE5 (39-81AE5) lm long. Basal pharyngeal bulb usually pyriform, with short overlap over intestine (about 5-10 lm). Lateral field with four, smooth inci- sures (Fig. 4i). Testis well developed, 1128 ± 183 (888- 1373) lm long. Bursa leptoderan, extending anteriorly to cloaca for about 1AE5 the anal body width and covering about 72-76% of tail length. Spicules arcuate ventrad, slightly cephalated anteriorly. Gubernaculum simple, slightly thickened in the central ...
Similar publications
Rosas-Valdez, R., Choudhury, A. & Pérez-Ponce de León, G. (2011). Molecular prospecting for cryptic species in Phyllodistomum lacustri (Platyhelminthes, Gorgoderidae). —Zoologica Scripta, 40, 296–305.
Partial sequences of the 28S ribosomal RNA and cytochrome c oxidase I (COI) genes were compared among populations of a widely distributed and morphol...
Citations
... These sequences, and the available Ditylenchus species, were used to construct phylogenetic analyses. Outgroup taxa for each dataset were chosen following previously published studies (Giblin-Davis et al., 2010;Vovlas et al., 2011;Skwiercz et al., 2017;Xue et al., 2019). Multiple nucleotide sequence alignments of the different genes were made using the FFT-NS-2 algorithm of MAFFT V.7.450 (Katoh et al., 2019). ...
The present study describes two new Ditylenchus species, isolated from the growing medium of Rhododendron simsii imported from Japan, at the Ningbo plant quarantine laboratory, Ningbo, P.R. China. Ditylenchus parvicauda n. sp. is an amphimictic species. Females have six incisures in the lateral fields, a medium length slim body, a short delicate stylet with asymmetrical stylet knobs, the secretory-excretory (S-E) pore located posterior to the isthmus and in the anterior region of the basal pharyngeal bulb, a posteriorly located vulva (V = 80.9-83.0), post-uterine sac (PUS) tube-like, and the tail cylindrical, tapering gradually towards finely rounded terminus. Males are similar to females in general morphology and have 10.1-14.9 μ m long spicules. The second new species, D. gracicauda n. sp. is characterised by having a long and slender body, the presence of a vulval flap, four lines in the lateral field, a narrow and low lip region not offset, the S-E pore located posterior to the isthmus but not in the anterior region of the basal pharyngeal bulb, a posteriorly located vulva (V = 71.1-76.2), a short post-vulval uterine sac short (4.5-9.2 μ m), and the tail slender, tapering gradually towards finely rounded to wedge-shaped terminus. The two new species were also characterised molecularly using 18S, ITS and the D2-D3 expansion segments of 28S rRNA genes. Our phylogenetic analyses showed their independent place among available Ditylenchus species. Several Ditylenchus species are regulated pests, and the introduction of these species into a new environment may result in diseases among native plants or vegetation in the area. Therefore, careful attention must be directed towards newly discovered species, particularly those under quarantine observation.
... Surprisingly, recent molecular analyses using ribosomal DNA (rDNA) sequence data have revealed that these two species are genetically further apart than previously believed [10]. On the otd, investigations into the evolutionary highly variable, non-coding internal transcribed spacers (ITS1 and ITS2) of the nuclear rDNA have highlighted significant relationships between D. dipsaci, the stem nematode, and gall-forming nematodes from the subfamily Anguininae [10][11][12]. As a result, rDNA-ITS genes have become a favored tool for identifying these nematodes, and various assays currently exist for detecting D. dipsaci and D. destructor, including restriction fragment length polymorphism (RFLP)-ITS, multiplex PCR, real-time PCR, recombinase polymerase amplification (RPA), and loop-mediated isothermal amplification (LAMP) [9,10,[13][14][15][16][17]. ...
Ditylenchus destructor and D. dipsaci are important nematodes that have a significant economic impact on agronomic and horticultural plants worldwide. Microscopic observation alone may not distinguish between D. destructor and D. dipsaci. Accurate and rapid identification of these two species is essential for effective pest management. In the present study, a species-specific PCR assay was developed to detect and differentiate D. destructor and D. dipsaci based on the rDNA-ITS sequences. The primers developed in this study can specifically amplify fragments of DNA from D. destructor and D. dipsaci in the target population, without amplifying DNA from other non-target nematodes within the genus Ditylenchus. The sensitivity test revealed that this procedure has the ability to detect single second-stage juveniles (J2) of D. dipsaci at a dilution of 1/128 and D. destructor at a dilution of 1/64. Additionally, it can detect genomic DNA (gDNA) at concentrations of 10 pg/µL for D. dipsaci and 1 ng/µL for D. destructor. These results align with previously reported results obtained through RPA and LAMP methods. Furthermore, the primers developed in this study for D. destructor not only were able to amplify six different haplotypes of nematodes but also successfully detected it in infested plant roots and soil samples, thereby shortening the time and reducing the number of steps required for detection. Thus, this assay, which does not necessitate taxonomic or morphological expertise, significantly enhances the diagnosis of D. destructor and D. dipsaci in infested fields. This advancement aids in the early control of these nematodes.
... These two genera have been problematic in other studies. For example, to amplify Ditylenchus either species-specific primers (Skwiercz et al., 2017) or targeted longer fragment (615 bp) rather than the most common I3-M11 partition of COX1 gene have been used (Vovlas et al., 2011). Similar difficulty has been observed for Merlinius, resulting in not even a single COX1 sequence available in the NCBI database regardless of its worldwide distribution and importance as a plant parasite. ...
• A new COX1 primer for soil nematode metabarcoding was designed, and this primer outperforms other commonly used COX1 primer pairs in species recovery and quantity of PCR products.
• The lack of reference database is the main reason that led to the low species recovery in COX1 metabarcoding.
• We expanded current NCBI database by adding 51 newly generated COX1 reference sequences.
Microscopic nematodes play important roles in soil ecosystems and often serve as bioindicators of soil health. The identification of soil nematodes is often difficult due to their limited diagnostic characters and high phenotypic plasticity. DNA barcoding and metabarcoding techniques are promising but lack universal primers, especially for mitochondrial COX1 gene. In this study a degenerated COX1 forward primer COIFGED was developed. The primer pair (COIFGED/JB5GED) outperforms other four commonly used COX1 primer pairs in species recovery and quantity of polymerase chain reaction (PCR) products. In metabarcoding analysis, the reads obtained from the new primer pair had the highest sequencing saturation threshold and amplicon sequence variant (ASV) diversity in comparison to other COX1 as well as 18S rRNA primers. The annotation of ASVs suggested the new primer pair initially recovered 9 and 6 out of 25 genera from mock communities, respectively, outperformed other COX1 primers, but underperformed the widely used 18S NF1/18Sr2b primers (16 out of 25 genera). By supplementing the COX1 database with our reference sequences, we recovered an additional 6 mock community species bringing the tally closer to that obtained with 18S primers. In summary, our newly designed COX1 primers significantly improved species recovery and thus can be supplementary or alternative to the conventional 18S metabarcoding.
... The pea cyst nematodes were reported by van Dam and Bouwmeester [37] to cause tissue damage in pea and broad bean plants. Stem nematodes were reported to destroy stem tissues of broad bean plants [26]. An important effect of nematode infection on crops is that they reduce the availability of nutrients and hinder metabolic processes, thereby resulting in reduced plant growth and yield [38]. ...
This reference provides comprehensive insights on the harm inflicted by pests and diseases on leguminous crops. Internationally acclaimed authors provide succinct reviews on breeding and impact of biotic stress factors such as insect pests, microbial pathogens, spiders, and vertebrate pests in legumes like soybean, cowpea, and common bean. The book also contains detailed technical analysis of methods such as the PCR-based detection, next generation sequencing / marker-assisted selections, low cost lethal-non-lethal vertebrate pest control and mechanisms of climate/nutrient induced resistance. The unique feature of this book is its focus on the optimization and development of environmentally friendly methods for pest and disease control in leguminous crops. Other features include structured sections for easy reading and a list of references for advanced readers.
Key themes:
Biotic Stress and Plant Resistance
Biotic Stress in Legumes (Cowpea and Soybean)
Diagnostic and Control Methods for Microbial Plant Pathogens
Viral Diseases of Legumes and Management:
Vertebrate Pests in Legumes and Economic Implications
Spiders in Legume Agroecosystems
Climate-Driven Factors and Insect Pests of Legumes
Sustainable Crop Nutrition for Biotic Stress Alleviation in Legumes
Physiological Responses in Legumes to Combined Stress Factors
... These sequences, and the available Ditylenchus species, were used to conduct phylogenetic analyses. Outgroup taxa for each dataset were chosen following previously published studies (Giblin-Davis et al., 2010;Vovlas et al., 2011;Skwiercz et al., 2017;Xue et al., 2019). Separate nucleotide sequence alignments of the different genes were made using the FFT-NS-2 algorithm of MAFFT V.7.450 (Katoh et al., 2013). ...
... holds a unique status and grouped with D. valveus in our phylogenetic analyses. Several published studies have reported the presence of different lineages in the genus Ditylenchus, as some species are involved in phytoparasitism (Nicol et al., 2011;Vovlas et al., 2011) and others are either mycophagous (Goodey, 1958;Perry & Moens, 2013;Zhang et al., 2014), or in phoretic association with insects in soil (Giblin-Davis et al., 2010;Xue et al., 2019). Our phylogenetic analyses showed that the majority of Ditylenchus species are not forming a distinct clade; rather, they grouped independently with long branch lengths. ...
The present study describes a new Ditylenchus species, isolated from the bulbs of the Persian buttercup (Ranunculus asiaticus L.) imported from Israel at the Ningbo plant quarantine lab, Ningbo, P.R. China. Ditylenchus israelensis n. sp. is an amphimictic species; females have six incisures in the lateral field, a long and slim body, a delicate, short stylet (7-8 μm) with small and rounded knobs, excretory pore in the anterior region of the basal pharyngeal bulb, posteriorly located vulva (V = 78.6-83.1), a short PUS (15.0-24.0 μm), and a long conical tail with a pointed terminus. Males are similar to females in general morphology and have 14.0-18.0 μm long spicules. The new species was also characterised molecularly using 18S, ITS and D2-D3 expansion segments of 28S rDNA genes. Our phylogenetic analyses showed its independent position among available Ditylenchus species and a close phylogenetic affinity with D. valveus. Several Ditylenchus species are regulated pests; their detection in a given sample can implement quarantine measures. However, to our knowledge D. israelensis n. sp. did not cause any damage to the R. asiaticus bulbs. In addition, future studies regarding fecundity and host association may shed some light on the pathogenic potential of D. israelensis n. sp.
... The nematode genus Ditylenchus Filipjev, 1936, belonging to the family Anguinidae Nicoll, 1935, was established for D. dipsaci (Kühn, 1857) Filipjev, 1936 as type species of the genus. Most species are present in temperate regions with more than 60 described species within the genus Ditylenchus (Siddiqi, 2000;Giblin-Davis et al., 2010;Vovlas et al., 2011Vovlas et al., , 2016. The majority of them are mycophagous; a few are parasites of higher plants (Sturhan & Brzeski, 1991) or entomophoretic species (Giblin-Davis et al., 2010). ...
... Accurate identification of some species within the genus Ditylenchus is challenging because some morphometric characters that are used for species determination are highly variable (Fortuner, 1982;Swart et al., 2015). Molecular methods have been employed for species identification and phylogenetic analysis of the genus (Subbotin et al., 2005;Vovlas et al., 2011Vovlas et al., , 2016Madani et al., 2015;Skwiercz et al., 2017). A detailed molecular phylogenetic analysis of Ditylenchus species was performed and concluded that D. dipsaci was a species complex (Subbotin et al., 2005). ...
A new species of the genus Ditylenchus was recovered from rhizosphere soil of a ‘TifEagle’ hybrid bermudagrass (Cynodon dactylon (L.) Pers. × C. transvaalensis (Burtt-Davy)) putting green located at the Pee Dee Research & Education Center, Clemson University, Florence, SC, USA. It is described herein as Ditylenchus dactylonae n. sp. and is characterised by possessing the combined characters of a medium body size (682-815 μm in females; 618-718 μm in males), six incisures at the lateral fields, a delicate stylet (7.6-8.0 μm) with rounded knobs, a bottle-shaped basal pharyngeal bulb (BPB), an excretory pore (EP) near anterior end of BPB, a posteriorly located vulva (V = 78-83%), a reflexed ovary, a uterus with crustaformeria anteriorly and nearly spherical structure posteriorly, a post-vulval uterine sac (30-50% of the vulva-anus distance), an elongate conoid and ventrally bent tail, a tylenchoid spicule (17-18 μm), and a leptoderan bursa. Ditylenchus dactylonae n. sp. was differentiated from other sequenced species by the partial small subunit (SSU) rRNA gene, D2-D3 expansion segments of the large subunit (LSU) rRNA gene and internal transcribed spacer (ITS) rRNA. Phylogenetic analysis revealed that D. dactylonae n. sp. belongs to the D. dipsaci-group, and is sister to D. medicaginis and/or D. ferepolitor based on SSU 18S, LSU D2-D3 and ITS sequences.
Keywords: description; internal transcribed spacer rRNA (ITS); large subunit rRNA (LSU); molecular; morphology; morphometrics; new species; phylogeny; small subunit rRNA (SSU); taxonomy
... Ditylenchus Filipjev [1] is the largest genus of the family Anguinidae Nicoll, [2,3] that has adapted to a wide range of ecological processes, including phytoparasitism [4][5][6], mycophagy [7][8][9], phoretic association with insects in soil [10,11], biocontrol of weeds [12], and acting as a vector for Corynebacterium spp. [13][14][15]. ...
... The majority of studied Ditylenchus members are fungal feeders [3,16]. However, D. africanus Wendt, Swart, Vrain and Webster [17]; D. angustus (Butler) Filipjev [1,18]; D. destructor Thorne [19]; D. dipsaci (Kühn) Filipjev [1,20]; D. gallaeformans Oliveira, Santin, Seni, Dietrich, Salazar, Subbotin, Mundo-Ocampo, Goldenberg and Barreto [12]; D. gigas Vovlas, Troccoli, Palomares-Rius, De Luca, Liebanas, Landa, Subbotin and Castillo [6]; and D. myceliophagus Goodey [7] have attracted attention due to their parasitic potential and quarantine regulations [4,6,[21][22][23][24]. Several Ditylenchus species are polyphagous and display endoparasitic behaviour; as a result, these species can be disseminated through seeds, plant material or contaminated field equipment [8,25,26]. ...
... The majority of studied Ditylenchus members are fungal feeders [3,16]. However, D. africanus Wendt, Swart, Vrain and Webster [17]; D. angustus (Butler) Filipjev [1,18]; D. destructor Thorne [19]; D. dipsaci (Kühn) Filipjev [1,20]; D. gallaeformans Oliveira, Santin, Seni, Dietrich, Salazar, Subbotin, Mundo-Ocampo, Goldenberg and Barreto [12]; D. gigas Vovlas, Troccoli, Palomares-Rius, De Luca, Liebanas, Landa, Subbotin and Castillo [6]; and D. myceliophagus Goodey [7] have attracted attention due to their parasitic potential and quarantine regulations [4,6,[21][22][23][24]. Several Ditylenchus species are polyphagous and display endoparasitic behaviour; as a result, these species can be disseminated through seeds, plant material or contaminated field equipment [8,25,26]. ...
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.
... Extensive, multifaceted analyses involving molecular, biochemical, and karyotypic approaches identified 13 minor species, and approximately 30 races of D. dipsaci split into two groups ( Jeszke et al., 2013). Phylogenetic analysis using the internal transcribed spacer (ITS) of rDNA from populations of the D. dipsaci collected from a variety of plant hosts separated the diploid (D. dipsaci sensu stricto) and D. dipasci polyploidal (Ditylenchus gigas) clades (Subbotin et al., 2005;Vovlas et al., 2011). An ITS-PCR method for detecting D. dipsaci in Fabaceae seeds was developed (Kerkoud et al., 2007), and integrating computer-assisted characterization of ribosomal DNA (Marek et al., 2010) was further expanded by Kierzek et al. (Kierzek et al., 2010). ...
... The morphological identification of Ditylenchus species is extremely difficult due to very small differences among species in terms of morphological characteristics and significant variability exists among individuals of the same species (Brzeski, 1991). Additionally, the presence of sibling or cryptic species (individuals genetically distinct but sharing common morphological diagnostic characters) has been identified inside the species of Ditylenchus (Vovlas et al., 2011). ...
... Ditylenchus dipsaci is considered a species complex (Sturhan & Brzeski, 1991;Subbotin et al., 2004Subbotin et al., , 2005. Several new species have been identified from the D. dipsaci complex such as D. gigas Vovlas, Troccoli, Palomares-Rius, De Luca, Liébanas, Landa, Castillo, 2011 andD. weischeri Chizhov, Borisov &Subbotin, 2010. ...
... So far, some studies concerning molecular phylogeny of the genus Ditylenchus have been performed based on SSU, LSU and ITS rDNA sequences. The former phylogenetic analyses had shown that Ditylenchus spp. is a paraphyletic taxon (Subbotin et al., 2006;Vovlas et al., 2011;Oliveira et al., 2013;Qiao et al., 2016;Esmaeili et al., 2017a, b;Yaghoubi et al., 2018). However, as proposed by Zhao et al. (2013), the results of the present study and the results of the recent study by Aliverdi et al. (2022) showed it is polyphyletic. ...
Ditylenchus pedrami n. sp., recovered from the rhizospheric soil of date palm in Khuzestan province, southwest Iran, is described and illustrated based upon morphological and molecular data. The new species is characterised by having six lines in the lateral field, lip region smooth and continuous with body contour, stylet 9-11 μm long, median pharyngeal bulb oval with small valve, pharyngeal bulb offset from the intestine, V = 83.9 (80.2-88.1), conoid tail with a pointed, dull or rounded tip and males with 20.1 (17-24) μm long spicules. Morphologically, the new species comes close to D. africanus, D. anchilisposomus, D. australiae, D. clarus, D. clavicaudatus and D. parcevivens, mainly by having shared features like six lines in the lateral fields, stylet length and somewhat similar tail tip. The new species was also compared with D. stenurus and D. sarvarae, two species with close phylogenetic affinities to it. The phylogenetic relationships of the new species with representatives of the family Anguinidae were reconstructed and discussed using partial sequences of the small subunit, D2-D3 expansion segments of the large subunit, and internal transcribed spacer regions of ribosomal DNA (SSU, LSU D2-D3 and ITS rDNA) based on Bayesian inference (BI).
... In addition, several of the plant parasites thrive on fungi (Sturhan & Brzeski, 1991). The agriculturally important members of the genus are limited to a few species, and can be found in both the D. dipsaci group and the D. triformis group, including D. dipsaci (Kühn, 1857) Filipjev, 1936 (Butler, 1913) Filipjev, 1936 (Vovlas et al., 2011), and D. weischeri Chizhov, Borisov & Subbotin, 2010 from the D. dipsaci group, and D. destructor Thorne, 1945, D. myceliophagus Goodey, 1958, and D. africanus Wendt, Swart, Vrain & Webster, 1995 in the D. triformis group (Qiao et al., 2016;Madani & Tenuta, 2018). ...
... Ditylenchus and Nothotylenchus have the most problematic species since many morphometric characters that are used for their species delimitation are highly variable (Fortuner, 1982), and accurate identification of their species is challenging (Swart et al., 2015). Molecular methods have been used in species identification and phylogeny of the genus Ditylenchus (Subbotin et al., 2005;Vovlas et al., 2011Vovlas et al., , 2016Madani et al., 2015;Skwiercz et al., 2017). Subbotin et al. (2005) provided a detailed molecular phylogenetic analysis of Ditylenchus species and concluded that D. dipsaci is a species complex. ...
... Since then, the species D. weischeri, D. gigas, and D. laurae (Skwiercz et al., 2017) were identified as closely related species to D. dipsaci sensu stricto. Among recently described species, D. weischeri attacks weed plants (Chizhov et al., 2010), D. gigas parasitises broad bean, garlic and several weeds (Vovlas et al., 2011;Tanha Maafi et al., 2013;Moghbeli et al., 2017;Saadi et al., 2019), and D. laurae is associated with the water plant Potamogeton perfoliatus L. (Skwiercz et al., 2017). Moreover, the sibling or cryptic species has been identified inside the species of Ditylenchus that have common morphological characters but are distinguishable molecularly (Wendt et al., 1993;Esquibet et al., 1998;Vovlas et al., 2011). ...
During a survey, three populations of a new stem nematode were isolated from galls on the shoots of tumble thistle ( Gundelia tournefortii ) plants in Fars province, Iran, and identified. Ditylenchus paraoncogenus n. sp. is described based on morphometric and morphological characters. It is characterised by having long-sized females, 1252 (943-1628) μ m long, narrow lateral fields with six incisures, rather developed stylet 9.9 (9.0-11.3) μ m long with round knobs, usually elongate and offset from intestine basal pharyngeal bulb, oocytes in two rows in distal part of ovary, V = 83.3 (80.3-86.2), post-vulval uterine sac 68.1 (46.9-86.1)% of vulva to anus distance long, bursa covering 63.2 (33.3-74.4)% of tail length, spicules 24.7 (21.0-27.9) μ m long with minute processes at the base of its manubrium and anteriorly pointed cuticle parts within the lamina, and thick conical tail, usually with a pointed terminus. In addition, the ITS and 18S rDNA sequences of 17 populations of D. destructor , D. dipsaci , D. medicaginis , D. myceliophagus , D. paraoncogenus n. sp., Ditylenchus sp. and Nothotylenchus geraerti plus one population of Anguinidae sp. were analysed. The results showed a close relationship between D. paraoncogenus n. sp. and the stem nematodes D. oncogenus , D. gigas , D. weischeri and D. dipsaci. Ditylenchus species were divided into two clades, one clade comprising stem nematodes and gall-forming nematodes of the family Anguinidae, and the other clade containing fungivorous species. Observations showed that the second-stage juvenile is the dormant stage of D. paraoncogenus n. sp. and can survive in anhydrobiotic condition for at least 4 years.
