Cyst-forming nematodes are the economical pests of cultivated crops and known to be reported from all the continents (Jones et al., 2013). The genus
Due to overlapping morphological characters and phenotypic plasticity, it is difficult to distinguish closely related
During 2018 and 2019, a population of cyst nematode was collected from the rhizosphere of
The nematodes were extracted from root and soil samples of
DNA samples were prepared according to Maria et al. (2018). Three sets of primers (synthesized by Tsingke Biotech Co. Ltd., Xi’an, China) were used in the PCR analyses to amplify sequences of the ITS, D2-D3 expansion segments of 28S, and
The newly obtained sequences for each gene (ITS-rDNA, D2-D3 region of 28S-rDNA, and
Species | Locality | Host-plant | Marker | Accession number |
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Germany |
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ITS | AF274414 |
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Lorestan, Doroud, Akbar Abad, Iran |
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ITS | AF498374 |
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Monopoly, Bari province, Italy |
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ITS | KY129827 |
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Yuekou village, Tianmen county, Hubei province, China | – | ITS | HM560794 |
|
Morroco | – | ITS | AY347918 |
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Creances, France |
|
ITS | AF274413 |
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South Africa |
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ITS | MG976790 |
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Brielle, The Netherlands |
|
ITS | AF274411 |
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Diksmuide, Belgium |
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ITS | AF274412 |
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Moscow, Russia |
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ITS | GU126668 |
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Xinzhuang village, Huangzhong county, Qinghai province, China | – | ITS | EU623623 |
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Haiyan county, Qinghai province, China | – | ITS | HM560791 |
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Haibei city, Qinghai province, China | – | ITS | HM370425 |
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Xining city, Qinghai province, China | – | ITS | HM370423 |
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Tehran, Dizin, Iran |
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ITS | AF498377 |
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Bremen, Germany |
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ITS | AY368994 |
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Muenster, Germany |
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ITS | AY368995 |
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Ontario province, Canada |
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28S | KX463292 |
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Ontario province, Canada |
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28S | KX463293 |
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Yuekou village, Tianmen county, Hubei province, China | – | 28S | HM560857 |
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Iran | – | 28S | GU456692 |
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Iran | – | 28S | KP114546 |
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Belgium | – | 28S | DQ328696 |
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Iran | – | 28S | DQ328697 |
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Haiyan county, Qinghai province, China | – | 28S | HM560855 |
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Haomen village, Menyuan county, Qinghai province, China | – | 28S | HM560856 |
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South Africa |
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MN820659 |
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Mesola, Forli-Cesena province, Italy |
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KX463299 |
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Mesola, Forli-Cesena province, Italy |
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KX463300 |
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Margherita, di Savoia, Italy |
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KX463301 |
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Margherita, di Savoia, Italy |
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KX463302 |
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Ontario province, Canada |
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KX463303 |
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Ontario province, Canada |
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KX463304 |
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Ontario province, Canada |
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KX463305 |
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Ontario province, Canada |
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KX463306 |
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Mexico |
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MG563227 |
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Mexico |
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MG563229 |
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Switzerland | – |
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MG563231 |
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Switzerland | – |
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MG563232 |
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France | – |
|
MG563233 |
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Belgium | – |
|
KC172916 |
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Faulkner county, Arkansas, USA |
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|
MK093155 |
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Faulkner county, Arkansas, USA |
|
|
MK093156 |
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California, USA | – |
|
MG563230 |
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Moscow region, Russia | – |
|
MG563234 |
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Monopoly, Bari province, Italy |
|
|
KY129829 |
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Monopoly, Bari province, Italy |
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KY129830 |
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Monopoly, Bari province, Italy |
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KY129831 |
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|
It is lemon-shaped with an obtuse vulval cone, neck extruding, and cuticle thick with an irregular zig-zag pattern. The color was white to pale to medium brown; remnants of the subcrystalline layer were rarely present. The egg sac was usually absent (Figs. 1G, 3B, C). The vulval cone was ambifenestrate-like waning crescent moon and separated by a well-developed vulval bridge. The anus area was distinct, bullae were absent (Figs. 1F, 3D, E). The vulval slit was longer than fenestral width (39.00 vs 37.75 µm); the underbridge was weak and often lost during cone preparation.
The female was lemon-shaped, pearl white, or pale yellow in color. It was rarely rounded with a protruding neck and vulva, the subcrystalline layer was present, and the egg sac absent (Figs. 2A, B, 3A). There was a labial region with two annuli. Labial sclerotization was weak, the stylet was strong, and basal knobs were rounded and anteriorly flattened. The excretory pore was indistinct, median bulb was rounded and massive, and other parts of the pharynx were not clearly discernable. There was vulval slit in a cleft on the cone terminus (Fig. 2C, D).
The body was straight or slightly curved ventrally after heat treatment (Fig. 4A). The lip region was offset and rounded, measuring 3.90 to 5.50 (4.63) µm in height and 9.65 to 12.75 (11.01)-µm wide. The cephalic framework was strongly sclerotized (Figs. 1B, 4C). The stylet was strong; knobs were well developed, rounded and flat, or slightly concave anteriorly (Figs. 1C, 4C). The dorsal esophageal gland orifice measured from 5.32 to 6.32 (5.61) µm posterior to the stylet knob. Median bulb was rounded with a strong valvular apparatus. The pharyngeal glands were well developed, overlapping the intestine dorsoventrally (Figs. 1A, 4B). The hemizoind was distinct from one to three annuli long (Fig. 4H), the excretory pore was situated 102.46 to 130.79 (114.40) µm from the anterior end, and one to two annules were posterior to the hemizonid (Fig. 4G). There was a lateral field with four incisures (Figs. 1D, 4G). The dorsal gland nucleus and subventral gland nuclei were distinct (Fig. 4E, F). Genital primordium situated at 59 to 62% of body length behind the anterior end, with two distinct nucleate cells (Fig. 4I). The tail was conoid, gradually tapering to a finely rounded terminus. The hyaline portion was irregularly annulated occupying 50% of tail length. Phasmid was absent (Figs. 1E, 4D).
Body hyaline without any markings was presented; juveniles folded six times (Fig. 3F).
The male was not found.
Holotype and paratype material (20 cysts, 20 females, and 20 second-stage juveniles) were deposited in the nematode collection of the Department of Plant Protection, Biocontrol Engineering Laboratory of Crop Diseases and Pests of Gansu Province, Lanzhou, China.
The species is named after the host of its isolation.
The new species belongs to the
The new species differs from
The new species is differentiated from
The new species differs from
The new species differs from
Compared with
The new species differs from
The new species differs from
Additionally, comparative morphological and morphometric characters of
Morphometrics of
Stage | Character | Holotype | Paratype |
---|---|---|---|
Cyst | |||
|
20 | ||
|
521.79 | 495.50 ± 41.01 (413.93-543.23) | |
Diam. | 419.33 | 384.29 ± 43.30 (304.96-455.51) | |
|
1.27 | 1.30 ± 0.09 (1.12-1.45) | |
Fenestral length | 30.72 | 31.14 ± 1.36 (28.33-32.78) | |
Fenestral width | 36.16 | 37.75 ± 1.61 (35.46-40.07) | |
Vulval slit length | 35.53 | 39.00 ± 2.78 (35.16-44.38) | |
Female | |||
|
20 | ||
Length | 454.21 ± 28.32 (381.62-496.48) | ||
Width | 326.47 ± 31.42 (256.32-421.63) | ||
Length/width | 1.40 ± 0.12 (1.28-1.56) | ||
Second-stage juveniles | |||
|
20 | ||
Body length | 567.73 ± 43.24 (505.62-627.92) | ||
Body width at mid-body | 23.19 ± 1.31 (20.39-25.43) | ||
|
24.54 ± 1.34 (21.97-27.67) | ||
|
4.37 ± 0.33 (3.91-5.00) | ||
|
10.07 ± 1.18 (8.56-12.52) | ||
|
4.26 ± 0.33 (3.63-4.90) | ||
Lip-region height | 4.63 ± 0.44 (3.90-5.50) | ||
Lip-region diam. | 11.07 ± 0.82 (9.65-12.75) | ||
Stylet length | 25.73 ± 1.21 (24.07-28.92) | ||
Stylet base height | 2.53 ± 0.33 (2.04-3.19) | ||
Stylet base width | 5.30 ± 0.54 (4.39-6.09) | ||
Median bulb from the anterior end (MB) | 85.57 ± 5.02 (76.37-95.26) | ||
Opening of dorsal pharyngeal gland from the stylet base (DGO) | 5.13 ± 0.72 (4.03-6.41) | ||
Excretory pore from the anterior end (EP) | 114.40 ± 6.89 (102.46-130.79) | ||
Median bulb width (MBW) | 12.33 ± 1.49 (10.51-15.82) | ||
Diam. at the anus | 13.23 ± 1.00 (11.24-15.26) | ||
Tail length | 56.67 ± 3.75 (48.90-60.80) | ||
Hyaline portion tail | 28.63 ± 1.91 (24.29-30.60) | ||
|
6.65 ± 0.37 (5.76-7.53) | ||
TL/H | 1.98 ± 0.10 (1.64-2.08) | ||
Egg | |||
|
20 | ||
Length | 111.61 ± 8.02 (100.21-124.65) | ||
Width | 50.34 ± 6.71 (35.64-71.51) | ||
Length/width | 2.26 ± 0.38 (1.43-3.26) |
Main morphological character of represent species from the
Species |
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Host |
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Locality | Germany | England | England | Iran | Northern Ireland | Germany | Germany | China |
Cyst | ||||||||
Size | 521 × 372 | 408 × 309 | 429 × 333 | 533 × 380 | 492 × 435 | 555 × 397 | 560 × 424 | 495×384 |
Fenestral length | 35 | 31 | 34 | 47 | 38 | 43 | 35 | 31 |
Underbridge length | 117 | 90 | 85 | 104 | Weak | 83 | 86 | Weak |
Bullae | Few | Absent | Absent | Present | Absent | Absent | Absent | Absent |
Vulval slit length | 39 | 47 | 45 | 49 | 46 | 48 | 43 | 39 |
Second-stage juvenile | ||||||||
Body length | 486 | 422 | 431 | 440 | 541 | 434 | 408 | 568 |
|
25 | 21 | – | 23 | 23 | 22 | 21 | 25 |
Stylet knobs | Smoothly rounded to slightly hooked shaped with recurved anterior surface | Concave anterior face | Anterior face flat to concave | Rounded or projecting slightly anterior, convex posteriorly | Slightly concave anteriorly | Rounded and slightly sloping posteriorly | Slightly convave anteriorly | Rounded and flat or slightly concave anteriorly |
Stylet length | 25 | 24 | 24 | 23 | 27 | 25 | 24 | 26 |
Lateral line | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 4 |
DGO | 5 | 5-6 | – | 6 | 8 | 6 | 5 | 5 |
MB | 70 | 66 | 68 | 70 | – | 70 | 62 | 86 |
Excretory pore from anterior end | 158 | 99 | 101 | 103 | 130 | 101 | 89 | 114 |
Tail | 60 | 52 | 50 | 47 | 58 | 52 | 47 | 57 |
Hyaline portion of tail length | 37 | 28 | 25 | 24 | 29 | 26 | 25 | 29 |
The
The D2-D3 of 28S-rRNA sequence (accession no. MT573436) of
The ITS-rDNA sequence (accession no. MT573437) divergence of
The
Taxonomy of
Phylogenetically, it is evident that
The present study described a new species found in the rhizosphere of