Descriptions of two new and one known species of Parkellus Jairajpuri, Tahseen and Choi, 2001 (Nematoda: Mononchidae) and their phylogenetic position among Mononchida
Publicado en línea: 25 ago 2021
Páginas: 1 - 22
Recibido: 03 dic 2020
DOI: https://doi.org/10.21307/jofnem-2021-076
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© 2021 Tam T.T. VU et al., published by Sciendo.
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
Predatory nematodes play a substantial role in the soil food-web as regulators of other trophic groups: bacterial, fungal, algae, and herbivorous feeders, they are also suitable bioindicators of soil condition (Ahmad and Jairajpuri, 2010; Ferris and Bongers, 2006; Ferris et al., 2001, 2012; Holterman et al., 2008; Moens et al., 2000). Unfortunately, many of the predaceous species which have been described still lack molecular characterization, while a great number might need to be discovered yet.
Herein, the descriptions of two new species of predatory soil nematodes of the genus
Of the 10
In the present study, two new species:
Soil samples were collected from a pristine forest in Vietnam and from an oak forest in Ukraine. Nematodes were extracted from soil samples using modified Baermann funnel technique (Southey, 1986).
They were heat killed, fixed in 4% formaldehyde (for morphological observations) or in a DESS mixture (Yoder et al., 2006) (for molecular analyses), transferred to anhydrous glycerol (Seinhorst, 1962), and mounted on glass slides for microscopic observation. Measurements were performed with a Nikon digital camera on a Nikon Eclipse Ni microscope at the Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology (VAST), Vietnam. Observations of morphological diagnostic features were performed in a Leica DM5000B light microscope using the Nomarsky differential interference contrast (DIC) technique. Illustrations were drawn and photographs were taken using a Leica DFC 500 camera on Leica DM5000B microscope at the Museum and Institute of Zoology Polish Academy of Sciences (PAS), Warsaw, Poland. Illustrations were edited by using Adobe Photoshop CC 2018. The spicule terminology is expressed according to Peña-Santiago et al. (2014).
After conducting the microscopic studies and preparing the photographic documentation, all nematodes subjected to molecular analyses were taken out from the temporary slides. Each retrieved nematode was transferred to a separate dish filled with PBS (phosphate buffered saline) solution. The dishes with nematodes were placed on a laboratory shaker. The nematodes were initially washed in PBS for 3 hr. Subsequently, the nematodes were transferred into dishes containing fresh PBS and were washed on a shaker overnight. In the final washing stage, the nematodes were transferred into dishes containing sterile milliQ water and were washed with it for 4 hr. After this procedure, the nematode individuals were transferred to separate 0.2 ml polymerase chain reaction (PCR) tubes containing 25 μl sterile water. An equal volume of the lysis buffer, as described in Holterman et al. (2006), was added to every tube. The lysis occurred in a thermal cycler (Veriti 96
Nearly full length 18S rDNA was amplified from the analyzed
All PCR reactions contained 12.5 μl Color Perpetual OptiTaq PCR Master Mix (2x) (EURx, Gdansk, Poland), 1 μl of the forward and reverse primer (5 μM each), the 3 μl DNA template and sterile Milli-Q water to 25 μl of the total volume. All PCR reactions were performed in Veriti 96
After sequencing the obtained
The newly obtained rDNA sequences were analyzed using the BioEdit program (Hall, 1999: v.7.2.5). The final 18S and 28S rDNA datasets for phylogenetic study included sequences from the three studied
The Bayesian phylogenies were constructed with the program MrBayes v. 3.1 (Ronquist and Huelsenbeck, 2003). GTR substitution model with a proportion of invariable sites and gamma distribution for both 18S and 28S data sets was used. Two independent runs were performed with four Markov chains per run. The program was run for 2 × 106 generations in case of the 18S rDNA data set and for 1 × 106 generations in case of the 28S rDNA data set. Sample frequency in both cases was 100 generations. The sampled trees from each run were combined in a single 50% majority-rule tree. Stabilization of the likelihood and parameters was checked with the program Tracer (Rambaut et al., 2014: v.1,6).
Systematics
Order Mononchida (Jairajpuri, 1969)
Suborder Mononchina (Kirjanova and Krall, 1969)
Superfamily Mononchoidea (Filipjev, 1934)
Family Mononchidae (Filipjev, 1934)
Genus
Figure 1:
Light micrographs of
Figure 2:
Light micrographs of
Figure 3:
Line drawings of
Morphometrics of females and males of
| Du Gia natural reserve | |||
|---|---|---|---|
| Characters/ratios* | Holotype | Paratypes | |
| n | 1 female | 1 female | 3 males |
| L (µm) | 2,112 | 1,769 | 2,162–2,900 |
| a | 26.0 | 27.2 | 29.0–34.9 |
| b | 3.9 | 3.7 | 3.8–4.1 |
| c | 16.4 | 15.2 | 21.4–23.2 |
| c′ | 2.8 | 2.7 | 1.7–2.1 |
| V | 69 | 70 | |
| Lip region height (µm) | 13.3 | 12.2 | 12.0–13.6 |
| Lip region width (µm) | 40.5 | 40.2 | 44.8–46.4 |
| Buccal cavity length (µm) | 54.4 | 50.8 | 55.4–60.2 |
| Buccal cavity width (µm) | 29.9 | 29.1 | 28.8–31.6 |
| Position of tooth apex (%) from anterior end of buccal cavity | 75 | 76 | 71–74 |
| Nerve ring from anterior end (µm) | 143 | 138 | 152–170 |
| Excretory pore from anterior end (µm) | 173 | 153 | 177–196 |
| Pharynx length (µm) | 539 | 473 | 566–713 |
| Maximum body width (µm) | 78.3 | 65.0 | 74.7–83.0 |
| Anal body width (µm) | 45.5 | 42.7 | 55.0–65.2 |
| Rectum/cloaca length (µm) | 38.7 | 33.4 | 41.0–51.4 |
| Spicules length (µm) | 82.3–97.3 | ||
| Lateral guiding piece length (µm) | 18.2–22.2 | ||
| Tail length (µm) | 128 | 116 | 95–136 |
Holotype female and two paratype males, in permanent mounts in glycerine, deposited in the nematode collection at the Department of Nematology, Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology. One paratype female and one paratype male deposited in the nematode collection of the Museum and Institute of Zoology, PAS, Warsaw, Poland.
Soil samples from pristine forest containing specimens originated from Du Gia natural conservation area at Minh Ngoc Commune, Bac Me District, Ha Giang Province (N 22°42′57″, E 105°11′45″, 350 m a.s.l.).
The name of the species refers to its geographical origin from Ha Giang Province in Vietnam.
Measurements see Table 1.
Relaxed specimens arcuate, more curved ventrally at posterior end. Body tapering slightly anterior to base of pharynx but more sharply toward posterior end. Maximum body width at the level of vulval region. Cuticle smooth, 6.4 (5.3–7.5) μm thick at the base of pharynx. Sublateral, subdorsal, and subventral body pores distinct along the entire body excluding tail.
Lip region rounded, 3.4 (3.1–3.7) times as wide as high, slightly offset by a depression, its diameter almost the same as the adjacent body. Labial papillae small, conical, slightly protruding. Cephalic papillae comparatively more prominent, broadly rounded, slightly protruding beyond the body outline. Amphidial fovea cup-shaped, its aperture 5.4 (5.1–5.8) µm wide, located 20.8 (18.6–22.8) µm from the anterior body end. Buccal cavity spacious, oval-shaped, 1.8 (1.7–2.1) times as long as wide, with funnel-shaped base, its wall strongly sclerotized. Dorsal tooth medium-sized, located at the base of the vertical dorsal plate of the buccal cavity, below the beginning of the pharynx. Apex of dorsal tooth located 41.1 (38.1–44.6) µm or 71–76% of buccal cavity length from its anterior end, opposite to it lies a thin, subventral longitudinal ridge. Nerve ring encircling cylindrical, muscular pharynx at about 26.5 (23.8–29.2%) of its length. Excretory pore distinct, males have there are three well developed ventral pores, first one at 40.7–46.6 µm above and the next two at 24.7–29.7 and 74.3–82.6 µm behind the excretory pore. Pharyngo-intestinal junction non-tuberculate. The intestine content nematodes, diatom shells, earthworm setae and detritus are visible. Rectum wide, arcuate, 0.8 times the anal body diameter long. Tail conical, ventrally bent, regularly tapering, with rounded tip. Hyaline part well developed, 17.0 (10.9–23.8) µm long. Caudal glands and terminal opening absent.
Genital system didelphic-amphidelphic, the sexual branches almost equally developed, anterior 225–238 µm long or 11–13% of body length, posterior 140–187 µm long or 8–9% of body length. Ovaries on alternate sides of the intestine, well developed, reflexed with numerous oocytes, not reaching the uterus-oviduct junction, oviduct takes the form of a slender tube, which then expands to form a well-developed
Genital system diorchic, testes opposed. Sperm cells elongate spindle shaped. Spicules total length along arc 1.2 times that at chord, 1.4–1.5 times longer than body diameter at cloacal aperture, relatively thin, 9.1–9.4 times longer than wide ventrally curved, curvature 114–119° median piece marked between hump and lateral guiding pieces, occupying 39.9–41.3% of spicule total length. Dorsal contour arcuate, ventral side with moderately expressed hump and hollow, the former located at 27.3–28.7% of spicule total length from its anterior end, head oval-shape, offset by a shallow depression, proximal part of spicules conical, posterior end bifurcate, 4.4–5.0 µm broad. Lateral guiding pieces with arched edges and bifurcate terminus, this furcation is symmetrical and poorly marked. Gubernaculum well developed, 31.9–34.7
In general appearance
Nearly full length (1,600 bp), identical 18S rDNA sequences were acquired from two individuals belonging to
Figure 4:
Light micrographs of
Figure 5:
Light micrographs of
Figure 6:
Line drawings of
Morphometrics of females and males of
| Cham Chu natural reserve | |||||
|---|---|---|---|---|---|
| Character | Holotype | Paratypes | Na Hang natural reserve | ||
| n | female | 3 females | 3 males | 11 females | 12 males |
| L (µm) | 2,205 | 2,185–2,487 | 2,235–2,648 | 2,995 ± 221.4 (2,726–3,363) | 2,753 ± 152.8 (2,545–3,067) |
| a | 29.8 | 25.5–31.8 | 28.7–31.7 | 30.5 ± 2.0 (28.0–30.0) | 32.8 ± 2.0 (28.4–34.6) |
| b | 3.6 | 3.8–4.0 | 3.8–4.0 | 4.4 ± 0.2 (4.1–4.7) | 4.2 ± 0.1 (4.0–4.5) |
| c | 17.2 | 18.2–19.8 | 17.3–26.3 | 19.7 ± 1.4 (18.1–22.4) | 21.8 ± 1.1 (19.7–23.5) |
| c′ | 2.6 | 2.5–2.7 | 1.7–2.1 | 2.8 ± 0.2 (2.3–3.0) | 2.1 ± 0.1 (1.9–2.3) |
| V | 68.0 | 69.0 | 68.7 ± 2.9 (67.0–73.0) | ||
| Lip region height (µm) | 12.6 | 11.1–14.6 | 12.3–13.9 | 10.6 ± 0.8 (8.8–11.4) | 11.3 ± 1.2 (9.7–13.2) |
| Lip region width (µm) | 43.1 | 40.9–47.4 | 41.2–43.8 | 45.4 ± 2.8 (41.4–50.2) | 44.8 ± 1.4 (43.0–46.6) |
| Buccal cavity length (µm) | 57.7 | 52.5–60.4 | 53.9–58.7 | 56.6 ± 1.7 (54.6–60.7) | 55.4 ± 1.6 (53.0–58.0) |
| Buccal cavity width (µm) | 28.2 | 28.0–29.3 | 27.7–28.5 | 30.1 ± 0.7 (29.0–30.8) | 29.0 ± 1.0 (27.3–30.8) |
| Position of tooth apex (%) from anterior end of buccal cavity | 64.0 | 60.0–62.0 | 60.0–67.0 | 66.4 ± 1.6 (63.0–68.3) | 66.9 ± 1.8 (64.0–70.0) |
| Nerve ring from anterior end (µm) | 149 | 140–163 | 155–163 | 172 ± 11.5 (151–191) | 170 ± 8.3 (158–180) |
| Excretory pore from anterior end (µm) | 185 | 175–195 | 180–194 | 204 ± 11.0 (189–223) | 199 ± 9.8 (185–216) |
| Pharynx length (µm) | 606 | 543–635 | 569–655 | 686 ± 35.0 (636–750) | 657 ± 26.6 (613–704) |
| Maximum body width (µm) | 73.9 | 78.1–83.4 | 78.0–83.6 | 98.6 ± 9.9 (81.0–110.0) | 86.1 ± 5.9 (76.5–96.8) |
| Anal body width (µm) | 48.3 | 47.6–50.8 | 59.4–62.7 | 55.5 ± 2.5 (49.5–58.5) | 61.2 ± 2.0 (58.5–65.0) |
| Rectum/cloaca length (µm) | 39.9 | 40.1–42.2 | 49.0–60.0 | 46.0 ± 4.2 (38.3–51.8) | 54,7± 3,9 (50.1–64.2) |
| Spicules length (µm) | 97.0–104.8 | 103.7 ± 5.8 (95.0–110.0) | |||
| Lateral guiding piece length (µm) | 12.6–17.8 | 16.3 ± 0.9 (15.0–17.6) | |||
| Tail length (µm) | 128 | 120–127 | 101–129 | 152 ± 13.6 (122–169) | 126.4 ± 7.6 (110–133) |
Holotype female, three paratype females, and three paratype males from Cham Chu and Na Hang population, in permanent mounts in glycerin, deposited in the nematode collection at the Department of Nematology, Institute of Ecology and Biological Resources, Vietnam Academy of Science and Technology. Nine paratype females and nine paratype males from Cham Chu and Na Hang population deposited in the nematode collection of the Museum and Institute of Zoology, PAS, Warsaw, Poland. Two paratype females and three paratype males from Na Hang population deposited in State Museum of Natural History NASU, Lviv, Ukraine.
Cham Chu population: soil samples from pristine forest containing specimens originated from Cham Chu natural conservation area at Yen Thuan Commune, Ham Yen District, Tuyen Quang Province (N 22°17′55″,E 104°59′42″, 820 m a.s.l.).
Na Hang population: soil samples from pristine forest containing specimens originated from Na Hang natural conservation area at Na Hang District, Tuyen Quang Province (N 22°20′53″,E 105°25′49″, ca 320 m a.s.l.).
The name of the species refers to its geographical origin from Tuyen Quang Province in Vietnam.
Measurements, see Table 2.
Relaxed specimens arcuate, more curved ventrally at posterior end. Body tapering slightly anterior to base of the pharynx but more sharply toward the posterior end. Maximum body width at the level of vulva. Cuticle smooth, 7.1 (6.2–8.5) μm thick at the base of the pharynx. Sublateral, subdorsal, and subventral body pores visible along the entire body excluding tail.
Lip region rounded, 3.4 (3.0–3.7) times as wide as high, slightly offset by a depression, its diameter slightly wider than an outline of the adjacent body. Labial papillae small, conical, slightly protruding. Cephalic papillae bigger, broadly rounded, slightly protruding beyond the body outline. Amphidial fovea cup-shaped, its aperture 5.2 (4.2–6.4) µm wide, located 19.5 (17.7–22.0) µm from the anterior body end. Buccal cavity spacious, oval-shaped, 2.0 (1.9–2.1) times as long as wide, with funnel-shaped base. Dorsal tooth small, located at the vertical dorsal plate of the buccal cavity, above the beginning of the pharynx. Apex of dorsal tooth located 35.7 (31.6–37.7) µm from anterior margin of the buccal cavity or 60–70% of the buccal cavity length from its anterior end, opposite to it lies a thin, subventral, longitudinal ridge. Nerve ring encircling cylindrical, muscular pharynx at about 25.6 (22.0–28.6%) of its length. Excretory pore, ampulla and renette cells well visible. Males with three or four very well-developed ventral pores near the excretory pore, first one located at 75.4 (71.9–83.8) µm and the second one (in three specimens only) at 22.0–52.4 µm above the excretory pore, the next two at 39.0 (15.6–47.4) and 83.4 (72.0–89.5) µm behind the excretory pore. Pharyngo-intestinal junction non-tuberculate. In the intestine content visible nematodes, diatom shells, earthworm setae and detritus. Rectum wide and arcuate, 0.8–0.9 times the anal body diameter long. Tail conical, ventrally bent, regularly tapering, with rounded tip. Hyaline part well developed, 16.8 (14.9–21.7) µm long. Caudal glands and terminal opening absent.
Genital system didelphic-amphidelphic, the sexual branches almost equally developed, anterior 364 (291–430) µm long or 12.9 (11.2–15.0%) of body length, posterior 322 (223–384) µm long or 11.4 (8.2–13.4%) of body length. Ovaries on alternate sides of intestine, well developed, reflexed with numerous oocytes, not reaching the uterus-oviduct junction, oviduct takes the form of a slender tube, which then expands to form a well-developed
Genital system diorchic, with opposed testes. Sperm cells elongate spindle-shaped. Ejaculatory glands in tandem, generally distinct. Spicules total length along arc 1.2–1.3 times that at chord, 1.5 (1.4–1.9) times longer than body diameter at cloacal aperture, relatively thin, 9.2 (7.8–10.1) times longer than wide, ventrally curved, curvature 115 (112–119º), median piece marked between hump and lateral guiding pieces, occupying 36.7% (31.0–40.5%) of spicule total length. Dorsal contour arcuate, ventral side with moderately expressed hump and hollow, the former located at 24.4% (18.4–29.6%) of spicule total length from its anterior end, head oval-shape, proximal part of spicule almost cylindrical, posterior end bifurcate, 5.4 (4.6–6.0) µm broad. Lateral guiding pieces with arched edges and bifurcate terminus, this furcation is symmetrical and poorly marked. Gubernaculum well developed, 33.9 (30.1–40.6) µm long. Ventromedian supplements 16–20 in number, conical, regularly arranged, occupies 12.9% (12.1–14.8%) of body length, the anterior most situated at 19.1 (15.7–29.0) µm from cloacal aperture, distance between the first and last supplement 334 (240–408) µm. Above the supplements visible two cuticular pores. Male tail with two pairs of sublateral and two pairs of subdorsal caudal pores and two pairs of small subventral papillae.
In general appearance
For the
(Figs. 7 and 8 and Table 3)
Figure 7:
Light micrographs of
Figure 8:
Light micrographs of
Morphometrics of females and males of
| Characters/ratios* | Uzhhorod | |
|---|---|---|
| n | 13 females | 11 males |
| L (µm) | 2900 ± 175.3 (2,569–3,174) | 2748 ± 152.5 (2,454–3,012) |
| a | 33.0 ± 2.4 (29.3–38.8) | 36.6 ± 1.4 (34.1–39.7) |
| b | 4.5 ± 0.2 (4.3–4.8) | 4.3 ± 0.1 (4.0–4.5) |
| c | 21.4 ± 1.7 (17.4–23.1) | 23.4 ± 2.1 (21.0–27.8) |
| c′ | 2.5 ± 0.2 (2.2–2.9) | 1.8 ± 0.2 (1.5–2.0) |
| V | 68.0 ± 1.3 (65.0–70.3) | |
| Lip region height (µm) | 12.8 ± 1.1 (10.1–13.9) | 12.4 ± 1.0 (10.6–13.8) |
| Lip region width (µm) | 42.7 ± 2.1 (38.7–46.8) | 42.4 ± 1.9 (39.4–44.7) |
| Buccal cavity length (µm) | 50.8 ± 1.6 (48.3–53.7) | 51.2 ± 1.8 (47.1–54.5) |
| Buccal cavity width (µm) | 24.9 ± 1.0 (23.3–26.6) | 25.0 ± 0.5 (23.8–25.5) |
| Position of tooth apex (%) from anterior end of buccal cavity | 54.5 ± 3.1 (47.4–59.5) | 55.8 ± 2.1 (51.7–58.4) |
| Nerve ring from anterior end (µm) | 189 ± 10.0 (169–202) | 188 ± 8.9 (171–200) |
| Excretory pore from anterior end (µm) | 218 ± 12.0 (197–241) | 218 ± 7.3 (202–229) |
| Pharynx length (µm) | 642 ± 35.2 (579–705) | 641 ± 21.1 (606–667) |
| Maximum body width (µm) | 88.0 ± 5.3 (75.3–93.2) | 74.9 ± 4.8 (65.7–82.1) |
| Anal body width (µm) | 53.4 ± 2.6 (50.8–60.4) | 66.4 ± 5.1 (60.1–75.8) |
| Rectum/cloaca length (µm) | 45.7 ± 2.5 (42.8–50.2) | 54.5 ± 2.6 (50.1–59.0) |
| Spicules length (µm) | 106 ± 2.9 (102–111) | |
| Lateral guiding piece length (µm) | 21.5 ± 1.3 (20.3–24.5) | |
| Tail length (µm) | 136 ± 8.6 (120–151) | 118 ± 10.8 (94–134) |
Specimens of
Measurements see Table 3.
Relaxed specimens arcuate, more curved ventrally at posterior end. Body tapering slightly anterior to base of pharynx but more sharply toward posterior end. Maximum body width at the level of vulva. Cuticle smooth, 4.3 (3.1–5.1) μm thick at the base of pharynx, subcuticle with faint transverse striae. Sublateral, subdorsal, and subventral body pores distinct along the entire body excluding tail. Tail with four pairs of sublateral caudal pores.
Lip region rounded, 3.4 (3.0–4.0) times as wide as high, offset by a depression, wider than outline of the adjacent body. Labial and cephalic papillae conical, protruding beyond of the body contour, cephalic papillae comparatively more prominent. Amphidial fovea cup-shaped, its aperture relatively large, 7.3 (6.4–9.5) µm wide, located 13.5 (12.0–16.0) µm from the anterior body end. Buccal cavity spacious, oval-shape, 2.0 (1.9–2.2) times as long as wide, with funnel-shaped base. Dorsal tooth small, at the vertical dorsal plate of the buccal cavity, above the beginning of the pharynx. Apex of dorsal tooth located 28.1 (24.7–30.3) µm from anterior margin of buccal cavity or 47–60% its length from anterior end, opposite to it lies a thin, subventral longitudinal ridge. Nerve ring encircling cylindrical, muscular pharynx at about 29.4% (27.7–31.5%) of its length. Excretory pore and the ampulla well marked. Pharyngo-intestinal junction non-tuberculate. In the intestine content visible nematodes, diatom shells, earthworm setae, and detritus. Rectum wide and arcuate, 0.8 (0.7–1.0) times the anal body diameter long. Tail conical, ventrally bent, regularly tapering, with rounded tip. Hyaline part well developed, 12.9 (9.4–18.6) µm long. Caudal glands and the terminal opening absent.
Genital system didelphic-amphidelphic, the sexual branches almost equally developed, anterior 348 (256–423) µm long or 12.1% (9.3–14.6%) of body length, posterior 349 (297–423) µm long or 12.1% (10.5–16.3%) of body length. Ovaries on alternate sides of intestine, reflexed and well developed with numerous oocytes, not reaching the uterus-oviduct junction, oviduct takes the form of a slender tube, which then expands to form a well-developed
Genital system diorchic, with opposed testes. Sperm cells elongate spindle shaped. Ejaculatory glands in tandem, generally distinct. Spicules total length along arc 1.3–1.4 times that at chord, 1.6 (1.4–1.8) times longer than body diameter at cloacal aperture; relatively thin, 8.4 (8.1–8.6) times longer than wide, ventrally curved, curvature 105.6°(104–109.5°), median piece marked between hump and lateral guiding pieces, occupying 26.3% (22.0–30.1%) of spicule total length. Dorsal contour arcuate, ventral side with moderately expressed hump and hollow, the former located at 30.2% (26.4–32.9%) of spicule total length from its anterior end, head narrow, on a dorsal side offset by a shallow depression, proximal part of spicules almost cylindrical, posterior end bifurcate, 4.9 (4.2–5.3) µm broad. Lateral guiding pieces with arched edges and a bifurcate terminus, this furcation is symmetrical and well-marked. Gubernaculum well developed, 41.6 (36.2–46.3) µm long. Ventromedian supplements 21–24 in number, conical, regularly arranged, occupies 13.1% (11.8–13.9%) of body length. Above the supplements two cuticular pores are visible, the posterior most situated at 15.6 (13.8–16.6) µm from cloacal aperture, distance between the first and last supplement 360 (317–399) µm. Parallel to the supplements, on both sides of them, five to six subventral papillae of varying sizes are visible, largest one lies at the level of the anus. Almost at half of the tail length, on its ventral side a large medioventral caudal papilla is situated, below it lies one pair of subventral and two pairs of subdorsal papillae.
Both, the 18S and 28S rDNA – derived sequences were acquired from 11 independent nematode individuals belonging to
Figure 9:
18S rDNA-based Bayesian phylogeny of the Mononchida. The new
Figure 10:
28S rDNA-based Bayesian phylogeny of the Mononchida. The new
Currently, 12 species of the genus
1.– Length of buccal cavity less than 61 µm............ 2
– Length of buccal cavity more than 65 µm......... 9
2.– Tail tip mucronate; gubernaculum thick, hooked proximally.......................................
– Tail tip without mucro; gubernaculum not hooked proximally.......................................................... 3
3.– Tail terminus slender, acute orsubacute............. 4
– Tail terminus conspicuously rounded................. 5
4.– Position of dorsal tooth apex 60–61% of buccal cavity length from its anterior end;
– Position of dorsal tooth apex 50–53% of buccal cavity length from its anterior end;
5.– Tail in posterior third cylindroid with broadly rounded terminus; body slender (ratio
– Tail uniformly narrowing with finely rounded terminus; body not so slender (ratio
6.– Dorsal tooth located at the base of the vertical dorsal plate below the beginning of the pharynx, its apex position more than 71% of buccal cavity length from its anterior end........
– Dorsal tooth located at the base of the vertical dorsal plate above the beginning of the pharynx, its apex position not more than 70% of buccal cavity length from its anterior end.........................
7.– Female tail 85–90 µm long; spicules 82–92 µm long, lateral guiding pieces with straight edges........................................................
– Female tail 103–169 µm long; spicules 95–131 µm long, lateral guiding pieces with arched edges........................................................................ 8
8.– Position of dorsal tooth apex 60–70% of buccal cavity length from its anterior end; lateral guiding pieces 13–18 µm long; males with ventromedian cuticular pores above and below of the excretory pore..........
– Position of dorsal tooth apex 47–60% of buccal cavity length from its anterior end; lateral guiding pieces 20–34 µm long; males without ventromedian cuticular pores above and below of the excretory pore........................
9.– Body mostly well over 3 mm long; tail 150–190 µm long............................................
– Body mostly 2.0–2.7 mm long; tail 90–130 µm long.......................................................................... 10
10. – Tail slightly curved (about 40°); dorsal tooth rounded in contour..........
– Tail strongly curved (90° or more); dorsal tooth more or less pointed.............................................. 11
11. – Buccal cavity shorter (66 µm); tail tip acute. .....................................................
– Buccal cavity longer (70–75 µm); tail tip rounded......................................................
Analysis of interspecific sequence variation and phylogenetic relationships of the investigated
Molecular sequences of three
Three studied
Our research delivers so far the only molecular data that are available for the genus
Two new species of the genus