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Description of a New Cryptic Rhabditid, Parasitorhabditis paraterebrana n. sp. (Nematoda: Rhabditidae), with Remarks on Two Known Species from Korea Cover

Description of a New Cryptic Rhabditid, Parasitorhabditis paraterebrana n. sp. (Nematoda: Rhabditidae), with Remarks on Two Known Species from Korea

Open Access
|Aug 2025

Figures & Tables

Figure 1:

Line drawings of Parasitorhabditis paraterebrana n. sp. (A-K): A: Female whole body; B: Male whole body; C: Female anterior region, including the pharynx region; D, E, F: Variation in lip shape and arrangement of teeth (D: Lateral view with all the four teeth; E: The two subventral teeth; F: The two subdorsal teeth); G, H: Male tail in right lateral view, with arrangement of bursal rays; I: Female tail in ventral view; J: Male tail in ventral view, with arrangement of bursal rays; K: Female tail in lateral view.
Line drawings of Parasitorhabditis paraterebrana n. sp. (A-K): A: Female whole body; B: Male whole body; C: Female anterior region, including the pharynx region; D, E, F: Variation in lip shape and arrangement of teeth (D: Lateral view with all the four teeth; E: The two subventral teeth; F: The two subdorsal teeth); G, H: Male tail in right lateral view, with arrangement of bursal rays; I: Female tail in ventral view; J: Male tail in ventral view, with arrangement of bursal rays; K: Female tail in lateral view.

Figure 2:

Photomicrographs of Parasitorhabditis paraterebrana n. sp. (A-G): A: Male reproductive system; B: Female reproductive system; C: Developing egg in the uterus; D: The reflexed region of ovary; E: The oviduct; F, G: The reflexed portion of the testis (Scale bars: A, B = 50 μm; C, D, E, F, G = 20 μm).
Photomicrographs of Parasitorhabditis paraterebrana n. sp. (A-G): A: Male reproductive system; B: Female reproductive system; C: Developing egg in the uterus; D: The reflexed region of ovary; E: The oviduct; F, G: The reflexed portion of the testis (Scale bars: A, B = 50 μm; C, D, E, F, G = 20 μm).

Figure 3:

Photomicrographs of Parasitorhabditis paraterebrana n. sp. (A-K): A: Female anterior region, including the pharynx region (arrow e and h indicate the position of secretory-excretory pore and hemizonid, respectively); B, C, D, E: Variation in lip shape and arrangement of teeth (B: Lateral view with all the four teeth; C: The two subventral teeth; D, E: The two subdorsal teeth); F, G: Posterior part of pharynx (arrow e and h indicate the position of secretory-excretory pore and hemizonid, respectively); H, I: Male tail region; J: Female tail in lateral view; K: Female tail in ventral view. (Scale bars: A = 50 μm; B, C, D, E, H, I, J, K = 10 μm; F, G = 20 μm).
Photomicrographs of Parasitorhabditis paraterebrana n. sp. (A-K): A: Female anterior region, including the pharynx region (arrow e and h indicate the position of secretory-excretory pore and hemizonid, respectively); B, C, D, E: Variation in lip shape and arrangement of teeth (B: Lateral view with all the four teeth; C: The two subventral teeth; D, E: The two subdorsal teeth); F, G: Posterior part of pharynx (arrow e and h indicate the position of secretory-excretory pore and hemizonid, respectively); H, I: Male tail region; J: Female tail in lateral view; K: Female tail in ventral view. (Scale bars: A = 50 μm; B, C, D, E, H, I, J, K = 10 μm; F, G = 20 μm).

Figure 4:

Photomicrographs of Parasitorhabditis obtusa (Fuchs, 1915) Chitwood and Chitwood, 1950 (A-H). A, B: Female anterior region; C, D: Male tail region; E, F, H: Variation in shape of female tail; G: Posterior part of pharynx (arrow e and h indicate the position of secretory-excretory pore and hemizonid, respectively). (A, B, E, F, H = 10 μm; C, D, G = 20 μm).
Photomicrographs of Parasitorhabditis obtusa (Fuchs, 1915) Chitwood and Chitwood, 1950 (A-H). A, B: Female anterior region; C, D: Male tail region; E, F, H: Variation in shape of female tail; G: Posterior part of pharynx (arrow e and h indicate the position of secretory-excretory pore and hemizonid, respectively). (A, B, E, F, H = 10 μm; C, D, G = 20 μm).

Figure 5:

Bayesian tree inferred under the GTR + I + G model from 18S rRNA gene sequences of Rhabditina Chitwood, 1933 species. Posterior probability values exceeding 50 % are given on appropriate clades. The studied population is indicated in bold text. Outgroups: Rhabditoides inermiformis (Osche, 1952) Dougherty, 1955 and Rhomborhabditis regina (Schulte and Poinar, 1991) Sudhaus, 2011.
Bayesian tree inferred under the GTR + I + G model from 18S rRNA gene sequences of Rhabditina Chitwood, 1933 species. Posterior probability values exceeding 50 % are given on appropriate clades. The studied population is indicated in bold text. Outgroups: Rhabditoides inermiformis (Osche, 1952) Dougherty, 1955 and Rhomborhabditis regina (Schulte and Poinar, 1991) Sudhaus, 2011.

Figure 6:

Bayesian tree inferred under the GTR + I + G model from LSU D2-D3 partial sequences of Rhabditina Chitwood, 1933 species. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroups: Rhabditoides inermiformis (Osche, 1952) Dougherty, 1955 and Rhomborhabditis regina (Schulte and Poinar, 1991) Sudhaus, 2011.
Bayesian tree inferred under the GTR + I + G model from LSU D2-D3 partial sequences of Rhabditina Chitwood, 1933 species. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroups: Rhabditoides inermiformis (Osche, 1952) Dougherty, 1955 and Rhomborhabditis regina (Schulte and Poinar, 1991) Sudhaus, 2011.

Figure 7:

Bayesian tree inferred under the GTR + I + G model from COI partial sequences of Rhabditina Chitwood, 1933 species. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroups: Chylorhabditis epuraeae Kanzaki, Hamaguchi and Takeuchi-Kaneko, 2021, and Rhabditis Dujardin, 1844 species.
Bayesian tree inferred under the GTR + I + G model from COI partial sequences of Rhabditina Chitwood, 1933 species. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroups: Chylorhabditis epuraeae Kanzaki, Hamaguchi and Takeuchi-Kaneko, 2021, and Rhabditis Dujardin, 1844 species.

Comparison of morphometrics of Parasitorhabditis paraterebrana n_ sp_ and Parasitorhabditis terebrana Massey, 1974 from Korea and topotype population by Massey (1974)_

CharacterParasitorhabditis paraterebrana n. sp.Parasitorhabditis terebrana

HolotypeParatypesKorea (Current study)USA (Massey, 1974)

♀♀♂♂♀♀♂♂♀♀♂♂
n202265??
L693.0673.3±54.6 (598.0–814.0)625.6±53.4 (553.5–732.5)877.8±87.0 (780.5–995.0)847.9±87.9 (746.0–979.0)770–810750
a19.019.0±0.6 (17.9–20.0)19.0±1.0 (16.9–21.7)21.4±1.2 (20.1–23.7)21.0±1.4 (19.0–22.5)19.7–20.119.5
b3.93.7±0.3 (3.2–4.3)3.6±0.2 (3.3–4.2)4.5±0.4 (4.0–5.1)4.4±0.2 (4.1–4.6)4.2–4.34.1
c21.823.0±3.0 (18.3–28.6)24.0±2.4 (20.8–28.8)25.9±2.5 (20.7–28.3)26.7±1.2 (25.2–28.4)26.2–27.327.3
c’1.61.7±0.3 (1.3–2.3)1.5±0.1 (1.3–1.7)1.6±0.2 (1.4–1.9)1.4±0.2 (1.2–1.7)
V91.691.7±0.7 (90.3–92.6)92.9±0.6 (92.0–93.5)93
G1/T (without flexure)46.547.9±2.5 (44.5–53.2)46.2±2.6 (41.0–51.4)
Lip height4.04.3±0.4 (3.5–5.0)3.7±0.5 (3.0–4.5)3.3±0.1 (3.0–3.5)3.1±0.2 (3.0–3.5)
Lip diameter11.011.3±0.7 (10.0–12.5)10.8±0.7 (9.5–12.5)12.5±0.4 (12.0–13.0)11.7±0.4 (11.0–12.5)
Stoma length22.021.9±1.2 (20.0–24.0)21.4±1.2 (19.5–23.5)20.5±0.7 (19.5–21.5)20.0±1.5 (18.0–22.0)21
Stoma width5.55.2±0.4 (4.5–6.0)4.2±0.4 (3.5–5.0)5.0±0.4 (4.0–5.5)4.1±0.4 (3.5–5.0)
Anterior to median valve89.092.3±3.8 (83.5–99.0)87.1±4.2 (77.0–92.5)100.5±5.8 (93.5–108.0)98.9±3.4 (93.5–102.5)
Anterior to nerve ring116.5112.2±7.6 (98.5–123.0)101.5±6.9 (89.5–114.0)110±7.4 (102.5–122.0)
Excretory pore126.0128.1±7.5 (113.0–141.0)123.9±6.2 (112.5–139.0)120.2±6.0 (100.5–125.0)
Pharynx length176.0179.6±6.5 (167.0–190.0)173.3±7.9 (159.0–187.0)193.5±9.6 (184.0–209.0)193.4±13.1 (180.0–212.0)
Maximum body diameter36.535.4±2.8 (31.0–43.0)33.0±3.4 (27.0–40.0)41.0±2.7 (38.0–44.5)40.4±2.5 (38.0–45.0)
Vulval body diameter29.528.0±2.4 (24.5–34.5)34.1±2.4 (30.5–38.5)
Vulva to anus length25.024.6±2.2 (21.5–31.5)30.7±2.6 (28.0–35.0)
Vulva to tail tip57.054.3±4.6 (46.5–65.0)64.8±5.2 (57.0–70.5)
Anal / cloacal body diameter20.017.7±1.5 (14.0–20.5)17.9±1.2 (15.5–20.0)20.8±0.9 (19.5–22.0)22.2±2.1 (20.0–25.0)
Tail length32.029.7±3.9 (22.5–37.0)26.1±2.2 (22.5–30.0)34.1±3.9 (28.5–39.0)31.6±2.0 (29.0–34.5)
Spicules34.1±2.0 (30.5–37.0)36.4±1.4 (34.5–38.0)34
Gubernaculum15.3±0.9 (14.0–17.0)16.2±0.6 (15.5–17.0)17

Comparison of morphometrics of Parasitorhabditis obtusa (Fuchs, 1915) Chitwood & Chitwood, 1950 from Korea with topotype and other populations_

CharacterKorea (Current study)Iran (Valizadeh et al., 2017)Germany? (Rühm, 1956)Germany (Fuchs, 1915)

♀♀♂♂♀♀♂♂♀♀♂♂♀♀*♂♂*
n15151010??21
L951.1±92.4 (784.0–1148)753.9±66.3 (635.0–872.0)959.0±92.0 (810–1067)746±104 (624–925)728–1115751–855957–1121640
a24.3±1.7 (21.7–27.0)24.6±2.3 (20.9–28.4)20.0±2.5 (16.9–23.6)21.1±3.6 (14.4–27.2)16.5–24.019.5–21.0
b5.0±0.4 (4.4–6.0)4.6±0.3 (4.0–5.0)5.1±0.5 (4.5–5.6)4.3±0.5 (3.6–5.3)4.0–5.84.2–4.6
c40.5±5.0 (34.2–49.9)17.3±1.4 (14.8–19.6)67.0±12.3 (50.0–88.9)35.9±5.0 (28–46)44.0–49.517.8–22.2
c’1.2±0.2 (0.8–1.3)2.0±0.2 (1.7–2.4)0.7±0.1 (0.6–0.9)1.4±0.3 (1.0–1.8)
V94.5±0.6 (93.4–95.3)95.8±0.9 (93.8–96.7)94.0–95.7
G1/T (without flexure)57.0±3.2 (49.9–62.7)57.4±3.3 (52.6–64.4)55.8±6.9 (41.5–63.5)56.4±6.4 (47.5–65.6)
Lip height4.4±0.4 (4.0–5.5)3.5±0.3 (3.0–4.0)
Lip diameter12.4±0.7 (11.5–13.5)10.3±0.5 (9.5–11.5)
Stoma length17.7±1.1 (15.5–19.5)16.1±0.8 (15.0–17.5)17.4±1.3 (16–20)15.5±1.2 (13–17)(16.0–20.0)16.0–21.017.017.0
Stoma width4.2±0.5 (3.5–5.5)3.3±0.4 (2.5–4.0)
Anterior to median valve82.6±3.5 (75.0–88.5)72.8±2.9 (68.5–78.0)
Anterior to nerve ring98.7±5.2 (91.5–108.0)94.9±6.3 (84.5–111.5)132.0±9.3 (121–150)114.0±8.4 (100–127)
Excretory pore124.3±4.2 (119.5–134.5)115.1±6.7 (102.0–126.0)143.0±8.2 (125–155)126.0±7.6 (115–142)
Pharynx length189.2±8.1 (169.0–201.0)165.1±7.3 (150.5–173.0)189.0±9.4 (172–201)172.0±7.5 (156–183)183.0–234.0168.0–185.0
Maximum body diameter39.1±3.0 (34.0–44.5)30.7±2.0 (27.5–34.5)48.1±4.3 (42–55)35.9±5.0 (28–46)42.0–53.039.0–44.034.0
Vulval body diameter30.3±2.6 (26.5–35.5)37.1±3.2 (33–42)
Vulva to anus length23.1±3.4 (19.5–32.0)21.0–43.034.0
Vulva to tail tip46.8±5.1 (38.0–57.0)54.0
Anal / cloacal body diameter20.6±1.5 (18.0–25.0)21.8±1.5 (19.0–23.5)21.2±2.3 (18–26)23.4±2.8 (20–28)
Tail length23.7±3.0 (18.5–27.0)43.7±2.4 (40.0–50.0)14.6±2.7 (12–19)31.6±7.2 (23–42)18.0–25.038.0–46.020.0
Spicules43.7±5.4 (33.0–49.0)35.1±3.5 (31–42)30.0–32.033.0
Gubernaculum17.8±0.8 (16.0–19.0)15.0 ± 1.6 (13–17)15.0–18.014.0
DOI: https://doi.org/10.2478/jofnem-2025-0027 | Journal eISSN: 2640-396X | Journal ISSN: 0022-300X
Language: English
Submitted on: Nov 17, 2024
Published on: Aug 31, 2025
Published by: Society of Nematologists, Inc.
In partnership with: Paradigm Publishing Services
Publication frequency: 1 times per year

© 2025 Abraham Okki Mwamula, Chang-Hwan Bae, Yi Seul Kim, Dong Woon Lee, published by Society of Nematologists, Inc.
This work is licensed under the Creative Commons Attribution 4.0 License.