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Description of A New Cryptic Species of the Papillosa Group, Pellioditis koreana n. sp. (Nematoda: Rhabditidae) from Korea Cover

Description of A New Cryptic Species of the Papillosa Group, Pellioditis koreana n. sp. (Nematoda: Rhabditidae) from Korea

Open Access
|Dec 2025

Figures & Tables

Figure 1:

Line drawings of P. koreana n. sp. (A–L): (A) female whole body; (B) male whole body; (C,G) female anterior region; (D) vulval region; (E,F) posterior region of male, including copulatory apparatus and the arrangement of GP (p = phasmid); (H) basal bulb region; (I) anterior region of dauer juvenile; (J) tail region of dauer juvenile; and (K,L) female tail region including the shape of phasmids. GP, genital papillae.
Line drawings of P. koreana n. sp. (A–L): (A) female whole body; (B) male whole body; (C,G) female anterior region; (D) vulval region; (E,F) posterior region of male, including copulatory apparatus and the arrangement of GP (p = phasmid); (H) basal bulb region; (I) anterior region of dauer juvenile; (J) tail region of dauer juvenile; and (K,L) female tail region including the shape of phasmids. GP, genital papillae.

Figure 2:

Photomicrographs of P. koreana n. sp. (A–H). (A–D) Female anterior region; (E) vulval region; and (F–H) posterior region of male, including copulatory apparatus and the arrangement of GP. The arrows labeled h and e indicate the position of hemizonid and excretory pore, respectively; p = phasmid (Scale bars: A = 50 μm; B–H = 20 μm). GP, genital papillae.
Photomicrographs of P. koreana n. sp. (A–H). (A–D) Female anterior region; (E) vulval region; and (F–H) posterior region of male, including copulatory apparatus and the arrangement of GP. The arrows labeled h and e indicate the position of hemizonid and excretory pore, respectively; p = phasmid (Scale bars: A = 50 μm; B–H = 20 μm). GP, genital papillae.

Figure 3:

Photomicrographs of P. koreana n. sp. (A–I). (A–C) Posterior region of the pharynx; (D,F,G) female tail region, (E) caudal part with prominent phasmids; and (H,I) dauer juvenile tail. The arrows labeled h and e indicate the position of hemizonid and excretory pore, respectively, (scale bars: A–G = 20 μm; H,I = 30 μm).
Photomicrographs of P. koreana n. sp. (A–I). (A–C) Posterior region of the pharynx; (D,F,G) female tail region, (E) caudal part with prominent phasmids; and (H,I) dauer juvenile tail. The arrows labeled h and e indicate the position of hemizonid and excretory pore, respectively, (scale bars: A–G = 20 μm; H,I = 30 μm).

Figure 4:

Photomicrographs of P. koreana n. sp. (A–D). (A,B): Dauer juvenile anterior region; (C) lateral field in female; and (D) lateral field in dauer juvenile. The arrows labeled h and e indicate the position of the hemizonid and excretory pore, respectively, (scale bars: A,B = 30 μm; C,D = 20 μm).
Photomicrographs of P. koreana n. sp. (A–D). (A,B): Dauer juvenile anterior region; (C) lateral field in female; and (D) lateral field in dauer juvenile. The arrows labeled h and e indicate the position of the hemizonid and excretory pore, respectively, (scale bars: A,B = 30 μm; C,D = 20 μm).

Figure 5:

Bayesian tree inferred under the GTR + I + G model from 18S-rRNA gene sequences of Rhabditid species. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroup taxa: O. citri, L. mediterranea and L. marina.
Bayesian tree inferred under the GTR + I + G model from 18S-rRNA gene sequences of Rhabditid species. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroup taxa: O. citri, L. mediterranea and L. marina.

Figure 6:

Bayesian tree inferred under the GTR + I + G model from LSU D2–D3 partial sequences of Rhabditid species. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroup taxa: L. mediterranea, R. axei and O. chongmingensis.
Bayesian tree inferred under the GTR + I + G model from LSU D2–D3 partial sequences of Rhabditid species. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroup taxa: L. mediterranea, R. axei and O. chongmingensis.

Figure 7:

Bayesian tree inferred under the GTR + I + G model from ITS-rRNA partial sequences of Rhabditid species. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroup taxa: O. tipulae, O. onirici and H. georgiana.
Bayesian tree inferred under the GTR + I + G model from ITS-rRNA partial sequences of Rhabditid species. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroup taxa: O. tipulae, O. onirici and H. georgiana.

Morphometrics of P_ koreana n_ sp_ from Korea_

CharacterHolotype ♀♀♀♂♂Dauer juveniles

n 202020
L1,530.01,520.0 ± 116.0 (1,265.0–1,734.0)1,181.4 ± 104.1 (998.0–1,374.0)585.9 ± 38.2 (517.0–643.0)
a18.119.7 ± 1.4 (17.2–23.7)22.0 ± 1.0 (20.4–23.6)22.9 ± 1.6 (20.7–26.8)
b6.66.8 ± 0.5 (5.7–7.4)6.1 ± 0.6 (4.3–6.7)4.5 ± 0.2 (4.1–4.7)
c29.127.4 ± 2.5 (23.3–31.0)34.8 ± 2.8 (30.0–39.3)4.9 ± 0.3 (4.4–5.4)
c'1.31.4 ± 0.1 (1.2–1.6)1.4 ± 0.1 (1.1–1.5)7.8 ± 0.7 (6.7–9.8)
V or T52.752.3 ± 1.0 (50.9–54.5)71.1 ± 2.9 (64.8–75.2)
G1%29.829.4 ± 2.8 (24.9–35.4)
G2%28.729.2 ± 3.0 (22.3–33.8)
Lip height6.55.1 ± 0.7 (4.0–6.5)5.1 ± 0.7 (3.0–6.5)2.0 ± 0.2 (1.5–2.5)
Lip diam.14.015.6 ± 0.9 (13.5–16.5)14.2 ± 1.0 (12.0–15.5)5.2 ± 0.5 (4.5–6.5)
Stoma length20.520.1 ± 0.5 (19.0–21.0)19.3 ± 1.3 (16.5–21.0)16.6 ± 0.9 (14.5–18.0)
Stoma diam.5.55.8 ± 0.5 (4.5–7.0)5.0 ± 0.7 (4.0–6.5)
Corpus length134.0130.2 ± 4.8 (120.0–138.0)113.3 ± 5.1 (103.5–123.0)79.4 ± 5.1 (64.0–89.0)
Metacarpal diam29.030.2 ± 1.7 (26.0–34.0)26.7 ± 1.7 (23.0–29.5)13.7 ± 1.4 (10.5–16.0)
Isthmus length59.553.3 ± 5.1 (44.5–62.5)45.4 ± 3.6 (40.0–52.0)31.5 ± 2.6 (24.5–35.0)
Basal bulb length40.039.5 ± 1.6 (37.0–43.5)33.9 ± 2.9 (29.5–40.5)18.0 ± 1.3 (14.0–20.0)
Basal bulb diam.39.537.2 ± 2.5 (32.5–41.5)30.5 ± 1.9 (27.0–33.5)16.3 ± 1.0 (14.0–18.5)
Cardia length12.89.8 ± 2.9 (6.5–15.0)7.6 ± 1.8 (6.0–12.5)3.4 ± 0.4 (3.0–4.0)
Anterior end to nerve ring151.5145.5 ± 6.2 (134.0–161.0)128.6 ± 8.0 (115.5–151.0)90.3 ± 6.8 (72.0–107.0)
Anterior end to hemizonid183.0177.6 ± 9.2 (160–191.0)155.3 ± 8.9 (136.5–169.0)107.2 ± 8.1 (88.0–119.0)
Anterior end to Ex. pore198.0191.8 ± 11.4 (171.0–206.0)170.6 ± 10.2 (148.5–185.5)115.3 ± 7.7 (99.0–129.0)
Pharynx length232.0224.7 ± 7.3 (212.0–239.0)194.8 ± 12.7 (175.5–234.5)130.8 ± 6.2 (121.5–145.0)
Vulval body diam.84.576.9 ± 7.5 (63.0–88.0)
Maximum body diam.86.077.6 ± 7.8 (63.0–88.5)53.9 ± 4.9 (44.5–63.0)25.6 ± 2.1 (22.0–30.0)
Rectum39.540.6 ± 4.0 (34.0–49.0)20.8 ± 2.0 (17.0–24.0)
Anal/cloacal body diam.42.041.2 ± 4.3 (34.5–50.5)25.2 ± 3.0 (22.0–32.5)15.4 ± 1.4 (11.5–17.5)
Tail length52.555.7 ± 4.7 (46.0–62.5)34.0 ± 2.5 (30.0–39.0)118.9 ± 6.3 (112.0–132.0)
Tail spike length21.525.3 ± 4.3 (17.0–38.0)
Spicules55.2 ± 5.6 (48.0–70.5)
Gubernaculum 23.6 ± 1.8 (20.5–28.0)
DOI: https://doi.org/10.2478/jofnem-2025-0056 | Journal eISSN: 2640-396X | Journal ISSN: 0022-300X
Language: English
Submitted on: Mar 15, 2025
Published on: Dec 10, 2025
Published by: Society of Nematologists, Inc.
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue 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.