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Description and molecular characterization of Geraldius jejuensis n. sp. (Nematoda: Chambersiellidae) from Korea Cover

Description and molecular characterization of Geraldius jejuensis n. sp. (Nematoda: Chambersiellidae) from Korea

Journal of Nematology
Volume 57 (2025): Issue 1 (February 2025)
By:
Open Access
|Jun 2025

Figures & Tables

Figure 1:

Line drawings of Geraldius jejuensis n. sp. (A–G): A: Anterior end, surface view; B: Vulval region; C: Female tail region; D: Anterior region with the entire esophagus; E: Anterior region with the corpus region; F: Female reproductive system; G: Male tail region, including the copulatory apparatus and arrangement of caudal papillae.
Line drawings of Geraldius jejuensis n. sp. (A–G): A: Anterior end, surface view; B: Vulval region; C: Female tail region; D: Anterior region with the entire esophagus; E: Anterior region with the corpus region; F: Female reproductive system; G: Male tail region, including the copulatory apparatus and arrangement of caudal papillae.

Figure 2:

Photomicrographs of Geraldius jejuensis n. sp. (A–M). A, F: Female anterior region; B: Female reproductive system; C: Lateral field; D: Ventral view of the vulva; E: Posterior region of female tail; G: Rectum and anal region; H: Female tail region; I: Anterior region of female tail, including position of phasmids; J: Anterior region with cirri; K, L, M: Variation in vulval region in lateral view. The arrow labeled eh indicates the position of excretory pore and hemizonid; v = transverse vulva; p = phasmids (Scale bars: A, B, H = 50 μm; C, D, E, G, I, J, K, L and M = 20 μm; F = 30 μm).
Photomicrographs of Geraldius jejuensis n. sp. (A–M). A, F: Female anterior region; B: Female reproductive system; C: Lateral field; D: Ventral view of the vulva; E: Posterior region of female tail; G: Rectum and anal region; H: Female tail region; I: Anterior region of female tail, including position of phasmids; J: Anterior region with cirri; K, L, M: Variation in vulval region in lateral view. The arrow labeled eh indicates the position of excretory pore and hemizonid; v = transverse vulva; p = phasmids (Scale bars: A, B, H = 50 μm; C, D, E, G, I, J, K, L and M = 20 μm; F = 30 μm).

Figure 3:

Photomicrographs of Geraldius jejuensis n. sp. (A–J). A, B, D: Posterior part of esophagus with variation in position of excretory pore and hemizonid; C: Male anterior region; E: Dorsal lateral view of the three papillae located in close proximity to cloaca; F: Arrangement of post–cloacal papillae, including the preceding trio; G, I: Male tail region with post–cloacal papillae arrangement; H: Arrangement of post–cloacal papillae in relation to phasmids; J: Male copulatory apparatus and cloacal opening with the three additional midventral papillae on anterior cloacal lip. The arrow labeled eh indicates the position of excretory pore and hemizonid; unlabeled arrows = position of papillae; p = phasmids (Scale bars: A, B, C, D, E, F, H, and J = 20 μm; G, I = 30 μm).
Photomicrographs of Geraldius jejuensis n. sp. (A–J). A, B, D: Posterior part of esophagus with variation in position of excretory pore and hemizonid; C: Male anterior region; E: Dorsal lateral view of the three papillae located in close proximity to cloaca; F: Arrangement of post–cloacal papillae, including the preceding trio; G, I: Male tail region with post–cloacal papillae arrangement; H: Arrangement of post–cloacal papillae in relation to phasmids; J: Male copulatory apparatus and cloacal opening with the three additional midventral papillae on anterior cloacal lip. The arrow labeled eh indicates the position of excretory pore and hemizonid; unlabeled arrows = position of papillae; p = phasmids (Scale bars: A, B, C, D, E, F, H, and J = 20 μm; G, I = 30 μm).

Figure 4:

Bayesian tree inferred under the GTR + I + G model from 18S–rRNA gene sequences of Geraldius spp. and other species from various genera. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroup taxa: Alloionema appendiculatum, Neoalloionema tricaudatum, Strongyloides robustus and Rhabditophanes sp.
Bayesian tree inferred under the GTR + I + G model from 18S–rRNA gene sequences of Geraldius spp. and other species from various genera. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroup taxa: Alloionema appendiculatum, Neoalloionema tricaudatum, Strongyloides robustus and Rhabditophanes sp.

Figure 5:

Bayesian tree inferred under the GTR + I + G model from LSU D2–D3 partial sequences of Geraldius spp. and other species from various genera. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroup taxa: Steinernema glaseri and Necator americanus.
Bayesian tree inferred under the GTR + I + G model from LSU D2–D3 partial sequences of Geraldius spp. and other species from various genera. Posterior probability values exceeding 50% are given on appropriate clades. The studied population is indicated in bold text. Outgroup taxa: Steinernema glaseri and Necator americanus.

Morphometrics of Geraldius jejuensis n_ sp_ from Korea_

CharacterHolotype ♀♀♀♂♂
n 1619
L1187.01163.4±61.4 (1040.0–1306.0)1112.8±92.7 (928.0–1255.0)
a24.826.9±1.9 (23.6–30.3)30.7±2.8 (26.8–36.5)
b5.45.4±0.2 (4.9–5.9)5.2±0.5 (4.1–6.0)
c7.47.4±0.3 (7.0–7.9)9.4±0.9 (8.1–11.0)
c'6.26.3±0.4 (5.7–7.2)3.7±0.4 (3.1–4.8)
V or T48.248.0±0.7 (46.8–49.3)64.2±3.9 (54.5–69.5)
G137.832.1±2.6 (27.6–37.8)–
G230.930.0±3.9 (23.9–40.3)–
Lip height3.53.4±0.3 (3.0–4.0)3.4±0.3 (3.0–4.0)
Lip diam.10.510.5±0.5 (9.5–11.5)10.3±0.6 (8.5–11.0)
Cheilostom length5.55.0±0.6 (4.0–6.0)4.7±0.5 (4.0–5.5)
Cheilostom diam.4.55.1±0.9 (4.0–6.5)5.5±0.5 (4.5–6.5)
Gymnostom length6.55.7±0.8 (4.5–7.5)5.5±0.5 (4.5–7.0)
Stegostom length18.518.2±1.4 (16.0–20.0)18.2±0.9 (17.0–20.0)
Total stoma length31.028.8±1.1 (27.0–31.0)28.5±0.8 (27.0–30.0)
Amphidial opening12.010.9±0.9 (9.5–13.5)10.9±1.1 (9.0–13.5)
Corpus length137.0131.4±4.5 (123.5–140.0)127.8±6.4 (112.0–142.5)
Metacorpal diam21.520.4±0.8 (19.0–22.0)19.3±1.1 (17.0–21.0)
Isthmus length53.553.2±2.2 (50.5–58.0)53.8±3.3 (48.0–59.0)
Corpus/isthmus2.62.5±0.1 (2.4–2.7)2.4±0.1 (2.2–2.6)
Anterior to nerve ring146.0145.0±6.7 (131.0–155.5)135.6±6.4 (124.0–149.0)
Anterior to Ex. pore156.0164.9±9.1 (148.0–183.0)151.6±11.5 (131.0–178.0)
Anterior to Deirid162.0165.4±8.2 (149.0–183.0)151.4±11.5 (132.0–179.0)
Anterior to Hemizonid156.0163.9±8.5 (147.5–180.0)151.1±11.4 (131.0–177.0)
Basal bulb length31.533.8±1.3 (31.5–36.0)33.5±1.9 (30.0–36.5)
Basal bulb diam.25.024.6±0.7 (23.0–26.0)23.7±1.7 (20.0–26.0)
Esophagus length220.5217.2±5.4 (207.0–227.0)213.6±8.9 (193.0–229.5)
Cardia length10.59.9±1.0 (7.0–11.5)10.2±1.4 (7.5–12.0)
Maximum body diam.48.043.3±3.2 (38.0–48.0)36.4±3.5 (30.0–43.0)
Vulval body diam.45.540.4±3.3 (33.5–45.5)–
Rectum36.038.5±2.7 (34.0–43.5)–
Anal / cloacal body diam.26.024.8±1.0 (22.5–27.0)32.5±3.1 (28.0–39.0)
Phasmids to anus59.064.8±6.4 (55.0–78.5)55.0±4.6 (44.5–66.0)
Tail length160.0156.4±9.8 (146.0–177.0)118.9±10.6 (101.0–135.0)
Phasmids/tail (%)39.341.4±2.7 (36.7–46.6)46.5±4.8 (40.2–54.2)
Spicules––54.3±2.6 (50.5–59.5)
Gubernaculum––30.7±1.7 (27.0–33.5)
DOI: https://doi.org/10.2478/jofnem-2025-0023 | Journal eISSN: 2640-396X | Journal ISSN: 0022-300X
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Language: English
Submitted on: Apr 10, 2025
Published on: Jun 21, 2025
Published by: Society of Nematologists, Inc.
In partnership with: Paradigm Publishing Services
Publication frequency: 1 times per year
Keywords:
molecular characterization,
morphology,
morphometrics,
new species,
phylogeny,
taxonomy
Related subjects:
Life sciences,
Life sciences, other

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

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