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A new stunt nematode, Geocenamus chengi n. sp. (Nematoda: Merliniinae) in the rhizosphere of tea (Camellia sinensis) from Zhejiang Province, China

Munawar Maria
Munawar Maria
, 
Wentao Miao
Wentao Miao
, 
Pablo Castillo
Pablo Castillo
 and 
Jingwu Zheng
Jingwu Zheng
   | Apr 16, 2020
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Published Online: Apr 16, 2020
Page range: 1 - 13
Received: Feb 02, 2020
DOI: https://doi.org/10.21307/jofnem-2020-042
Keywords
© 2020 Munawar Maria et al., published by Sciendo.
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Figure 1:

Line drawings of Geocenamus chengi n. sp. A: pharyngeal region; B, C: en face view; D: lateral lines: E: female gonad; F: male gonad; G: vulval region; H-J: female tails: K-M: male tails (Scale bars = A; D-M = 10 μm, B,C = 5 μm).
Line drawings of Geocenamus chengi n. sp. A: pharyngeal region; B, C: en face view; D: lateral lines: E: female gonad; F: male gonad; G: vulval region; H-J: female tails: K-M: male tails (Scale bars = A; D-M = 10 μm, B,C = 5 μm).

Figure 2:

Light photomicrographs of Geocenamus chengi n. sp. Female. A: entire body; B: lateral lines; C, D: pharyngeal regions, arrow pointing on the excretory pore (exp): E: gonad; F: vulval region arrows pointing on vulva (v) and spermatheca (sp); G, H: vulval region; I-K: female tails arrows pointing on anus (a) and phasmid (ph) (Scale bars = A = 100 μm; B-K = 10 μm).
Light photomicrographs of Geocenamus chengi n. sp. Female. A: entire body; B: lateral lines; C, D: pharyngeal regions, arrow pointing on the excretory pore (exp): E: gonad; F: vulval region arrows pointing on vulva (v) and spermatheca (sp); G, H: vulval region; I-K: female tails arrows pointing on anus (a) and phasmid (ph) (Scale bars = A = 100 μm; B-K = 10 μm).

Figure 3:

Light photomicrographs of Geocenamus chengi n. sp. Male. A: entire body; pharyngeal regions, arrow pointing on the excretory pore (exp); C: tail with bursa; D: gonad; E, F: tail in ventral view; G, I: male tail arrows pointing on phasmid (ph) (Scale bars = A = 100 μm; B-I = 10 μm).
Light photomicrographs of Geocenamus chengi n. sp. Male. A: entire body; pharyngeal regions, arrow pointing on the excretory pore (exp); C: tail with bursa; D: gonad; E, F: tail in ventral view; G, I: male tail arrows pointing on phasmid (ph) (Scale bars = A = 100 μm; B-I = 10 μm).

Figure 4:

Scanning electron microscopy of Geocenamus chengi n. sp. A: anterior region; B-C: en face view; D-F: vulval regions; G, H: female tail regions arrows pointing anus (a); I: anal area at higher resolution, arrow pointing on the position of anus; J: cloacal area at higher resolution, arrow pointing on the position of cloaca (c); K, L: male tail; M: lateral field with phasmid (ph); N: lateral field. Abbreviation: am, apmphid; ds, dorsal sectors; vs, =ventral sectors; ld, labial disc (Scale bars, A, E, I, J, M, N = 10 μm; B, C, D, E, F = 5 μm; G, K = 30 μm; H = 50 μm; L = 20 μm).
Scanning electron microscopy of Geocenamus chengi n. sp. A: anterior region; B-C: en face view; D-F: vulval regions; G, H: female tail regions arrows pointing anus (a); I: anal area at higher resolution, arrow pointing on the position of anus; J: cloacal area at higher resolution, arrow pointing on the position of cloaca (c); K, L: male tail; M: lateral field with phasmid (ph); N: lateral field. Abbreviation: am, apmphid; ds, dorsal sectors; vs, =ventral sectors; ld, labial disc (Scale bars, A, E, I, J, M, N = 10 μm; B, C, D, E, F = 5 μm; G, K = 30 μm; H = 50 μm; L = 20 μm).

Figure 5:

Phylogenetic relationships of Geocenamus chengi n. sp. with other merlinids as inferred from Bayesian analysis using the 18 S rRNA gene sequence data set with the TIM3ef + G model. Posterior probability more than 70% is given for appropriate clades. Newly obtained sequences are indicated in bold.
Phylogenetic relationships of Geocenamus chengi n. sp. with other merlinids as inferred from Bayesian analysis using the 18 S rRNA gene sequence data set with the TIM3ef + G model. Posterior probability more than 70% is given for appropriate clades. Newly obtained sequences are indicated in bold.

Figure 6:

Phylogenetic relationships of Geocenamus chengi n. sp. with other merlinids as inferred from Bayesian analysis using the D2-D3 of 28 S rRNA gene sequence data set with the GTR + I + G model. Posterior probability more than 70% is given for appropriate clades. Newly obtained sequences are indicated in bold.
Phylogenetic relationships of Geocenamus chengi n. sp. with other merlinids as inferred from Bayesian analysis using the D2-D3 of 28 S rRNA gene sequence data set with the GTR + I + G model. Posterior probability more than 70% is given for appropriate clades. Newly obtained sequences are indicated in bold.

Figure 7:

Phylogenetic relationships of Geocenamus chengi n. sp. with other merlinids as inferred from Bayesian analysis using the ITS rRNA gene sequence data set with the TIM2 + I + G model. Posterior probability more than 70% is given for appropriate clades. Newly obtained sequences are indicated in bold.
Phylogenetic relationships of Geocenamus chengi n. sp. with other merlinids as inferred from Bayesian analysis using the ITS rRNA gene sequence data set with the TIM2 + I + G model. Posterior probability more than 70% is given for appropriate clades. Newly obtained sequences are indicated in bold.

Morphometric data for Geocenamus chengi n. sp. All measurements are in µm and in the form of mean ± SD (range).

Holotype Paratype
Female Male
n 20 10
Body length 884.8 879.0 ± 59.6 (783–997) 822.8 ± 34.2 (772–892)
a 33.3 33.3 ± 2.6 (28–39) 32.9 ± 1.2 (31–34)
b 6.0 6.1 ± 0.3 (5.5–6.6) 6.1 ± 0.2 (5.8–6.6)
c 10.4 10.5 ± 0.6 (9.2–11.7) 9.7 ± 0.6 (8.7–10.3)
c' 4.7 4.6 ± 0.4 (4.2–5.5) 4.8 ± 0.3 (4.5–5.2)
V 52.8 52.5 ± 1.6 (49.5–55.7) 39.4 ± 5.4 (33.1–47.4)
Lip height 7.5 7.6 ± 2.4 (7.0–8.0) 7.6 ± 0.3 (7.0–8.0)
Lip width 3.7 3.8 ± 0.3 (3.4–4.5) 3.7 ± 0.3 (3.2–4.0)
Stylet length 22.3 22.2 ± 0.6 (21–23) 21.5 ± 0.7 (20–23)
DGO distance from stylet knobs 2.0 2.0 ± 0.1 (1.7–2.2) 2.1 ± 0.1 (1.9–2.3)
Excretory pore from anterior end 122.8 120.6 ± 5.2 (109–126) 108.3 ± 5.2 (101–116)
Hemizonid from anterior end 118.4 116.7 ± 5.1 (104–123) 103.0 ± 6.7 (94–113)
Pharynx length 148.4 145 ± 5.7 (130–152) 134 ± 3.6 (127–139)
Maximum body diam. 26.6 26.6 ± 2.5 (22–33) 25.0 ± 1.0 (23–27)
Vulval body diam. 25.4 26.6 ± 2.3 (23–32) −
Anal/cloacal body diam. 18.3 18.1 ± 1.2 (16–21) 17.7 ± 0.9 (16–19)
Tail length 85.2 83.8 ± 5.4 (76–92) 85.2 ± 5.4 (78–93)
Hyaline tail part length 25.2 22.4 ± 2.2 (19–25) 21.3 ± 1.9 (18–24)
Phasmid position from anus/cloaca 12.4 15.5 ± 4.1 (10–19) 24.6 ± 3.9 (19–29)
Phasmid % of tail 14.6 17.4 ± 4.0 (12–20) 29.5 ± 4.0 (24–35)
Spicule length − 23.4 ± 1.9 (22–25)
Gubernaculum − 8.0 ± 0.7 (7–9)
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Language:
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