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Description of Geocenamus vietnamensis sp. n. (Nematoda: Merliniidae) from Vietnam

Journal of Nematology
Volume 51 (2019): Issue 1 (January 2019)
By:
Open Access
|May 2019

Figures & Tables

Figure 1:

Geocenamus vietnamensis n. sp. (♀). (A): Entire body; (C): Pharyngeal region; €: Head region; (F): Lateral field at mid-body; (G): Vulva region with posterior gonad; (H): tail region; (K): Vulva region. (♂). (B): Entire body; (D): Pharyngeal region; (I): Tail region; (L): Cloacal region showing spicule and gubernaculum.
Geocenamus vietnamensis n. sp. (♀). (A): Entire body; (C): Pharyngeal region; €: Head region; (F): Lateral field at mid-body; (G): Vulva region with posterior gonad; (H): tail region; (K): Vulva region. (♂). (B): Entire body; (D): Pharyngeal region; (I): Tail region; (L): Cloacal region showing spicule and gubernaculum.

Figure 2:

Geocenamus vietnamensis n. sp. (Light microscope). (A): Entire body of female and male (female in the left side and male in the right side); (B): Head region of the female; (C): Head region of the male; (D): Vulva region with spermatheca at arrow position; (E): Female pharyngeal region; (F): Spicule and Gubernaculum; (G): Phasmid in the tail of the male; (H): Vulva region; (I): Tail of the male; (J): Phasmid in the tail of the female; (K): Lateral field; (L): Tail of the female.
Geocenamus vietnamensis n. sp. (Light microscope). (A): Entire body of female and male (female in the left side and male in the right side); (B): Head region of the female; (C): Head region of the male; (D): Vulva region with spermatheca at arrow position; (E): Female pharyngeal region; (F): Spicule and Gubernaculum; (G): Phasmid in the tail of the male; (H): Vulva region; (I): Tail of the male; (J): Phasmid in the tail of the female; (K): Lateral field; (L): Tail of the female.

Figure 3:

Geocenamus vietnamensis n. sp. (SEM ♀). (A): Labial region; (B): Head region; (C): Enface view with amphid orifice (ap) at arrow position; (D): Vulva region with lateral field at arrow position; €: Secretory–excretory pore (ep); (F): Vulva with epyptigma (ept) at arrow position; (G): anus position (a) and phasmid position (ph); (H): phasmid position; (I): Tail region; (J): Tail tip.
Geocenamus vietnamensis n. sp. (SEM ♀). (A): Labial region; (B): Head region; (C): Enface view with amphid orifice (ap) at arrow position; (D): Vulva region with lateral field at arrow position; €: Secretory–excretory pore (ep); (F): Vulva with epyptigma (ept) at arrow position; (G): anus position (a) and phasmid position (ph); (H): phasmid position; (I): Tail region; (J): Tail tip.

Figure 4:

Geocenamus vietnamensis n. sp. (SEM ♂). (A): Labial region; (B): Head region; (C): Enface view with amphid orifice (ap) at arrow position; (D): Lateral field; (E): Secretory–excretory pore; (F): Tail region with spicule (sp); (G): Tail tip; (H): Side view of tail with spicule (sp) and phasmid (ph) positions; (I): Cloacal region; (I): Cloaca with hypotigma; (J): Phasmid position.
Geocenamus vietnamensis n. sp. (SEM ♂). (A): Labial region; (B): Head region; (C): Enface view with amphid orifice (ap) at arrow position; (D): Lateral field; (E): Secretory–excretory pore; (F): Tail region with spicule (sp); (G): Tail tip; (H): Side view of tail with spicule (sp) and phasmid (ph) positions; (I): Cloacal region; (I): Cloaca with hypotigma; (J): Phasmid position.

Figure 5:

Phylogenetic tree generated from D2–D3 of 28S rDNA sequences based on ML method (TN93 + G model) with 1,000 replications.
Phylogenetic tree generated from D2–D3 of 28S rDNA sequences based on ML method (TN93 + G model) with 1,000 replications.

Figure 6:

Phylogenetic tree generated from ITS rDNA sequences based on ML method (GTR + G model) with 1,000 replications.
Phylogenetic tree generated from ITS rDNA sequences based on ML method (GTR + G model) with 1,000 replications.

Morphometric data of Geocenamus vietnamensis n_ sp_ from fixed specimens_ All measurements are in μ m (except for ratio) and in the form: mean ± s_d_ (range)_

Paratypes
Geocenamus measurementHolotype femaleAllotype maleFemale (n = 18)Male (n = 15)
Body length (L)877712875 ± 64 (776–979)706 ± 35 (631–754)
Lip region height3.13.63.6 ± 0.5 (3.1–4.2)3.4 ± 0.3 (3.1–3.6)
Lip region width6.25.76.5 ± 0.7 (5.2–7.3)6.1 ± 0.5 (5.2–6.8)
Stylet cone18.715.615.7 ± 1.4 (13.5–18.7)15.1 ± 1.4 (13–17.7)
Stylet shaft9.48.310.4 ± 0.5 (9.4–11.4)8.8 ± 1.6 (5.7–10.9)
Stylet length282426 ± 1 (24–28)24 ± 1 (23–26)
Stylet knob height2.11.62.0 ± 0.4 (1.6–2.6)1.9 ± 0.4 (1.6–2.6)
Stylet knob width4.23.13.5 ± 0.8 (1.6–4.2)3.6 ± 0.2 (3.12–3.6)
Stylet base to dorsal gland orifice (DGO)3.13.122.9 ± 0.3 (2.6–3.1)3.0 ± 0.3 (2.6–3.6)
Body width at stylet base16.611.916.7 ± 2.8 (13.0–20.8)13.7 ± 1.0 (11.9–15.6)
Maximum body diameter (MBD)312229 ± 3 (25–34)22 ± 1 (22–25)
Body width at vulva22 27 ± 3 (22–34)
Body width at anus18.71319.1 ± 2.4 (15.6–23.9)16.1 ± 2.6 (13–21.8)
Anterior end to the end of pharynx152125138 ± 9 (124–152)122 ± 7 (114–135)
Anterior end to the end of median bulb897381 ± 8 (74–99)72 ± 5 (67–81)
Anterior end to median valve786572 ± 7 (66–88)63 ± 5 (57–71)
Median bulb width10.99.811.0 ± 0.7 (10.4–12.5)9.6 ± 1.2 (6.8–10.4)
Median bulb length15.615.617.0 ± 1.6 (14.6–18.7)15.5 ± 1.2 (13.5–17.7)
Anterior end to nerve ring868690 ± 6 (83–104)83 ± 8 (74–99)
Anterior end to secretory–excretory pore948994 ± 5 (86–102)86 ± 6 (76–97)
Isthmus length393132 ± 4 (26–39)30 ± 2 (26–31)
Basal bulb length272125 ± 2 (23–28)22 ± 2 (19–25)
Tail length8675104 ± 14 (85–125)84 ± 9 (68–96)
Spicule length 21 20 ± 1 (19–22)
Gubernaculum length 5.2 6.5 ± 1.0 (5.2–7.8)
Anus to phasmid2317.723 ± 3 (18.7–26)18.6 ± 2.6 (13.5–23)
Tail annuli (ventral)614864 ± 5 (58–73)59 ± 6 (48–65)
a = L/MBD283330 ± 3 (25–34)32 ± 1 (29–33)
b′ = L/distance from anterior end to pharyngo–intestinal valve5.85.76.4 ± 0.5 (5.8–7.2)5.8 ± 0.2 (5.5–6.2)
c = L/Tail length10.29.58.5 ± 0.8 (7.3–10.2)8.5 ± 0.7 (9.3–9.5)
c′ = Tail length/ABD4.65.85.5 ± 0.7 (4.3–6.5)5.3 ± 0.7 (4.3–6.3)
V = Anterior end to vulva/L ×10050 49 ± 2 (47–52)
M = stylet conus length/stylet length ×100676560 ± 3 (56–67)62 ± 4 (57–69)
MB = % distance from anterior end to median bulb in relation to the length of pharynx515252 ± 3 (49–59)51 ± 1 (50–53)
O = % distance of dorsal pharyngeal gland opening from stylet knobs in relation to the stylet length11.113.011.0 ± 1.3 (9.6–13.0)12.5 ± 1.3 (10.2–14.3)
Phasmid % tail272422 ± 2 (18.3–27)22 ± 3 (17–28)
DOI: https://doi.org/10.21307/jofnem-2019-025 | Journal eISSN: 2640-396X | Journal ISSN: 0022-300X
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Language: English
Page range: 1 - 12
Submitted on: Dec 4, 2018
Published on: May 27, 2019
Published by: Society of Nematologists, Inc.
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year
Keywords:
Morphology,
Molecular,
New species,
SEM,
Taxonomy,
D2–D3,
ITS,
28S,
Casuarinaceae,
Zingiberaceae
Related subjects:
Life sciences,
Life sciences, other

© 2019 Huu Tien Nguyen, Thi Mai Linh Le, Thi Duyen Nguyen, Gracia Liebanas, Thi Anh Duong Nguyen, Quang Phap Trinh, published by Society of Nematologists, Inc.
This work is licensed under the Creative Commons Attribution 4.0 License.

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