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Description of Panagrolaimus namibiensis n. sp. (Rhabditida: Panagrolaimidae), an Anhydrobiotic Nematode from the Namib Desert of Namibia

Journal of Nematology
Volume 56 (2024): Issue 1 (March 2024)
By:
Open Access
|Oct 2024

Figures & Tables

Figure 1:

A) Soil collection site for isolation of Panagrolaimus namibiensis n. sp. Soils were collected from under Arthraerua leubnitziae shrubs (inset). B) Map of Namibia showing location of soil collection site (blue dot). Red dots indicate other soils containing a Panagrolaimus nematode morphologically indistinct from P. namibiensis n. sp.
A) Soil collection site for isolation of Panagrolaimus namibiensis n. sp. Soils were collected from under Arthraerua leubnitziae shrubs (inset). B) Map of Namibia showing location of soil collection site (blue dot). Red dots indicate other soils containing a Panagrolaimus nematode morphologically indistinct from P. namibiensis n. sp.

Figure 2:

Panagrolaimus namibiensis n. sp. line drawings. A: Anterior body region. B: Anterior body end, showing stoma and rhabdia. C: Full body, female. D: Full body, male. E: Lateral field. F: Basal bulb, excretory pore. G: Posterior body end, female. H: Posterior body end, male.
Panagrolaimus namibiensis n. sp. line drawings. A: Anterior body region. B: Anterior body end, showing stoma and rhabdia. C: Full body, female. D: Full body, male. E: Lateral field. F: Basal bulb, excretory pore. G: Posterior body end, female. H: Posterior body end, male.

Figure 3:

Panagrolaimus namibiensis n. sp. light micrographs. A: Anterior body region and pharynx. B: Lip region, stoma, stegostomal dorsal tooth (DT). C: Full body, female. D: Part of reproductive tract, female. E: Lateral field. F: Part of testis, male. G: Posterior body end, spicule (S), gubernaculum (G), male. H: Posterior body end, rectum, female.
Panagrolaimus namibiensis n. sp. light micrographs. A: Anterior body region and pharynx. B: Lip region, stoma, stegostomal dorsal tooth (DT). C: Full body, female. D: Part of reproductive tract, female. E: Lateral field. F: Part of testis, male. G: Posterior body end, spicule (S), gubernaculum (G), male. H: Posterior body end, rectum, female.

Figure 4:

Panagrolaimus namibiensis n. sp. scanning electron microscopic images. A: Anterior body region. B: Lip region in frontal view. C: Full body, female. D: Excretory pore (EP), anterior deirids (AD). E: Anterior deirid (AD). F: Lateral field. G, H: Vulva. I: Anus, phasmid (P), female. J: Posterior end, posterior deirid (PD), female. K: Posterior end, spicule, pre- and post-cloacal genital papillae (GP), midventral papillae (MP), male.
Panagrolaimus namibiensis n. sp. scanning electron microscopic images. A: Anterior body region. B: Lip region in frontal view. C: Full body, female. D: Excretory pore (EP), anterior deirids (AD). E: Anterior deirid (AD). F: Lateral field. G, H: Vulva. I: Anus, phasmid (P), female. J: Posterior end, posterior deirid (PD), female. K: Posterior end, spicule, pre- and post-cloacal genital papillae (GP), midventral papillae (MP), male.

Figure 5:

Phylogenetic tree inferred by Bayesian analysis of SSU sequences showing the relationship of Panagrolaimus namibiensis n. sp. (highlighted in blue) to other members of Panagrolaimidae and other taxa. Support for internal clades is shown by posterior probability (pp) values placed next to nodes. Scale bar represents 0.21 estimated substitutions per site.
Phylogenetic tree inferred by Bayesian analysis of SSU sequences showing the relationship of Panagrolaimus namibiensis n. sp. (highlighted in blue) to other members of Panagrolaimidae and other taxa. Support for internal clades is shown by posterior probability (pp) values placed next to nodes. Scale bar represents 0.21 estimated substitutions per site.

Figure 6:

Phylogenetic tree inferred by Bayesian analysis of LSU sequences showing the relationship of Panagrolaimus namibiensis n. sp. (highlighted in blue) to other members of Panagrolaimidae and other taxa. Support for internal clades is shown by posterior probability (pp) values placed next to nodes supported by greater than 0.5 pp. Scale bar represents 0.26 estimated substitutions per site.
Phylogenetic tree inferred by Bayesian analysis of LSU sequences showing the relationship of Panagrolaimus namibiensis n. sp. (highlighted in blue) to other members of Panagrolaimidae and other taxa. Support for internal clades is shown by posterior probability (pp) values placed next to nodes supported by greater than 0.5 pp. Scale bar represents 0.26 estimated substitutions per site.

Figure 7:

A) Panagrolaimus namibiensis n. sp. survival (% of population regaining motility) after exposure to three treatments. Baseline nematodes were maintained at 100% RH for 24 h. Pre-conditioned nematodes were slowly exposed to increasingly lower RH levels before 24 h at 0%. Direct exposure nematodes were directly exposed to 0% RH. Boxplots represent the interquartile range with lines representing the median value. Whiskers represent the minimum/maximum values, and circles are outliers. N = 8 replicates per treatment. Bars with different lowercase letters are statistically different from each other (Tukey’s HSD test). B) SEM of a coiled and anhydrobiotic P. namibiensis n. sp.
A) Panagrolaimus namibiensis n. sp. survival (% of population regaining motility) after exposure to three treatments. Baseline nematodes were maintained at 100% RH for 24 h. Pre-conditioned nematodes were slowly exposed to increasingly lower RH levels before 24 h at 0%. Direct exposure nematodes were directly exposed to 0% RH. Boxplots represent the interquartile range with lines representing the median value. Whiskers represent the minimum/maximum values, and circles are outliers. N = 8 replicates per treatment. Bars with different lowercase letters are statistically different from each other (Tukey’s HSD test). B) SEM of a coiled and anhydrobiotic P. namibiensis n. sp.

j_jofnem-2024-0039_tab_002

SSU rDNALSU rDNA D2-D3
Taxon NameAccession NumberTaxon NameAccession Number
Acrobeles complexusKU180671Acrobeles complexusKU180682
Alloionema appendiculatusKP204844Alloionema appendiculatumKP204846
Baldwinema ilamenseKM454870Baldwinema golestanenseKM454875
Baujardia mirabilisAF547385Baldwinema ilamenseKM454871
Caenorhabditis elegans N2MN519140Caenorhabditis elegans N2MN519140
Halicephalobus gingivalisKP875567Halicephalobus gingivalisKP875568
Halicephalobus sp. AA4MF470238Halicephalobus sp. AA4MG051261
Neoalloionema tricaudatumKR817916Panagrellus redivivus PS1163DQ408250
Panagrellus redivivus PS1163AF083007Panagrobelus stammeriDQ145649
Panagrobelus stammeriAF202153Panagrolaimidae sp. DS129MK087078
Panagrolaimidae sp. DS129MK087064Panagrolaimus detritophagus S136ON927889
Panagrolaimus sp. ES6FJ590961Panagrolaimus kolymaensisJAJQJQ010000137
Panagrolaimus artyukhovskiiMK636578Panagrolaimus labiatus SN14MZ546405
Panagrolaimus davidi AC_Pd2HQ270131Panagrolaimus sp. B14OP720885
Panagrolaimus davidiFJ590981Panagrolaimus sp. DS127MK087076
Panagrolaimus detritophagusFJ590980Panagrolaimus sp. HMM472KY750812
Panagrolaimus detritophagus BS0008EU543176Panagrolaimus sp. HMM476KY750816
Panagrolaimus facetusKY119819Panagrolaimus sp. HMM550KY750827
Panagrolaimus kolymaensisJAJQJQ010000793Panagrolaimus sp. L73PP786565
Panagrolaimus labiatus SN14MW412913Panagrolaimus sp. LA5PP786566
Panagrolaimus paetzoldi 452FJ040414Panagrolaimus sp. PS1159EU253569
Panagrolaimus paetzoldiON713642Panagrolaimus sp. PS1159DQ059061
Panagrolaimus sp. isolate rigidus1MK547102Panagrolaimus sp. R18EF417146
Panagrolaimus rigidusFJ590974Panagrolaimus sp. RS-2007aEF417144
Panagrolaimus sp. 10 ARA-2018MH399798Panagrolaimus sp. RS-2007bEF417145
Panagrolaimus sp. 4164MK301117Panagrolaimus sp. S33ON927890
Panagrolaimus sp. AS01KC522708Panagrolaimus sp. S71ON927888
Panagrolaimus sp. DL0117FJ590986Panagrolaimus sp. S91ON927891
Panagrolaimus sp. DL0128FJ590987Panagrolaimus sp. SAN-15DQ145651
Panagrolaimus sp. DL0139FJ590989Panagrolaimus sp. T6_4_6MZ425430
Panagrolaimus sp. ES1FJ590960Plectonchus huntiKU180689
Panagrolaimus sp. ES2FJ590962Rhabditophanes sp. KR3021AY294185
Panagrolaimus sp. ES3FJ590963Tarantobelus arachnicidaMZ656003
Panagrolaimus sp. ES5FJ590972Turbatrix acetiKU180690
Panagrolaimus sp. 3 GVDU-2019MN082330
Panagrolaimus sp. JB051FJ590971
Panagrolaimus sp. JB115FJ590969
Panagrolaimus sp. JB131FJ590968
Panagrolaimus sp. JU765FJ590956
Panagrolaimus sp. PS1159U81579
Panagrolaimus sp. PS1159FJ590977
Panagrolaimus sp. PS1162FJ590958
Panagrolaimus sp. PS1579FJ590976
Panagrolaimus sp. PS1732FJ590959
Panagrolaimus sp. PS1806FJ590957
Panagrolaimus sp. PS3966FJ590983
Panagrolaimus sp. PS443KC522712
Panagrolaimus sp. PS443FJ590978
Panagrolaimus sp. SN103FJ590970
Panagrolaimus subelongatusAY284681
Panagrolaimus superbusKC522707
Panagrolaimus superbusFJ590973
Panagrolaimus trilabiatusKF011487
Plectonchus wygantiKJ636307
Procephalobus sp. 1 WB-2008EU543179
Propanagrolaimus sp. LC91KJ434175
Propanagrolaimus sp. WTM1KJ434176
Rhabditophanes sp. KR3021AF202151
Strongyloides procyonisAB205054
Tarantobelus arachnicidaMZ655999
Turbatrix acetiKU180673

Measurements of Panagrolaimus namibiensis n_ sp_ from the gravel plains of the Namib Desert of Namibia_ Measurement units are μm ± the standard deviation, with the range in parentheses_

CharacterFemalesMales
HolotypeParatypesParatypes
n-1213
L900.8897.8 ± 44.9 (831.5–976.7)764.6 ± 49.3 (717.7–853.0)
a22.021.1 ± 3.0 (16.5–25.2)22.0 ± 1.9 (18.0–25.3)
b5.96.2 ± 0.4 (5.7–7.0)5.7 ± 0.3 (5.2–6.3)
c17.521.5 ± 1.3 (19.3–23.6)19.5 ± 1.6 (17.5–22.4)
c’1.91.8 ± 0.2 (1.4–2.1)1.6 ± 0.2 (1.3–1.9)
V (%)60.959.3 ± 1.5 (57.2 – 61.6)-
Lip region width8.98.5 ± 0.5 (7.7–9.3)7.5 ± 0.5 (7.0–8.6)
Stoma length11.412.1 ± 0.8 (10.9–13.3)11.5 ± 0.9 (10.4–12.8)
Stoma width2.22.4 ± 0.2 (2.1–2.8)2.2 ± 0.2 (1.9–2.7)
Corpus length89.788.3 ± 3.4 (81.7–92.6)79.9 ± 5.6 (69.8–90.9)
Corpus width19.719.7 ± 1.8 (17.5–23.6)15.8 ± 2.6 (12.4–21.1)
Isthmus27.728.9 ± 2.0 (25.3–32.6)29.0 ± 1.9 (25.5–32.9)
Basal bulb27.227.1 ± 2.1 (24.8–31.3)24.7 ± 2.3 (22.5–29.4)
Pharynx length144.6144.9 ± 4.9 (135.2–152.2)133.6 ± 6.8 (123.9–149.0)
Neck152.8154.8 ± 6.1 (145.9–166.1)140.6 ± 7.2 (131.0–155.9)
Neck-base body diameter36.438.7 ± 4.6 (32.9–47.8)33.2 ± 4.5 (25.0–40.4)
Nerve ring - ant. end115.0115.3 ± 7.1 (102.2–127.4)105.7 ± 9.1 (91.7–123.2)
Excretory pore - ant. end141.0141.1 ± 11.3 (115.1–157.6)136.0 ± 12.2 (115.4–157.0)
Deirid - ant. end141.0141.7 ± 11.3 (115.4–157.1)136.5 ± 12.6 (115.4–157.6)
Mid-body diameter40.943.4 ± 5.8 (34.6–55.4)35.1 ± 4.2 (29.5–41.9)
Cuticle annuli thickness1.21.2 ± 0.1 (1.1–1.4)1.2 ± 0.1 (1.0–1.4)
Lateral field3.73.7 ± 0.4 (3.2–4.3)3.5 ± 0.4 (3.1–4.2)
Vulva - ant. end548.5532.3 ± 26.5 (499.0–572.8)-
Vulval body diameter41.644.1 ± 5.1 (35.9–50.5)-
Vulva-anus distance298.2302.6 ± 14.8 (275.2–321.1)-
Vagina length13.714.2 ± 1.5 (11.3–16.5)-
Ovary length342.3389.7 ± 30.0 (326.8–430.3)-
Post-vulval sac25.521.9 ± 3.4 (16.5–27.2)-
Rectum length27.925.8 ± 2.8 (20.1–30.3)-
Testes length--207.8 ± 22.3 (184.1–254.9)
Spicule length--29.3 ± 2.0 (24.5–31.6)
Gubernaculum length--12.6 ± 1.5 (10.9–15.4)
Tail51.442.3 ± 2.3 (39.2–45.9)39.4 ± 3.6 (32.5–45.9)
Phasmid-anus distance23.118.5 ± 3.5 (13.3–24.2)18.9 ± 3.7 (14.3–28.7)
Anal body diameter26.823.4 ± 2.9 (20.4–31.0)24.7 ± 2.9 (20.8–29.3)
DOI: https://doi.org/10.2478/jofnem-2024-0039 | Journal eISSN: 2640-396X | Journal ISSN: 0022-300X
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Language: English
Submitted on: Feb 24, 2024
Published on: Oct 31, 2024
Published by: Society of Nematologists, Inc.
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year
Keywords:
Cryptobiosis,
morphology,
phylogeny,
scanning electron microscopy,
taxonomy
Related subjects:
Life sciences,
Life sciences, other

© 2024 Christopher J. Rawson, London Nemmers, Stacey Criswell, Ashleigh B. Smythe, Alison K. Burke, Eugene Marais, Gillian Maggs-Kölling, Amy M. Treonis, published by Society of Nematologists, Inc.
This work is licensed under the Creative Commons Attribution 4.0 License.

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