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.
Table 1:
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.
| Character | Females | Males | |
|---|---|---|---|
| Holotype | Paratypes | Paratypes | |
| n | - | 12 | 13 |
| L | 900.8 | 897.8 ± 44.9 (831.5–976.7) | 764.6 ± 49.3 (717.7–853.0) |
| a | 22.0 | 21.1 ± 3.0 (16.5–25.2) | 22.0 ± 1.9 (18.0–25.3) |
| b | 5.9 | 6.2 ± 0.4 (5.7–7.0) | 5.7 ± 0.3 (5.2–6.3) |
| c | 17.5 | 21.5 ± 1.3 (19.3–23.6) | 19.5 ± 1.6 (17.5–22.4) |
| c’ | 1.9 | 1.8 ± 0.2 (1.4–2.1) | 1.6 ± 0.2 (1.3–1.9) |
| V (%) | 60.9 | 59.3 ± 1.5 (57.2 – 61.6) | - |
| Lip region width | 8.9 | 8.5 ± 0.5 (7.7–9.3) | 7.5 ± 0.5 (7.0–8.6) |
| Stoma length | 11.4 | 12.1 ± 0.8 (10.9–13.3) | 11.5 ± 0.9 (10.4–12.8) |
| Stoma width | 2.2 | 2.4 ± 0.2 (2.1–2.8) | 2.2 ± 0.2 (1.9–2.7) |
| Corpus length | 89.7 | 88.3 ± 3.4 (81.7–92.6) | 79.9 ± 5.6 (69.8–90.9) |
| Corpus width | 19.7 | 19.7 ± 1.8 (17.5–23.6) | 15.8 ± 2.6 (12.4–21.1) |
| Isthmus | 27.7 | 28.9 ± 2.0 (25.3–32.6) | 29.0 ± 1.9 (25.5–32.9) |
| Basal bulb | 27.2 | 27.1 ± 2.1 (24.8–31.3) | 24.7 ± 2.3 (22.5–29.4) |
| Pharynx length | 144.6 | 144.9 ± 4.9 (135.2–152.2) | 133.6 ± 6.8 (123.9–149.0) |
| Neck | 152.8 | 154.8 ± 6.1 (145.9–166.1) | 140.6 ± 7.2 (131.0–155.9) |
| Neck-base body diameter | 36.4 | 38.7 ± 4.6 (32.9–47.8) | 33.2 ± 4.5 (25.0–40.4) |
| Nerve ring - ant. end | 115.0 | 115.3 ± 7.1 (102.2–127.4) | 105.7 ± 9.1 (91.7–123.2) |
| Excretory pore - ant. end | 141.0 | 141.1 ± 11.3 (115.1–157.6) | 136.0 ± 12.2 (115.4–157.0) |
| Deirid - ant. end | 141.0 | 141.7 ± 11.3 (115.4–157.1) | 136.5 ± 12.6 (115.4–157.6) |
| Mid-body diameter | 40.9 | 43.4 ± 5.8 (34.6–55.4) | 35.1 ± 4.2 (29.5–41.9) |
| Cuticle annuli thickness | 1.2 | 1.2 ± 0.1 (1.1–1.4) | 1.2 ± 0.1 (1.0–1.4) |
| Lateral field | 3.7 | 3.7 ± 0.4 (3.2–4.3) | 3.5 ± 0.4 (3.1–4.2) |
| Vulva - ant. end | 548.5 | 532.3 ± 26.5 (499.0–572.8) | - |
| Vulval body diameter | 41.6 | 44.1 ± 5.1 (35.9–50.5) | - |
| Vulva-anus distance | 298.2 | 302.6 ± 14.8 (275.2–321.1) | - |
| Vagina length | 13.7 | 14.2 ± 1.5 (11.3–16.5) | - |
| Ovary length | 342.3 | 389.7 ± 30.0 (326.8–430.3) | - |
| Post-vulval sac | 25.5 | 21.9 ± 3.4 (16.5–27.2) | - |
| Rectum length | 27.9 | 25.8 ± 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) |
| Tail | 51.4 | 42.3 ± 2.3 (39.2–45.9) | 39.4 ± 3.6 (32.5–45.9) |
| Phasmid-anus distance | 23.1 | 18.5 ± 3.5 (13.3–24.2) | 18.9 ± 3.7 (14.3–28.7) |
| Anal body diameter | 26.8 | 23.4 ± 2.9 (20.4–31.0) | 24.7 ± 2.9 (20.8–29.3) |
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.
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.
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.
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.
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.
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.
| SSU rDNA | LSU rDNA D2-D3 | ||
|---|---|---|---|
| Taxon Name | Accession Number | Taxon Name | Accession Number |
| Acrobeles complexus | KU180671 | Acrobeles complexus | KU180682 |
| Alloionema appendiculatus | KP204844 | Alloionema appendiculatum | KP204846 |
| Baldwinema ilamense | KM454870 | Baldwinema golestanense | KM454875 |
| Baujardia mirabilis | AF547385 | Baldwinema ilamense | KM454871 |
| Caenorhabditis elegans N2 | MN519140 | Caenorhabditis elegans N2 | MN519140 |
| Halicephalobus gingivalis | KP875567 | Halicephalobus gingivalis | KP875568 |
| Halicephalobus sp. AA4 | MF470238 | Halicephalobus sp. AA4 | MG051261 |
| Neoalloionema tricaudatum | KR817916 | Panagrellus redivivus PS1163 | DQ408250 |
| Panagrellus redivivus PS1163 | AF083007 | Panagrobelus stammeri | DQ145649 |
| Panagrobelus stammeri | AF202153 | Panagrolaimidae sp. DS129 | MK087078 |
| Panagrolaimidae sp. DS129 | MK087064 | Panagrolaimus detritophagus S136 | ON927889 |
| Panagrolaimus sp. ES6 | FJ590961 | Panagrolaimus kolymaensis | JAJQJQ010000137 |
| Panagrolaimus artyukhovskii | MK636578 | Panagrolaimus labiatus SN14 | MZ546405 |
| Panagrolaimus davidi AC_Pd2 | HQ270131 | Panagrolaimus sp. B14 | OP720885 |
| Panagrolaimus davidi | FJ590981 | Panagrolaimus sp. DS127 | MK087076 |
| Panagrolaimus detritophagus | FJ590980 | Panagrolaimus sp. HMM472 | KY750812 |
| Panagrolaimus detritophagus BS0008 | EU543176 | Panagrolaimus sp. HMM476 | KY750816 |
| Panagrolaimus facetus | KY119819 | Panagrolaimus sp. HMM550 | KY750827 |
| Panagrolaimus kolymaensis | JAJQJQ010000793 | Panagrolaimus sp. L73 | PP786565 |
| Panagrolaimus labiatus SN14 | MW412913 | Panagrolaimus sp. LA5 | PP786566 |
| Panagrolaimus paetzoldi 452 | FJ040414 | Panagrolaimus sp. PS1159 | EU253569 |
| Panagrolaimus paetzoldi | ON713642 | Panagrolaimus sp. PS1159 | DQ059061 |
| Panagrolaimus sp. isolate rigidus1 | MK547102 | Panagrolaimus sp. R18 | EF417146 |
| Panagrolaimus rigidus | FJ590974 | Panagrolaimus sp. RS-2007a | EF417144 |
| Panagrolaimus sp. 10 ARA-2018 | MH399798 | Panagrolaimus sp. RS-2007b | EF417145 |
| Panagrolaimus sp. 4164 | MK301117 | Panagrolaimus sp. S33 | ON927890 |
| Panagrolaimus sp. AS01 | KC522708 | Panagrolaimus sp. S71 | ON927888 |
| Panagrolaimus sp. DL0117 | FJ590986 | Panagrolaimus sp. S91 | ON927891 |
| Panagrolaimus sp. DL0128 | FJ590987 | Panagrolaimus sp. SAN-15 | DQ145651 |
| Panagrolaimus sp. DL0139 | FJ590989 | Panagrolaimus sp. T6_4_6 | MZ425430 |
| Panagrolaimus sp. ES1 | FJ590960 | Plectonchus hunti | KU180689 |
| Panagrolaimus sp. ES2 | FJ590962 | Rhabditophanes sp. KR3021 | AY294185 |
| Panagrolaimus sp. ES3 | FJ590963 | Tarantobelus arachnicida | MZ656003 |
| Panagrolaimus sp. ES5 | FJ590972 | Turbatrix aceti | KU180690 |
| Panagrolaimus sp. 3 GVDU-2019 | MN082330 | ||
| Panagrolaimus sp. JB051 | FJ590971 | ||
| Panagrolaimus sp. JB115 | FJ590969 | ||
| Panagrolaimus sp. JB131 | FJ590968 | ||
| Panagrolaimus sp. JU765 | FJ590956 | ||
| Panagrolaimus sp. PS1159 | U81579 | ||
| Panagrolaimus sp. PS1159 | FJ590977 | ||
| Panagrolaimus sp. PS1162 | FJ590958 | ||
| Panagrolaimus sp. PS1579 | FJ590976 | ||
| Panagrolaimus sp. PS1732 | FJ590959 | ||
| Panagrolaimus sp. PS1806 | FJ590957 | ||
| Panagrolaimus sp. PS3966 | FJ590983 | ||
| Panagrolaimus sp. PS443 | KC522712 | ||
| Panagrolaimus sp. PS443 | FJ590978 | ||
| Panagrolaimus sp. SN103 | FJ590970 | ||
| Panagrolaimus subelongatus | AY284681 | ||
| Panagrolaimus superbus | KC522707 | ||
| Panagrolaimus superbus | FJ590973 | ||
| Panagrolaimus trilabiatus | KF011487 | ||
| Plectonchus wyganti | KJ636307 | ||
| Procephalobus sp. 1 WB-2008 | EU543179 | ||
| Propanagrolaimus sp. LC91 | KJ434175 | ||
| Propanagrolaimus sp. WTM1 | KJ434176 | ||
| Rhabditophanes sp. KR3021 | AF202151 | ||
| Strongyloides procyonis | AB205054 | ||
| Tarantobelus arachnicida | MZ655999 | ||
| Turbatrix aceti | KU180673 | ||