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

Rawson, Christopher J.; Nemmers, London; Criswell, Stacey; Smythe, Ashleigh B.; Burke, Alison K.; Marais, Eugene; Maggs-Kölling, Gillian; Treonis, Amy M.

doi:10.2478/jofnem-2024-0039

Figures & Tables

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.

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. 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. 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.

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 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.

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 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

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)

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

Figures & Tables

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j_jofnem-2024-0039_tab_002

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_

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