Taxonomy of Tobrilidae species from the Alkaline Lakes of the western Nebraska Sandhills

Mullin, Peter G.; Harris, Timothy; Higgins, Rebecca; Dutta, Enakshy; Porazinska, Dorota L.; Powers, Kirsten; Powers, Thomas

Taxonomy of Tobrilidae species from the Alkaline Lakes of the western Nebraska Sandhills

Journal of Nematology

Volume 56 (2024): Issue 1 (March 2024)

By:

Peter G. Mullin, Timothy Harris, Rebecca Higgins, Enakshy Dutta, Dorota L. Porazinska, Kirsten Powers and Thomas Powers

Open Access

|Aug 2024

Figures & Tables

Map of Nebraska with the Sandhills region outlined. Area of research on the alkaline lakes in this region is indicated in an enlarged map inset. A second enlarged map inset shows the area of research in eastern Nebraska on an agrichemical contamination site. Red circles indicate the location of sample collections from the stream sediment.

llustration of selected characters in Tobrilidae. A) Female heads (NID 12586, 13994) with teeth and tooth distance annotated. B) Female heads with differing tooth pocket arrangements. C) Male (NID 12533) posterior illustrating the numbering of supplements from the cloacal opening forward, with I designating the most posterior supplement and VII the most anterior.

A maximum likelihood COI phylogenetic tree of 90 Nebraska specimens and 21 GenBank accessions. Highlighting in labels indicates lake pH. Green equals neutral, orange equals pH >8.5. Blue boxes around labels identify three specimens that display incongruence between COI and 18S trees. Nematode Identification numbers (NID) start with the prefix N followed by the number of the specimen.

Comparison of the heads of specimens from each of the six Haplotype Groups, with their identification number and lake from which they were collected. Stoma shape, pockets, and tooth distance are featured. Blue box indicates incongruent specimen between COI and 18S trees.

Comparison of male spicules and supplements from haplotype groups one through six. The nematode identification (NID) number and collection location are shown for each. Groups 1, 4, and 5 have supplements that do not conspicuously protrude from the cuticle surface. Groups 2, 3, and 6 have protruding supplements. Group 4 has notably long spicules compared to other groups. The blue box around the label for NID 12595 denotes a specimen incongruent for COI and 18S trees.

Scanning electron micrographs of the male posterior region showing the intersupplementary structures known as micropapillae. A, B) NID 4829 from Border Lake, micropapillae in ventral view appear as four ridges between supplements; C) NID 4841 from Border Lake, micropapillae in lateral view appear as small bumps or papillae.

Scanning electron micrographs of Group 4 male spicules, all from Gimlet Lake, displaying possible pores at the tip. A) NID 4913 tail and close-up of spicules; B) NID 4926 posterior and close-up of spicules; C) NID 4899 spicules.

Comparison of the musculature associated with the vaginal canal in haplotype groups one through six. The Tobrilinae, Groups 1 and 5, display weak or poorly developed vaginal musculature. Group 3 appears to have moderately developed musculature, and Groups 2, 4, and 6 are all characterized by strongly developed muscles arranged in a multi-layered, bulb-like configuration. Blue box around NID 12574 indicates incongruent specimen with respect to the COI and 18S trees and has a strong, bulb-like musculature characteristic of Group 2.

Scanning electron micrographs of the head, amphid and cephalic setae of selected specimens from alkaline lakes in the Nebraska Sandhills. Amphid shapes were categorized as tiny, oval or slit-like. Slit-like amphids were positioned closest to cephalic setae. Inner labial setae are notably shorter than the outer labial and cephalic setae, which are of similar lengths.

Entire body images of female and male specimens from each of the six haplotype groups. The nematode identification (NID) number and collection location are shown for each. Blue box indicates incongruent specimen.

Comparison of female tails from each of the six haplotype groups. The nematode identification (NID) number and collection location is shown for each. Blue box in Group four indicates specimen, NID 12574, considered incongruous between the COI and 18S phylogenies, and which displays differing morphology from the other two individuals.

Linear discriminant analysis (LDA) of haplotype groupings using combined morphological and ecological attributes for A) females; B) males.

A maximum likelihood 18S phylogenetic tree of 88 Nebraska specimens and 19 GenBank accessions. Tobrilus Groups 1 and 5 are identical for the 18S barcode, and they are united in a strongly supported clade (99 bootstrap value) with Semitobrilus Group 4 and GenBank accessions identified as Tobrilus and Semitobrilus. Blue boxes identify specimens incongruous between COI and 18S trees.

Tobrilidae (order Triplonchida) of North America (Holovachov and Shoshin, 2014)

Sub-family	Tribe	Species
Neotobrilinae Tsalolikhin, 2001	Neotobrilini Tsalolikhin, 1981	Neotobrilus longus (Leidy, 1852) Tsalolikhin, 1981
Neotobrilinae Tsalolikhin, 2001	Neotobrilini Tsalolikhin, 1981	Neotobrilus nicsmolae Abebe, Ferebee, Taylor, Mundo-Ocampo, Mekete & De Ley, 2013
Neotobrilinae Tsalolikhin, 2001	Neotobrilini Tsalolikhin, 1981	Neotobrilus filipjevi (Ebsary, 1982) Tsalolikhin and Shoshin, 2009
Neotobrilinae Tsalolikhin, 2001	Neotobrilini Tsalolikhin, 1981	Neotobrilus hopei (Loof and Riemann, 1976) Tsalolikhin, 1981
Neotobrilinae Tsalolikhin, 2001	Neotobrilini Tsalolikhin, 1981	Semitobrilus pellucidus Bastian, 1865
Neotobrilinae Tsalolikhin, 2001	Neotobrilini Tsalolikhin, 1981	Semitobrilus ebsaryi Tsalolikhin, 2000
Neotobrilinae Tsalolikhin, 2001	Epitobrilini Tsalolikhin, 2001	Epitobrilus sablensis (Ebsary, 1982) Tsalolikhin, 2001
Tobrilinae Tsalolikhin, 2001	Tobrilini Filipjev, 1918	Tobrilus gracilis Bastian, 1865
Tobrilinae Tsalolikhin, 2001	Tobrilini Filipjev, 1918	Tobrilus aberrans (Schneider, 1925) Andrassy, 1959
Tobrilinae Tsalolikhin, 2001	Tobrilini Filipjev, 1918	Tobrilus affinis Gagarin, 1996
Tobrilinae Tsalolikhin, 2001	Tobrilini Filipjev, 1918	Eutobrilus graciliformis (Altherr and Delamare Deboutteville, 1972) Tsalolikhin, 1981
Tobrilinae Tsalolikhin, 2001	Tobrilini Filipjev, 1918	Eutobrilus steineri (Micoletzky, 1925) Zullini, 2006

Tobrilidae specimen information by Nematode Identification (NID) number, and molecular grouping by COI marker_

NID #	COI Group^a	Genus or Sub-family	Gender/Stage	Collection Location			GenBank accession #
NID #	COI Group^a	Genus or Sub-family	Gender/Stage	County in NE	Site	Latitude; Longitude	Marker- 18S	Marker- COI
7157	NA	Neotobrilus sp.	Female	Lancaster	Lincoln landfill	40.871597; −96.654336	PP854262
11092	NA	Neotobrilus sp.	Juvenile	Garden	Kokjohn Lake	41.78259; −102.52226	PP854263
11093	2	Neotobrilus sp.	Female	Garden	Kokjohn Lake	41.78259; −102.52226		PP855138
11096	NA	Neotobrilus sp.	Juvenile	Garden	Kokjohn Lake	41.78259; −102.52226	PP854264
11097	NA	Neotobrilus sp.	Juvenile	Garden	Kokjohn Lake	41.78259; −102.52226	PP854265
11105	NA	Neotobrilinae	Intersex	Garden	Gimlet Lake	41.758702; −102.438185	PP854246
11890	2	Neotobrilus sp.	Female	Garden	Bean Lake	41.77776; −102.53009		PP855143
12093	Singleton 1	Neotobrilinae	Female	Garden	Border Lake	41.79170; −102.53385	PP854247	PP855091
12103	NA	Neotobrilinae	Female	Garden	Border Lake	41.79170; −102.53385	PP854248
12127	1	Tobrilus sp.	Female	Garden	Gimlet Lake	41.75911; −102.43817	PP854219	PP855098
12129	NA	Tobrilus sp.	Female	Garden	Gimlet Lake	41.759109; −102.438171	PP854227
12138	1	Tobrilus sp.	Female	Garden	Gimlet Lake	41.75911; −102.43817	PP854220	PP855097
12141	NA	Neotobrilus sp.	Female	Garden	Kokjohn Lake	41.782081; −102.522884	PP854266
12144	2	Neotobrilus sp.	Male	Garden	Kokjohn Lake	41.78208; −102.52288	PP854267	PP855137
12168	NA	Tobrilus sp.	Female	Garden	Island Lake	41.733602; −102.410585	PP854218
12193	3	Brevitobrilus sp.	Male	Garden	Island Lake	41.73466; −102.41114	PP854261	PP855127
12194	NA	Brevitobrilus sp.	Female	Garden	Island Lake	41.734664; −102.411136	PP854260
12195	NA	Tobrilus sp.	Female	Garden	Island Lake	41.734664; −102.411136	PP854208
12204	Singleton 2	Neotobrilinae	Juvenile	Garden	Island Lake	41.73466; −102.41114	PP854243	PP855101
12397	NA	Brevitobrilus sp.	Male	Garden	Island Lake	41.73481; −102.41120	PP854259
12400	NA	Tobrilinae	Female	Garden	Island Lake	41.73481; −102.41120	PP854244
12406	3	Brevitobrilus sp.	Female	Garden	Island Lake	41.73481; −102.41120	PP854258	PP855126
12408	3	Brevitobrilus sp.	Female	Garden	Island Lake	41.73481; −102.41120	PP854257	PP855124
12417	3	Brevitobrilus sp.	Male	Garden	Island Lake	41.73481; −102.41120	PP854255	PP855125
12420	NA	Brevitobrilus sp.	Female	Garden	Island Lake	41.73481; −102.41120	PP854256
12422	NA	Neotobrilus sp.	Female	Garden	Border Lake	41.79230; −102.53349	PP854268
12423	NA	Neotobrilus sp.	Juvenile	Garden	Border Lake	41.79230; −102.53349	PP854269
12424	NA	Neotobrilus sp.	Female	Garden	Border Lake	41.79230; −102.53349	PP854270
12425	NA	Neotobrilus sp.	Juvenile	Garden	Border Lake	41.79230; −102.53349	PP854271
12426	2	Neotobrilus sp.	Juvenile	Garden	Border Lake	41.79230; −102.53349	PP854272	PP855128
12427	NA	Neotobrilus sp.	Male	Garden	Border Lake	41.79230; −102.53349	PP854273
12428	NA	Neotobrilus sp.	Juvenile	Garden	Border Lake	41.79230; −102.53349	PP854274
12429	NA	Neotobrilus sp.	Male	Garden	Border Lake	41.79230; −102.53349	PP854275
12431	NA	Neotobrilus sp.	Juvenile	Garden	Border Lake	41.79230; −102.53349	PP854276
12432	NA	Neotobrilus sp.	Juvenile	Garden	Border Lake	41.79230; −102.53349	PP854277
12433	NA	Neotobrilus sp.	Juvenile	Garden	Border Lake	41.79230; −102.53349	PP854278
12434	NA	Neotobrilus sp.	Juvenile	Garden	Border Lake	41.79230; −102.53349	PP854279
12435	NA	Neotobrilus sp.	Juvenile	Garden	Border Lake	41.79230; −102.53349	PP854280
12442	2	Neotobrilus sp.	Male	Garden	Border Lake	41.79230; −102.53349	PP854281	PP855130
12444	NA	Neotobrilus sp.	Male	Garden	Border Lake	41.79230; −102.53349	PP854282
12522	Singleton 3	Neotobrilinae	Juvenile	Garden	Border Lake	41.757717; −102.434	PP854283	PP855120
12523	2	Neotobrilus sp.	Female	Garden	Border Lake	41.757717; −102.434	PP854284	PP855136
12524	2	Neotobrilus sp.	Juvenile	Garden	Border Lake	41.757717; −102.434		PP855133
12525	2	Neotobrilus sp.	Juvenile	Garden	Border Lake	41.757717; −102.434	PP854285	PP855131
12528	2	Neotobrilus sp.	Female	Garden	Border Lake	41.79212; −102.53420	PP854286	PP855134
12533	2	Neotobrilus sp.	Male	Garden	Border Lake	41.79212; −102.53420	PP854291	PP855140
12537	2	Neotobrilus sp.	Male	Garden	Border Lake	41.79212; −102.53420	PP854292	PP855139
12538	2	Neotobrilus sp.	Female	Garden	Border Lake	41.79212; −102.53420	PP854251	PP855141
12539	2	Neotobrilus sp.	Female	Garden	Border Lake	41.79212; −102.53420	PP854287	PP855142
12540	2	Neotobrilus sp.	Female	Garden	Border Lake	41.79212; −102.53420	PP854288	PP855135
12554	4	Neotobrilinae	Male	Garden	Gimlet Lake	41.75543; −102.43447		PP855086
12556	1	Tobrilinae	Female	Garden	Gimlet Lake	41.75543; −102.43447		PP855099
12559	4	Semitobrilus sp.	Juvenile	Garden	Gimlet Lake	41.75543; −102.43447		PP855059
12561	4	Semitobrilus sp.	Juvenile	Garden	Gimlet Lake	41.75632; −102.43877		PP855083
12563	2	Neotobrilus sp.	Juvenile	Garden	Bean Lake	41.77068; −102.52883	PP854250	PP855144
12574	4	Semitobrilus sp.	Female	Garden	Bean Lake	41.77068; −102.52883	PP854289	PP855082
12575	2	Neotobrilus sp.	Female	Garden	Bean Lake	41.77068; −102.52883	PP854254	PP855132
12577	NA	Neotobrilus sp.	Juvenile	Garden	Bean Lake	41.77068; −102.52883	PP854290
12582	2	Neotobrilus sp.	Immature Female	Garden	Bean Lake	41.77068; −102.52883		PP855129
12586	1	Tobrilus sp.	Female	Garden	Gimlet Lake	41.75792; −102.43418	PP854228	PP855092
12587	1	Tobrilus sp.	Male	Garden	Gimlet Lake	41.75792; −102.43418	PP854221	PP855096
12588	1	Tobrilus sp.	Male	Garden	Gimlet Lake	41.75792; −102.43418	PP854217	PP855095
12591	1	Tobrilus sp.	Female	Garden	Gimlet Lake	41.75792; −102.43418	PP854229	PP855093
12592	4	Semitobrilus sp.	Male	Garden	Gimlet Lake	41.75792; −102.43418		PP855081
12593	4	Semitobrilus sp.	Female	Garden	Gimlet Lake	41.75792; −102.43418	PP854234	PP855084
12595	4	Semitobrilus sp.	Male	Garden	Gimlet Lake	41.75792; −102.43418	PP854206	PP855080
12596	4	Semitobrilus sp.	Male	Garden	Gimlet Lake	41.75792; −102.43418	PP854207	PP855079
12597	NA	Semitobrilus sp.	Female	Garden	Gimlet Lake	41.75792; −102.43418	PP854235
12598	NA	Semitobrilus sp.	Male	Garden	Gimlet Lake	41.75792; −102.43418	PP854241
12599	4	Semitobrilus sp.	Male	Garden	Gimlet Lake	41.75792; −102.43418		PP855078
12601	4	Semitobrilus sp.	Male	Garden	Gimlet Lake	41.75792; −102.43418		PP855085
12602	4	Semitobrilus sp.	Female	Garden	Gimlet Lake	41.75792; −102.43418		PP855077
12605	4	Semitobrilus sp.	Female	Garden	Gimlet Lake	41.75792; −102.43418	PP854249	PP855076
12606	1	Tobrilus sp.	Juvenile	Garden	Gimlet Lake	41.75792; −102.43418		PP855094
12607	1	Tobrilus sp.	Female	Garden	Gimlet Lake	41.75792; −102.43418	PP854222	PP855100
12613	4	Semitobrilus sp.	Juvenile	Garden	Island Lake	41.73257; −102.40362	PP854240	PP855075
12614	4	Semitobrilus sp.	Juvenile	Garden	Island Lake	41.73257; −102.40362	PP854236	PP855074
12615	4	Semitobrilus sp.	Juvenile	Garden	Island Lake	41.73257; −102.40362	PP854237	PP855073
12616	4	Semitobrilus sp.	Juvenile	Garden	Island Lake	41.73257; −102.40362	PP854238	PP855089
12617	4	Semitobrilus sp.	Juvenile	Garden	Island Lake	41.73257; −102.40362	PP854242	PP855072
12622	NA	Neotobrilinae	Juvenile	Garden	Island Lake	41.73257; −102.40362	PP854245
12623	NA	Semitobrilus sp.	Juvenile	Garden	Island Lake	41.73257; −102.40362	PP854239
12624	4	Semitobrilus sp.	Juvenile	Garden	Island Lake	41.73257; −102.40362		PP855071
12765	4	Semitobrilus sp.	Juvenile	Garden	Island Lake	41.73849; −102.40540		PP855070
12769	4	Semitobrilus sp.	Female	Garden	Island Lake	41.73849; −102.40540		PP855069
12770	4	Semitobrilus sp.	Immature Female	Garden	Island Lake	41.73849; −102.40540		PP855068
12773	4	Semitobrilus sp.	Immature Female	Garden	Island Lake	41.73849; −102.40540		PP855067
12774	4	Semitobrilus sp.	Female	Garden	Island Lake	41.73849; −102.40540		PP855087
12775	4	Semitobrilus sp.	Male	Garden	Island Lake	41.73849; −102.40540		PP855066
12776	4	Semitobrilus sp.	Juvenile	Garden	Island Lake	41.73849; −102.40540		PP855065
12778	4	Semitobrilus sp.	Female	Garden	Island Lake	41.73849; −102.40540		PP855090
12779	4	Semitobrilus sp.	Female	Garden	Island Lake	41.73849; −102.40540		PP855064
12780	4	Semitobrilus sp.	Female	Garden	Island Lake	41.73849; −102.40540		PP855063
12782	4	Semitobrilus sp.	Female	Garden	Island Lake	41.73849; −102.40540		PP855062
12786	4	Semitobrilus sp.	Immature Female	Garden	Island Lake	41.73849; −102.40540		PP855061
12827	4	Semitobrilus sp.	Female	Garden	Gimlet Lake	41.75767; −102.43452		PP855060
12836	4	Semitobrilus sp.	Female	Garden	Gimlet Lake	41.75767; −102.43452		PP855088
13994	6	Neotobrilus sp.	Female	Saunders	Johnson Creek 1	41.23383; −96.46355		PP855121
14003	6	Neotobrilus sp.	Male	Saunders	Johnson Creek 1	41.23383; −96.46355	PP854252	PP855122
14023	6	Neotobrilus sp.	Female	Saunders	Johnson Creek 2	41.204850; −96.44180	PP854253	PP855123
14034	5	Tobrilus sp.	Female	Saunders	Johnson Creek 3	41.19345; −96.42583	PP854216	PP855114
14036	5	Tobrilus sp.	Male	Saunders	Johnson Creek 3	41.19345; −96.42583	PP854230	PP855109
14041	5	Tobrilus sp.	Male	Saunders	Johnson Creek 3	41.19345; −96.42583	PP854223	PP855108
14042	5	Tobrilus sp.	Female	Saunders	Johnson Creek 3	41.19345; −96.42583		PP855112
14044	5	Tobrilus sp.	Male	Saunders	Johnson Creek 3	41.19345; −96.42583	PP854215	PP855110
14045	5	Tobrilus sp.	Female	Saunders	Johnson Creek 3	41.19345; −96.42583	PP854231	PP855107
14047	5	Tobrilus sp.	Female	Saunders	Johnson Creek 3	41.19345; −96.42583	PP854224	PP855115
14053	5	Tobrilus sp.	Female	Saunders	Johnson Creek 3	41.19345; −96.42583	PP854214	PP855106
14054	5	Tobrilus sp.	Male	Saunders	Johnson Creek 3	41.19345; −96.42583	PP854232	PP855105
14059	5	Tobrilus sp.	Male	Saunders	Johnson Creek 4	41.19048; −96.42437	PP854225	PP855116
14061	5	Tobrilus sp.	Male	Saunders	Johnson Creek 4	41.19048; −96.42437	PP854213	PP855117
14063	5	Tobrilus sp.	Female	Saunders	Johnson Creek 4	41.19048; −96.42437	PP854233	PP855102
14065	5	Tobrilus sp.	Female	Saunders	Johnson Creek 4	41.19048; −96.42437	PP854226	PP855103
14067	5	Tobrilus sp.	Female	Saunders	Johnson Creek 4	41.19048; −96.42437	PP854209	PP855104
14071	5	Tobrilus sp.	Male	Saunders	Johnson Creek 4	41.19048; −96.42437		PP855113
14072	5	Tobrilus sp.	Male	Saunders	Johnson Creek 4	41.19048; −96.42437	PP854212	PP855118
14080	5	Tobrilus sp.	Male	Saunders	Johnson Creek 5	41.17043; −96.40668	PP854211	PP855111
14081	5	Tobrilus sp.	Female	Saunders	Johnson Creek 5	41.17043; −96.40668	PP854210	PP855119

Within- and between-group mean distances of 9 tobrilid COI groups_ Within-group distance is shown in bold type_

	Group 4	Group 1	Group 5	Group 6	Group 3	Group 2	Group 7	Group 9	Group 8
Group 4	0.000639
Group 1	0.159155	0.000651
Group 5	0.165664	0.060499	0.002543
Group 6	0.157512	0.126478	0.111416	0.001826
Group 3	0.158968	0.123860	0.124103	0.096937	0
Group 2	0.164354	0.131401	0.133042	0.094518	0.093262	0.005378
Group 7	0.141845	0.141270	0.126408	0.131963	0.140716	0.151729	0.027397
Group 9	0.141204	0.110544	0.107067	0.117939	0.117579	0.124228	0.130528	0.007567
Group 8	0.173377	0.128000	0.145053	0.158447	0.133743	0.144301	0.183562	0.117613	0.004566

Standard morphological measurements, abbreviations, and definitions_

Gender		Character	Description (all measurements in μm)
Females		Vulva	Length from anterior to vulva
Females	Males	L	Overall body length
Females	Males	Tail	Portion of body from anus or cloaca to posterior terminus
Females	Males	a	Body length/greatest body diameter
Females	Males	b	Body length/distance from anterior to pharyngo-intestinal valve
Females	Males	c	Body length/tail Length
Females	Males	c′	Tail length/body diameter at anus or cloaca
Females		V	% Vulva position/body length
Females		VA/T	Distance from vulva to anus/tail length
Females	Males	Tail %	% Tail length/body length
Females	Males	C set/lrw	Cephalic seta length/lip region width
Females	Males	L set/lrw	Labial seta length/lip region width
Females	Males	StomaL	Length of sclerotized portion of stoma (buccal cavity)
Females	Males	Dist	Distance between teeth
	Males	Spic	Spicule length
	Males	Spic/L	% Spicule length/body length
	Males	Gub	Gubernaculum length
	Males	Cl-III	Distance between supplement III and cloaca
	Males	SR	Length of supplement row (I–VI)
	Males	SR/L	% Length of supplement row/total body length

Soil sample chemistry analyses, abbreviations, and definitions_

Parameter	Methodology
Soil pH	Soil pH-soil pH 1:1 (1 volume of soil in 1 volume of water)
% OM	% Organic Matter-Measure of organic matter in soil by % LOI
NO3	Nitrate ppm-Nitrate, KCl extractable
K	Potassium ppm-extracted by ammonium acetate
SO4	Sulfate ppm-extracted by Mehlich S-III
Zn	Zinc ppm-DTPA (diethylenetriaminepentaacetic acid) micronutrient extraction method
Fe	Iron ppm-DTPA (diethylenetriaminepentaacetic acid) micronutrient extraction method
Mn	Manganese ppm-DTPA (diethylenetriaminepentaacetic acid) micronutrient extraction method
Cu	Copper ppm-DTPA (diethylenetriaminepentaacetic acid) micronutrient extraction method
Ca	Calcium ppm-extracted by ammonium acetate
Mg	Magnesium ppm-extracted by ammonium acetate
Na	Sodium ppm-extracted by ammonium acetate
B	Boron ppm-hot water extracted
CEC	CEC (meq/100g)-Cation Exchange Capacity: Sum (in meq) of the 4 cations(K+Ca+Mg+Na+)/100g soil
% H	%H Sat-%Base Saturation
% K	%K Sat-%Base Saturation
% Ca	%Ca Sat-%Base Saturation
% Mg	%Mg Sat-%Base Saturation
% Na	%Na Sat-%Base Saturation
Cl-	Chloride ppm-Chloride
P	Phosphorus ppm-Phosphorus, extracted by Mehlich P-III

Comparisons of selected morphological characteristics of the main groups (mean ± standard deviation with range of values)

	Group 1 *Tobrilus* *Female (n=7)*	Group 2 *Neotobrilus* *Female (n=9)*	Group 3 *Brevitobrilus* *Female (n=4)*	Group 4 *Semitobrilus* *Female (n=4)*	Group 5 *Tobrilus* *Female (n=17)*	Group 6 *Neotobrilus* *Female (n=3)*
L	2366.7 ± 236.6 (2073–2863)	1999.3 ± 301.7 (1449–2341)	2032.8 ± 197.9 (1727–2229)	2729.6 ± 192.1 (2415–2937)	2079.3 ± 209.8 (1769–2739)	1225.4 ± 157.7 (1087–1446)
a	31.2 ± 2.1 (29.7–36.1)	31.5 ± 5.9 (21.8–41.1)	35.8 ± 2.3 (32.8–39.0)	33.7 ± 1.1 (32.4–35.2)	29.7 ± 2.4 (24.1–33.5)	26.4 ± 1.9 (24.2–28.8)
b	5.6 ± 0.2 (5.4–6.0)	5.4 ± 0.5 (4.1–6.0)	6.4 ± 0.3 (6.1–6.7)	6.7 ± 0.2 (6.4–6.9)	5.5 ± 0.4 (4.5–6.0)	4.9 ± 0.2 (4.6–5.2)
c	8.9 ± 0.7 (7.4–9.6)	10.6 ±1.0 (8.4–11.6)	7.9 ± 0.4 (7.1–8.2)	7.1 ± 0.2 (6.9–7.3)	10.0 ± 2.5 (8.5–19.8)	9.5 ± 1.8 (7.7–12.0)
c′	6.8 ± 0.7 (6.0–8.0)	4.6 ±0.4 (4.2–5.3)	7.4 ± 0.5 (6.9–8.1)	7.8 ± 0.4 (7.2–8.2)	5.8 ± 0.8 (2.8–6.8)	5.2 ± 1.2 (3.4–6.1)
V	44.7% ± 2.4% (42.0%–48.5%)	46.1% ± 3.8% (43.6%–56.4%)	41.0% ± 1.2% (39.6%–43.0%)	48.7% ± 1.6% (46.3%–50.6%)	42.5% ± 3.9% (32.4%–47.1%)	42.1% ± 1.2% (41.2%–43.8%)
Tail	265.1 ± 19.3 (239–297)	188.5 ± 17.6 (154 –210)	257.8 ± 13.5 (242 –275)	385.7 ± 23.9 (350–414)	216.2 ± 34.4 (97–264)	131.4 ± 11.7 (121–148)
V-A/T	3.9 ± 0.4 (3.2–4.4)	4.7 ± 0.8 (2.7–5.5)	3.6 ± 0.2 (3.3–3.8)	2.6 ± 0.1 (2.5–2.8)	4.7 ± 1.3 (3.7–9.7)	4.5 ± 1.1 (3.5–6.0)
LRW	30.7 ± 2.7 (28–36)	28.9 ± 2.9 (24–34)	24.3 ± 2.6 (21–28)	28.9 ± 1.7 (27–31)	26.8 ± 2.9 (22–31)	15.4 ± 1.3 (14–17)
Set L	5.9 ± 2.4 (2–8)	6.1 ± 2.3 (4–10)	4.6 ± 1.1 (3–5)	8.2 ± 0.7 (8–9)	6.7 ± 1.2 (5–8)	4.5 ± 1.2 (3–5)
Set L/LRW	19.5% ± 8.4% (4.9%–28.9%)	21.6% ± 9.3% (13.8%–38.9%)	19.0% ± 5.1% (12.5%–25.0%)	28.4% ± 2.1% (25.2%–30.9%)	25.0% ± 3.6% (17.6%–31.8%)	28.7% ± 6.8% (19.6%–36.1%)
Stoma L	12.3 ± 1.2 (10–14)	9.7 ± 1.2 (8–12)	8.5 ± 0.5 (8–9)	7.5 ± 1.5 (6–10)	13.1 ± 1.2 (10–15)	8.3 ± 0.7 (7–9)
Ant tooth pos	17.8 ± 4.8 (9–23)	20.3 ± 4.7 (15–29)	19.9 ± 4.9 (15–26)	17.2 ± 2.3 (15–20)	20.9 ± 1.7 (18–24)	11.6 ± 1.4 (10–13)
Post tooth pos	24.2 ± 2.4 (19–27)	32.7 ± 3.8 (25–39)	29.1 ± 4.6 (24–35)	24.0 ± 4.9 (19–32)	23.0 ± 2.2 (20–27)	22.7 ± 2.3 (19–24)
Tooth dist	6.3 ± 3.8 (2–13)	12.4 ± 2.7 (8–16)	11.3 ± 1.2 (10–12)	6.7 ± 3.2 (5–12)	2.1 ± 0.8 (1–4)	11.0 ± 1.0 (10–12)

DOI: https://doi.org/10.2478/jofnem-2024-0025 | Journal eISSN: 2640-396X | Journal ISSN: 0022-300X

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Language: English

Submitted on: May 10, 2024

Published on: Aug 24, 2024

Published by: Society of Nematologists, Inc.

In partnership with: Paradigm Publishing Services

Publication frequency: 1 times per year

Keywords:

Aquatic nematodes,

DNA barcoding,

extreme environments,

Related subjects:

© 2024 Peter G. Mullin, Timothy Harris, Rebecca Higgins, Enakshy Dutta, Dorota L. Porazinska, Kirsten Powers, Thomas Powers, published by Society of Nematologists, Inc.
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

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Taxonomy of Tobrilidae species from the Alkaline Lakes of the western Nebraska Sandhills

Figures & Tables

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Tobrilidae (order Triplonchida) of North America (Holovachov and Shoshin, 2014)

Tobrilidae specimen information by Nematode Identification (NID) number, and molecular grouping by COI marker_

Within- and between-group mean distances of 9 tobrilid COI groups_ Within-group distance is shown in bold type_

Standard morphological measurements, abbreviations, and definitions_

Soil sample chemistry analyses, abbreviations, and definitions_

Comparisons of selected morphological characteristics of the main groups (mean ± standard deviation with range of values)

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