2urn:lsid:arphahub.com:pub:45048D35-BB1D-5CE8-9668-537E44BD4C7Eurn:lsid:zoobank.org:pub:91BD42D4-90F1-4B45-9350-EEF175B1727AZooKeysZK1313-29891313-2970Pensoft Publishers10.3897/zookeys.212.34642963Research ArticleDorylaimidaBiodiversity & ConservationTaxonomyNeogeneRussiaStudies of the genus
Enchodelus Thorne, 1939 (Nematoda, Nordiidae) from Arctic polar deserts. 1. Species with long odontostyle:
E. makarovae sp. n. and
E. groenlandicus (Ditlevsen, 1927) Thorne, 1939, with an identification key to the species of the
E. macrodorus group
ElshishkaMilka1urn:lsid:zoobank.org:author:79DCEFF6-47EB-41DF-ABE3-69213F54806BLazarovaStelaurn:lsid:zoobank.org:author:83C802AD-6631-4008-8E2E-3B8F3ACA1F5CPenevaVlada K.urn:lsid:zoobank.org:author:D066DD81-0D99-4117-835C-34CD35BE6F41Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of SciencesBulgarian Academy of SciencesSofiaBulgaria
Corresponding author: Vlada K. Peneva (vpeneva@ecolab.bas.bg)
Academic editor: Sergei Subbotin
20123072012212123FFA71C24-FFF6-FF9E-373D-9919FFC7FFFA577419660A1144-1BCA-4D4B-9589-189B73CA77D715620122672012Milka Elshishka, Stela Lazarova, Vlada K. PenevaThis is an open access article distributed under the terms of the Creative Commons Attribution License 3.0 (CC-BY), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.urn:lsid:zoobank.org:pub:660A1144-1BCA-4D4B-9589-189B73CA77D7
Two nematode species of the genus Enchodelus Thorne, 1939, one new and one known from Arctic polar deserts were studied. Enchodelus makarovaesp. n. is an amphimictic species, characterised by females with body length of 1.57–2.00 mm, lip region 15–17.5 µm wide, amphid duplex, odontostyle 38–43 µm long or 2.3–2.8 times lip region diam. Odontophore with flanges, 1.2–1.4 times as long as odontostyle; pharynx length 320–377 µm, pharyngeal expansion 113–130 µm long or 32–37% of total pharynx length; female genital system amphidelphic, uterus tripartite, pars refringens vaginae with two trapezoid sclerotisations, vulva a transverse slit (V=45–51%); tail bluntly conoid (25–35 µm, c=45.8–70.3, c’=0.6–0.9 in females, and 29–33 µm, c=46.4–58.9, c’=0.7–0.8 in males). Males with 65–74 µm long spicules and 10–12 spaced ventromedian supplements. Additional information for Enchodelus groenlandicus is provided, this being a new geographic record for the Putorana Plateau, Russian Arctic.
TaxonomymorphologymorphometricsNematodacold desertnew geographic record
Introduction
Currently, the genus Enchodelus Thorne, 1939 (Nordiidae, Pungentinae) contains 28 species distributed mainly in the northern hemisphere (Peña-Santiago et al. 2005); only one species (Enchodelus signyensis Loof, 1975) has been described from Antarctica. The members of the genus are common at high altitudes (1260-4400 m a.s.l) and latitudes, frequently associated with mosses and rock vegetation (Ahmad and Jairajpuri 1980, Eliava and Eliashvili 1990, Peneva et al. 2009). According to their feeding habits, representatives of the genus Enchodelus are attributed to the omnivorous trophic group (Yeates et al. 1993).
Ahmad and Jairajpuri (1980) provided a revision of the genus and grouped species into five subgenera(Enchodelus, Paraenchodelus, Heterodorus, Rotundus, Nepalus) on the basis of tail shape, odontostyle length, odontophore morphology and presence of a peculiar chamber in the female reproductive system. Recently, Guerrero et al. (2007a, 2008) divided the genus into three groups, based on tail shape and odontostyle length: species with long odontostyle (>35 μm) and rounded tail; species with medium size odontostyle (<35 μm) and rounded tail, and species with conical tail. The subgenera of Enchodelus are also not recognized by Andrássy (2009a) and species with conical tail are considered as belonging to the genus Heterodorus Altherr, 1952 (Andrássy 2011).
Here we provide data on two species of Enchodelus which belong to the first group with long odontostyles recovered from Arctic polar deserts.
Materials and methods
Soil samples were collected by Dr Olga Makarova (Institute for Problems of Ecology and Evolution, Russia)from two arctic regions, i.e. Bol’shevik Island, Severnaya Zemlya Archipelago, representing a zonal type of landscape (polygonal polar desert) and the highlands of Putorana Plateau, southern Taymyr, representing an altitudinal analogue of the zonal polar deserts, i.e. a nival desert. Nematodes were extracted from 1–3 g of soil by using a Baerman funnel method for 48 hours exposition, killed by gentle heat and fixed in 4% formalin.
Nematodes were processed in anhydrous glycerin by a Seinhorst method (1959) and mounted on permanent slides. Drawings and photographs were taken using an Olympus BX51 compound microscope. Images were taken with a ColorView IIIu camera and Cell^P software (Olympus Soft Imaging Solutions Gmbh). Measurements were made using an Olympus BX 41 light microscope with a drawing tube and digitizing tablet (CalComp Drawing Board III, GTCO CalCom Peripherals, Scottsdale, AZ, USA) and Digitrak 1.0f computer program (Philip Smith, John Hutton Institute), Dundee, UK). Identification key was performed by DELTA-package software (Dallwitz 1974).
Eight females, six males and two first stage juveniles collected from Bol’shevik Island, Severnaya Zemlya Archipelago, Russian Arctic (Table 1).
Measurements.
See Table 2.
Description.
Female. Body slightly ventrally curved after fixation, rarely adopting an open C shape. Cuticle smooth when viewed under light microscopy, composed of several layers with optically different appearance. Cuticle 2–4 µm thick at postlabial region, 2–3 µm - at mid body and 8–11 µm on tail, posterior to anus. Subcuticle clearly striated. Lateral chord 6–9 µm wide, occupying10–12 % of mid body diam. Lip region with slightly angular appearance, offset by depression, 2.3–3.1 times as broad as high. Labial and cephalic papillae distinct. Amphid duplex, amphidial fovea cup-shaped, opening at level of depression. Cheilostom almost cylindrical with a narrower mid-section. Odontostyle 2.3–2.8 times longer than lip region diam. or 2.0–2.6% of total body length. Odontophore 1.2–1.4 times as long as odontostyle, with flanges. Guiding ring double, located at 1.4–2.0 lip region diam. from anterior end, collar (distance between the first and second guiding ring) 3 μm. Pharynx attains the full width at 65–70% of its length from anterior end. Pharyngeal expansion 113–130 µm long or 32–37% of total pharynx length. Pharyngeal characters are presented at Table 3. Nuclei of dorsal glands 4.5–5 μm diam. and ventrosublateral 1 μm and 3–4 μm of the first and second pair, respectively. Cardia small, rounded to elongate conoid. Genital system amphidelphic, both branches almost equally developed, anterior 264–310 µm, posterior 240–310 µm. Ovaries large, 206–218 µm long; oocytes first in two or more rows, then in one row. Oviduct 168–172 µm long, 2.1–2.4 times body diam., pars dilatata oviductus well developed. Sphincter between oviduct and uterus distinct. Uteri long, anterior and posterior uterus with almost equal length (267.6±56.3 (220–346) μm, n=5 and 284.0±25.5 (256–332) μm, n=6), or 2.9–4.9 times corresponding body diam. Uterus tripartite, consisting of a wider proximal portion with distinct lumen (146 μm, n=1), followed by a slender median portion (118, 112 μm, n=2) and ending with a well developed spheroid pars dilatata distalis uteri. Vagina extending inwards 27–42 μm or 38–59% of body diam., pars proximalis 24x26μm (n=1), pars refringens with two trapezoid sclerotisations, with a combined width of 20–21μm and length 6–8μm (n=2), pars distalis 5–7 μm, n=4. Two females with 3 and 4 uterine eggs, respectively, measuring 37–45 × 98–106 µm. Prerectum variable in length, 2.1–3.5 times the anal body width; rectum 0.6–1.1 anal body diam. long. Tail bluntly conoid with elongated saccate bodies present mostly along ventral side. Hyaline part of tail 8–12 µm thick or 24–47 % of total tail length. Two pairs of subterminal caudal pores, one subdorsal, another lateral.
Male. General morphology similar to that of the female, except for genital structures. Arrangement of pharyngeal gland nuclei is presented at Table 3. Lateral chord very narrow (4–6 μm) occupying10–12 % of mid body diam. with scattered glandular bodies. Reproductive system diorchic, composed of two opposed testes, anterior 311, 319 µm (n=2) and posterior 275, 285 µm (n=2) long. Sperm cells spindle-shaped, measuring 6–9 × 2 µm. Spicules dorylaimoid, 1.5–1.7 times anal diam. long, lateral accessory pieces paired, more or less cylindrical with bifurcate end, measuring 16–18 × 3 µm (n=2). Ventromedian supplements 10–12 in number preceded by one adcloacal pair of papillae located at 8–11 µm apart from cloacal opening, 0–1 in the range of spicules; moderately developed postcloacal papilla present. Prerectum 3.3–4.0 anal body diam. long. Tail bluntly conoid, ventrally almost straight, dorsally convex with broadly rounded terminus, two pair of caudal pores.
Juveniles. Two first stage juveniles were recovered. Body almost straight. Lip region flat, continuous with the body, genital primordium 11 μm long, tail conical with long central peg, 30, 33 μm long.
Diagnosis and relationships.
The new species Enchodelus makarovae sp. n. is an amphimictic species distinguished by females with body length of 1.57–2 mm, lip region 15–17.5 µm wide, amphid duplex, odontostyle 38–43 µm long or 2.3–2.8 times lip region diam. Odontophore with flanges, 1.2–1.4 times as long as odontostyle, pharynx length 320–377 µm, pharyngeal expansion 113–130 µm long or 32–37% of total pharynx length, female genital system amphidelphic, uterus tripartite, pars refringens vaginae with two trapezoid sclerotisations, vulva transverse slit, V=45–51%, tail rounded conoid (25–35 µm, c=45.8–70.3, c’=0.6–0.9 in females, and 29–33 µm, c=46.4–58.9, c’=0.7–0.8 in males). Males with 65–74 µm long spicules and 10–12 spaced ventromedian supplements.
Based on tail morphology and odontostyle length this species can be assigned to the Enchodelus macrodorus – group as defined by Guerrero et al. (2008). Thisgroup includes Enchodelus babakicusPedram et al. 2009, Enchodelus carpaticus Ciobanu et al., 2010, Enchodelus distinctus Ahmad & Jairajpuri, 1980, Enchodelus groenlandicus (Ditlevsen, 1927) Thorne, 1939, Enchodelus macrodorus (de Man, 1880) Thorne, 1939, Enchodelus microdoroides Baqri & Jairajpuri, 1974 and Enchodelus saxifragae Popovici, 1995. This homogeneous group is characterised by the presence of a rather long odontostyle (>35µm), odontophore with well developed flanges, uterus tripartite (except for Enchodelus distinctus, which has been described with a bipartite uterus (Ahmad and Jairajpuri 1980) and hemispheroid to rounded conoid tail.
In having a lip region set off by a depression the new species is most similar to Enchodelus carpaticus, Enchodelus groenlandicus, Enchodelus macrodorus and Enchodelus microdoroides. However, it can be separated from Enchodelus carpaticus by its shorter pharyngeal expansion (113–130 vs 136–167 µm), different arrangement of pharyngeal glands, DN and S2N situated more posteriorly (DN=69–72% vs DN=63–65%, S2N=86–89% vs SN=82–86 %, respectively), absence of dorsal cell mass near cardia vs presence, ovaries large (206–218 µm long) vs short (61–155 µm long), prerectum shorter (87–140 vs 164–272 μm or 2.1–3.5 vs 4.1–6.6 anal body diam), saccate bodies present vs absent, males abundant vs absent (in Enchodelus carpaticus males not found, but sperm cells were observed in one female from a Romanian population (Ciobanu et al. 2010)); it should be mentioned also that there are differences in average values of odontostyle (av. 40.7 (38–43 µm) vs av. 43.3 (39.5–47 µm) and tail length (av. 29.2 (25–35) vs av. 23.7 (21–29) μm), and c’ value (c’= av. 0.7 (0.6–0.9) vs av. 0.6 (0.5–0.7); from Enchodelus groenlandicus by its shorter odontostyle (38–43 vs 44–53 µm), somewhat more anteriorly located guiding ring (24–28 vs 27–37 µm), narrower lip region (15–17.5 vs 19–22 µm), males present vs absent; from Enchodelus macrodorus this new species differs in having a longer ovarium and oviduct (206–218 vs 83–188 μm and 168–172 vs 97–159 μm, respectively (Thorne’s specimens), longer uterus (220–346 vs 61–143 and 56–115 μm) and shorter prerectum (2.1–3.5 vs 3.9–5.8 anal body diam), tail somewhat longer (25–35 vs 18–24 and 22–28 μm) and differently shaped (bluntly conoid vs rounded to hemispherical), saccate bodies large elongated vs small round; males abundant vs males rare; longer tail in males (29–33 vs 18–22 μm, c=46.4–58.9 vs 67–100 and c’=0.7–0.8 vs 0.6) (Guerrero et al. 2007b, 2008); from Enchodelus microdoroides by its longer body in females (1.57–2 vs 0.94–1.29 mm), wider lip region (15–17.5 vs 13–14 µm),guiding ring located more anteriorly (24–28 vs 28–39 µm from anterior end), different shape of pars refringens vaginae (trapezoid vs rectangular), longer tail (25–35 vs 13–27 µm) and males with longer spicules (65–74 vs 45–50 µm).
The new species can be distinguished from the remaining three species of Enchodelus macrodorus group by its lip differentiation: lip region set off by depression vs offset by a distinct constriction. Further, it differs from Enchodelus babakicus by its longer body in female (1.57–2 vs 1.21–1.56 mm), ovaries longer (206–218 µm vs 39–63 µm), longer uterus (220–346 vs 130–175 μm) and tail (25–30 vs 16–22 μm); shorter prerectum (87–140 vs 151–232 μm or 2.1–3.5 vs 4.5–8.5 anal body diam. long), males with longer spicules (65–74 vs 49–61 µm) and narrower lateral chord (10–12 vs 15–20% of corresponding body diam.); different tail shape in first stage juvenile (straight vs ventrally curved); from Enchodelus distinctus the new species is differentiated by its longer odontostyle (38–43 vs 36 µm), more posteriorly located guiding ring (24–28 vs 21–23 µm), different structure of uterus (tripartite vs bipartite), saccate bodies present vs absent. Finally, the new species can be distinguished from Enchodelus saxifragae by a narrower lip region (15–17.5 vs 18–22 µm or 2.3–2.8 vs 1.8–2.3 odontostyle as lip region diam.), shorter pharyngeal expansion (av.121 (113–130) vs av.153 (144–162.5) and av. 147 (116–186) µm), shorter prerectum (87–140 vs 140–294 μm or 2.1–3.5 vs 4–8 anal body diam ) and fewer ventromedian supplements (10–12 vs 13–16) (Popovici 1995, Guerrero et al. 2008).
Type-locality and habitat.
Different types of vegetation from a polygonal polar desert on Bol’shevik Island, Severnaya Zemlya Archipelago, Russian Arctic (Table 1).
Type-material.
Holotype, 5 paratype females, 4 paratype males and 2 juveniles deposited in the Nematode collection of the Institute of Biodiversity and Ecosystem Research, BAS; one female and one male paratypes each at the nematode collections of the following institutions: The Center of Parasitology of Institute for Problems of Ecology and Evolution, RAS, Russia and Plant Protection Service, Wageningen, The Netherlands.
Etymology.
The species is named in honor of Dr. Olga Makarova (Institute for Problems of Ecology and Evolution, Russia) who is an outstanding biologist investigating polar habitats and has kindly provided us with numerous nematode materials from Arctic polar deserts.
Enchodelus makarovae sp. n. Female: A Anterior region C Entire body D Pharyngeal bulb, dorsal and ventrosublateral glands E, F Vulval region. Male: B Entire body. Scale bars: A, D, E, F 50 µm; B, C 0.5 mm.
https://binary.pensoft.net/fig/19837
Enchodelus makarovae sp. n. A, BFemale: A Anterior genital branch B Neck region Male: C,D, E Posterior ends. Scale bars: A–E 50 µm.
https://binary.pensoft.net/fig/19838
Enchodelus makarovae sp. n. A–CFemale: Variability of female tail. Scale bars: A–C 50 µm.
https://binary.pensoft.net/fig/19839
Enchodelus makarovae sp. n. A–JFemale: A–C Variability of anterior region D Amphidial fovea G Entire body E, F, J Variability of tail with saccate bodies H, I Tail end K–MJuvenilesK Anterior region L Genital primordium M Tail. Scale bars: A–D H–M 50 µm; G 1 mm, E, F 10 µm.
https://binary.pensoft.net/fig/19840
Enchodelus makarovae sp. n. FemaleA Pharyngeal bulb, dorsal and ventrosublateral glands B Cardia C, DPars dilatata oviductus and ovarium EPars dilatata distalis uteriF–G Vulval region. Scale bars: A–G 50 µm.
https://binary.pensoft.net/fig/19841
Enchodelus makarovae sp. n. A–JMale: A–C Anterior ends D Amphidial fovea E Entire body F Sperm cells in testis G Lateral piece H, I Tail ends J Tail with saccate bodies. Scale bars: A–D, F–J 50 µm; E 1 mm.
Distribution of Enchodelus makarovae sp. n. and Enchodelus groenlandicus in Arctic polar deserts.
Locality and samples
Type of landscape and vegetation
Abbreviation
Nematode species
Bol’shevik Island Severnaya Zemlya Archipelago 78°12'N, 103°17'E
Polygonal polar desert
Enchodelus makarovae sp. n.
Site 1Collected on 09.08.1997
Sample № 2
Alopecurus alpinus Sm.
AA
3♀ 1♂
Sample № 3
Gymnomitrium coraloides Nees.
GC
1♀ 1♂
Site 2Collected on 13.08.2000
Samples № 6, 8 and 9
Gymnomitrium coraloides and Lopadium sp.
GC & L
4♀ 3♂
Sample № 13
Black crust with a small tuft Deshampsia borealis (Trautv.) Roshev.
DB
1♂
Sample № 7
Black crust
BC
2 J1
Putorana Plateau Taymyr Peninsula69°09'N, 91°52'E
Polygonal nival desert
Enchodelus groenlandicus
750 m a.s.lCollected on 3.08.1996
Sample № 7
Old Deshampsia borealis tuft with Gymnomitrium corralioides and Cladonia sp.
DB, GC, C
3♀
Samples № 9 and 10
Large green Deshampsia borealis tuft
DB1
7♀
Morphometrics of Enchodelus makarovae sp. n. from Bol’shevik Island, Severnaya Zemlya. All measurements, unless indicated otherwise, are in µm.
Characters
GC&L
GC
AA
DB
Range
BC
Holotype
Female
Male
Female
Male
Female
Male
Male
Femalen=8
Malen=6
J1n=2
L (mm)
2.00
1.76, 1.79, 1.62
1.70; 1.67; 1.79
1.85
1.71
1.64,1.57,1.85
1.77
1.49
1.76±0.1(1.57-2.00)
1.69±0.1(1.49-1.79)
0.62, 0.53
a
28.3
33.1, 25.6, 21.6
28.1, 26.5, 29.2
24.2
29.8
22.6,23.1, 23.1
23
19.6
25.2±3.8(21.6-33.1)
26.0±3.9(19.6-29.8)
24.7, 25.7
b
5.6
5.7, 5.3, 4.4
5.4, 4.4, 5.3
4.9
4.9
5.1, 4.7, 5.3
5.2
4.5
5.1±0.4(4.4-5.7)
4.9±0.4(4.4-5.4)
3.9, 3.4
c
70.3
69.9, 60.5, 45.8
58.9, 54.9, 55.8
59.7
51.7
54.1, 49.6, 61.2
53.0
46.4
61.1±7.6(45.8-70.3)
53.4±4.2(46.4-58.9)
11.4, 9.8
c‘
0.6
0.6, 0.7, 0.9
0.7, 0.7, 0.8
0.7
0.8
0.8, 0.9, 0.6
0.7
0.8
0.7±0.1(0.6-0.9)
0.7±0.1(0.7-0.8)
2.9, 3.1
V %
51
49, 51, 48
-
49
-
48, 48, 45
-
-
48.6±1.8(45-51)
-
Lip region width
17
17, 17, 16
16, 17, 17.5
17.5
16
17, 16, 15
17
16
16.6±0.8(15-17.5)
16.7±0.5(16-18)
9, 9
Odontostyle
40
41, 41.5, 38
44, 39, 44
43
44
38.5, 42, 41
44.5
43
40.7±1.6(38-43)
42.9±2.1(39-44.5)
10, 9.5
Replacement odontostyle
-
-
-
-
-
-
-
-
12, 11
Odontophore
54
49, 49.5, 50
49, 50, 53
57.5
52
47, 53, 57
52
54
52.3±3.9(47-57.5)
51.3±1.6(49-54)
-
Spear
95
90, 91, 89
93, 89, 96
100.5
96
85.5, 95, 99
96
97
93±5.1(85.5-100.5)
94.3±2.9(89-97)
-
Anterior end guiding ring
26
24, 24, 24
22, 25, 28
26
27
25, 28, 28
26
28
25.7±1.8(24-28)
25.9±2.0(22-28)
5.5, 6.0
Neck length
355
320, 336, 366
318, 384, 342
377
354
321, 341, 349
340
333
345.7±20.3(320-377)
344.9±22.3(318-384)
160, 155
Width at pharynx base
63
51, 63, 69
56, 62, 58
66.5
60
66, -, 69
72
70
64.0±6.1(51-69)
62.9±6.6(56-72)
25, 22
Width at mid-body
71
54, 70, 75
61, 63, 62
77
58
73, 68, 80
77
76
70.9±8.06(54-80)
66.0±8.3(58-77)
25, 21
Prerectum length
138
87, -, 139
-, 185, 132
126
163
140,-,138
-
163
128±20.6(87-140)
160.7±21.7(132-185)
53, -
Rectum length
40
23, 47, 40
-
49
-
41, -, 42
-
-
40.3±8.3(23-49)
10, -
Tail
29
25, 30, 35
29, 31, 32
31
33
30, 32, 30
33
32
29.2±3.3(25-35)
31.7±1.6(29-33)
55, 55
Spicules
-
-
65, 73, 67
-
71
-
74
70
70.1±3.5(65-74)
Ventromedian supplements
-
-
10, 12, 10
-
11
-
12
11
10-12
Pharyngeal characters of Enchodelus makarovae sp. n. and Enchodelus groenlandicus. For abbreviations see (*) Loof and Coomans (1970) and (**) Andrássy 1998. All data are given in percent.
Ten females collected from Putorana Plateau, Russian Arctic (Table 1).
Measurements.
See Table 4.
Description.
Female. Nematodes of medium to large size, habitus from slightly curved ventrad to open C- shape after fixation. Cuticle with fine, but distinct transverse striations, especially visible at neck and on tail regions; 4–6 µm thick at postlabial region, 3–4 µm at mid-body and 7–8 µm on tail. Lateral chord narrow, 6–9 µm wide or occupying ca 9–13 % of mid body diam. Lip region rounded, offset by a depression, 2.3–3.1 times as wide as high. Amphidial fovea cup-shaped, located at level of labial depression, occupying 65% of lip diam. Cheilostom cylindrical. Odontostyle long, 2–2.5 times longer than lip region diam. or 2.2–2.7% of total body length. Odontophore distinctly flanged, 1.1–1.3 times as long as odontostyle. Guiding ring double, located 1.4–1.6 lip region diam. from anterior end. Pharynx attains full width at 56–64% of its length from anterior end. Pharyngeal characters are presented at Table 3. Cardia rounded measuring 6–10 × 15–17 µm. Genital system amphidelphic, both branches equally and well developed, anterior 277–370 µm, posterior 287–375 µm long. Ovaries relatively large, 142–303 µm long; oocytes firstly in two or more rows, then in a single row. Anterior and posterior oviduct 119–143 µm (n=9) and 119–153 µm (n=8) long, 1.6–1.9 and 1.6–2.0 times body diam. respectively, consisting of slender part and well developed pars dilatata oviductus. Sphincter distinct. Uterus thick walled, tripartite, consisting of a wider proximal portion with distinct lumen, followed by a narrower median portion (43–115 µm (n=4)) and ending with a well developed spheroid pars dilatata distalis. Vagina extending inwards 42–53 μm or 53–68 % of body diam., pars proximalis 25–30 µm × 21–22 µm, pars refringens with two trapezoid sclerotisations, with a combined width of 18–18.5μm and length 6–8 μm(n=2) pars distalis 6 µm long (n=2). Vulva a transverse slit, pre-equatorial (40–47%). Eggs observed in eight females, measuring 96–109 × 43–64 µm, most frequently located in pars dilatata oviductus (n=6), rarely in uterus (n=2). Prerectum 3–4.5 anal diam. long, rectum 0.8–1.0 times anal body width. Tail hemispheroid. Numerous small elongated saccate bodies observed on tail, mostly on ventral side. Hyaline part of tail 8.0–10 µm thick or 25–33 % of total tail length.
Male. Unknown
Locality and plant associations.
Different types of vegetation from a polygonal polar desert on Plateau Putorana, Russian Arctic (Table 1).
Remarks.
The data on Enchodelus groenlandicus geographical distribution, i.e. the original description from Disko Island, Greenland (Ditlevsen 1927) and recent reports from Spain, Albania and Iran (Guerrero et al. 2008, Andrássy 2009b, Pedram et al. 2011) indicate a disjunctive type of range. It occurs at high altitudes 950 m to 2450 m a.s.l in Southern Europe and Iran, and at high latitudes in the polar region (Putorana Plateau and Greenland), Guerrero et al. (2008) hypothesize that such a distribution pattern might stem from quaternary glacial events. The specimens examined generally agree well with data reported for this species, although some differences occurred: the Arctic population has somewhat shorter odontostyles (43–47 vs 44–53 µm) and a more anterior position of the vulva (40–46 vs 41.5–49.4%, see Table. 4 for details); Iranian specimens had shorter female tails (19–24 vs 28–33 μm and c’= 0.4–0.6 vs 0.5–0.7). We consider the morphometric differences as representing intraspecific variation.
Enchodelus groenlandicus. A–DFemaleA Neck region B Anterior genital branch C, D Entire body. Scale bars: A, B 50 µm; C, D 500 µm.
https://binary.pensoft.net/fig/19843
Enchodelus groenlandicus. A–FFemaleA, C Vulval region and uterus B Vulval region D Anterior region, lateral view E Amphidial fovea F Anterior region, ventral view. Scale bars: A–F 50 µm.
Enchodelus groenlandicus. A–KFemale:A, B Anterior region C, D Amphideal fovea E Entire body F–H Tail ends I Subterminal caudal pores indicated by arrows J Tail with saccate bodies K Tail in ventral view, anus marked by an arrow. Scale bars: A–D, F–K 50 µm; E 1 mm.
https://binary.pensoft.net/fig/19846
Enchodelus groenlandicus. A–EFemale: A Pharyngeal bulb BPars dilatata distalis uteri (arrows) C Vulval region in subventral view D, E Vulval region in lateral view. Scale bars: A–E 50 µm.
https://binary.pensoft.net/fig/19847
Morphometrics for females of Enchodelus groenlandicus (Ditlevsen, 1927) Thorne, 1939. All measurements, unless indicated otherwise, are in µm (and in the form: mean±SD (range).
Characters
Russia – Putorana Plateau
Greenland
Spain
Albania
Iran
Present study
Ditlevsen 1927
Guerrero et al. 2008
Andrássy 2009
Pedram et al. 2011
DB1
DB, GC, C
n
7
3
1*
14
2
4
L (mm)
1.94±0.16(1.8-2.16)
1.77, 1.70, 1.92
2.5
1.78±0.15(1.57-2.07)
1.54-1.68
1.86±0.09(1.76-1.97)
a
24.4±1.8(21.7-25.9)
24.3, 25.9,
25
23.4±1.6(21.3-25.3)
22-23
23.0±2.5(20.3-26.0)
b
5.3±0.3(5-5.6)
4.6, 4.7, 4.8
6
5.1±0.3(4.5-5.5)
4.0-4.6
5.0±0.2(4.6-5.1)
c
64.9±4.9(59.9-70.8)
61.5, 52.4, 62.1
50
67.5±9.2(53-83)
40-46
85.5±14.0(73-104)
c’
0.6±0.1(0.5-0.7)
0.6, 0.7, 0.7
0.7
0.7±0.1(0.6-0.8)
0.7-0.8
0.5±0.1(0.4-0.6)
V %
42.4±1.8(40-44)
46, 43, 42
43
44.2±1.9(41.6-49.4)
44-45
42.5±1.0(41.5-44.0)
Lip region width
19.8±0.8(19-20.5)
21, 21, 19
20
20.5±0.9(19-22)
19-20
22.5±0.5(21-23)
Odontostyle
46.7±0.4(46-47)
47, 44, 43
48-49
49.3±2.3(44-53)
50-51
48.5±0.5(48-49)
Odontophore
49±0.2(48.7-49)
50, 48, 55
49
50.4±2.9(45-55)
52-54
52±1(51-53)
Spear
95.6±0.3(95-96)
97.5, 93, 98
98
100±4.1(94-108)
102-106
102.5±1.0(101-103)
Anterior end to guiding ring
30.4±1.9(29-33)
30, 28, 30
29
32.8±2.4(27-37)
-
-
Neck length
376.6±12.4(361-398)
389, 361, 398
417
354±24.0(322-401)
-
377.5±19.0(350-392)
Width at pharynx base
68.5±3.9(65-75)
69, 60, 62
-
66.0±9.0(49-75)
-
78.5±5.0(75-82)
Width at mid body
79.5±4.1(75.5-83)
73, 66, 68
100
76.1±5.5(67-87)
77-80
82.0±9.5(68-89)
Prerectum length
185.6±10.6(178-193)
187,-, 213
50
186±36(116-252)
-
203.0±19.5(176-223)
Rectum length
42.1±2.5(39-44.5)
38, 46, 42
-
42.1±7.3(27-52)
-
-
Tail
29.9±1.7(28-32)
29, 33, 31
31
26.8±4.2(22-37)
28-30
22.0±2.5(19-24)
*followed by Guerrero et al. 2008
Identification key to species belonging to Enchodelus macrodorus group
Lip region wide, > 19 μm, males absent (♀ L=1.54–2.5 mm, a=20.3–25.9, b=4.0–6.0, c=40–104, c’=0.4–0.8, V=40–49%, Odontostyle=43–51 μm) (Greenland, Spain, Albania, Iran, Russia – Putorana Plateau)
Enchodelus groenlandicus (Ditlevsen, 1927)
Acknowledgements
This study was partly funded by FP7 Capacities project WETLANET, project “Development of scientific potential in the field of faunistic diversity and the protection of environment” funded by the Ministry of Education, Youth and Science and the European Social Fund, Operative Programme “Human Resources Development’’ and project ANIDIV, funded by the Bulgarian Academy of Sciences. We would like to thank Dr O. Makarova for collecting nematode materials and Mrs. V. Atanassova for technical assistance. The authors are thankful to Prof Derek JF Brown, Institute of Biodiversity and Ecosystem Research, BAS for critical reading of the manuscript and helpful suggestions.
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