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Morphological and Molecular note on the identity of Mylonchulus sigmaturus Cobb, 1917 (Nematoda: Mylonchulidae) from Pakistan


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Fig. 1.

Mylonchulus sigmaturus Cobb, 1917, Female: A: Pharyngeal region; B: Anterior region; C. Tail; D: Reproductive system; E. Cardia; Male: F: Anterior region, G. Tail region, H. whole body; I. Tail having precloacal genital papillae.
Mylonchulus sigmaturus Cobb, 1917, Female: A: Pharyngeal region; B: Anterior region; C. Tail; D: Reproductive system; E. Cardia; Male: F: Anterior region, G. Tail region, H. whole body; I. Tail having precloacal genital papillae.

Fig. 2.

Mylonchulus sigmaturus Cobb, 1917, A–D: Anterior region of P1–P4 populations; E–H: Cardiac Junction (P1–P4); I: Vulval region; J: Whole-body female; K: Male tail; L–O: Female tail (P1–P4).
Mylonchulus sigmaturus Cobb, 1917, A–D: Anterior region of P1–P4 populations; E–H: Cardiac Junction (P1–P4); I: Vulval region; J: Whole-body female; K: Male tail; L–O: Female tail (P1–P4).

Fig. 3.

Principal component analysis biplot for M Mylonchulus sigmaturus from Pakistan and Mylonchulus arenicolus.
Principal component analysis biplot for M Mylonchulus sigmaturus from Pakistan and Mylonchulus arenicolus.

Fig. 4.

18S rDNA Bayesian tree inferred from known and newly sequenced Mylonchulus sigmaturus from Pakistan.
18S rDNA Bayesian tree inferred from known and newly sequenced Mylonchulus sigmaturus from Pakistan.

Fig. 5.

28S rDNA Bayesian tree inferred from known and newly sequenced Mylonchulus sigmaturus from Pakistan.
28S rDNA Bayesian tree inferred from known and newly sequenced Mylonchulus sigmaturus from Pakistan.

Fig. 6.

Phylogenetic median-joining network showing the relationships between the 18S rRNA gene sequences of Mylonchulus sigmaturus. The sizes of circles are proportional to the number of identical sequences. The number of changes between haplotypes are given in hatch marks.
Phylogenetic median-joining network showing the relationships between the 18S rRNA gene sequences of Mylonchulus sigmaturus. The sizes of circles are proportional to the number of identical sequences. The number of changes between haplotypes are given in hatch marks.

Genetic pairwise distance estimating for different populations of M. sigmaturus (numbers 1–7) and M. arenicolus (number 8) [upper matrix indicates standard error).

species Accession number Locality 1 2 3 4 5 6 7 8
1 M. sigmaturus N18_988 OM278259 Pakistan 0.003 0.004 0.003 0.003 0.004 0.003 0.004
2 M. sigmaturus N19_988 OM278260 Pakistan 0.008 0.004 0.003 0.004 0.003 0.004 0.003
3 M. sigmaturus N21_988 OM278261 Pakistan 0.012 0.016 0.004 0.007 0.008 0.006 0.007
4 M. sigmaturus N22_988 OM278262 Pakistan 0.007 0.010 0.016 0.003 0.004 0.003 0.003
5 M. sigmaturus AB361447 Japan 0.012 0.012 0.045 0.009 0.002 0.000 0.002
6 M. sigmaturus AY284755 The Netherlands 0.014 0.010 0.047 0.012 0.008 0.002 0.001
7 M. sigmaturus AB361446 Japan 0.012 0.012 0.033 0.009 0.000 0.008 0.002
8 M. arenicolus AF036596 UK 0.013 0.010 0.042 0.010 0.007 0.002 0.008

Morphometric data of different populations of Mylonchulus sigmaturus along with other populations of M. sigmaturus from different ecological zones. All measurements are in µm except body length.

References Present specimens Koohkan et al., (2014) Ahmad et al., (2010) Farahmand et al., (2009) De Bruin & Heyns (1992) Chaves (1990) Khan & Saeed (1987) Coetzee (1966) Mulvey (1961)

Locality Pakistan Iran Japan Iran South Africa Argentina Pakistan South Africa Sweden

n 40♀♀ 1♂ 5 ♀♀ 10♀♀ 11♀♀ 1 ♀ 18 ♀♀ 1♀ 4 ♀ 58♀♀
L 1.22 ±1.056 (1.04– 1.46) 1.21 1.294 ± 4.94 (1.22 – 1.36) 1.30 ± 0.08 (1.16 – 1.46) 1.20 ±1.29 (1.01 – 1.46) 1.25 1.12 ± 0.1 (1.0 – 1.32) 0.95 1.1 (1.1 – 1.2) 1 – 1.7
a 28.04 ±2.02 (25.8 – 33.7) 31.8 31.7 ± 1.3 (30.1 – 33.3) 29.7 ± 1.27 (27.3 – 31.8) 28.0 ± 2.1 (24.1 – 30.7) 34.7 29.7 ± 2.3 (26 – 36.2) 23 23.1 (29 – 33) 24 – 47
b 3.475 ± 0.196 (3.1 – 3.9) 3.4 3.5 ± 0.1 (3.4 – 3.6) 3.37 ± 0.12 (3.16 – 3.55) 3.7 ± 0.2 (3.2 – 3.9) 3.3 3.3 ± 0.2 (3.2 – 3.8) 4 3.2 (3.1 – 3.3) 3 – 4
c 35.17 ± 3.52 (26.0 – 40.93) 28.8 32.8 ± 5.6 (27.8 – 42.1) 35 ± 2.4 (30.5 – 38.6) 27.5 2.6 (26.6 – 30.7) 37.9 30 ± 2.6 (2558 – 32.2) 17.9 26.9 (25 – 29) 24 – 39.2
ć 1.205 ± 0.115 (1.0 – 1.42) 1.2 1.5 ± 0.2 (1.2 – 1.9) 1.21 ± 0.07 (1.1 – 1.3) 1.4 ± 0.2 (1.1 – 1.8) 1.5 1.4 ± 0.2 (1.2 – 1.6) 1.2 1.4 1 – 1.8
V 65.72 ± 2.217 (60.41 – 70.6) -- 64 ± 1.1 (63.1 – 65.9) 65.14 ± 1.4 (62.9 – 67.3) 62.8± 1.9 (59.7 – 66.4) 65 64.6 ± 1.5 (62 – 68) 58.4 66.0 (66 – 67) 50 – 77
G1 9.92 ± 1.50 (6.1 – 14.0) -- 18.7 ± 1.5 (18 – 20) 14.15 ± 3.69 (7 – 20) 12.1 ± 0.8 (11.1 – 12.9) - - 13.7 1.4 (9.2 – 11.8) -
G2 9.731 ± 1.77 (5.4 – 14.4) -- 18.0 ± 4.0 (13 – 22) 11.3 ± 2.5 (9 – 18) 10.5± 1.3 (8.5 – 11.7) - - - 9.5 (9.1 – 9.8) -
Lip region width 24.54 ± 1.44 (22 – 27) 22 24.2 ± 1.5 (23 – 27) 25.1 ± 1.4 (23 – 27) 24.6±1.8 (22.4 – 28) 23 21.5 ± 1.8 (20 – 25) 23.2 19.1 -
Buccal cavity length 25.75 ± 1.198 (25 – 27) 26 24.7 ± 0.8 (24 – 26) 25 ± 1.06 (24 – 27) 22.9± 1.4 (21 – 25.2) 26 22.7 ± 1.4 (20 – 25) 26.5 22.1 20 – 31
Buccal cavity width 16 ± 2.01 (15 – 17) 15 14.1 ± 0.4 (14 – 15) 15.2 ± 0.4 (15 – 16) 15.8±0.7 (15.4 – 16.8) 13 14.3 ± 1.0 (13 – 16) 13.1 9.6 11 – 17
Dorsal tooth apex % of buccal cavity 78.5 ± 1.945% (74 – 80%) 77 81.2 ± 2.6 (79 – 85) 80.2±4.6 (72.2 – 87.6) 15 77.2 ± 2.6 (74 – 81) 20 -
Amphid position from anterior end 9 ± 1.07 (8 – 10) 11 12±0.0 (12) - - - - - -
Amphidial aperture diameter 4.50±0.31 (4 – 5) 5 3.0±0.0 (3) - - - - - - -
Excretory pore from anterior end 102.5 ± 3.05 (94 – 113) -- - - - - - - - -
Nerve ring from anterior end 82.166 ± 3.46 (80– 90) 84 104.9±11.3 (89 – 117) 108 ± 3.6 (102 – 114) 99.6±11.9 (87.5 – 122.5) - - - -
Neck length 348.8 ± 17.6 (318 – 372) 352 367.5± 10.2 (355 – 379) 386 ± 12 (370 – 410) 330.6±29.3 (297.5 – 392) - 293.7 ± 12.3 (279 – 309) - -
Body diameter at: -- - - - - - - -
Neck base 37.12 ± 3.91 (30 – 47) 36 37.1±1.8 (35 – 39) - - - - - - -
Mid body 43.75 ± 3.78 (38 – 50) 38 40.9±2.3 (39 – 44) - - - - - - -
Anus 29.04 ± 1.92 (26 – 33) 37 27.3±3.0 (24 – 31) - 30.9±1.4 (28 – 31.5) - - - - -
Rectum 21.91 ± 1.49 (20 – 24) -- 21.4±2.1 (18 – 24) 21 ± 2.4 (17 – 25) 24.5±3.1 (21 – 28) - - - -
Tail length 35 ± 4.20 (30 – 50) 42 40.3±6.2 (31 – 47) 38.6 ± 2.6 (35 – 42) 44.2±5.5 (35 – 52.5) 33 33.2 ± 3.5 (29 – 37) 26.5 -
Tail length as % of total body length 2.76 ± 0.288 (2.26% – 3.38%) 3.46 3.1±0.5 (2 – 4) - - - - - - -
Spicules -- 46 -- -- -- -- -- -- -- --
Gubernaculum -- 18 -- -- -- -- -- -- -- --

Factor score for different populations of M. sigmaturus.

Observation F1 F2
P1 −0.629 −1.704
P2 −0.112 −2.305
P3 0.224 0.378
P4 0.436 0.645
Koohkan et al., (2014); Iran −0.725 1.769
Chaves (1990); Argentina −2.506 0.567
Coetzee (1966); South Africa −2.479 −0.303
de Bruin & Heyns (1992); South Africa −1.260 2.193
Khan & Saeed (1987); Pakistan −1.636 −4.145
Ahmad et al., (2010); Japan −0.034 1.920
Farahmand et al., (2009); Iran 0.122 −0.773
Mulvey (1961); Sweden −0.414 2.491
M. arenicolus 9.168 −0.271

Factor loading for different populations of M. sigmaturus.

F1 F2
Body length (BL) 0.486 0.360
a 0.170 0.833
b 0.110 −0.568
c 0.106 0.550
c′ −0.621 0.398
V 0.116 0.430
G1 −0.799 0.256
G2 −0.816 0.231
Lip region width (LW) 0.897 −0.109
Buccal cavity length (BCL) 0.576 0.164
Buccal cavity width (BCW) 0.614 0.350
Dorsal tooth apex (DTA%) 0.141 −0.357
Amphid to anterior end 0.109 0.532
Amphid diameter 0.082 −0.769
Nerve ring to anterior end (NR) 0.412 0.150
Neck length 0.851 0.005
Neck base diameter (NBD) 0.104 0.646
Mid-body diameter (MBD) 0.980 −0.123
Anal body diameter (ABD) 0.867 −0.180
Rectum 0.941 −0.123
Tail length (TL) 0.903 0.083
TL%BL 0.803 0.380
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