Tylencholaimus vulvulatus Rahman, Jairajpuri, Ahmad & Ahmad, 1987

Ahad, Sumaya & Ahmad, Wasim, 2016, Description of two new and six known species of the genus Tylencholaimus de Man, 1876 (Nematoda: Dorylaimida) with a diagnostic compendium and key to species, Zootaxa 4107 (4), pp. 451-490: 460-464

publication ID

http://doi.org/10.11646/zootaxa.4107.4.1

publication LSID

lsid:zoobank.org:pub:262D02B9-E5CF-429C-B0DF-D1BB42BDB604

persistent identifier

http://treatment.plazi.org/id/03CA87C4-FFCC-FFDA-15E1-D237FEC8FC39

treatment provided by

Plazi

scientific name

Tylencholaimus vulvulatus Rahman, Jairajpuri, Ahmad & Ahmad, 1987
status

 

Tylencholaimus vulvulatus Rahman, Jairajpuri, Ahmad & Ahmad, 1987 

( Figs. 5View FIGURE 5 & 6View FIGURE 6)

Measurements: See Table 3.

Description. Female: Small sized nematodes, 0.68–0.92 mm, slightly curved upon fixation; body cylindrical, tapering gradually towards both extremities. Cuticle with two distinct layers, 2–4 Μm thick at midbody and 3–4 Μm on tail. Outer cuticle smooth; inner layer irregular with radial refractive elements. Lateral chords occupying about one-fifth of midbody diameter. Lateral, dorsal and ventral body pores indistinct.

Lip region cap-like, offset by constriction, 2.3 times as wide as high or about one-third of the body diameter at neck base; lips amalgamated and rounded, inner part projecting. Amphids cup-shaped, their aperture located at level of cephalic constriction and occupying about one-third of lip region diameter. Stoma a truncate cone. Odontostyle 0.8 –1.0 times the lip region diameter long, its aperture about one-third of its length. Odontophore with minute basal knobs, 1.0– 1.3 times the odontostyle length. Guiding ring simple, refractive, at 0.5–0.6 times lip region diameter from anterior end. Pharynx consists of a slender, slightly muscular anterior part, expanding gradually into a cylindrical basal bulb with thick-walled lumen, occupying about 37–44 % of total neck length. Pharyngeal gland nuclei and their orifices are located as follows: DO = 55–56, DN= 58–61, S 1 N 1 = 74–76, S 1 N 2 = 77–79, S 2 N = 85–93, S 2 O = 86–93. Nerve ring located at 38–47 % of neck length from anterior end. Cardia rounded, hemispheroid, about one-fourth of the corresponding body diameter long.

Genital system pseudo-monoprodelphic. Ovary reflexed, measuring 54–123 µm long, reaching the oviductuterus junction; oocytes arranged in single row except near tip. Oviduct joining the ovary subterminally, measuring 117–160 µm, consisting of a tubular distal and a wider proximal part containing spindle-shaped sperms. Oviductuterus junction marked by weak sphincter. Uterus long and tubular, measuring 66–86 µm. Posterior genital branch reduced to a long uterine sac, 2.7–3.6 times the corresponding body diameter. Vagina cylindrical; pars proximalis vaginae 5–9 µm long, its wall encircled by muscles; pars distalis vaginae short, 2–4 µm with slightly curved walls; pars refringens absent. Vulva apparently a transverse slit; vulval lips asymmetrical, anterior lip enlarged, swollen, rarely symmetrical. Prerectum 4.6–6.3 and rectum 0.8 –1.0 anal body diameter long. Tail convex-conoid with bluntly rounded terminus, 0.7–0.9 times anal body diameter long, with a distinct terminal caudal pore.

Male: General morphology similar to female but the posterior body region is more ventrally curved. In addition to adcloacal pair, situated at 10 µm from cloacal aperture, there are three ventromedian supplements, located outside the range of spicules; first ventromedian supplement located at 43 µm from adcloacal pair, second at 30 µm from first and third at 22 µm from second ventromedian supplement. Spicules 1.4–1.6 times cloacal body diameter long. Lateral guiding pieces prominent, about one-fourth the spicules length. Tail short and conoid, ventrally almost straight and dorsally convex, 0.7–0.8 anal body diameter long, with a distinct terminal caudal pore.

Habitat and locality. Soil samples collected from the grassland and forest trees of the Kaziranga National Park, Assam, India.

Remarks. Rahman et al. (1987) described T. vulvulatus  from Meghalaya, India. Peña-Santiago and Coomans (1996), redescribed this species based on the study of a paratype female and a male. Our present population agrees fairly well with the original material, except for having slightly longer odontostyle (6–7 µm vs 5.5 µm), and shorter neck (150–197 µm vs 202 µm) and the tail is more rounded (vs more conoid) and shorter (13–17 µm vs 19–20 µm; c = 50–61 vs 40–49). The tail length is quite variable in our specimens and is distinctly shorter than the original material.

T. vulvulatus  is closely related to T. stecki Steiner, 1914  and T. koreanus Ahmad, Park, Lee & Choi, 2009  because of its perioral region without disc; slender part of pharynx muscular, expanding gradually and posterior genital branch with large post-uterine sac. However, it differs, from T. stecki  in having comparatively higher a ratio (vs 22.6–25.6); slightly longer odontostyle (vs 5.0– 5.5 µm); shorter neck (vs 213–236 µm); vulval lips asymmetrical (vs symmetrical); long prerectum (vs 38 µm); tail convex-conoid with bluntly rounded terminus (vs hemispherical, sometimes conoid); slightly longer spicules (vs 23–27 µm) and lateral guiding piece (vs 4–6 µm).

From T. koreanus  , it differs in having larger body size (vs 0.49–0.58 mm); higher a, b, and c ratios (vs 22.1–24.5, 3.2–3.5 and 33.1–41.4 respectively); longer anterior genital branch (vs 113–141 µm); asymmetrical vulval lips (vs symmetrical); relatively long prerectum (vs 55–77 µm); more ventromedian supplements (3 vs 2); and longer spicules (28–32 µm vs 20–22 µm).

Peña-Santiago (2008) synonymised Protylencholaimus longisaccus Dhanam & Jairajpuri, 1999  with T. vulvulatus  , an action which is accepted here. However, the present population differs from P. longisaccus  in having smaller body size (vs 0.90 –1.0 mm), lower a ratio (vs 34–37), smaller pharyngeal bulb (vs 78–101 µm) and shorter tail (vs 18–22 µm).

Table 3. Morphometrics of Tylencholaimus vulvulatus Rahman, Jairajpuri, Ahmad & Ahmad, 1987 (All measurement in µm)

  Kaziranga National Park grassland Population Kaziranga National park forest tree Population
Characters Females Males Females
n 2 4 4
L 751, 922 908±58.8 (826-972) 817±84.6 (681-894)
Body diameter at neck base 25, 24 24.7±1.9 (22-27) 23.5±1.4 (21-25)
Body diameter at mid body 27, 30 27.2±2.2 (25-30) 26±1.8 (23-28)
Body diameter at anus 19, 21 19.2±0.4 (19-20) 17.3±1.2 (16-19)
a 27.8, 30.7 33.3±1.0 (32.4-35.1) 31.3±1.1 (29.6-32.6)
b 3.8, 4.8 4.7±0.2 (4.3-5) 4.8±0.2 (4.5-5.2)
c 50, 54.2 57.5±2.6 (54.9-60.7) 56.9±3.2 (52.3-59.6)
c` 0.9, 0.8 0.7±0.04 (0.7-0.8) 0.7±0.09 (0.7-0.9)
V 76.8, 70.1 - 68.2±2.1 (64.6-69.9)
G1 23.4, 31.1 - 26.5±1.2 (24.7-28.2)
G2 14.6, 11.8 - 9.2±0.2 (8.8-9.5)
Lip region diameter 7, 7 7.5±0.5 (7-8) 7.0
Lip region height 3, 3 3.1±0.2 (3-3.5) 3.0
Amphid aperture 2, 2 3.0 2.5
Odontostyle length 6, 6 6.0 6.7±0.4 (6-7)
Odontophore length 8, 7 7.8±0.5 (7-8.5) 7.0
Guiding ring from anterior end 4.5, 4.5 4.6±0.4 (4-5) 4.1±0.2 (4-4.5)
Nerve ring from anterior end 80, 82 80±3 (77-83) 71.2±2.1 (70-75)
Neck length 197, 189 190.2±6.4 (182-200) 167.5±12.9 (150-186)
Expanded part of Pharynx 74, 72 73.5±3.6 (68-79) 68.2±7.0 (58-77)
Cardia length 8, 8 8.7±1.7 (6-11) 5.7±0.4 (5-6)
Anterior genital branch 176, 287 - 216.5±19.8 (183-233)
Posterior genital branch 110, 109 - 75.7±7.6 (65-84)
Vaginal depth 16, 16 - 15.2±1.9 (12-17)
Vulva from anterior end 577, 647 - 557±53.5 (471-617)
Prerectum length 89, 110 - 116.6±22.8 (94-148)
Rectum length 18, 17 - 16±2.1 (14-19)
Tail length 15, 17 15.7±0.4 (15-16) 14.3±0.9 (13-15)
Spicules length - 30.2±1.4 (28-32) -
Lateral guiding pieces - 8±0.7 (7-9) -
Ventromedian supplements - 3.0 -

Kingdom

Animalia

Phylum

Nematoda

Class

Adenophorea

Order

Dorylaimida

Family

Dorylaimidae

Genus

Tylencholaimus

Loc

Tylencholaimus vulvulatus Rahman, Jairajpuri, Ahmad & Ahmad, 1987

Ahad, Sumaya & Ahmad, Wasim 2016

2016
Loc

T. koreanus

Ahmad, Park, Lee & Choi 2009

2009
Loc

Protylencholaimus longisaccus

Dhanam & Jairajpuri 1999

1999
Loc

T. stecki

Steiner 1914

1914