Anterior region of Tylencholaimellus zeinabadensis (from Vazifeh et al., 2019)

• Moderately slender to slender nematodes of medium size, 1.2-1.7 mm long.

• Cuticle dorylaimid, two-layered, 3-4 Î¼m thick in anterior region, 4-6 Î¼m at mid-body and 7-12 Î¼m on tail, outer layer thin, with distinct radial striation.

• Lateral chord occupying one-fifth to one-fourth of mid-body diam.

• Lip region offset by deep and broad constriction, somewhat discoid, with nearly flat anterior margin, 2.7-4.0 times as wide as high and one-fifth to one-fourth of body diam. at esophagus base, lips mostly amalgamated, with low labial and cephalic papillae.

• Amphidial fovea cup-like, aperture occupying t2/3 to 3/4 of lip region diam.

• Odontostyle typical of genus, 1.2-2.0 lip region diam. long, dorsal stiffening piece covering entire dorsal arm, aperture very short, about 1/9 of total length. Guiding ring simple, located at one lip region diam. from anterior end.

• Odontophore 30-60% of odontostyle length, with distinct basal knobs 3-6 Î¼m broad

• Esophagus with a slender, weakly muscular anterior region, and a nearly cylindrical basal bulb occupying 12-23% of total esophagus length.

• Cardia short, hemispherical, 3.5-6 × 6-12 Î¼m.

• Prerectum 1.4-3.6 and rectum 0.5-1.0 anal body diam. long.

• Tail short and rounded to conoid, slightly more straight on its ventral contour

Female:

• Monodelphic-opisthodelphic; anterior genital branch reduced to a simple uterine sac,  occasionally with sperm cells inside. Posterior branch with ovary reflexed, not reaching oviduct-uterus junction

• Oocytes arranged first in two or more rows, then in a single row, oviduct joining ovary subterminally,

• Oviduct and uterus separated by a weak sphincter,

• Uterus a simple tube-like structure often containing sperm cells.

• Vagina perpendicular to body axis, extending inwards for 34-56% of body diam., with pars proximalis 14-18 Î¼m long and surrounded by weak circular musculature, and pars distalis 4-7.5 Î¼m long.

• Vulva a transverse slit.