Twelve females and fourteen males from two localities, in variable state of preservation.

See Table 1.

Adult. Moderately slender to slender nematodes of medium size, 1.95–2.90 mm long. Body cylindrical, distinctly tapering towards the anterior end, less so towards the posterior one because the caudal region is rounded. Habitus regularly (often strongly) curved ventrad after fixation, usually spiral-shaped. Cuticle three-layered, especially distinguishable at caudal region, where it consists of thinner outer layer bearing very fine transverse striation through the entire body, thicker intermediate layer with radial striation and thin inner layer; thickness 3–5 µm at anterior region, 4–7 µm in mid-body and 9.0–12.5 µm on tail. Lateral chord 8–20 µm wide at mid-body, occupying one-eighth to less than one-fifth (12–18%) of mid-body diameter. Three ventral and three dorsal body pores are usually present at level of mural odontostyle-odontophore, their corresponding ducts appearing especially thickened beneath intermediate cuticle layer. Lip region offset by deep constriction, 2.7–3.3 times as wide as high and one-fifth to two-sevenths (18–30%) of body diameter at neck base; lips (under SEM) amalgamated; labial papillae button-like, very perceptible and protruding under LM, surrounded by a ring-like annulus (occasionally two annuli), the inner ones at the margin of oral field; cephalic papillae larger than the labial ones, with an oval transverse slit; oral aperture a dorso-ventral, slightly hexagonal orifice, the lip region hence showing a biradial symmetry. Amphid fovea cup-shaped, its opening occupying 9–11 µm or one-half to two-thirds (52–64%) of lip region diameter. Cheilostom nearly cylindrical, lacking any differentiation. Mural odontostyle attached subventrally and comparatively short, 4.1–5.4 times as long as wide, 0.6–0.8 times as long as lip region diameter, and 0.43–0.61% of body length; aperture 8–9 µm long or up to five-sevenths (62–71%) its length. Guiding ring simple, somewhat plicate, at 0.6–0.8 lip region diameters from anterior end. Odontophore linear, rod-like, 3.4–4.2 times the mural odontostyle length. Anterior region of pharynx enlarging very gradually; basal expansion 9.5–12.6 times as long as wide, 4.6–7.2 times as long as body diameter, and occupying 58–66% of total neck length; gland nuclei obscure in most specimens examined, DN = 50 (n=1) and S₂N = 84 (n=1). Nerve ring located at 154–185 µm from anterior end or 21–26% of total neck length. Cardia rounded conoid, 10–14 × 14–18 µm; a ring-like structure is present surrounding its junction to pharyngeal base. Tail short and rounded; inner core with irregular shape at tail end. Caudal pores two pairs, one lateral, another sub-lateral.

Female. Genital system didelphic-amphidelphic, with both branches almost equally and well developed, the anterior 207–254 µm long or 9–10% of body length and the posterior 233–300 µm long or 9–13% of body length. Ovaries moderately sized, usually not surpassing the sphincter level, the anterior 95–365 µm, the posterior 106–316 µm long; oocytes arranged first in two or more rows, then in a single row. Oviduct 96–124 µm long or 1.0–1.4 times the corresponding body diameter, and consisting of a slender part with prismatic cells and a well developed pars dilatata bearing wide lumen that often containing sperm cells inside. Oviduct-uterus junction marked by a sphincter. Uterus a short, simple, tube-like structure 85–182 µm long or 1.0–2.1 times the corresponding body diameter, most specimens with abundant sperm cells inside. Uterine eggs ovoid, 153 (n=1) × 79, 85 (n=2) µm, 1.8 (n=1) times as long as wide. Vagina extending inwards 43–57 µm or four-ninths to two-thirds (45–65%) of body diameter: pars proximalis 32–44 × 28–34 µm, with somewhat sigmoid walls and surrounded by weak musculature; pars refringens absent; and pars distalis well developed, 11–14 µm long. Vulva a post-equatorial transverse slit. Prerectum 1.8–2.6, rectum 1.0–1.2 anal body diameters long.

Male. Genital system diorchic, with opposite testes. In addition to the ad-cloacal pair, situated at 15–20 µm from cloacal aperture, there is only one ventromedian supplement located out the range of spicules, at 48, 58 (n=2) µm from ad-cloacal pair. Spicules distinctly robust and massive, especially in its posterior half, 3.4–4.6 times its maximum width, 1.2–1.7 times the body diameter at level of the cloacal aperture: dorsal contour regularly convex, ventral contour very weakly concave, with shallow or weak hump and hollow; curvature 126–142°; head occupying 7–21% of spicule total length, its dorsal contour conspicuously curved at its anterior end and longer than the ventral one, which is short and straight; median piece 7.2–10.9 times as long as wide, occupying 35–50% of spicule maximum width, reaching the posterior tip; posterior end 5–9 µm wide. Lateral guiding pieces 13–17 µm long, 3.5–5.1 times as long as wide. Prerectum 2.9–4.4, cloaca 1.1–1.3 the corresponding body widths long.

Figure 1. 

Aporcelaimoides brevistylum sp. n. (Line drawing). A Lip region in surface, lateral view B Anterior region in median lateral view C Neck D Female, anterior genital branch and vagina E Vagina F Male, posterior body region G Spicule H Lateral guiding piece I Female, posterior body region J Female, entire K Male, entire.

Figure 2. 

Aporcelaimoides brevistylum sp. n. (LM, type population). A Anterior region in surface, lateral view B, E Anterior region in median, lateral view C, D Uterus, containing sperm cells inside F Pharyngo-intestinal junction G Vagina H Spicule I, M Male, caudal region J Male, posterior body region K Female, posterior body region L, N Female, caudal region. Scale bars: 10 µm (A, B, E, H, I); 20 µm (C, D, F, G, J–N).

Figure 3. 

Aporcelaimoides brevistylum sp. n. (LM, other population). A Anterior region in surface, lateral view B, E Anterior region in median, lateral view C Pharyngo-intestinal junction D Pharyngeal expansion F Female, posterior body region G Male, caudal region H Spicules I Female, caudal region. (Scale bars: 10 µm (A, B, E, G, H); 20 µm (C, F, I); 50 µm (D).

Figure 4. 

Aporcelaimoides brevistylum sp. n. A–E and A. silvaticum sp. n. F–I (SEM, juvenile). A, C, F Lip region in ventral view B, G, H Lip region in face view D, E, I Caudal region in lateral (D) or subventral (E, F) view. Scale bars: 2 µm (A–C, F–H); 5 µm (D, E, I).

The new species is characterized by its body 1.95–2.90 mm long, lip region offset by deep constriction and 17–18 µm broad, ventral side of mural odontostyle 11–14 µm with aperture occupying 62–71% of its length, neck 663–767 µm long, pharyngeal expansion 387–508 µm long or occupying 58–66% of total neck length, uterus a simple tube and 85–182 µm long or 1.0–2.1 times the corresponding body diameter, pars refringens vaginae absent, V = 55–63, female tail short and rounded (35–46 µm, c = 58–76, c’ = 0.6–0.8), male tail similar to that of female (34–42 µm, c = 49–69, c’ = 0.6–0.8), spicules 67–86 µm long, and one ventromedian supplement bearing hiatus.

In having short mural odontostyle (11–14 µm at its ventral side) and pars refringens vaginae absent, the new species is morphologically close to A. californicum Heyns, 1965 and A. probulbum Heyns, 1965, but it can be distinguished from both species in its smaller (L = 1.95–2.90 vsL = more than 3) and less slender (a = 25–35 vsa ≥ 41) body. Besides, A. brevistylum sp. n. differs from A. californicum in its comparatively longer neck (b = 3.3–3.7 vsb = 7.6), larger mural odontostyle aperture (occupying 62–71% vs one-half of its length), more posterior vulva (V = 55–63 vsV = 51), shorter uterus (85–182 µm or 1.0–2.1 times the corresponding body diameter vs about 430 µm long or about 5.3 times the corresponding body diameter), comparatively shorter female tail (c = 58–76, c’ = 0.6–0.8 vsc = 126, c’ = 1.0), and male present (vs absent). And from A. probulbum in its shorter neck (663–767 µm, b = 3.3–3.7 vs 883–1011 µm, b = 3.9–5.2), narrower lip region (17–18 vs about 21 µm), and comparatively longer tail (c = 49–76 vsc = 75–127).

Moreover, in having short mural odontostyle (11–14 µm at its ventral side) the new species resembles A. haguei (Hunt, 1978), comb. n., but it differs in its smaller general size (L = 1.95–2.90 and neck 663–767 µm long vsL = 4.67–5.42 and neck 1172–1178 µm long), less slender body (a = 25–35 vsa = 52–62), absence (vs presence of rows of minute denticles on stomatal wall, indeed a very relevant feature), pars refringens vaginae absent (vs present), comparatively longer female tail (c = 49–76 vsc = 99–118), and male present (vs absent).

Vietnam, Dak Lak province, Chu Yang Sin National Park, where it was collected from soil of a pristine forest in October 2012.

Vietnam, Lam Dong Province, Bidoup-Nui Ba National Park, from soil of a pristine forest, collected in June 2013.

Female holotype and seven female and nine male paratypes deposited in the nematode collection of the University of Jaén, Spain. One female and one male paratypes deposited in the nematode collection of the Institute of Ecology and Biological Resources, Vietnam.

The specific epithet is a compound Latin term referring to the short mural odontostyle that characterizes this species.

The two populations examined are very similar in their morphological features and morphometrics, but some minor differences have been also noted, which are herein regarded as intraspecific variation. Thus, the population from Dak Lak province shows a shorter mural odontostyle (ventral side 11–13 vs 13–14 µm, dorsal side 13–14 vs 14–17 µm, in females) and comparatively longer neck (b = 3.3–3.4 vsb = 3.5–3.7).

Ten females from three localities, in good state of preservation.

See Table 2.

Female. Moderately slender to slender nematodes of medium size, 2.09–2.61 mm long. Body cylindrical, distinctly tapering towards the anterior end, less so towards the posterior one as the caudal region is very short and rounded to truncate. Habitus regularly curved ventrad after fixation, often spiral-shaped. Cuticle three-layered, especially distinguishable at caudal region: thin outer layer bearing fine transverse striation through the entire body, a much thicker intermediate layer with radial striation, and a thin inner layer; thickness 3.0–4.5 µm at anterior region, 4.5–6.5 µm in mid-body and 6.5–9.5 µm on tail. Lateral chord 7–13 µm wide at mid-body, occupying one-tenth to less than one-sixth (9–15%) of mid-body diameter. Two ventral and two dorsal body pores are usually present at level of mural odontostyle-odontophore, their corresponding ducts appearing especially thickened beneath intermediate cuticle layer. Lip region offset by deep constriction, 2.8–3.3 times as wide as high and one-fifth to less than one-third (21–30%) of body diameter at neck base; lips mostly amalgamated, somewhat angular; papillae perceptible, somewhat protruding. Amphid fovea cup-shaped, its opening occupying 8–10 µm or up to one-half (44–50%) of lip region diameter. Cheilostom nearly cylindrical, lacking any differentiation. Mural odontostyle attached subventrally, 6.7–7.7 times as long as wide, 0.7–0.9 times as long as lip region diameter, and 0.54–0.72% of body length; aperture 11–13 µm long or up to six-sevenths (73–84%) its length. Guiding ring simple, somewhat plicate, at 0.6–0.8 lip region diameters from anterior end. Odontophore linear, rod-like, irregular at its base, in lateral view with the ventral side longer that the dorsal one (figure 7A, C), and 2.0–2.4 times the mural odontostyle length. Anterior region of pharynx enlarging very gradually; basal expansion 8–12 times as long as wide, 4.1–5.3 times as long as body diameter and occupying 57–66% of total neck length; gland nuclei obscure in most specimens examined, DN = 54 (n=1) and S₂N = 92 (n=1). Nerve ring located at 158–177 µm from anterior end or 24–31% of total neck length. Cardia rounded conoid, 11–19 × 14–18 µm; a ring-like structure is present surrounding its junction to pharyngeal base. Genital system didelphic-amphidelphic, with both branches almost equally and well developed, the anterior 174–207 µm long or 7–9% of body length and the posterior 168–220 µm long or 7–9% of body length. Ovaries variably sized, the anterior 93–191 µm, the posterior 84–175 µm long; oocytes arranged first in two or more rows, then in a single row. Oviduct 73–103 µm long or 0.9–1.1 times the corresponding body diameter, and consisting of a slender part with prismatic cells and a weakly developed pars dilatata. Oviduct-uterus junction marked by a sphincter. Uterus a short, simple, tube-like structure 44–69 µm long or 0.5–0.9 times the corresponding body diameter, lacking sperm cells inside. Vagina extending inwards 38–51 µm or two-fifths to one-half (43–53%) of body diameter: pars proximalis 25–35 × 15–20 µm, with somewhat sigmoid walls and surrounded by weak musculature; pars refringens with two small, triangular to drop-shaped pieces measuring 8–10 × 6–8 µm and with a combined width of 14–19 µm; and pars distalis short, 3.0–5.5 µm long. Vulva a transverse slit. Prerectum 1.4–2.1, rectum 0.8–1.1 anal body diameters long. Tail very short and rounded to truncate. Caudal pores two pairs, one sublateral, another sub-dorsal.

Male. Unknown.

Figure 5. 

Aporcelaimoides minor sp. n. (Female, line drawing). A Lip region in surface, lateral view B Anterior region in median, lateral view C Neck D Anterior genital branch and vagina E Posterior body region F Vagina G Entire.

Figure 6. 

Aporcelaimoides minor sp. n. (LM, female, type population). A Anterior region in surface, lateral view B, E Anterior region in median, lateral view C Neck region D Genital system F Pharyngo-intestinal junction G Vagina H Posterior body region I, J Caudal region. Scale bars: 10 µm (A, B, E–G, I, J); 100 µm (C); 50 µm (D); 20 µm (H).

Figure 7. 

Aporcelaimoides minor sp. n. (LM, female, other populations). A, B, F (Population from Cao Bang Natural Reserve) C–E, G, H (Population from Chu Yang Sin National Park) A, C Anterior region in median, lateral view B Pharyngeal expansion D Anterior region in median, ventral view E Vulva in ventral view F–H Caudal region. Scale bars: 10 µm (A, C, D, E, H); 50 µm (B); 20 µm (F, G).

The new species is characterized by its body 2.09–2.61 mm long, lip region offset by deep constriction and 19–20 µm broad, mural odontostyle 14–16 µm long at its ventral side with aperture occupying 73–84% of its length, neck 579–649 µm long, pharyngeal expansion 331–423 µm long or occupying 57–66% of total neck length, uterus a simple tube and 44–69 µm long or less than (0.5–0.9 times) the corresponding body diameter, pars refringens vaginae well developed, V = 48–56, female tail very short and rounded to truncate (14–26 µm, c = 90–146, c’ = 0.3–0.6), and male unknown.

This species resembles A. haguei comb. n. in having relatively small mural odontostyle (up to 17 µm long) and pars refringens vaginae present. It can be, however, easily distinguished from this in its smaller general size (L = 2.09–2.61, neck 579–649 µm long vsL = 4.67–5.42, neck 1112–1178 µm long), less slender body (a = 23–33 vsa = 52–62), the absence (vs presence) of rows of minute denticles on stomatal wall), and its much shorter female tail (14–26 µm, c’ = 0.3–0.6 vs 46–47 µm, c’ = 0.7).

Besides, in having short mural odontostyle (11–14 µm at its ventral side) the new species resembles A. brevistylum sp. n. and A. californicum, but it differs from these in its well developed pars refringens vaginae (vs absent). Moreover, it differs from A. brevistylum sp. n. in its shorter neck (579–649 vs 663–767 µm), wider lip region (19–20 vs 17–18 µm), smaller mural odontostyle aperture (occupying 73–84% vs 62–71% its length), shorter female tail (14–26 µm, c = 90–146, c’ = 0.3–0.6 vs 35–46 µm, c = 58–76, c’ = 0.6–0.8), and male absent (vs present). And from A. californicum in its shorter (L = 2.09–2.61 vsL = 5.53) and less slender (a = 23–33 vsa = 75) body, larger mural odontostyle aperture (occupying 73–84% vs one-half of its length), shorter uterus (44–69 µm long or less than one body diameter vs about 430 µm long or about 5.3 times the corresponding body diameter), and shorter female tail (14–26 µm, c’ = 0.3–0.6 vs 44 µm, c’ = 1.0).

Vietnam, Bac Giang Province, Tay Yen Tu Natural Reserve, collected from soil in a pristine tropical forest, in July 2008.

Vietnam, Cao Bang Province, Cao Bang Natural Reserve (GPS coordinates: 22°34'07"N and 105°52'34"), in a tropical evergreen forest soil in association with Dipterocarpus sp. and Cinnamomum sp., collected in 2013. Dak Lak province, Chu Yang Sin National Park, in October 2012.

Female holotype and one female paratype deposited in the nematode collection of the University of Jaen, Spain. One female paratype deposited in the nematode collection of the Institute of Ecology and Biological Resources, Vietnam.

The specific epithet means ‘small’ and refers to the comparatively small general size of the new species.

In spite of it was collected from three localities, the material examined is very similar in its main morphological features and morphometrics. Nevertheless, some differences have been also observed, especially affecting the female tail shape as some specimens show a short and rounded-conoid caudal region whereas it becomes extremely short and truncate in other individuals.

Two females and four males, in variable state of preservation.

See Table 2.

Adult. Moderately slender to slender nematodes of medium size, 2.09–2.60 mm long. Body cylindrical, distinctly tapering towards the anterior end, less so towards the posterior one because the caudal region is rounded conoid. Habitus regularly curved ventrad after fixation, to a more or less open C, occasionally more curved at posterior body region, spiral-shaped in only one male specimen. Cuticle three-layered, especially visible distinct at caudal region, consisting of thin outer layer bearing fine transverse striation through the entire body, a much thicker intermediate layer with radial striation, and a thin inner layer; thickness 2.5–4.0 µm at anterior region, 5–6 µm in mid-body and 8–10 µm on tail. Lateral chord 7–12 µm wide at mid-body, occupying one-tenth to one-eighth (10–12%) of mid-body diameter. Three ventral and three dorsal body pores are usually present at level of odontostyle-odontophore, their corresponding ducts appearing especially thickened beneath inner cuticle layer. Lip region visibly narrower than adjacent body, offset by depression, 2.2–2.6 times as wide as high and one-fifth to one-fourth (19–27%) of body diameter at neck base; lips (under SEM) amalgamated; papillae button-like, the inner labial ones rather close the margin of oral field and surrounded by one or two ring-like annuli, whereas the outer labial ones are surrouned by only one annulus and the cephalic ones lack a such differentiation; oral aperture a dorsoventral, nearly hexagonal orifice, the lip region hence showing a biradial symmetry. Amphid fovea cup-shaped, its opening at level of cephalic depression and occupying 12–13 µm or up to three-fourths (72–75%) of lip region diameter. Cheilostom nearly cylindrical, lacking any differentiation. Mural odontostyle attached subventrally and comparatively short, 4.5–4.9 times as long as wide, 0.6–0.7 times as long as lip region diameter, and 0.44–0.54% of body length; aperture 7–8 µm long or up to two-thirds (60–66%) its length. Guiding ring simple, somewhat plicate, at 0.5–0.7 lip region diameters from anterior end. Odontophore linear, rod-like, 3.8, 4.1 (3.5, 3.7 in males, n=2) times the odontostyle length. Anterior region of pharynx enlarging very gradually; basal expansion 8.3–11.0 times as long as wide, 5.0–5.8 times as long as body diameter, and occupying 58–64% of total neck length; gland nuclei obscure in all the specimens examined. Nerve ring located at 139–169 µm from anterior end or 23–26% of total neck length. Cardia rounded conoid, 10–16 × 12–18 µm; a ring-like structure is present surrounding its junction to pharyngeal base. Tail short, rounded to rounded conoid, its inner core bearing a finger-like projection at tail end. Caudal pores two pairs, one lateral, another sub-lateral.

Female. Genital system didelphic-amphidelphic, with both branches almost equally and well developed, the anterior 246, 387 µm long or 10, 15% of body length and the posterior 301 µm long or 12% (n=1) of body length. Ovaries moderately sized, usually not surpassing the sphincter level, the anterior 82, 119 µm, the posterior 66, 103 µm long; oocytes arranged first in two or more rows, then in a single row. Oviduct 99–107 µm long or 1.2, 1.3 times the corresponding body diameter, and consisting of a slender part with prismatic cells and a moderately developed pars dilatata with visible lumen but no sperm cell. Oviduct-uterus junction marked by a sphincter. Uterus a short, simple, tube-like structure 128–243 µm long or 2.1, 2.8 times the corresponding body diameter, one female containing abundant sperm cells inside. Vagina extending inwards 31, 32 µm or about three-eighths (36%, n=1) of body diameter: pars proximalis 23, 24 × 25, 26 µm, with somewhat sigmoid walls and surrounded by weak musculature; pars refringens with two small, triangular to drop-shaped pieces measuring 5 × 4, 5 µm and with a combined width of 9, 10 µm; and pars distalis 1.0, 1.5 µm long. Vulva a post-equatorial transverse slit. Prerectum 2.3, 2.5, rectum 0.8, 1.2 anal body diameters long.

Male. Genital system diorchic, with opposite testes. In addition to the ad-cloacal pair, situated at 16–19 µm from cloacal aperture, there is a series of two or three widely spaced (22–42 µm apart) ventromedian supplements, the posteriormost of which lying out the range of spicules, but very close to the spicules end, being situated at 42–63 µm from ad-cloacal pair. Spicules relatively robust, 3.5–4.6 times its maximum width, 1.3–1.6 times the body diameter at level of the cloacal aperture: dorsal contour regularly convex, ventral contour bearing weak hump and hollow; curvature 140–143º; head occupying 8–10% of spicule total length, with both contours nearly straight, and its dorsal side longer than the ventral one; median piece 6.5–8.3 times as long as wide, occupying 45–54% of spicule maximum width, reaching the posterior tip; posterior end 5–6 µm wide. Lateral guiding pieces 19–23 µm long, 6.4–7.8 times as long as wide. Prerectum 3.0–3.3, cloaca 1.2–1.4 times the corresponding body width long.

Figure 8. 

Aporcelaimoides silvaticum sp. n. (Line drawing). A Lip region in surface, lateral view B Anterior region in lateral, median view C Neck D Female, posterior body region E Female, anterior genital branch and vagina F Spicule G Lateral guiding piece H Vagina I Female, entire J Male, entire K Male, posterior body region.

Figure 9. 

Aporcelaimoides silvaticum sp. n. (LM). A Female, entire B Male, entire C Anterior region in surface, lateral view showing four lateral pores D, E Anterior region in median, lateral view F, G Anterior region in surface, lateral view showing the amphid fovea H Pharyngo-intestinal junction I Vagina J Female, posterior body region K Male, posterior body region L Female, posterior genital branch M Male, caudal region N Female, caudal region O Spicules P Sperm cells. Scale bars: 500 µm (A, B); 20 µm (C); 10 µm (D–F, H, I, M–P); 5 µm (G); = 50 µm (J–L).

The new species is characterized by its body 2.09–2.60 mm long, lip region offset by depression and 17–18 µm broad, mural odontostyle 11–12 µm long at its ventral side with aperture occupying 60–66% of its length, neck 597–720 µm long, pharyngeal expansion 353–452 µm long or occupying 58–64% of total neck length, uterus a simple tube and 128–243 µm long or 2.1–2.8 times the corresponding body diameter, pars refringens vaginae well developed, V = 58–60, female tail short and rounded to rounded conoid (31–37 µm, c = 69–83, c’ = 0.7), male tail similar to that of female (27–31 µm, c = 67–94, c’ = 0.6–0.7), spicules 64–75 µm long, and two or three widely spaced ventromedian supplements bearing hiatus.

The new species differs from its relatives by its lip region offset by depression (vs constriction). Besides, in having pars refringens vaginae and short mural odontostyle (11–12 µm long at its ventral side), A. silvaticum sp. n. is morphologically similar to A. haguei comb. n. and A. minor sp. n., but it can be distinguished from them in its narrower lip region (17–18 vs equal or 19 µm or more) and more posterior vulva (V = 58–60 vsV up to 57). It also differs from A. haguei comb. n. in its smaller general size (L = 2.09–2.60, neck 597–720 µm long vsL = 4.67–5.42, neck 1112–1178 µm long), less slender body (a = 28–33 vsa = 52–62), absence (vs presence) of rows of minute denticles on stomatal wall), shorter female tail (31–37 vs 46–47 µm), and male present (vs absent). And from A. minor sp. n. in its shorter mural odontostyle (11–12 vs 14–16 µm at its ventral side) with smaller aperture (occupying 60–66% vs 73–84% of its length), longer female tail (27–31 µm, c = 67–94, c’ = 0.6–0.7 vs 14–26 µm, c = 90–146, c’ = 0.3–0.6), and male present (vs absent). Finally, the new species also resembles A. brevistylum sp. n. in having short mural odontostyle, but it differs from this in its well developed (vs absent) pars refringens vaginae and higher number of ventromedian supplements (two or three vs one).

Northern Vietnam, Cuc Phuong National Park, where the new species was collected from soil of a pristine tropical forest in 2009.

Female holotype and one female and three male paratypes, deposited in the nematode collection of the University of Jaen, Spain. One male paratype deposited in the nematode collection of the Institute of Ecology and Biological Resources, Vietnam.

The specific epithet is a Latin term meaning ‘from the jungle’, and refers to the habitat where the species dwells.