Aporcelaimellus acaudatus Andrássy 2010, sp. n.

Aporcelaimellus acaudatus sp. n. (Fig. 2 A–G)

Holotype female. L = 2.32 mm; a = 22; b = 4.0; c = 126; c’ = 0.3; V = 50 %.

Paratype females (n = 4). L = 2.22–3.10 mm; a = 22–25; b = 3.8–4.5; c = 122–150; c’ = 0.2–0.3; V = 47–52 %.

Type specimens. Holotype female on slide No. 14983. Paratypes: 4 females and 4 juveniles. They will be preserved in the zoological collection of the Hungarian Natural History Museum, Budapest.

Type habitat and locality. Soil with grass roots, Olmedo, Prov. Pichincha, Ecuador; collected in April 1971 by J. BALOGH (Budapest).

General characters. Large species with body more or less ventrally curved and 95–128 µm wide at middle. Cuticle smooth, 3–5 µm thick in most regions and 12–15 µm thick on tail terminus, consisting of the usual two layers of different refraction. Lip region offset by a deep constriction, 20–21 µm wide, narrower than adjoining body. Lips rounded, moderately separated. Body at posterior end of pharynx 4–5 times as wide as head. Cervical lacunae between cuticle and longitudinal muscle band not roomy. Amphids cup-shaped with apertures occupying half width of corresponding body.

Odontostyle 23–24 µm long with aperture occupying half its length. Guiding apparatus aporcelaimoid. Pharynx 552–625 µm long, gradually widened at its middle. Distance between posterior end of pharynx and vulva as long as or slightly longer than oesophagus itself. Dorsal pharyngeal nucleus located at 60–63% of pharynx length or 15% of total body length. Other gland nuclei inconspicuous. Glandularium 346–350 µm long. Cardia simple, conoid.

Female. Amphidelphic. Genital branches about equal in length, comparatively short, each 2.2–3.0 body widths long or occupying 10–14% of body length. Vulva a transverse slit with well-sclerotized inner lips. Vagina 36–42 µm long, distinctly shorter than half corresponding body diameter. Uterus a simple tube. Sphincter present in uterus–oviduct junction. Two females possessed a uterine egg each, 95–110 × 48–66 µm; eggshell smooth. No sperm found in the uteri. Rectum as long as 0.8–1.1, prerectum as 1.1–1.7 anal body widths. Distance vulva–anus 56–76 times as long as tail. Tail exceedingly short with unusually broad terminus, 15–25 µm, shorter than one-third anal body diameter, on its terminus with very thin outer but heavily thickened inner layer of cuticle.

Male. Not found.

Diagnosis and relationships. A large-sized Aporcelaimellus species with moderately long odontostyle, strongly sclerotized vulva, short prerectum, short genital branches, and unusually short, broadly terminated tail with strongly thickened inner cuticle.

As for the size and shape of the tail, this new species differs from all of its congeners. Such a short (practically almost non-existent) tail can occur in two Aporcelaimellus species: A. krygeri (DITLEVSEN, 1928) HEYNS, 1965 and A. duhouxi (ALTHERR, 1963) BAQRI & KHERA, 1975. The new species clearly differs from them by the shape of the tail which is not rounded, but plump and broadly truncated at its terminus.

Etymology. The species epithet acaudatus comes from the Latin meaning tailless, and refers to the almost missing tail.