Tubixaba saccata Popovici 1995, sp. n.

Tubixaba saccata sp. n.

(Fig. 1 A-G, Fig. 2; measurements in Table I)

Female (n = 6): Medium size, fairly plump. Body almost straight to slightly curved ventrad upon fixation.

Cuticle multilayered, about 4 gum thick at midbody, increasing to 15 gum around tail tip. Transverse striae on outer layer of cuticle more prominent towards both extremities. Lateral chord (Fig. 1 G) about one-fifth of the body diameter at midbody. Lateral, ventral and dorsal body pores present.

Lip region distinctly set off by a constriction (Fig. lA, B), about 27-32% of the body width at base of neck. Lips rounded, partially amalgamated. Oral aperture hexagonal (Fig. 1 C). Amphid aperture about half the lip region width (8- 9 p. m). Odontostyle 20-23 pm long, cylindrical, 1.2-1.3 times lip region width, the aperture 7-9 µm. Odontophore simple, slightly longer (1.2-1.5 times) than odontostyle. Guiding ring 10-12 µm from anterior end, single, unsclerotized (Fig. 1B). Nerve ring encircling anterior part of oesophagus. Anterior slender part of oesophagus less muscular than the basal expanded part (Fig. 1 A). Basal, gradually enlarged, portion of oesophagus is 57-61% of the neck length, its maximum width about 56-65% of the corresponding body diameter. Position of oesophageal gland nuclei (difficult to observe) as follows (n = 5): DO = 44.9- 49.5; DN = 47.4-51.4; DO-DN = 10-15 µm; S1N1 = 67.8-78.1; S1N2 = 70.8-78.9; S2N = 84.6-90; K = 90.0 (86-97) (Fig. 2). Oesophago-intestinal disc absent. Cardia conoid-rounded, 19-27.5 µm long.

TABLE I

Reproductive system didelphic, amphidelphic; ovaries reflexed 37-62%. Pars dilatata oviductus and pars dilatata uteri separated by a distinct sphincter muscle.

Vulva a transverse slit, vagina about half the corresponding body diameter, strongly muscular, thickwalled, with slightly trapezoidal sclerotized pieces. Sperm cells and eggs present in some specimens (Fig. 1 E).Rectum about equal to, prerectum 2-3.7 times, anal body diameter. Tail short, conoid and bluntly rounded with saccate bodies ventrally or all around the tail tip. Two pairs of caudal pores present (Fig. ID).

Male (n = 13); Similar to female but posterior part of body is more curved ventrad. Diorchic with testes opposed. Spicules arcuate, slender (Fig. 1 F). Lateral guiding pieces almost straight. Supplements consisting of an adanal pair situated 10-13 pm anterior to cloacal opening, and a row of 22-28 regularly spaced ventromedian ones, ending 10-30 gm anterior to the spicules. There are 50-65 copulatory muscles which exceed the ranges of ventromedian supplements. Prerectum 4.5 and rectum 1.2 times body diameter at cloacal opening. The intestine-prerectum junction located in the range of supplement series. Three rectal glands present. Tail similar to that of female with saccate bodies (Fig. IF).

Diagnosis. The species is distinguished by its medium size, odontostyle 20-23 gum long, shape of tail, presence of saccate bodies and males with numerous (22-28) regularly spaced ventromedian supplements.

Differential diagnosis: Tubixaba saccata sp. n. is close to T. minima Botha & Heyns, 1990 and T. parva Pretorius, Kruger & Heyns, 1987 (Syn. T. tswanorum Nell & Heyns, 1987). It can be distinguished from T. minima by longer body (2.13-2.74 mm vs 1.72-2.12 mm), longer odontostyle (20-23 J. 1m vs 16.5-19 Jl.m) and tail (33-47.5 gum vs 23-31 1 pm),by the shape of tail and lack of male in T. minima.

T. saccata sp. n. can be distinguished from T. parva by its shorter body size (2.13-2.74 mm vs 3.27-4.97 mm), longer odontostyle (20-23 pm vs 14-19 gum) and larger number of supplements (22-28 vs 14-19).

From the type species, T. tuxaua Monteiro & Lordello, 1980, the new species can be separated very easily by smaller size ofbody, odontostyle and spicules (L = 9.44-11.66 mm, odontostyle 29-33 pm, spicules 195-206 pm in T. tuxaua), by thinner cuticle (4 J. 1 m vs 12-14 pm at midbody, 10-15 pm vs 18-20 gm on tail) and by larger number of supplements (22-28 vs 10- 13).

Type locality and habitat: The type population, consisting of six females and 13 males, was collected in September, 1975 from an alluvial typic vermic soil (Pop & Postolache, 1987) of a montane grassland situated at 1000 m altitude, in the Poiana Ponor, Padis karstic region of the Bihor Mountains (Western Carpathians), Romania.

Type specimens: Holotype female and one paratype male on slide no. 49994 deposited in the Collection of the Natural Historical Museum " Gr. Antipa ", Bucharest, Romania; two slides with two paratype females and respectively three paratype males in the Nematology Department, Agricultural University Wageningen, the Netherlands. Other paratypes deposited in the Department of Ecology, Biological Research Institute, Cluj-Napoca, Romania.