Pungentus textilis ( Thorne & Swanger, 1936 ) Thorne, 1939

Álvarez-Ortega, Sergio & Peña-Santiago, Reyes, 2011, Re-description of two atypical species of Pungentus Thorne & Swanger, 1936, with proposal of Stenodorylaimus gen. n. (Nematoda, Dorylaimida, Nordiidae), Zootaxa 2799, pp. 49-62 : 54-58

Pungentus textilis ( Thorne & Swanger, 1936) Thorne, 1939

( Figs. 3–5 )

Material examined. Nine females, eight males and four juveniles; in variable states of preservation since some specimens have become flattened and internal organs were not always readily perceptible.

Measurements. See Tables 3 & 4.

Description. Adult: Very slender nematodes of large size, 3.70–5.06 mm long. Body cylindrical, tapering towards both extremities, but more so towards the anterior end. Habitus curved ventrad after fixation, especially in posterior body region, C-shaped. Cuticle with fine transverse striation, more perceptible at level of caudal region; 1.5–2.5 μm thick in anterior region, 3.5–5.5 μm at mid-body and 4.5–7.0 μm on tail. Lateral chords 12.5–15.5 μm wide or 21–24% of mid-body diameter. Lip region offset by constriction, 2.6–2.9 times as wide as high and less than one-third (26–30%, non-flattened specimens) of body diameter at neck base; lips rounded, separate; labial papillae low. Amphid fovea funnel-shaped, its aperture 9 μm (n=3) or occupying four-sevenths to two-thirds (55– 64%) of lip region diameter. Cheilostom nearly cylindrical, with thickened walls; a thin perioral, weakly sclerotized ring is distinguishable in several specimens. Odontostyle comparatively long and slender, 13.9–16.9 times as long as wide, 2.0–2.3 (2.7 in only one specimen) times as long as lip region diameter, and 0.71–0.87% of body length; aperture short, 4–5 μm long or occupying one-eighth to one-seventh (12–14%) its length. Guiding ring double. Odontophore linear, rod-like, 1.0–1.1 times the odontostyle. Anterior region of pharynx enlarging very gradually; basal expansion 6.0–8.9 times as long as wide, 3.2–5.2 times as long as body diameter, and occupying 48– 53% of total neck length; pharyngeal gland nuclei located as follows: DN = 54–55, S1N1 = 69–72 (n=2), S1N2 = 78 (n=1), S2N = 88–89. Nerve ring located at 155–193 μm or 31–35% of total neck length from anterior end. Cardia rounded, 10.5–17.0 x 13.0–16.5 μm; a ring-like structure is present surrounding its junction to pharyngeal base. Female: Genital system didelphic-amphidelphic, with both branches equally and well developed, the anterior 600– 735 μm long or 13–15% of body length, and the posterior 611, 672 μm long or 13% (n=2) of body length. Ovaries well developed, the anterior 145–293 μm and the posterior 156–272 μm long; oocytes arranged first in two or more rows, then in a single row. Oviduct consisting of slender part with prismatic cells and well developed pars dilatata, the anterior 197–284 μm long or 2.1–3.3 times the corresponding body diameter, and the posterior 185–232 μm long or 2.2–2.7 times the corresponding body diameter. Oviduct and uterus are separated by a sphincter. Uterus apparently (its detailed morphology difficult to observe with accuracy in the females examined) bipartite, i.e. with two sections of nearly the same length but differing in their respective texture: distal region with globular wall, while the proximal one shows smooth and thicker walls; the anterior 335–435 μm long or 4.2–5.0 times the corresponding body diameter, and the posterior 390–410 μm long or 4.6–4.7 times the corresponding body; in some cases the uteri contain sperm cells. Vagina extending inwards 34–35 μm or about two-fifths (38–43%) of body diameter; pars proximalis 24.0–25.5 x 22.5–25.0 μm, with somewhat sigmoid walls and surrounded by weak musculature; pars refringens with two closely spaced triangular to trapezoidal pieces measuring 8.5–9.5 x 3–4 μm and with a combined width of 14.5–17.0 µm. Vulva slightly post-equatorial, with transverse oval opening. Prerectum 3.9 (n=1) anal body widths long. Rectum 44–51 µm long or 0.9–1.2 times the anal body diameter. Tail rounded conoid. Caudal pores two pairs, one dorsal and other subdorsal.

Male: Genital system diorchic, with opposite testes. In addition to the adcloacal pair, situated at 7.5–10.5 μm from cloacal aperture, there is a series of 14–19 slightly irregularly spaced (9–22 µm apart) ventromedian supplements, the two or three more posterior of which lie within the range of spicules and the hindmost of them situated at 20.5–26.5 μm from the adcloacal pair. Spicules curved ventrad and relatively slender, 5.8–6.5 times as long as wide and 1.4–1.8 times as long as anal body diameter. Lateral guiding pieces 13.5–15.5 μm long, 4.5–5.1 times as long as wide. Prerectum 2.6–3.8 anal body widths long. Rectum 44–51 µm long or 0.9–1.2 times the anal body diameter. Tail conoid with rounded terminus, ventrally straighter, dorsally convex. Caudal pores more or less similar to female.

Juveniles: Only two juvenile stages (J3 and J4) are present in the material herein studied. Their general morphology is similar to that of adults.

Diagnosis (based on specimens examined). This species is characterized by its body 3.70–5.06 mm long, lip region offset by constriction and 14.0–16.5 μm broad, odontostyle 31.5–37.0 μm long or 2.0–2.3 (one specimen 2.7) times the lip region width and with aperture occupying 12–14% of its length, neck 496–583 μm long, pharyngeal expansion 242–292 μm long or 48–53% of total neck length, uterus bipartite and 335–435 μm long or 4.2–5.0 times the corresponding body diameter, pars refringens vaginae with two sclerotized pieces, V = 50–54, female tail rounded conoid (34–39 μm, c = 109–149, c’ = 0.7–0.8), male tail conoid with rounded terminus (33–41 μm, c = 96–129, c’ = 0.7–1.0), spicules 66–73 μm long, and 14–19 irregularly spaced ventromedian supplements which lack hiatus.

Remarks. The specimens examined are certainly part of type material originally studied by Thorne and Swanger (1936) since the information on the label of one of the slides herein studied perfectly fits the ‘habitat’ mentioned by these authors: “… desert soils, near Elberta and Tooele, Utah and Bunkerville, Nevada, U.S.A. ”. The above description agrees very well with the original one although, of course, many new morphological details and morphometrics are now provided. Moreover, a few differences have been noted, such as a wider lip region (14.0– 16.5 vs 10.5–13.5 μm), longer odontostyle in males (31.5–36.5 vs 26.5–31.5 µm) and lower number of ventromedian supplements (14–19 vs 18–22), which should be interpreted as intraspecific variations and/or original errors in taking original measurements.

Figures

FIGURE 3. Pungentus textilis (Thorne & Swanger, 1936) Thorne, 1939. A: Anterior region in median view. B: Neck region. C: Female, posterior genital branch. D: Vagina. E: Female, caudal region. F: Male, posterior body region. G: Spicule and lateral guiding piece.

FIGURE 4. Pungentus textilis (Thorne & Swanger, 1936) Thorne, 1939 (female). A – C: Anterior region in median view. D: Lip region in surface view. E: Pharyngeal expansion. F, G: Vagina. H: Posterior body region. I, J: Caudal region. (Scale bars: A, C, I, J = 20 µm; B, D, F, G = 10 µm; E, H = 100 µm).

FIGURE 5. Pungentus textilis (Thorne & Swanger, 1936) Thorne, 1939 (male). A, B, F: Posterior body region. C: Spicules. D, E: Caudal region. (Scale bars: A: 100 µm; B, F = 50 µm; C – E = 20 µm).