Egtitus biformis, Andrássy, 2012

Andrássy, István, 2012, On the “ Paractinolaimus ” genus group (Nematoda: Actinolaimidae), with description of five new and two rare species of Egtitus Thorne, 1967, Journal of Natural History 46 (7 - 8), pp. 453-494 : 479-482

Egtitus biformis sp. nov.

( Figures 10A–E and 11A–C )

Holotype (smaller) female: L = 1.72 mm; a = 45; b = 3.2; c = 10; ć = 6.7; V = 50%.

Paratype (larger) females (n = 2): L = 2.27–2.42 mm; a = 36–38; b = 3.7–4.0; c = 10.7–11.0; ć = 6.5–6.8; V = 48%. Paratype male: L = 1.62 mm; a = 34; b = 3.0; c = 49; ć = 1.0.

General characters

Body mostly twisted upon fixation, strongly tapered toward anterior end, 40–48 µm (smaller specimens) or 62–64 µm (larger specimens) wide at mid-region. Cuticle practically smooth, 3.0–4.0 µm thick on most of body. Lip region slightly offset, rounded, 16–17 µm wide, somewhat wider than adjoining neck. Body at posterior end of pharynx 2.8–3.3 times as wide as lip region. Amphids caliciform with aperture half the corresponding body width.

Labial and dental chambers well separated, the former 10 µm, the latter 6–7 µm broad. No pharyngeal denticles. Stylet chamber unusually roomy and thick-walled, 9 µm broad, seen clearly under lower magnification. Guiding ring at 17–18 µm from anterior end. Onchia as usual, simple. Odontostyle 24–26 µm long, 1.5–1.6 times longer than labial diameter, 2.0–2.2 µm thick at middle, slightly thicker than cuticle at the same level. The aperture occupying about one-third stylet length. Pharynx 550–610 µm long, at 48–49% expanded. Because of the strong muscular structure, the pharyngeal gland nuclei are rather indistinct. D = 50–52%, AS nuclei not visible, PS = 68–70%. Glandularium 260–296 µm long. Posterior end of pharynx with a shallow disc; cardia conoid.

Female

Reproductive system didelphic, amphidelphic. Gonads long, anterior branch 5.5–6.2 body widths long or occupying 15–16% of body length, posterior branch 6.6–6.8 body widths long or occupying 17–18% of body length. Vulva a short longitudinal slit, with sclerotized inner labia. Vagina 22 µm (shorter female) or 32–33 µm (longer females), occupying half or less of the body width. Uteri bipartite with proximal roomy and distal narrower sections. The roomy chambers of the uteri in two females (the longer ones) were packed with sperm. Uterine eggs not found. Distance between posterior end of pharynx and vulva shorter (0.7–0.9 times) than the pharynx itself. Rectum 1.5–1.8 times and pre-rectum 3.2–4.0 times the anal body diameter long. Vulva–anus distance equal to 3.9–4.7 tail lengths. Tail 178–220 µm long or 9–10% of entire length of body, first conoid then strongly tapered to its very fine filiform tip, slightly bent dorsally.

Male

Testes two, comparatively short, each three body widths long with reflexed distal end. Spermatozoa fusiform. Spicula dorylaimoid, 58 µm long in curvature. Ventromedial supplements distinct, well spaced, 10 in number. Pre-rectum beginning at the level of the second supplement. Tail 34 µm long or 2.0% of body length, conoid-rounded.

Diagnosis and relationships

Body either under 2 mm and slender, or over 2 mm and more robust, lip region narrow, stylet chamber unusually roomy, odontostyle about one-and-a-half times the lip region width long, female gonads long, male gonads short and distally ventrally reflexed, supplements 10, female tail medium long, finely pointed.

This interesting species shows the usual structures typical for Egtitus , but at the same time it has some special characters. These latter are: the stylet chamber is roomy, the testes are reflexed on their distal ends, and the body size is different among specimens of the same population (the shorter female amounts to 71–75% the length of the longer females). As for the shape of the stylet chamber, the representatives of Stopractinca are similar in this respect, but their onchia are bi-tipped and the males have a great number (18–25) of supplements.

Type specimens

Holotype female on slide no. 13711. Paratypes: two females, one male and one juvenile. Deposited at the Department of Systematic Zoology of the ELTE University , Budapest .

Type habitat and locality

Wet fallen leaves from a rain forest, Kiunga by the Fly River, Western Province, Papua New Guinea; collected in September 1969 by J. Balogh .

Etymology

The epithet biformis comes from the Latin, and means: dimorphous, or, of dual shape.

Figures

Figure 10. Egtitus biformis sp. nov. (A) Anterior end; (B) cardial region; (C) vulval region; (D, E) female tails. Scale bars 20 µm.

Figure 11. Egtitus biformis sp. nov. (A) Tip of the anterior testis; (B) tip of the posterior testis; (C) posterior end of male. Scale bars 20 µm.