Enchodelus macrodorus ( de Man, 1880 ) Thorne, 1939

Guerrero, Pablo & Santiago, Reyes Peña-, 2007, Redescription of Enchodelus species studied by Thorne in 1939 (Dorylaimida: Nordiidae), Nematology 9 (1), pp. 93-121 : 112-116

Enchodelus macrodorus ( de Man, 1880) Thorne, 1939 = Dorylaimus macrodorus de Man, 1880 = Dorylaimus (Doryllium) macrodorus ( de Man, 1880) Ditlevsen, 1928 = Dorylaimellus macrodorus ( de Man, 1880) Thorne & Swanger, 1936

( Figs 10 , 11 )

Nine females, five of them mounted on a slide labelled Enchodelus macrodorus 1h, and collected from Aspen Creek, Utah, USA, on 22 June 1932, in very good condition. The other four females mounted on slide labelled Enchodelus macrodorus 1d, and collected from Strawberry Reservoir, Utah, USA, in sage brush soil, in September, 1924, three of them also in good condition.

MEASUREMENTS

See Table 4.

DESCRIPTION

Female

Moderately stout nematodes of medium size, 1.5- 1.7 mm long. Habitus after fixation slightly ventrad curved. Body cylindrical, tapering towards both ends but more so towards anterior. Cuticle 3.0-4.5 µ m thick at anterior region, 3.5-4.5 µ m at mid-body and 8.5-11.0 µ m at tail; its outer layer practically smooth or bearing very fine transverse striations, and much thinner than inner, specially at level of tail. Lateral chord very narrow, less than one-tenth of mid-body diam., lacking any particular differentiation. Lateral pores obscure. Lip region rounded, offset by a marked depression, 2.5-3.5 times as broad as high and ca one-third of body diam. at neck base. Lips amalgamated, perioral area hardly differentiated; labial and cephalic papillae visibly protruding from lip region contour. Amphid fovea cup-shaped, opening at level of cephalic depression and occupying one-half to two-thirds of corresponding body diam. Cheilostom a truncate cone, with thickened walls. Odontostyle long and slender, with distinct walls and narrow lumen; 11- 18 times as long as wide or 1.9-2.4 times as long as lip region diam.; aperture small, ca one-twelfth of total length. Odontophore bearing distinct flanges occupying ca half of total length; scarcely longer (1.0-1.2 times) than odontostyle. Guiding ring double, at 25-28 µ m or 1.3-1.5 times lip region diam. from anterior end. Pharynx consisting of slender but well muscled anterior portion expanding gradually into basal expansion at 59-62% of total neck length, reaching maximum diam. at 64- 68%; pharyngeal expansion occupying 35-38% of total neck length, and one-half to two-thirds of corresponding body diam. Pharyngeal gland nuclei located as follows: DN = 65-68; S 1 N 1 = 24-36; S 1 N 2 = 27-37; S 2 N 1 = 54-59; S 2 N 2 = 57-61. Base of pharyngeal expansion surrounded by weak membrane-like structure. Cardia very small, rounded conoid, and wider than long (12- 19 × 9-16 µ m). Genital system didelphic-amphidelphic, with both branches equally and well developed. Ovaries relatively large, 83-188 µ m long, but usually not reaching sphincter level; oocytes first in two or more rows, then one. Oviduct 97-159 µ m long, consisting of slender portion with prismatic cells and well developed pars dilatata with distinct lumen. Sphincter distinct, located between oviduct and uterus. Uterus short, tripartite: wider proximal portion having distinct lumen followed by a narrower intermediate region with narrow lumen joining a small spheroid pars dilatata distalis; length 61-143 µ m or 1.1-2.0 times body diam. at its level. Sperm not observed in genital tract. Two eggs observed inside both genital branches of one female, measuring 57 × 92 and 55 × 87 µ m. Vagina extending inwards to ca half (47-57%) of body diam.; pars proximalis 17-21 × 21-27 µ m, with almost straight or somewhat sigmoid walls, and enveloped by moderately developed circular musculature; pars refringens with (in lateral view) two close trapezoidal sclerotisations with a combined width of 19-20 µ m; pars distalis short, 4.0-6.0 µ m long. Vulva a transverse slit. Prerectum long, 3.9-5.8 anal body diam. Rectum almost equal to anal body diam. Tail short rounded to hemispheroid. Two pairs of caudal pores, both subterminal, one subdorsal, another subventral; most specimens bearing some small irregularities between inner and outer layers of cuticle, mainly at ventral side of the tail, sometimes appearing as vesicles in dorsal view.

Male

Not seen.

DIAGNOSIS

Enchodelus macrodorus is distinguished by its body 1.5-1.7 mm long, lip region offset by marked depression and 17.5-20 µ m diam., odontostyle 38-43 µ m long or 1.9-2.4 times the lip region diam., odontophore provided with distinct basal flanges and slightly longer (1.0-1.2 times) than odontostyle, neck length 303-345 µ m long, pharyngeal expansion 111-130 µ m long and occupying 35-38% of total neck length, female genital system amphidelphic, uterus tripartite, pars refringens vaginae with two sclerotisations, vulva in form of a transverse slit and uniquely anterior (V = 41-44), and tail short rounded to hemispherical (18-24 µ m, c = 68-91, cļ = 0.5-0.6).

REMARKS

Thorne (1939) wrote that this species was “common at elevations of 8,000 to 12,000 feet in Wasatch and Uinta Mountains, Utah, U.S.A.”, and, although he did not mention the two localities from where the specimens studied herein were collected, it seems more than likely that this material belongs to that studied by him since his morphometric and morphological details fit perfectly with those given above. Thorne (1939) described the male of the species but unfortunately nomale was found in the two available slides from the USDA Nematode Collection.

The present description and that of Thorne (1939) of American specimens of E. macrodorus apparently fit very well that of de Man (1880), although, of course, the latter is not very detailed.

Enchodelus macrodorus seems to be very widely distributed in Holartic areas.

Figures

Fig. 10. Enchodelus macrodorus (de Man, 1880) Thorne, 1939 (female). A: Entire body; B: Anterior region; C: Reconstruction of superficial appearance of cephalic region; D: Vulval region; E: Pharyngeal region; F: Anterior genital branch; G: Tail. (Scale bars: A = 500 µm; B-D, G = 50 µm; E, F = 100 µm.)

Fig. 11. Enchodelus macrodorus (de Man, 1880) Thorne, 1939 (female). A: Variability of anterior region; B: Expanded part of pharynx, showing dorsal nucleus (large arrow) and one of subventral nuclei (small arrow); C: Anterior genital branch showing sphincter (arrows); D: Base of pharynx; E: En face view of vulva; F: Egg; G: Variability of vulval region; H: Variability of tail. (Scale bars: A, D, E-H = 25 µm; B, C = 50 µm.)