Enchodelus ponorensis Popovici, 1995

Ciobanu, Marcel, Popovici, Iuliana, Guerrero, Pablo & Santiago, Reyes Peña-, 2010, Nematodes of the order Dorylaimida from Romania. The genus Enchodelus Thorne, 1939. 2. Species with rounded tail and medium-sized odontostyle, Nematology 12 (3), pp. 381-397 : 394-396

Enchodelus ponorensis Popovici, 1995

( Fig. 6 )

MATERIAL EXAMINED

Six female paratypes, in not very good condition, collected from the Poiana Ponor area located within the Padiş karstic plateau , Bihor Mountains (Western Romanian Carpathians); sites 1 and 3 in Table 1.

MEASUREMENTS

See Table 3 . Female (based on material examined)

Slender nematodes of medium size, 1.63-2.04 mm long. Habitus after fixation curved ventrad, C-shaped. Body cylindrical, tapering towards both ends, but more so anteriorly. Cuticle 3.0 µm in anterior region, 3.0-4.0 µm at mid-body 7.0-8.0 µm on dorsal region of tail, and 11- 13 µm at tail terminus, its outer layer with very fine transverse striations and much thinner than inner one, especially on tail. Lateral chord 16-19 µm wide or occupying almost one-third (29-33%) of mid-body diam., lacking any particular differentiation. Body pores, if present, inconspicuous. Lip region more or less rounded, offset by a marked constriction, 2.5-3.0 times as broad as high and ca one-third (29-33%) of body diam. at neck base. Lips amalgamated, labial and cephalic papillae inconspicuous, barely protruding above cephalic contour. Amphid fovea cup-shaped, opening at level of cephalic depression, occupying 6.0-6.5 µm ca two-fifths (38-41%) of corresponding body diam. Cheilostom almost cylindrical. Odontostyle comparatively robust, 8.2-10.4 times as long as wide, 1.5-1.6 times longer than lip region diam. or 1.3-1.6% of total body length, aperture small, but precise extent not distinguishable in material examined. Odontophore 1.2-1.4 times as long as odontostyle, with small basal thickenings, no evidence of knobs or flanges observed. Guiding ring double, located at 14-16 µm or 0.8- 0.9 times lip region diam. from anterior end. Pharynx consisting of a slender muscular anterior portion expanding gradually; pharyngeal expansion occupying ca two-fifths (37-45%) of total neck length, 5.5-7.2 times as long as wide or 3.0-3.4 times corresponding body diam. Pharyngeal gland nuclei located as follows: DN = 62-67; S 1 N obscure; S 2 N = 80-85. Cardia rounded conoid, nearly as long as broad, (13-20) × (12-15) µm. Genital system didelphic-amphidelphic; both branches equally and well developed, anterior branch 155-225 µm, posterior branch 180-228 µm long. Ovaries 66-130 µm long, often extending to sphincter level, oocytes initially in two or more rows, then in one row. Oviduct 60-88 µm or 1.0-1.5 corresponding body diam. long, consisting of a slender portion with prismatic cells and a moderately developed pars dilatata with visible lumen. Sphincter prominent, located between oviduct and uterus. Uterus long, 70-90 µm or 1.2-1.6 times corresponding body diam., bipartite, i.e., consisting of a wider proximal region with distinct lumen followed by a narrower and shorter distal portion with narrow lumen and surrounded by a cluster of hyaline cells. Vagina extending inwards 30-33 µm or 54-59% of body diam., pars proximalis nearly as long as broad, (14-15) × (11-15) µm, with sigmoid to straight walls and enveloped by weak circular musculature; pars refringens with (in lateral view) two trapezoidal sclerotisations measuring (3.0- 5.0) × (8.0-9.0) µm and with a combined width of 16- 18 µm, pars distalis 4.0-5.0 µm long. Vulva a transverse slit. Prerectum 6.0-6.6 and rectum 1.1-1.3 anal body diam. long. Tail conoid, slightly straighter ventrally, most specimens lacking saccate bodies. Two pairs of caudal pores at middle of tail, one subdorsal, another practically lateral.

The genus Enchodelus from Romania

Male

Unknown.

DIAGNOSIS

Based on the original description and the present study, E. ponorensis is distinguished by its 1.63-2.07 mm long body, lip region offset by a marked constriction and 15- 16.5 µm diam., odontostyle 23-26 µm or 1.5-1.6 lip region diam. long and comprising 1.3-1.6% of total body length, odontophore 31-38 µm long and with small thickenings, neck 355-520 µm long, pharyngeal expansion 150-245 µm long or 41-47% of total neck length, female genital system amphidelphic, uterus short and bipartite, pars refringens vaginae with two trapezoidal sclerotisations, V = 44-52, tail rounded conoid (35-45 µm long, c = 40-57, cļ = 0.9-1.3) and males unknown.

REMARKS

The description herein perfectly agrees with the original one ( Popovici, 1995), although some additional morphological details have now been incorporated, especially those concerning the female genital system.

Enchodelus ponorensis is an interesting taxon within the genus. It is an atypical round-tailed species due to its comparatively short, bipartite uterus, whereas all other similar species examined by the authors (Guerrero & Peña-Santiago, 2007; Guerrero et al., 2008a, b) are characterised by having a long, tripartite uterus, only E. macrodorus showing a shorter, but distinctly tripartite, uterus. Thus, somewhat surprisingly, in its short, bipartite uterus, E. ponorensis resembles the conical-tailed species of the genus (see Guerrero & Peña-Santiago, 2007; Guerrero et al., 2008b). On the other hand, E. ponorensis is peculiar in having a relatively short and robust (8-10 times as long as wide) odontostyle, long pharyngeal expansion and comparatively longer and more conoid female tail, similar to that found in some species of the genus Crassolabium Yeates, 1967 (= Thonus Thorne, 1974 ), for instance C. tenuistylum ( Ciobanu, Popovici, Abolafia & Peña-Santiago, 2008) Peña-Santiago & Ciobanu, 2008 , also known from Romania. Nevertheless, E. ponorensis conforms better to the general pattern of Enchodelus in the form of its lip region, odontophore, location of S 2 N and uterus.

Figures

Fig. 6. Enchodelus ponorensis Popovici, 1995 (Female). A: Anterior region in median, lateral view; B: Lip region in median, lateral view; C: Same in surface view; D, E: Vagina; F-H: Caudal region. (Scale bars: 10 µm.)