Enchodelus lucinensis Popovici, 1978

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 : 382-387

Enchodelus lucinensis Popovici, 1978

( Fig. 2 )

MATERIAL EXAMINED

Four female paratypes, in acceptable condition, and two males (but see remarks) from Bihor Mountains , in a good state of conservation.

MEASUREMENTS

See Table 3.

DESCRIPTION

Female

Moderately slender nematodes of medium size, 1.24- 1.46 mm long. Habitus after fixation curved ventrad, Cshaped. Body cylindrical, tapering towards both ends, but more so anteriorly. Cuticle 2.0 µm in anterior region, 3.0-4.5 µm at mid-body and 6.0-8.0 µm on dorsal side of tail, its outer layer with fine, but distinct transverse striations and much thinner than inner one, especially on tail. Lateral chord 11-15 µm wide or occupying one-fifth to one-fourth (21-26%) of mid-body diam., lacking any particular differentiation. Body pores obscure in material examined. Lip region somewhat angular, offset by a weak depression, 2.2-2.6 times as broad as high, ca one-fourth (22-28%) of body diam. at neck base. Lips amalgamated, labial and cephalic papillae slightly protruding above cephalic contour. Amphid fovea funnel-shaped, opening at level of cephalic depression, occupying 5-6 µm or ca one-half of corresponding body diam. Cheilostom almost cylindrical, with thick walls. Odontostyle comparatively robust, 10-14 times as long as wide and 1.6-1.9 times longer than lip region diam. or 1.4-1.7% of total body length, aperture small, 4-5 µm long or 14-17% of total length. Odontophore 1.4-1.5 times as long as odontostyle, lacking distinct basal thickenings or flanges (but see remarks). Guiding ring double, located at 10-12 µm or 1.1-1.3 lip region diam. from anterior end. Pharynx consisting of a slender muscular anterior portion gradually expanding, pharyngeal expansion occupying more than two-fifths (44-46%) of total neck length and ca one-half of corresponding body diam. Pharyngeal gland nuclei located as follows: DN = 61-65; S 1 N obscure; S 2 N = 83-86. Nerve ring at 85-112 µm from anterior end or 36-38% of total neck length. Cardia rounded conoid, nearly as long as broad, (10-15) × (11-14) µm in size. Genital system didelphic-amphidelphic; both branches equally and well developed: anterior branch 262-293 µm, posterior branch 310-353 µm long. Ovaries 80-109 µm long, usually reaching or slightly surpassing sphincter level; oocytes initially in two or more rows, then one. Oviduct 70-87 µm, or 1.3-1.4 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, 153-203 µm or 3.1-3.9 corresponding body diam., more or less twisted in females examined, tripartite, i.e., consisting of a wider proximal region with distinct lumen followed by a narrower and shorter intermediate portion with narrow lumen and surrounded by a cluster of hyaline cells, and ending with a well developed spheroid pars dilatata distalis. Sperm often abundant in proximal region of uteri. Vagina extending inwards 25-32 µm for one-half to three-fifths (51-61%) of body diam., pars proximalis longer than broad, (14-15) × (10-14) µm, usually with straight walls and enveloped by weak circular musculature, pars refringens with (in lateral view) two massive, granular, square sclerotisations measuring (5.0-6.0) × (6.0-7.0) µm and with a combined width of 13-14 µm; pars distalis 4.0 µm long. Vulva a transverse oval slit, preceded by a pronounced depression in body surface. Prerectum 2.2-2.9 and rectum 0.7-1.1 anal body diam. long. Tail short, rounded conoid, with abundant and distinct saccate bodies along ventral region, inner cuticle layer marked by radial striation, its ventral margin slightly irregular, barely separated from outer layer, cuticle 8-10 µm thick or 40-60% of tail length at terminus. Two pairs of subterminal caudal pores, one subdorsal, another practically lateral.

Male (see remarks)

General morphology similar to that of female, but with somewhat shorter body, 1.13 mm long. Genital system diorchic, with opposed testes. In addition to adcloacal pair, located at 10 µm from cloacal aperture, a series of seven or nine spaced ventromedian supplements, 8- 25 µm apart, extending anteriorly, posteriormost located at 17 or 22 µm from adcloacal pair, well within range of spicules. Other supplement located at level of anterior end of spicules. Spicules conspicuously robust, 3.8 or 4.2 times as long as wide and 2.1 or 2.3 anal body diam. long. Lateral guiding pieces 12 or 12.5 µm long, ca four times as long as wide. Tail somewhat more conoid than in female, saccate bodies present, but not so distinct (certainly due to fixation).

DIAGNOSIS AND RELATIONSHIPS

This diagnosis is based on the original description and a re-examination of the paratypes. Enchodelus lucinensis is distinguished by its 1.24-1.62 mm long body, lip region offset by weak depression and 11-14 µm diam., odontostyle 19-23 µm or 1.6-1.9 lip region diam. long and 1.4-1.7% of total body length, odontophore rod-like (but see remarks) and 29-32 µm long, neck length 238- 286 µm long, pharyngeal expansion 111-132 µm long or 42-46% of total neck length, female genital system amphidelphic, uterus long and tripartite, pars refringens vaginae with two massive and granular sclerotisations, V = 45-53, tail rounded conoid (18-21 µm long, c = 61- 76, cļ = 0.5-0.7), spicules 50-56 µm long and 7-9 spaced ventromedian supplements, the posteriormost one or two within the range of the spicules.

In having a comparatively small body (<1.7 mm long), short odontostyle (up to 23 µm) and short rounded tail, E. lucinensis resembles E. teres Thorne, 1939 and E. parateres Baqri & Jairajpuri, 1974 . It differs from E. teres , a nearly identical species (see remarks) in its longer pharyngeal expansion (vs ca two-fifths of total neck length) and shorter tail with less saccate bodies (vs 30 µm, c = 50, cļ = 1.0 as calculated from Thorne’s original drawing). Moreover, Thorne mentioned that the ovaries were “reflexed halfway to vulva”, an indication that the female genital tract is relatively short and the uterus (tentatively) not very long. It can be distinguished from E. parateres by its lip region offset by depression (vs deep constriction), longer pharyngeal expansion (vs 34- 40% of total neck length) and uterus tripartite (vs bipartite, lacking a spherical distal section).

DISTRIBUTION

Peat bog at Lucina nature reserve (Suceava District, Northern Moldavia; type locality) and mezohygrophilous meadow at Gheţar-Scărişoara, Bihor Mountains (Western Romanian Carpathians); sites 7 and 2 in Table 1.

REMARKS

As expected, the above description perfectly fits the original although new morphological details are added herein, particular for the female genital system.

Some doubts persist as to the true identity and/or taxonomy of E. lucinensis . The precise nature of the odontophore base could not be assessed with accuracy in the available specimens, but the observations suggest that it is simple, rod-like, at most with weak basal thickening and without evidence of distinct knobs or flanges, i.e., in agreement with the original description.

Its separation from E. teres is very problematic and based (see above) on minor differences. Unfortunately, available information about this species is very poor and many important morphological details are lacking, therefore preventing a detailed comparison. Zullini (1970) recorded E. teres from Italy, but only provided its basic ratios which, however, fit well with those of both E. lucinensis and E. teres . Until additional information about E. teres is available, separate status for these two species should be maintained.

Some doubts persist as to the conspecificity of the two males from the Bihor Mountains with the four female paratypes due to their shorter body and, mainly, because of their separate geographical origin. However, the general morphology and morphometry are very similar, including lip region diam., odontostyle length, etc., and the morphology of male sexual structures is practically identical with the only male paratype known. Thus, they are provisionally considered to belong to E. lucinensis .

Figures

Fig. 2. Enchodelus lucinensis Popovici, 1978. A: Female, entire; B, C: Anterior region in median, lateral view; D: Neck region; E, F: Vagina; G, H: Female, caudal region; I: Male, caudal region. (Scale bars: A = 200 µm; B, C, E-I = 10 µm; D = 100 µm.)