Enchodelus groenlandicus (Ditlevsen, 1927) Thorne, 1939

Elshishka, Milka, Lazarova, Stela & Peneva, Vlada K., 2012, Studies of the genus Enchodelus Thorne, 1939 (Nematoda, Nordiidae) from Arctic polar deserts. 1. Species with long odontostyle: E. makarovae sp. n. and E. groenlandicus (Ditlevsen, 1927) Thorne, 1939, with an identification key to the species of the E. macrodorus group, ZooKeys 212, pp. 1-23 : 6-9

Enchodelus groenlandicus (Ditlevsen, 1927) Thorne, 1939 Figs 711

Material examined.

Ten females collected from Putorana Plateau, Russian Arctic (Table 1).

Measurements.

See Table 4.

Description.

Female. Nematodes of medium to large size, habitus from slightly curved ventrad to open C- shape after fixation. Cuticle with fine, but distinct transverse striations, especially visible at neck and on tail regions; 4-6 µm thick at postlabial region, 3-4 µm at mid-body and 7-8 µm on tail. Lateral chord narrow, 6-9 µm wide or occupying ca 9-13 % of mid body diam. Lip region rounded, offset by a depression, 2.3-3.1 times as wide as high. Amphidial fovea cup-shaped, located at level of labial depression, occupying 65% of lip diam. Cheilostom cylindrical. Odontostyle long, 2-2.5 times longer than lip region diam. or 2.2-2.7% of total body length. Odontophore distinctly flanged, 1.1-1.3 times as long as odontostyle. Guiding ring double, located 1.4-1.6 lip region diam. from anterior end. Pharynx attains full width at 56-64% of its length from anterior end. Pharyngeal characters are presented at Table 3. Cardia rounded measuring 6-10 × 15-17 µm. Genital system amphidelphic, both branches equally and well developed, anterior 277-370 µm, posterior 287-375 µm long. Ovaries relatively large, 142-303 µm long; oocytes firstly in two or more rows, then in a single row. Anterior and posterior oviduct 119-143 µm (n=9) and 119-153 µm (n=8) long, 1.6-1.9 and 1.6-2.0 times body diam. respectively, consisting of slender part and well developed pars dilatata oviductus. Sphincter distinct. Uterus thick walled, tripartite, consisting of a wider proximal portion with distinct lumen, followed by a narrower median portion (43-115 µm (n=4)) and ending with a well developed spheroid pars dilatata distalis. Vagina extending inwards 42-53 μm or 53-68 % of body diam., pars proximalis 25-30 µm × 21-22 µm, pars refringens with two trapezoid sclerotisations, with a combined width of 18-18.5μm and length 6-8 μm (n=2) pars distalis 6 µm long (n=2). Vulva a transverse slit, pre-equatorial (40-47%). Eggs observed in eight females, measuring 96 -109 × 43-64 µm, most frequently located in pars dilatata oviductus (n=6), rarely in uterus (n=2). Prerectum 3-4.5 anal diam. long, rectum 0.8-1.0 times anal body width. Tail hemispheroid. Numerous small elongated saccate bodies observed on tail, mostly on ventral side. Hyaline part of tail 8.0-10 µm thick or 25-33 % of total tail length.

Male. Unknown

Locality and plant associations.

Different types of vegetation from a polygonal polar desert on Plateau Putorana, Russian Arctic (Table 1).

Remarks.

The data on Enchodelus groenlandicus geographical distribution, i.e. the original description from Disko Island, Greenland ( Ditlevsen 1927) and recent reports from Spain, Albania and Iran ( Guerrero et al. 2008, Andrássy 2009b, Pedram et al. 2011) indicate a disjunctive type of range. It occurs at high altitudes 950 m to 2450 m a.s.l in Southern Europe and Iran, and at high latitudes in the polar region (Putorana Plateau and Greenland), Guerrero et al. (2008) hypothesize that such a distribution pattern might stem from quaternary glacial events. The specimens examined generally agree well with data reported for this species, although some differences occurred: the Arctic population has somewhat shorter odontostyles (43-47 vs 44-53 µm) and a more anterior position of the vulva (40-46 vs 41.5-49.4%, see Table. 4 for details); Iranian specimens had shorter female tails (19-24 vs 28-33 μm and c’ = 0.4-0.6 vs 0.5-0.7). We consider the morphometric differences as representing intraspecific variation.

Identification key to species belonging to Enchodelus macrodorus group