Enchodelus geraldi Winiszewska-Slipinska, 1987

Guerrero, Pablo & Santiago, Reyes Peña-, 2007, Redescription of Enchodelus species studied by Thorne in 1939 (Dorylaimida: Nordiidae), Nematology 9 (1), pp. 93-121 : 103-108

Enchodelus geraldi Winiszewska-Slipinska, 1987 = Enchodelus macrodoroides apud Thorne, 1939

( Figs 6 , 7 )

MATERIAL EXAMINED

Eleven females and an intersex. One of the females and the intersex mounted on slide labelled Enchodelus striatus, collected from Broads Fork & Twin Peaks , Utah in August 1924, 5-6; another female on slide labelled Enchodelus striatus, Broads Fork & Twin Peaks , Aug. 1924, 6-6; five females on slide labelled Enchodelus macrodoroides 2e, collected fromsummit soil, Lone Peak , Utah on July 4, 1926; and four females mounted on slide labelled Enchodelus macrodoroides 2a, collected from Wellsville Hill on March 28, 1925. The specimens are generally in acceptable condition, although some flattening is perceptible.

MEASUREMENTS

See Table 3 .

Female

Slender nematodes of medium size, 1.7-2.0 mm long. Body cylindrical, tapering towards both ends but more so towards posterior. Cuticle 3.0-3.5 µ m thick at anterior region, 3.0-4.0 µ m at mid-body and 4.5-7.5 µ m at tail; its outer layer thinner than inner, with distinct transverse striations. Lateral chord occupying one-sixth to one-fourth of mid-body diam., lacking any particular differentiation. Lateral pores obscure. Lip region rounded, offset by constriction and relatively high, ca 2.1-2.7 times as broad as high and ca one-third of body diam. at neck base; perioral area weakly differentiated. Lips amalgamated. Labial and cephalic papillae slightly protruding, clearly perceptible. Amphid fovea cup-shaped, opening at level of cephalic constriction and occupying ca two-fifths of lip region diam. Cheilostom a truncate cone, with notably thickened walls at posterior end. Odontostyle slender, with thick walls, very narrow lumen and very small aperture, slightly arcuate in some individuals; its length 14-19 times its width and 2.7-3.2 times as long as lip region diam. Odontophore as long as odontostyle; lacking distinct basal flanges, but differing from typical rod-like form by having a very distinct junction with pharyngeal lining, indicating a peculiar specialisation whose true nature is difficult to appreciate in longitudinal view (Thorne’s Fig. 77b shows a hexaradiate odontophore in cross section). Guiding ring apparently double, at 25-28 µ mor 1.5-2.0 lip regiondiam. from anterior end. Pharynx consisting of a slender, but well muscular, anterior portion expanding gradually into basal expansion at 57-64% of total neck length, reaching its maximum diam. at 64-69%; pharyngeal expansion occupying 34-40% of total neck length, and ca three-fifths of the corresponding body diam. Pharyngeal gland nuclei located as follows: DN = 66-71; S 1 N 1 = 24-29; S 1 N 2 = 29-36; S 2 N 1 = 45-54; S 2 N 2 = 47-55. Base of pharyngeal expansion surrounded by weak membrane-like structure. Cardia rounded conoid, wider than long (12-18 × 9-16 µ m). Genital system didelphic-amphidelphic, with both branches equally and well developed. Ovaries relatively large, 100-316 µ m long, usually reaching and surpassing sphincter level; oocytes first in two or more rows, then in one row. Oviduct 120-254 µ m long or 1.8-4.2 times corresponding body diam., consisting of a slender portion with prismatic cells and a moderately developed pars dilatata with no distinct lumen. Sphincter present separating oviduct and uterus. Uterus bipartite, i.e., with a wider proximal portion having distinct lumen, and a narrower distal part with narrow lumen and refractive inner lining; length 75-132 µ m or 1.2-2.4 times body diam. at its level; a peculiar structure consisting of a group of cells present around narrower part of uterus; very small refractive granules have been observed covering uterus inner lining, and located just behind sphincter. Uterine eggs seen in three of the females from Wellsville, measuring 109-121 × 36- 47 µ m. Sperm observed in genital tract of one of females from Broads Fork and Twin Peaks. Vagina extending inwards ca two-fifths (36-47%) of body diam.; pars proximalis vaginae 12-19 × 12-20 µ m, with sigmoid walls and enveloped by weakly developed circular musculature; pars refringens vaginae with (in lateral view) two more or less distinct trapezoidal sclerotisations which have a combined width of 14.0-18.5 µ m; pars distalis vaginae short, 2.5-6.5 µ m long. Vulva a transverse slit, often preceded by a depression in body surface. Prerectum 2.8-6.0, rectum 0.9-1.3 anal body diam. long. Tail conical, regularly ventrad curved, with coarsely rounded tip; hyaline terminal portion 12.5-19.0 µ m or 24-34% of total length. Two pairs of caudal pores at middle of tail: one subdorsal, other practically lateral.

Male

Not seen.

Intersex

General morphology similar to female. Male genital system diorchic, with opposite testes. In addition to adanal pair a series of four irregularly spaced ventromedian supplements present outside spicules range. Spicules relatively slender, ventrally curved and ca 1.3 times anal body diam. long, and 5.3 times as long as wide. Lateral guiding pieces obscure. Female genital system didelphic-amphidelphic. Vulva a transverse slit, located slightly posterior to midbody (V = 52%). Tail regularly ventrad curved, with rounded tip; its hyaline portion occupying 14.5 µ m or 26% of total tail length.

Enchodelus geraldi is distinguished by its body 1.7- 2.0 mm long, outer cuticle with distinct transverse striations along the entire body, lip region rounded and 14- 16.5 µ m diam., odontostyle 41-45 µ m long or 2.7-3.2 times the lip region diam., odontophore lacking distinct flanges, clearly separated from pharyngeal lining and equal in length to odontostyle, neck length 322-396 µ m long, pharyngeal expansion 118-150 µ m long and occupying 34-40% of total neck length, female genital system amphidelphic, uterus bipartite, pars refringens vaginae with two, more or less distinct, sclerotisations, vulva in form of a transverse slit and slightly posterior (V = 49- 53), tail conical and regularly ventrad curved (52-66 µ m, c = 26-38, cļ = 1.6-2.0), spicules 45 µ m long, and four spaced, ventromedian supplements (intersex).

REMARKS

Thorne (1939) reported this species from mountain areas in Utah (USA) and mentioned the existence of one additional female from Pompeii (Italy) in Cobb’s nematode collection, and classified it as Enchodelus macrodoroides Steiner, 1914.

Jairajpuri and Loof (1968) discussed the identity of E. macrodoroides, calculated some of the most relevant measurements of the young specimen originally described by Steiner (1914) (for instance, lip region ca 11 µ m diam., odontostyle length ca 25 µ m), and concluded that the new species described by them (E. longidens) and also the material described by Thorne (1939) were different from the original E. macrodoroides and regarded the latter as species inquirenda. Some of our observations confirm those by Jairajpuri and Loof (1968).

Jairajpuri and Loof (1968) compared E. longidens to E. macrodoroides apud Thorne (1939), and concluded that both were different, but they did not propose any nomenclatorial change for Thorne’s material.

Loof (1971) described Enchodelus cf. macrodoroides from Spitzbergen (an Arctic Norwegian archipelago), but several measurements show this material is not conspecific with that of Thorne (for instance, L = 1.4-1.5, odontostyle 23-24 µ m long or 1.6-1.8 lip region diam.).

Thorne (1974) again recorded E. macrodoroides from several localities in North America and, although he illustrated the species with his same figures published in 1939, the new material clearly does not compare to the former because the odontostyle is very short (15 µ m) and with a wide aperture (one-third of its length), and the vulva is more posterior (V = 56).

Winiszewska-Slipinska (1987) described E. geraldi from Poland and considered the material identified by Thorne (1939) as E. macrodoroides to belong to the former species. Four paratype females of E. geraldi, deposited at the Museum and Institute of Zoology, Polish Academy of Sciences, were available for study by courtesy of Dr Winiszewska-Slipinska. These individuals completely agree with the original description, although an error in Winiszewska-Slipinska’s measurements has been detected: the odontostyle was said to be 2.1-2.3 lip diam. long; however, the lip region is 14-15 µ m wide and the odontostyle is 39-42 µ m long, so the latter must be at least 2.6 times the lip region diam. This is completely supported by our observations on the paratypes of E. geraldi examined whose lip region is 14.0-14.5 µ m in diam. and odontostyle is 41-42 µ m long, or 2.8-3.0 times the lip region diam., i.e., practically the same as American individuals. With regard to the remaining morphometric and morphological features, the Polish and American populations are almost identical.

SEPARATION OF E. GERALDI FROM E. LONGIDENS

With the new information here provided, E. geraldi becomes very close to E. longidens. In describing the former species, Winiszewska-Slipinska (1987) differentiated it from the latter by its longer prerectum, much narrower lip region and shorter odontostyle (2.1-2.3 vs 3.0- 4.0 times the lip region diam., although the odontostyle of E. geraldi is actually not so short – see above). Lip region diam. was not explicitly given by Jairajpuri and Loof (1968) (see also Ahmad & Jairajpuri, 1980) in their original description of E. longidens, but their Figure 2B suggests that the lip region is ca 14 µ m, i.e., more or less equal to that of E. geraldi. The prerectum is scarcely longer in E. geraldi (3-4 and 3.6-6.0 anal body diam. in Polish and American populations of E. geraldi, respectively, vs 1-3 anal body diam. in E. longidens) but, if we take into account that only a small number of specimens of E. longidens are known, such a difference might not be significant. Concerning the odontostyle length, there isapparently a more reliable (although small) difference (2.7- 3.0 vs 3.0-4.0 times the lip region diam.). Amore significant difference between these species is the length of the pharyngeal expansion, distinctly shorter in E. longidens (29-31% of total neck length vs 35-37% in Polish material of E. geraldi and 37-40% in American specimens studied herein). The intersex of E. geraldi described here presents some differences with the known males of E. longidens, having the former shorter spicules (45 vs 53-56 µ m) and fewer ventromedian supplements (4 vs 7-8). Finally, the geographical range of the species is different (holartic in E. geraldi vs paleotropical in E. longidens). In tentative conclusion, both taxa should be regarded as separate and valid species.

Figures

Fig. 6. Enchodelus geraldi Winiszewska-Slipinska, 1987 (female). A: Anterior region; B: Reconstruction of superficial appearance of cephalic region; C: Anterior genital branch; D: Entire body; E: Pharyngeal region; F: Tail; G: Vulval region. (Scale bars: A, B, F, G = 50 µm; C, E = 100 µm; D = 500 µm.)

Fig. 7. Enchodelus geraldi Winiszewska-Slipinska, 1987. A: Variability of female anterior region; B: Female pharyngeal region showing dorsal nucleus (large arrow) and one of posterior subventral nuclei (small region); C: Female posterior genital branch; D: Female base of pharynx showing membrane-like structure (arrows); E: Female vulval region; F, G: Female genital branch showing group of cells around narrow distal part of uterus (arrows); H: Intersex posterior region showing vagina (arrow), spicules and ventromedian supplements (detailed photograph); I: Variability in female tail. (Scale bars: A, D, E, G, I = 25 µm; B, H = 100 µm; C, F = 50 µm.)

Fig. 2. Enchodelus arcuatus Thorne, 1939 (female). A: Anterior region; B: Reconstruction of superficial appearance of cephalic region; C: Entire body; D: Vulval region; E: Pharyngeal region; F: Anterior genital branch; G: Tail. (Scale bars: A, B, D, G = 25 µm; C = 250 µm; E, F = 100 µm.)

Tables

Table 3. Morphometrics of Enchodelus geraldi Winiszewska-Slipinska, 1987. All measurements are in µm (except L in mm), and in the form: mean ± standard deviation (range).

Population	Broads Fork &		Lone Peak	Wellsville Hill	Total range
	Twin Peaks		(Utah)	(Utah)
	(Utah)
Character	Females	Intersex	Females	Females	Females
n	2	1	5	4	11
L	1.89, 1.69	1.71	1.76 ± 0.07	1.88 ± 0.11	1.69-2.00
			(1.69-1.88)	(1.74-2.00)
a	34.0, 28.2	27.6	28.7 ± 1.7	32.7 ± 4.6	26.7-38.8
			(26.7-30.6)	(28.0-38.8)
b	4.8, 4.4	4.9	4.8 ± 0.3	5.3 ± 0.3	4.4-5.8
			(4.5-5.3)	(5.0-5.8)
c	33.6, 25.7	30.7	32.2 ± 1.3	34.4 ± 3.4	25.7-37.8
			(30.2-33.8)	(31.0-37.8)
cļ	1.8, 1.6	1.5	1.7 ± 0.1	1.7 ± 0.2	1.6-2.0
			(1.6-1.9)	(1.6-2.0)
V	51.4, 52.5	52.1	51.4 ± 0.9	50.5 ± 1.1	49.2-52.5
			(50.5-52.5)	(49.2-51.9)
Lip region diam.	14, 14	15.5	14.7 ± 0.5	15.0 ± 1.3	14-16.5
			(14-15)	(14-16.5)
Odontostyle length	45, 41	43	41.6 ± 1.3	42.9 ± 1.7	41-45
			(41-44)	(41-45)
Odontophore length	43, 40	41	43.9 ± 1.8	42.2 ± 2.4	40-47
			(42-47)	(40-45)
Guiding ring from ant. end	27, 28	27	25.2 ± 0.3	25.6 ± 1.0	25-28
			(25-25)	(25-27)
Neck length	396, 380	351	370 ± 8	355 ± 26	322-396
			(357-378)	(322-377)
Pharyngeal expansion length	144, 138	128	142 ± 5	129 ± 10	118-150
			(136-150)	(118-143)
Diam. at neck base	31, 32	33	32.2 ± 1.8	28.2 ± 1.5	27-34
			(30-34)	(27-30)
at midbody	56, 60	62	62.2 ± 2.9	58.2 ± 5.9	50-66
			(59-66)	(50-62)
at anus	31, 40	36	31.8 ± 1.1	31.8 ± 2.0	29-40
			(31-34)	(29-33)
Prerectum length	142,?	190	145 ± 37	124 ± 25	92-192
			(111-192)	(92-149)
Rectum length	41, 43	43	39.7 ± 1.5	30.7 ± 1.4	29-43
			(38-41)	(29-32)
Tail length	56, 66	56	54.7 ± 2.0	54.9 ± 2.9	52-66
			(53-58)	(52-58)
Spicule length	–	45	–	–	–
Ventromedian suppl.	–	4	–	–	–