Enchodelus striatus 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 : 116-120

Enchodelus striatus Thorne, 1939

( Figs 12 , 13 )

MATERIAL EXAMINED

Fourteen females, 15 males and a juvenile. Of them, three females and eight males on slide labelled Enchodelus striatus 8, and ten females, six males and one juvenile on slide labelled Enchodelus striatus 8b, both from Broads Fork and Twin Peaks, Utah, USA, collected in August 1924; one female and one male on slide labelled Enchodelus macrodoroides 2e, collected from summit soil in Lone Peak, Utah, USA, on 4 July 1926. Several specimens are in quite good condition, but most are damaged to some extent.

MEASUREMENTS

See Table 5 . Female

Moderately slender to slender nematodes of medium size, 1.5-2.0 mm long. Body cylindrical, tapering towards both ends but more so towards posterior. Cuticle 2.5- 3.5 µ m thick at anterior region, 2.5-4.5 µ m at mid-body and 4.0-6.0 µ m at tail; its outer layer provided with coarse transverse striations. Lateral chord 9-13 µ m wide or one-sixth to one-fifth of mid-body diam., lacking any particular differentiation. Lateral pores obscure. Lip region offset by marked constriction, sometimes appearing narrower than adjacent body, 2.1-2.8 times as wide as high and ca one-third of body diam. at neck base; perioral area weakly differentiated; lips practically amalgamated; labial and cephalic papillae rounded but protruding. Amphid fovea cup-shaped, opening at level of cephalic constriction and occupying ca half of lip region diam. Cheilostom a truncate cone, with no particular differentiation. Odontostyle slender, 14-21 times as long as wide or 2.5-3.0 times as long as lip region diam.; aperture small, less than one-tenth of total length. Odontophore rod-like, lacking any specialisation, 1.0-1.2 times the odontostyle length. Guiding ring apparently double, at 19.5-21.5 µ m or 1.4- 1.6 times lip region diam. from anterior end. Pharynx consisting of a slender but well muscled anterior portion expanding gradually into basal expansion at 60-65% of total neck length, reaching full diam. at 67-72%; pharyngeal expansion occupying 32-37% of total neck length, and ca half of corresponding body diam. Pharyngeal gland nucleilocatedas follows: DN = 71-75; S 1 N 1 =?; S 1 N 2 =?; S 2 N 1 = 47-53; S 2 N 2 = 49-55. Base of pharyngeal expansion surrounded by faint membrane-like structure. Cardia rounded conoid, practically as long as wide (11- 16 × 8-14 µ m). Genital system didelphic-amphidelphic, with both branches equally and well developed. Ovaries relatively large, 105-218 µ m long, usually not reaching sphincter level; oocytes first in two or more rows, then in one. Oviduct 123-218 µ m long or 2.0-4.4 times corresponding body diam., consisting of slender portion with prismatic cells and well developed pars dilatata bearing distinct lumen and containing sperm. Distinct sphincter present between oviduct and uterus. Uterus bipartite, i.e., with a wider proximal portion having distinct lumen and containing sperm, and a more slender distal part with narrow lumen, refractive inner lining and completely surrounded by a group of hyaline cells; length 114-223 µ m or 2.1-3.3 times the body diam. at its level. Vagina extending inwards one-third to one-half body diam.; pars proximalis vaginae 13-22 × 12-22 µ m, with sigmoid walls and enveloped by moderately developed circular musculature; pars refringens vaginae with (in lateral view) two triangular to trapezoidal sclerotisations with a combined width of 12-16 µ m; pars distalis vaginae well developed, 4.0-8.0 µ m long. Vulva a transverse slit, preceded by a depression in body contour; vulval lips distinctly raised. Prerectum 3.1-5.9, rectum 0.9-1.2 anal body diam. long. Tail conical, regularly ventrad curved, with rounded tip; hyaline terminal portion 12-19 µ m or 24-36% of total length. Two pairs of caudal pores at the middle of tail; one subdorsal, another practically lateral.

).

Male

General morphology similar to female, but with posterior body region more ventrally curved, G-shaped. Genital system diorchic, with opposite testes. In addition to adanal pair a series of 6-9 regularly spaced ventromedian supplements present outside of spicule range. Spicules dorylaimoid, relatively slender, ventrally curved, 5.1-7.7 times as long as wide and 1.3-1.9 times anal body diam. long. Lateral guiding pieces 12-14 µ m long and ca four times as long as wide, with bifurcate tip. Tail regularly ventrad curved, with rounded tip; hyaline portion occupying 12- 14 µ m or 19-25% of total length.

DIAGNOSIS

Enchodelus striatus is distinguished by its body 1.5- 2.0 mm long, outer cuticle with coarse transverse striations along the entire body, lip region offset by constriction and 12.5-14.5 µ m diam., odontostyle 35-38 µ m long or 2.5-3.0 times the lip region diam., odontophore lacking distinct flanges and equal in length to odontostyle, neck length 267-316 µ m long, pharyngeal expansion occupying 93-109 µ m or ca one-third (32-37%) of total neck length, female genital system amphidelphic, uterus bipartite, pars refringens vaginae with distinct trapezoidal sclerotisations, vulva in form of a transverse slit (V = 46-52), tail conical and regularly ventrally curved (46-59 µ m, c = 28-36, cļ = 1.6-1.9 in females; 51-63 µ m, c = 25-32, cļ = 1.5-1.8 in males), spicules 49-58 µ m long and presence of 6-9 regularly spaced ventromedian supplements.

REMARKS

Thorne (1939) originally described this species and provided the only report. The above description fits well with the original, although of course many new morphological details have been added. Concerning the odontophore, Thorne wrote “often appearing almost flanged” (see also his Fig. 80); however, our observations do not confirm any major specialisation of this structure. Other minor morphometric differences have also been observed.

Enchodelus striatus might be endemic to the Neartic region.

Figures

Fig. 12. Enchodelus striatus Thorne, 1939. A: Female anterior region; B: Reconstruction of superficial appearance of cephalic region; C: Female vulval region; D: Female entire body; E: Male entire body; F: Female pharyngeal region; G: Female anterior genital branch; H: Male spicule; I: Female tail; J: Male posterior end. (Scale bars: A-C, H, I = 50 µm; D, E = 500 µm; F, G = 100 µm; J = 100 µm.)

Fig. 13. Enchodelus striatus Thorne, 1939. A: Variability of female anterior region; B: Female expanded part of pharynx showing dorsal nucleus (large arrow) and one of posterior subventral nuclei (small arrow); C: Female anterior genital branch showing sphincter between uterus and oviduct (arrow); D: Variability of female vulval region; E: Variability of female tail; F: Male posterior region. (Scale bars: A, D, E = 25 µm; B, F = 50 µm; C = 100 µm.)

Tables

Table 5. Morphometrics for Enchodelus striatus Thorne, 1939. Measurements are in µm (except L in mm), and in the form: mean ± standard deviation (range

Population	Broads Fork & Twin Peaks (Utah)		Lone Peak (Utah)
Character	Females	Males	Female	Male
n	10	13	1	1
L	1.71 ± 0.12	1.64 ± 0.08	1.57	1.48
	(1.59-1.97)	(1.49-1.73)
a	27.8 ± 1.7	32.1 ± 3.4	32.0	33.6
	(25.3-30.1)	(26.9-37.2)
b	5.9 ± 0.5	5.5 ± 0.4	5.6	?
	(5.1-6.7)	(4.6-6.1)
c	31.6 ± 2.1	28.2 ± 2.0	34.0	29.0
	(28.1-35.8)	(25.1-31.8)
cļ	1.7 ± 0.1	1.7 ± 0.1	1.7	1.6
	(1.6-1.9)	(1.5-1.8)
V	48.0 ± 1.2	–	51.5	–
(45.5-49.3)
Lip region diam.	13.7 ± 0.5	13.8 ± 0.5	13	14
	(12.5-14.5)	(13-14.5)
Odontostyle length	36.6 ± 1.1	36.0 ± 1.0	35	31
	(35-38)	(35-38)
Odontophore length	39.3 ± 1.3	37.5 ± 1.5	35	40
	(37-42)	(35-40)
Guiding ring from anterior end	20.7 ± 0.6	20.4 ± 0.8	19.5	19
	(19.5-22)	(19-22)
Neck length	293 ± 17	298 ± 13	281	?
	(267-316)	(284-323)
Pharyngeal expansion length	101 ± 6	95 ± 7	100	?
	(93-109)	(79-105)
Diam. at neck base	27.1 ± 2.5	26.0 ± 3.5	21	?
	(22-30)	(22-33)
at midbody	62.2 ± 4.8	51.5 ± 4.5	49	44
	(54-71)	(45-60)
at anus	31.6 ± 2.5	34.7 ± 3.0	27	32
	(27-35)	(31-42)
Prerectum length	147 ± 38	159 ± 48	124	185
	(84-199)	(97-226)
Rectum length	32.6 ± 3.0	43.1 ± 4.4	32	41
	(30-38)	(38-51)
Tail length	54.8 ± 3.1	58.3 ± 3.5	46	51
	(50-59)	(53-63)
Spicule length	–	55.0 ± 1.9	–	49
		(51-58)
Ventromedian supplements	–	8.0 ± 0.9	–	9
		(6-9)