Labronemella labiata Andrássy, 1985

Peña-Santiago, Reyes, Abolafia, Joaquín & Pedram, Majid, 2012, New data on Labronemella labiata Andrássy, 1985 (Dorylaimida: Qudsianematidae) from Iran, with SEM study and a compendium of the genus, Zootaxa 3271, pp. 43-54 : 44-49

Labronemella labiata Andrássy, 1985

( Figs 1–4 )

Measurements. See Table 1 .

the form average ± standard deviation (range)

Description

Material examined: Five females and six males, in good state of preservation.

Adult: Moderately slender to slender nematodes of medium size, 2.00– 2.61 mm long. Habitus curved ventrad upon fixation, C-shaped in both sexes. Cuticle two layered: outer layer thin, nearly smooth under LM, but SEM pictures show that very fine transverse striation is present throughout the body; inner layer thicker (3–4 times) than outer one, bearing distinct radial striation; cuticle 4–6 μm thick at anterior region, 5–7 μm in mid-body and 6–9 μm on tail. Lateral chord 14–20 μm wide at mid-body, occupying one-fifth to one-fourth (21–26%) of body diameter. Lip region offset by constriction, 3.3–4.3 times as wide as high and one-third to two-fifths (33–43%) of body diameter at neck base. Its detailed morphology elucidated under SEM: lips completely amalgamated, forming a disc- or sucker-like structure, whose anterior surface (oral field) appears distinctly sunken but with its inner (perioral) area differentiated in six large, separated liplets protruding on oral field; lateral, perioral liplets trapezoidal and visibly larger than subdorsal and subventral ones, which are triangular, so that lip region shows a bi-radial symmetry; inner labial papillae migrated to the margin of labial disc, being located close to outer labial and cephalic papillae. Amphidial fovea funnel-like, its aperture 14–18 μm or about two-thirds (59–71%) of lip region width; SEM pictures show that fovea does not bulge on body surface and that aperture is a very narrow slit within the labial constriction.

Odontostyle straight and narrow, 9–14 times as long as wide, with slender walls and distinct lumen, 1.1–1.3 times longer than lip region width and 1.13–1.52% of body length; aperture 9–13 μm long or up to two-fifths (29–40%) of its total length. Guiding ring double, at 14–20 μm or 0.5–0.6 times the lip region width from anterior end. Odontophore rod-like, 1.6–2.1 times the odontostyle. Pharynx consisting of a slender but distinctly muscular anterior part, enlarging gradually; basal expansion 6.5–8.5 times as long as wide or 3.5–4.4 times longer than body diameter at neck base, and occupying up to one-half (45–50%) of total neck length. Pharyngeal gland nuclei and outlets situated as follows: DN = 52–57, DO = 53–56, S1N1 = 73–75, S1N2 = 77–79, S2N = 82–85. Nerve ring at 163–200 μm or 30–36% of neck length from anterior end. Cardia well developed, tongue-like, 23 μm long, 1.5 times as long as wide, surrounded by intestinal tissue that forms a conical extension measuring 40 μm including the cardia.

Female: Genital system didelphic-amphidelphic, with both genital branches equally and very well developed, the anterior 321–479 µm, the posterior 320–540 µm long. Ovaries large, occasionally surpassing the sphincter level, the anterior 67–336 µm, the posterior 69–295 µm long; oocytes numerous, arranged first in two or more rows and then in one single row. Oviduct 143–279 µm long or 2.1–3.2 times the body diameter, joining subterminally the ovary and consisting of a tubular part and a well developed, elongate pars dilatata often with visible lumen. Sphincter separating oviduct from uterus, but not very marked. Uterus long but often convoluted and difficult to measure with accuracy, 184–279 µm long or 2.5–3.6 times the body diameter; it is tripartite since it bears an intermediate, slightly dilated portion with thicker walls and narrower lumen, while the proximal and distal regions are tubular and with thinner walls and distinct lumen. Vagina 33–41 µm long, extending inwards about one-half (49–54%) of the corresponding body diameter: pars proximalis 15– 23 x 20–26 μm, with slightly sigmoid walls and surrounded by moderately developed musculature; pars refringens with two small drop-shaped, close together, sclerotized pieces measuring 9– 10 x 3–4 μm and with a combined width of 6–9 μm; pars distalis short, 4–7 μm. Vulva a transverse slit, about 12 µm long. Prerectum 1.7–2.8 anal body diameters long. Rectum 41–48 µm long or 1.0–1.2 times the anal body diameter. Tail short and rounded to hemispheroid; three pairs of caudal pores at the posterior half of tail, two subventral and the other lateral.

Male: Prerectum 2.9–4.7 anal body diameters long. Genital system diorchic, with opposite testes. In addition to the adcloacal pair, situated at 8–11 µm from cloacal aperture, there is a series of 14–17, contiguous, ventromedian supplements 6–8 µm apart, the posteriormost of which located at 69–77 μm from the pre-cloacal pair, out the range of spicules. Spicules dorylaimoid, curved ventrad, 5.5–6.5 times as long as wide and 1.6–2.0 times the body diameter at level of cloacal aperture. Lateral guiding pieces 14–18 µm long, 4–6 times as long as wide. Tail short and rounded; caudal pores four pairs.

Diagnosis (emended). This species is characterized by its body 2.00– 2.66 mm long, lip region sucker-like and 23–26 µm wide, odontostyle 29–34 µm long or 1.1–1.3 times the lip region width, neck 521–619 µm long, pharyngeal expansion 246–300 µm long or occupying 45–50% of total neck length, female genital system amphidelphic, uterus long and tripartite, V = 50–56, tail short and rounded (20–30 µm, c = 84–117, c’ = 0.4–0.8), spicules 65–77 µm long and 14–17 contiguous ventromedian supplements.

Relationships. Labronemella labiata is similar to L. cernowitzensis , from which it differs in having wider lip region (vs 20–22 µm) and longer odontostyle (vs 25 µm). It is also morphometrically very close to L. hemicaudata , but it can be easily separated from this by its long, tripartite uterus (vs short and simple).

Locality and habitat. Namak Abroud (approx. 36° 39' N, + 51° 18' E), northern Iran, where it was collected in soil of a natural forest.

Remarks. Above description of Iranian specimens fits very well those of the male and the female studied by Andrássy (1985) and Ciobanu et al. (2010), respectively, although some minor morphometric differences have been also noted: slightly wider lip region (vs 23–25 µm), shorter pharyngeal expansion (vs 300 µm), shorter tail (vs 27–30 µm, c’ = 0.6–0.8), and longer spicules (vs 65 µm). These differences are herein regarded as intraspecific, geographical variations.

Figures

FIGURE 1. Labronemella labiata Andrássy, 1985. A: Anterior region in median view. B: Lip region in lateral view. C: Female, anterior genital branch. D: Female, posterior body region. E: Female, entire. F: Male, entire. G: Pharyngeal expansion and cardia. H: Spicules. I: Male, posterior body region. J: Vagina.

FIGURE 2. Labronemella labiata Andrássy, 1985 (Female, LM). A: Entire. B, C: Anterior body region in median view. D: Posterior genital branch. E: Pharyngeal expansion. F: Pharyngo-intestinal junction. G: Posterior body region. H: Vagina. (Scale bars: A = 500 µm; B, C, F = 20 µm; D, G = 50 µm; E = 100 µm; H = 10 µm).

FIGURE 3. Labronemella labiata Andrássy, 1985 (Male, LM). A: Entire. B: Ventromedian supplements. C: Caudal region. D: Posterior body region. E: Caudal region and spicules. F: Spicules. (Scale bars: A = 500 µm; B, E, F = 20 µm; C = 10 µm; D = 50 µm).

FIGURE 4. Labronemella labiata Andrássy, 1985 (SEM). A: Lip region in ventral, view. B: Same in frontal view. C: Male, posterior body region. D: Lip region in lateral, subfrontal view. E: Female, caudal region in ventral view showing anus. F: Male, cuadal region in ventral view showing cloacal aperture and pre-cloacal pair of genital papillae. G: Vagina in ventral view (Scale bars: A, B, D = 10 µm; C = 40 µm; E-G = 20 µm).

Tables

TABLE 1. Morphometric data of Labronemella labiata Andrássy, 1985. Measurements in μm (except L in mm) and in

Character n	5Ƥ	633
L	2.26 ± 0.19 (2.00–2.46)	2.40 ± 0.21 (2.15–2.66)
a	30.2 ± 1.9 (28–33)	35.2 ± 3.3 (32–41)
b	4.1 ± 0.4 (3.6–4.7)	4.3 ± 0.3 (3.9–4.7)
c	101 ± 11 (92–117)	102 ± 10 (85–116)
c'	0.5 ± 0.1 (0.4–0.6)	0.6 ± 0.0 (0.6)
V	52.6 ± 2.3 (50–56)	-
Lip region diameter	25.2 ± 0.8 (25–26)	25.3 ± 0.6 (25–26)
Odontostyle length	29.8 ± 0.9 (29–31)	31.4 ± 1.6 (29–34)
Odontophore length	53.0 ± 3.0 (49–56)	55.1 ± 5.5 (51–63)
Guiding ring from anterior end	17.1 ± 2.1 (14–19)	18.6 ± 1.0 (17–20)
Neck length	566 ± 34 (521–605)	560 ± 27 (521–592)
Pharyngeal expansion length	264 ± 12 (246–276)	264 ± 14 (244–281)
Body diameter - neck base	70.7 ± 5.3 (65–77)	65.6 ± 4.6 (61–74)
mid-body	75.0 ± 8.7 (67–87)	68.6 ± 6.4 (63–81)
anus/cloacal aperture	41.8 ± 4.6 (35–47)	41.7 ± 3.8 (35–45)
Prerectum length	94.4 ± 19.7 (75–126)	149 ± 21 (119–177)
Tail length	22.4 ± 1.8 (20–25)	23.8 ± 2.5 (20–26)
Spicules length	-	73.8 ± 2.0 (71–77)