Paravulvus moroccanus, Gilarte, Patricia, Carreira, José Antonio & Peña-Santiago, Reyes, 2013

Gilarte, Patricia, Carreira, José Antonio & Peña-Santiago, Reyes, 2013, Description of Paravulvus moroccanus sp. n. (Nematoda, Dorylaimida, Nygolaimidae) from the High Atlas Mountains, Morocco, with notes on the taxonomy of the genus, Zootaxa 3734 (5), pp. 545-558 : 546-550

Paravulvus moroccanus sp. n.

( Figs 1–3 )

Material examined. Ten females from two locations, in variable, but in general acceptable, state of preservation.

Morphometrics. See Table 1 .

Description

Female: Slender nematodes of medium size, 1.06–1.36 mm long. Body cylindrical, tapering towards both ends. Habitus regularly curved ventrad after fixation, discernibly more so in posterior body region, to G-shaped. Cuticle two-layered, bearing very fine transverse striation hardly perceptible under LM, but very distinct under SEM; thickness 1.0 Μm at postlabial region, 1.0–1.5 Μm in mid-body and 3.0–4.5 Μm on tail tip. Lateral chord 10– 15 Μm wide at mid-body, occupying one-fourth to one-third (23–32%) of mid-body diameter, with granular texture but lacking any special differentiation. Body pores, if present, obscure. Lip region slightly truncate, offset by deep depression, with smooth or slightly angular contour, 2.0–2.5 times as wide as high and ca. two-fifths (37–43%) of body diameter at neck base. SEM observations: lips amalgamated; labial and cephalic papillae prominent, buttonlike, with perceptible opening and surrounded by a ring-like, concentric elevation of the surface of lips; perioral area delimited by a circular incisure. Amphid fovea cup-shaped, its aperture 5.5–6.0 Μm or up to one-half (46– 50%) of lip region diameter; fusus located at about 2.5 times the lip region width from the anterior end. Cheilostom nearly cylindrical. Mural tooth solididentoid, its anterior one-half to two-thirds apparently solid or needle-like, whereas the posterior part shows a narrow but distinguishable lumen; its length ca. one-half (45–57%) of lip region diameter. Guiding ring simple. Anterior region of pharynx enlarging very gradually, the three best specimens examined bearing a mucro 2.5, 3.0, 6.0 µm long at dorsal side with its base located at 25, 34, 29 µm from anterior end (see also remarks); basal expansion 5.9–8.3 times as long as wide, 3.4–4.0 times as long as body diameter, and occupying less than one-half (42–48%) of total neck length. Pharyngeal gland nuclei following the typical (although unusual) pattern for the genus: DO = 65–67, DN = 73–75; S1N = 81–86; S2N = 87–89. Nerve ring located at 90–106 Μm from anterior end or 36–39% of total neck length. Cardia rounded-conoid, 8 Μm long x 7 Μm wide; cardiac glands longitudinal (longer than wide), 6.5–9.5 x 3.0–5.5 µm. Only one dorsal cell mass, 63–90 µm long, is present at level of pharyngo-intestinal junction and/or anterior end of intestine. Genital system didelphicamphidelphic, with both branches equally and moderately developed, the anterior 105–125 Μm long or 8–12% of body length and the posterior 104–128 Μm long or 8–11% of body length: ovaries short, usually not surpassing the sphincter level, the anterior 37–89 Μm, the posterior 34–79 Μm long; oocytes arranged first in two or more rows, then in a single row; oviduct 49–81 Μm long or 1.1–2.4 times the corresponding body diameter, and consisting of a slender part made of prismatic cells and a developed pars dilatata longer than wide and without perceptible lumen; oviduct-uterus junction barely marked; uterus a short, simple, tube-like structure 27–47 Μm long or 0.7–1.1 times the corresponding body diameter; vagina extending inwards 14–17 Μm or less than one-half of body diameter, with pars proximalis 9–12 x 10 –12 Μm and having somewhat sigmoid walls surrounded by weak musculature, pars refringens with (in lateral view) two slender pieces measuring 2.5–4.0 x 1.0–1.5 Μm and separated by an intermediate hyaline area resulting in a combined width of 8.5–10.5 µm, and pars distalis 1.5–2.5 Μm long; vulva (under SEM) a short (ca. 2 µm long) longitudinal slit surrounded by a circular area with radial incisures. Prerectum 1.1–1.9, rectum 0.8–1.1 anal body widths long. Tail conoid with broadly rounded terminus, ventrally straight or weakly curved ventrad, dorsally convex. Caudal pores two pairs at the middle of tail, one dorsal, another lateral.

Male: Unknown.

Diagnosis. The new species is characterized by its 1.06–1.36 mm long body, lip region offset by marked depression and 11–13 µm broad, mural tooth solididentoid and 5.5–6.5 µm long, neck 229–270 µm long, pharyngeal expansion 108–126 µm long or occupying less than one-half (42–48%) of total neck length, uterus 27– 47 Μm long or 0.7–1.1 times the corresponding body diameter, V = 46–56, paravulvae absent, female tail rounded conoid (21–27 µm, c = 42–64, c’ = 1.1–1.5), and male unknown.

Relationships. The most characteristic feature of Paravulvus moroccanus sp. n. is the morphology (solididentoid) of the mural tooth. Only one out of the 16 currently valid species of the genus, namely P. acuticaudatus (Thorne, 1930) Heyns, 1968 , bears this kind of protruding structure. Nevertheless, the latter species is conical-tailed and thus easily distinguishable from the new species herein described.

In having short (up to 7 µm) mural tooth, lacking paravulvae and its conoid tail with broadly rounded terminus, P. moroccanus sp. n. resembles P. japonicus Ahmad, Araki & Kaneda, 2003 and P. kyeryongensis Choi & Jairajpuri, 1998 . It differs from P. japonicus by its larger general size (vs L = 0.84–1.05 mm, n = 21), cheilostom without any peculiar feature (vs basket-like), shorter uterus (vs 53–72 µm or 1.0–2.0 times the corresponding body diameter, and longer female tail (vs 14–17 µm, c’ = 0.8–0.9). And from P. kyerongyensis by its smaller general size (vs L = 1.31–1.49, neck 299–324 µm long; n = 4), less slender body (a = 24–41 vs a = 41–46) and shorter uterus (vs 76–92 µm long or 2–3 times the corresponding body diameter). The new species is also morphometrically similar to P. papillatus Ahmad & Jairajpuri, 1982 , P. rhodopensis Lazarova, Peneva & Loof, 2002 and P. teres (Thorne, 1930) Heyns, 1968 . It can be separated from P. papillatus in its shorter mural tooth (vs 8–9 µm), shorter pharyngeal expansion (vs 55–60% of total neck length), and male unknown (vs known). From P. rhodopensis in its shorter neck (vs 310–384 µm in females), absence (vs presence) of paravulvae and absence of males (vs as frequent as females). And from P. teres in its nearly smooth outer cuticle layer (vs bearing distinct transverse striation throughout the body) and shorter mural tooth (vs 7–10 µm) and neck (vs 310–405 µm).

Type locality and habitat. Halfway from Tounfite to Sidi Yahia Ou Youssef, in the eastern High Atlas, Morocco (coordinates N 32 26 43.2, W 5 21 38.4; elevation 1980 m); in soil of Cedrus atlantica forests on marly limestones. Physico-chemical properties of the soil habitat: pH, 8.3±0.2; calcium carbonate, 27.3±1.3 %; organic matter by loss on ignition, 9.5±3.8 %; total carbon, 6.1±1.1 %,; total nitrogen, 0.17±0.08 %; cation exchange capacity, 24.6±1.5 meq/ 100g; base saturation, 100 %; KCl-extractable ammonium, 3.5±0.9 µg N/g, and nitrate, 4.6±2.3 µg N/g; Olsen phosphate, 10.1±4.5 µg P/g.

Other locality and habitat. Near Tamaloute, in the eastern High Atlas, Morocco (coordinates N 32 17 14.9, W 5 17 48.4; elevation 2340 m); in soil of Cedrus atlantica forests on marls. Physico-chemical properties of the soil habitat: pH, 7.3±0.3; calcium carbonate, 1.9.3±0.2 %; organic matter by loss on ignition, 5.8±1.2 %; total carbon, 1.1±0.6 %; total nitrogen, 0.10±0.03 %; cation exchange capacity, 26.1±0.3 meq/ 100g; base saturation, 86.4±4.4 %; KCl-extractable ammonium, 2.8±0.5 µg N/g, and nitrate, 6.4±2.3 µg N/g; Olsen phosphate, 6.8±2.0 µg P/g.

Type material. Female hototype and three female paratypes deposited with nematode collection of the Departamento de Biología Animal, Biología Vegetal y Ecología, University of Jaén, Spain.

Etymology. The specific epithet refers to the geographical origin of the new taxon.

Remarks: As mentioned above, the three best specimens examined bear a mucro at the anterior region of pharynx. Coomans (1964 & 1966) reported a nearly identical structure in members of the genus Discolaimus , and referred to it as “vestigial spear tip (mucro)” (1966: p. 293). In two of the three females the mucro is a short, conical, tooth-like element, comparatively robust and with visible lumen ( Fig. 2 E, arrow head) whereas the third female has a larger and more slender tooth, more similar to the functional solididentoid tooth ( Fig. 1 B). The three specimens in question are not young females as their genital branches appear totally developed. Taking into consideration their morphology (conical with perceptible lumen) and size (two of them distinctly much shorter than the functional tooth), the mucros should not be interpreted as replacement teeth, but maybe better as remains of the tooth formation process.

Figures

FIGURE 1. Paravulvus moroccanus sp. n. (female). A: Neck region. B: Anterior region in median, lateral view. C: Lip region in lateral, surface view. D: Posterior genital branch. E: Posterior body region. F: Entire.

FIGURE 2. Paravulvus moroccanus sp. n. (female, LM). A: Entire. B, C: Anterior region in median lateral view. D: Pharyngo-intestinal junction. E: Anterior region in median lateral view showing the mucro (arrow head) located at dorsal side of pharynx. F: Anterior body region in submedian lateral view. G, H: Vagina. I, J: Posterior body region. K: Posterior genital branch. L: Coelomocyte in dorsal position at level of oviduct-uterus junction. (Scale bars: A = 200 µm; B, C, F – H = 5 µm; D, I – L = 20 µm; E = 10 µm.)

FIGURE 3. Paravulvus moroccanus sp. n. (female, SEM). A: Anterior region in subventral view. B: Lip region in frontal view. C: Caudal region. D: Vulva area. (Scale bars: A, B = 3 µm; C = 5 µm; D = 1 µm.)

Tables

TABLE 1. Morphometrics of Paravulvus moroccanus sp. n., in the form: average ± standard deviation (range). Measurements in µm except L in mm.

Population	Sidi Yahia (type)	Tamaloute
	Holotype Paratypes
Character n	♀ 3 ♀♀	6 ♀♀
L	1.09 (1.17–1.30)	1.25 ± 0.11 (1.10–1.36)
a	30 (28–41)	34.3 ± 6.0 (25–41)
b	4.4 (4.8–6.5)	5.0 ± 0.3 (4.7–5.4)
c	49 (53–55)	51.6 ± 6.8 (43–64)
c'	1.1 (1.2–1.3)	1.4 ± 0.1 (1.2–1.5)
V	52 (46–53)	53 ± 3 (49–56)
Lip region diam.	11 (11–12)	11.7 ± 0.5 (11–12)
Odontostyle length	6.0 (5.5–6.5)	6.1 ± 0.2 (6.0–6.5)
Neck length	242 (180–261)	248 ± 14 (229–268)
Phar. expansion length	115 (92–122)	113 ± 8 (108–125)
Body diam. at neck base	31 (29–32)	29.5 ± 1.6 (28–32)
mid-body	35 (32–45)	37.2 ± 6.7 (30–46)
anus	20 (18–19)	17.7 ± 0.5 (17–18)
Prerectum length	21 (30)	29.0 ± 3.5 (25–33)
Rectum length	18 (15–19)	16.8 ± 0.8 (16–18)
Tail length	22 (22–24)	24.3 ± 2.4 (21–27)