Paradorylaimus andinus, Orselli, Lara, Clausi, Mirella & Vinciguerra, Maria Teresa, 2012

Orselli, Lara, Clausi, Mirella & Vinciguerra, Maria Teresa, 2012, The genus Paradorylaimus Andrássy, 1969 (Nematoda: Dorylaimida) with description of three new species from Ecuador, Zootaxa 3302, pp. 25-43 : 26-29

Paradorylaimus andinus sp. n.

( Figs. 1 and 3 A–E ; Table 1 )

Female. Body ventrally curved in fixed specimens. Cuticle 2.5–5.0 µm thick at midbody and 2.0–3.0 µm at level of odontostyle; subcuticle very finely transversely striated. Lateral chords occupying about one third of maximum body diameter. Two ventral and two dorsal body pores clearly visible in all specimens at odontostyle level. Lip region truncate, distinctly set off from adjoining body by a depression, two and half times as wide as high. Lips amalgamated, slightly angular, with 10 inner and 6 outer papillae slightly protruding. Amphidial fovea cup-like, its aperture corresponding to about 50% of corresponding body diameter. Odontostyle dorylaimoid, straight or slightly sinuate, with wide lumen, about eight times as long as wide extending 1.7–2.6 times the lip region diameter; its aperture 24–34 % of its length. Guiding ring clearly double in most specimens, obscure in few of them, located 11– 18 µm from anterior end. Odontophore linear, 2.3–3 lip region diameters long. Pharynx constituted by an anterior slender, though muscular, part gradually expanding into a wider, cylindrical, posterior part which occupies 45–50% of total pharynx length. Nerve ring encircling the slender part of pharynx at 32.5–47.4% of its length. In the pharynx glandularium AS 1 is much smaller than all the other nuclei, often not distinguishable at all, and it is always anterior to AS 2, while PS1 and PS2, always conspicuous, are closer, sometime at the same level. The location of pharyngeal gland nuclei, according to Andrássy’s formula, is as follows: (n=13): DN = 57.2–62.9; AS 1 = 18.6– 26.9; AS 2 = 33.3–47.5; PS1 = 63.9–76.3; PS2 = 67.2–76.7. Cardia composed of a disc-like and a conoid part. Reproductive apparatus didelphic amphidelphic. The reflexed ovaries are generally long, occupying 60–70 % of each genital branch, extending past the oviduct-uterus junction. Oocytes in a single row except that at the ovary tip. Oviduct a simple tube, 2.1–4.3 body diameters long; it ends with a pars dilatata 17–31 µm long followed by a sphincter at the junction oviduct-uterus, marked by a protruding muscular ring at uterus base. Uterus 2–3 body diameters long, bipartite, with narrower lumen in its distal part, characterised by a very thick wall with cells protruding in the lumen, particularly near the junction with each oviduct and better observable when uterus is empty; in most specimens uterus is full of small oval spermatozoa 2–2.5 µm long and often it contains one or two eggs, 53–74 µm long and 28–43 µm wide. The vulva is the opening of a funnel-shaped depression not clearly oriented when observed from a lateral view (apparently elongated longitudinally) but the opening of pars refringens vaginae is a transverse slit between the sclerotized pieces. Vagina extending inward for about half body diameter; pars proximalis vaginae cylindrical, measuring 19–31 Μm; pars refringens vaginae, measuring 4–6 µm, constituted by two strongly sclerotized pieces, appearing pear-like from a lateral view; pars distalis vaginae relatively well developed, 3–8 µm deep. A variable number of advulval papillae is present in 50% of specimens: 1–3 pre-vulval and 1–5 post-vulval. In some specimens these papillae are well developed and provided with innervation crossing all layers of the cuticle; in other cases only superficial, pit-like formations are visible.

Pre-rectum very short, 1.1–2.4 anal body diameters long; rectum in some cases longer than pre-rectum, 1.3– 2.1 anal body diameters long. Tail elongate-filiform, convex conoid in its anterior part, then gradually narrowing till becoming filiform, 6–10 anal body diameters long; the hyaline part representing 16–33 % of tail length. A subventral and a subdorsal pair of caudal pores are present.

Male. Similar to female in general morphology. A series of 13–14 contiguous ventral pre-anal supplements is present in addition to the adcloacal pair. The distance between the latter and the most posterior supplement ranges between 45 and 75 Μm. 6–7 sub-ventral papillae are visible at the sides of supplements series. Spicula dorylaimoid, 1.5–2.2 cloacal body diameters long; lateral guiding pieces 12–17 Μm long. In all specimens a granular glandular structure, not visible in the other species of Paradorylaimus observed by us, surrounds the proximal extremities of spicules. Pre-rectum very short, 1.2–2.3 anal body diameters long, starting at level with the series of supplements. Rectum 1.3–1.8 anal body diameters long. Tail short, dorsally convex and showing ventrally a marked concavity, with blunt terminus. Two subventral and two subdorsal pairs of caudal pores are present.

Differential diagnosis and relationships. The new species is characterized by 1.65–2.26 mm long female body, lip region distinct by a depression, odontostyle 26.5–32. 5 Μm long; pre-rectum very short; 0–3 prevulval and 0–5 postvulval papillae; spicules 60–80 µm long; 13–14 ventral supplements. Female tail elongate-filiform, 6–10 anal body diameters long, the hyaline part representing 16–33 % of tail length; male tail short, 0.7–1 anal body diameters long, dorsally convex and showing ventrally a marked concavity, with blunt terminus.

Absolute measurements in µm, except for L in mm. Values in the form of Mean ± SD (range).

(123.5–181)

continued on next page (60–80)

P. andinus sp. n. for its general size and morphometrics much resembles P. vacillans ( Loof, 1996) Andrássy 2009 and P. esquiveli ( Ahmad & Shaheen, 2004) Andrássy 2009 . It differs from both species by the presence of a variable number of advulval papillae in many females, the shorter male pre-rectum (vs. 3.4–4.5 a.b.w. in P. esquiveli and more than 3 a.b.w. in P. vacillans ), the different male tail shape (absence of ventral concavity in P. e s q u i v e l i and P. vacillans ); moreover it differs from P. v a c i l l a n s by the shorter odontostyle (vs. 31–36 µm) and the relatively longer female tail (vs. c = 11.7–15.9; c’ = 4.1–5.9); from P. esquiveli it can be distinguished also by a less angular lip region and the different arrangement of the first pair of pharyngeal gland nuclei (of similar size and position in P. esquiveli ) and by the nature of vaginal sclerotization. Probably the similarities between the three species, which live in close geographical regions, may be due to the origin by a relatively recent common ancestor. P. andinus sp. n. can also be compared to P. cardiacus ( Banyamuddin & Ahmad, 2006) Andrássy 2009 , P. jankowskyi ( Tsalolikhin 1977) Andrássy, 1988 , P. wilhelmschneideri ( Andrássy, 1959) Andrássy 1969 , to P. parafecundus ( De Coninck, 1935) Andrássy, 1969 and to P. tenuistriatus (Schneider, 1935) Andrássy, 1969 . It can be distinguished from P. cardiacus , besides the different cardia shape, mainly by a definitely shorter odontostyle (vs. 34–34.5 µm), shorter pre-rectum (vs. 2.3–3.2 anal body diameters in female and 5.6 anal body diameters in male) and relatively posterior vulva (vs. V = 46–49); it can be distinguished by P. jankowskyi by having a differently shaped lip region, shorter male pre-rectum (vs. 3.4–4.5 a.b.w.), smaller sperm and fewer supplements (vs. 18); from P. wilhelmschneideri it differs by having smaller body (vs. L = 2.84 mm) and a much shorter female tail (vs. c = 2.3; c’ = 50); it differs from P. parafecundus by its smaller size (vs. L = 2.2–3.0 mm), shorter odontostyle (vs. 41–46 µm), relatively shorter female tail (vs. c = 4.2–5; c’ = 13–14) and from P. tenuistriatus by its smaller size (vs. L=2.5–3.1), posterior vulva (vs. V=41–45) and shorter female tail (vs. c’=17–21).

Type habitat and locality. Moss and litter. Calacal, Geobotanical Reserve of Pululahua, Pichincha, Ecuador.

Type specimens. Holotype female, 15 paratype females, 10 paratype males deposited in the nematode collection of the Department of Biological, Geological and Environmental Sciences, University of Catania ( Italy); 1 paratype female and 1 paratype male deposited in the collection of Prof. I. Andrássy, University of Budapest ( Hungary); 1 paratype female and 1 paratype male deposited at USDA collection, Beltsville, MD, USA.

Etymology. The specific epithet refers to the geographical type locality, which is located in the Andes mountain chain.

Figures

FIGURE 1. Paradorylaimus andinus sp. n. A: Female anterior end; B: Anterior end showing amphid; C: Expanded pharynx; D: Female reproductive apparatus (posterior); E: Detail of vulval region; F: Female posterior region; G: Male posterior region; H – L: Entire body; H: Male, L: Female.

FIGURE 3. A – E Paradorylaimus andinus sp. n. A, B: Female anterior ends; C: Vulval region; D: Uterus with sperm; E: Male posterior end. F – I Paradorylaimus longicaudatus sp. n. F: Male posterior end; G: Female anterior end; H: Vulval region and uterus with sperm; I: Detail of the pars dilatata of oviduct. Scale bar 25 µm.

Tables

TABLE 1. Morphometrics of Paradorylaimus andinus n. sp.

Character	Female holotype	Female paratypes	Male paratypes
n L (mm)	2.12	19 1.96±0.17	12 1.67±0.17
a	34	(1.65–2.26) 28.3±3.6	(1.30–1.88) 25.2±3
b	4.6	(23–33) 4.2±0.3	(21–30) 3.7±0.3
c	7.9	(3.5–4.7) 7.7±0.8	(3–4.2) 50.5±6.6
c’	8.6	(6.7–9.5) 8.1±1.2	(42.2–65.3) 0.8±0.1
V	50.5	(6.1–10.4) 51.5±1.7	(0.7–1)
G1 G2 Amphid aperture	14.3 12.4 8.5	(48.9–55.4) 15.3±2.3 (10.2–18.8) 15.7±1.8 (11.9–17.8) 8.2±0.8	7.8±0.9
Amphids from anterior end	7	(6–9.5) 7.1±0.9	(6.5–9.5) 6.7±1.1
Lip region width	16.5	(6–9.5) 14±0.9	(5–8.5) 13.8±0.6
Lip region height	6	(13–15.5) 5.7±0.5	(13–14.5) 5.7±0.7
Odontostyle length	30	(5–6) 29.9±1.7	(5–7) 29.1±1.3
Odontostyle width	3.5	(26.5–32.5) 3.6±0.5	(27.5–32.5) 3.6±0.4
Odontophore length	38.5	(3–4.5) 36.1±1.7	(3–4) 35.7±3.5
Neck length	462	(33.5–39.5) 469±23.9	(27.5–39.5) 448.4±19.5
Nerve ring from anterior end	167	(397–505) 170.6±19.3	(425–480) 171.6±16
Cardia length	31	(143–226) 32.6±7.2	(158–217) 26.3±4.4
Body diameter at neck base	62	(25–46.5) 63.3±8.9	(21.5–34) 65.5±7.7
Body diameter at midbody	62	(53.5–84) 69.2±8.2	(48–72) 65.5±7.7
Body diameter at anus	31	(60.5–93) 32.1±3.5	(48–80.5) 37.9±3.1
Anterior genital branch	304	(30–43.5) 307.7±50	(33.5–43.5)
Posterior genital branch	264	(217–363) 318.8±51.1
Anterior ovary	155	(202–400) 185.1±65
Posterior ovary	167	(96–279) 205.3±53.6
Anterior oviduct	132.5	(102–285) 144.4±17.9
Posterior oviduct	120	(120–172) 144.9±20.3