Paradorylaimus longicaudatus, 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 : 29-33

Paradorylaimus longicaudatus n.sp.

(Figs. 2 and 3 F–I; Table 2)

Female. Body ventrally curved in fixed specimens. Cuticle 2.5–3.5 µm thick at midbody and 2.0–2.5 µm at level of odontostyle. Lateral chords occupying about one third of maximum body diameter. Two ventral and two dorsal body pores, very close to each other, clearly visible in all specimens at odontostyle level. Lip region truncate, narrower than adjoining body, set off from it by a depression, about two times as wide as high. Lips amalgamated, rounded, with inner and outer papillae slightly protruding, papillae arrangement obscure. Amphidial fovea cuplike; its aperture about 50% of corresponding body diameter. Odontostyle dorylaimoid, straight, appearing protruded in all specimens, with relatively narrow lumen, nine–ten times as long as wide, extending 2.2–2.4 times the lip region diameter; its aperture 26–32 % of its length. Guiding ring appearing double, fixed ring located 18–19 µm from anterior end. Odontophore linear, 2.7–3.2 lip region diameters long. Expanded part of pharynx 45–50% of its total length. Nerve ring encircling the slender part of pharynx at 35–42 % of its length. In the pharynx glandularium all subventral nuclei are small and hardly visible excepting AS 2 which is about as large as DN. The location of pharyngeal gland nuclei, according to Andrássy’s formula, in the single specimen where all the nuclei were observed, is as follows: (n=1): DN = 57.9; AS 1 = 35.9; AS 2 = 47.4; PS1 = 74.4; PS2 = 77.8. Cardia composed of a disc-like and a conoid part. Reproductive apparatus didelphic, amphidelphic. The reflexed ovaries are generally long, occupying 50–70 % of each genital branch, extending to the oviduct-uterus junction or beyond it. Oocytes in a single row except at the ovary tip. Oviduct a simple tube, 1.7–2.9 body diameters long; it ends with a pars dilatata 18–20 µm long followed by a sphincter at the oviduct-uterus junction, marked by a protruding muscular ring at uterus base. Uterus 2.9–3.3 body diameters long, in two parts: the distal part, 43–47 µm long, has a thick wall with narrow lumen; the proximal portion, 96–100 µm long, has a thinner wall and wider lumen; in most specimens it contains numerous small oval spermatozoa 1–2.5 µm long and in a female two eggs, 59–65 µm long and 25 µm wide. Vulva longitudinal. Vagina extending inward for about 40% of body diameter; pars proximalis vaginae cylindrical measuring 15.5–23 Μm; pars refringens vaginae, measuring 5–6 µm, consisting of three strongly sclerotized pieces, appearing triangular from a lateral view; pars distalis vaginae 2.5–3.5 µm deep. No paravulval papillae observed. Pre-rectum very short, 1.3–2.3 anal body diameters long; rectum only slightly shorter than pre-rectum, 1.1–2 anal body diameters long. Tail elongate-filiform, gradually narrowing to its pointed tip, 11–16 anal body diameters long; the hyaline part representing 22–35 % of tail length. Two subventral and a subdorsal pair of caudal pores are present.

Male. Similar to female in general morphology. A series of 11–13 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 48 and 69.5 Μm. Six to seven pairs of sub-ventral papillae are visible at the sides of supplements series. Spicules dorylaimoid, 1.5–1.8 anal body diameters long; lateral guiding pieces 11–15.5 Μm long. Pre-rectum not as short as in female, 2–3.5 anal body diameters long, starting at level with the series of supplements. Rectum 1.3–1.6 anal body diameters long. Tail short, convex-conoid, with blunt terminus. A subventral and two subdorsal pairs of caudal pores are present.

Differential diagnosis. The new species is characterized by 1.78–2.14 mm long female body, lip region slightly set off from adjoining body, odontostyle 30–32. 5 Μm long; pre-rectum very short; vulva longitudinal as well as the slit between the sclerotized pieces; spicules 44.5–62.5 µm long; 11–13 ventral supplements. Female tail elongate-filiform, 11–16 anal body diameters long, the hyaline part representing 22–35 % of tail length; male tail short, 0.8–0.9 cloacal body diameters long, convex-conoid, with blunt terminus.

P. longicaudatus sp. n. differs from P. andinus sp. n. mainly in the narrower odontostyle (vs. 3–4.5 µm), longer female tail (vs. c’ 6.1–10.4), longer male pre-rectum (vs. 1.2–2.3), absence of paravulval papillae; it differs from P. vacillans by the relatively longer female tail (vs. c = 11.7–15.9; c’ = 4–5.9); from P. esquiveli it can be distinguished by the shorter male pre-rectum (vs. 3.4–4.5 anal body diameters in P. esquiveli ), by the different arrangement of the first pair of pharyngeal gland nuclei (of similar size and position in P. esquiveli ). It can be distinguished from P. cardiacus , in addition to the different cardia shape, mainly by the rather shorter odontostyle (vs. 34–34.5 µm), and the shorter pre-rectum (vs. 2.3–3.2 anal body diameters in female and 5.6 cloacal body diameters in male); it can be distinguished from P. jankowskyi by having a differently shaped lip region, shorter male pre-rectum (vs. 3.4–4.5 cloacal body diameters), 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); from P. parafecundus it differs by its smaller size (vs. L = 2.2–3.0 mm) and shorter odontostyle (vs. 41–46 µm); from P. tenuistriatus it differs by its smaller size (vs. L=2.5–3.1) and shorter female tail (vs. c’=17–21).

Type habitat and locality. Moss and litter. Rio Verde, Lita (Imbabura), Ecuador.

Type specimens. Holotype female, 1 paratype female, 5 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 species name refers to the relatively long female tail.

FIGURE. 2. Paradorylaimus longicaudatus sp. n. A: Female anterior end; B: Anterior end showing amphid; C: Expanded pharynx; D: Male posterior end; E Female posterior end; F: Female reproductive apparatus (posterior); G–H: Entire body; G: Female, H: Male.

Table 2. Morphometrics of Paradorylaimus longicaudatus n. sp.

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

(149–214)

continued on next page