Pseudodesmodora lacrima, Leduc & Wharton, 2010

Leduc, D. & Wharton, D. A., 2010, New free-living marine nematode species (Nematoda: Desmodoridae) from the coast of New Zealand, Zootaxa 2611 (1), pp. 45-57 : 52-56

Pseudodesmodora lacrima n. sp.

( Fig. 5–7 , Table 1)

Material examined. Holotype Adult male, collected in December 2003 from the Firth of Thames, northern New Zealand 37º 3’S, 175º24’E. Muddy sediment (75% mud) at 5 m water depth ( NNCNZ 266 ).

Allotype Adult female, same data as holotype ( NNCNZ 2582 ).

Paratypes Two males, two females, same data as holotype ( NNCNZ 2580-1 , 2583-4 ); two males, two females, same data as holotype ( NIWA 48775 ) .

Description. Males Body stout (a = 17–19), orange-brown, cylindrical, tapering towards both extremities. Cuticle thick with coarse annuli, no lateral differentiation. Eight longitudinal rows of short, sparse somatic setae. The anterior and/or posterior body regions of several specimens constricted by thin rings ( Fig. 7 C and 7 E ).

Cephalic capsule rounded, smooth, with lip region separated from main region by conspicuous groove (sutura) in the cuticle. Lip region collapsed in some specimens ( Fig. 7 A ). Six setiform internal labial papillae and six setiform external labial papillae; four cephalic setae at level of sutura. Internal labial papillae inconspicuous when lip region is collapsed. Spiral fovea amphidialis, 1.25 turns, with central spot; large unispiral apertura amphidialis located on main head region, in centre of amphidial plate. Amphidial plate small, only slightly larger than amphid, consists of thickened cuticle giving distinct three-dimensional aspect to amphid ( Figure 5 B and 7 B ).

Buccal cavity strongly cuticularised with one large dorsal tooth and two small ventrosublateral teeth. Vestibulum with 12 cheilorhabdia ( Fig. 7 B ). Ducts extending from head sensillae towards nerve ring clearly visible, dark orange in colour. Pharynx cylindrical with elongated tripartite bulb. Nerve ring inconspicuous, excretory pore not observed. Cardia short.

Reproductive system monorchic with one anterior outstretched testis located on the right of intestine. Mature sperm globular, 12–18 µm in diameter. Ejaculatory duct 276–316 µm long, situated ventrally to intestine. Spicules arcuate with small capitulum, Small gubernaculum which proximally surrounds the tip of the spicules. Pre-cloacal ventral ala ( Fig. 6D ); one pre-cloacal seta. Tail conical with clear spinneret; caudal glands not observed.

Females: Similar to males, but slightly wider body and smaller amphids. Reproductive system with two opposed and reflexed genital branches located either both on the right or both on the left of intestine. Vulva located slightly post median. Cuticular vagina vera and vagina uterina surrounded by constrictor muscle. Tail with few, short somatic setae.

Diagnosis and relationships. Pseudodesmodora lacrima n. sp. is characterised by a stout body, cephalic capsule with conspicuous sutura between lip region and main region, large unispiral apertura amphidialis on amphidial plate, and presence of conspicuous ducts in the head region.

Description of the only other species of the genus, P. amphidiscata Boucher 1975 , only included female specimens. Female specimens of P. lacrima n. sp. ressembles P. ampidiscata in body length and amphid structure, but can be distinguished from the latter species by the presence of conspicuous ducts in the head region, lower a value (16 vs 33), greater maximum body width (66 vs 33 µm), shorter external labial sensillae (1–2 vs 5 µm), shorter cephalic setae (4 vs 8 µm), and longer tail (4 vs 3 cbd).

Etymology. The species name refers to the conspicuous ducts in the head region which resemble streaming tears.

Figures

FIGURE 5. Pseudodesmodora lacrima n. sp. Male. A. Entire male. B. Lateral surface view of head. C. Lateral view of head showing internal structures. D. Posterior body region showing copulatory apparatus. Scale bar: A = 80 µm; B, C, D = 20 µm.

FIGURE 6. Pseudodesmodora lacrima n. sp. Female. A. Entire female. B. Lateral surface view of head. C. Posterior body region showing details of cuticle in surface view. Scale bar: A = 110 µm; B, C = 30 µm.

FIGURE 7. Pseudodesmodora lacrima n. sp. SEM. A. Lateral view of male anterior region. B. Face view of female head. C. Female anterior body region showing head in face view and position of constricting ring. D. Ventral view of male posterior body region with ventral ala. E. Female posterior body region showing position of constricting ring. Scale bars: A, B, C, D = 15 µm; E = 30 µm.