Paramphimonhystrella echinocauda, Leduc, Daniel, 2014

Leduc, Daniel, 2014, Four new Paramphimonhystrella species (Nematoda: Xyalidae) from the continental slope of New Zealand, Zootaxa 3814 (4), pp. 478-494 : 492

Paramphimonhystrella echinocauda n. sp.

( Fig 10 , Table 2 )

Type specimen. Holotype male ( NIWA 89979), collected on 15 April 2010 ( NIWA cruise TAN1004, station 4), open slope habitat on southern Hikurangi Margin (175.6642ºE, 41.6837ºS); water depth: 1046 m.

Etymology. The species name is derived from the the greek word echinos (= spiky) and the latin word cauda (= tail), and refers to the presence of several long setae on the tail of this species.

Description. Male. Body cylindrical, tapering slightly towards both extremities. Cuticle ~0.8 µm thick, with fine striations ~1.2 µm apart beginning halfway between cephalic setae and anterior edge of amphids. Somatic setae ~4 µm long, sparse, irregularly arranged. Head tapering anteriorly. Inner labial sensillae not observed; six outer labial setae, ~1.5 µm long, situated immediately anterior to four cephalic setae, 2 µm long. Two rings of subcephalic setae; anterior ring consists of eight setae at level of amphids, 2 µm long; second ring consists of ten setae 3–7 µm long, situated ~0.5 cbd posterior to first ring of sub-cephalic setae ( Figure 10 A, B). Amphids with round or slightly oval outline, lightly cuticularised. Buccal cavity 7 µm deep, 4 µm wide, with cylindrical anterior portion and funnel-shaped posterior portion, completely surrounded by pharyngeal tissue. Pharynx muscular, widening slightly posteriorly but not forming true bulb. Cardia elongated, ~9 µm long, surrounded by intestine tissue. Nerve situated at 44% of pharynx length from anterior. Secretory-excretory system not observed.

Male reproductive system diorchic with outstretched testes; both testes situated to the left of intestine. Sperm cells large, globular in shape, ~7–9 × 5–7 µm. Spicules slightly curved, 1.8 abd long, lightly cuticularised, with slender proximal portion and widening distally, distal tip with three pointed projections ( Figure 7 D); gubernaculum present, thin, parallel to spicules; pre-cloacal supplements absent. Tail conico-cylindrical, with several setae in middle portion, 6–13 µm long. Two lateral setae near tail tip, 6–7 µm long, and one terminal seta, 7 µm long. Three caudal gland; anterior-most gland conspicuously larger than other two ( Figure 10 E).

Diagnosis. P. echinocauda n. sp. is characterised by buccal cavity with cylindrical anterior portion and funnelshaped posterior portion, round amphids, two rings of 8–10 sub-cephalic setae, distal tip of slender spicules with three pointed projections, thin gubernaculum, and tail with several long setae in middle portion, two lateral setae near tail tip and one terminal seta.

Differential diagnosis. P. echinocauda n. sp. can be differentiated from all other species of the genus by the spicules with slender proximal portion and distal tip with three pointed projections, and by the tail with several long setae in middle portion, two lateral setae near tail tip, and one terminal seta.

Figures

FIGURE 7. Paramphimonhystrella scutula A: Lateral view of male head; B: lateral view of female head; C: female anterior body region; D: left-hand side view of vulva and hammer-shaped cuticularised piece; E: male posterior body region; F: sperm; G: female posterior body region; H: male posterior body region. Scale bar = 20 µm.

FIGURE 10. Paramphimonhystrella echinocauda Holotype. A: Lateral view of head; anterior body region; C: entire specimen; D: spicule and gubernaculum; E: posterior body region. Scale bar: A and D = 10 µm; B and E = 18 µm; C = 65 µm.