Sabatieria bathycopia, Leduc, Daniel, 2013

Leduc, Daniel, 2013, Seven new species and one new species record of Sabatieria (Nematoda: Comesomatidae) from the continental slope of New Zealand, Zootaxa 3693 (1), pp. 1-35 : 29-30

Sabatieria bathycopia sp. n.

( Fig. 19–21 , Table 4)

Material examined. Holotype male (NIWA 866001), collected 6 April 2007, southwest Chatham Rise (1240 m water depth), 44.4864°S, 177.1407°E. Characteristics of surface sediment layer (0–5 mm): mostly silt/clay (82.9%), with very fine sand (9.4%), and fine sand (7.7%); calcium carbonate content: 38.4%; total organic matter content: 1.9%; chloroplastic pigment concentration: 3501 ng /gDW sediment. Three male and five female paratypes (NIWA 866002), same data as holotype.

Etymology. The species name is derived from the latin bathys (= deep) and copia (= abundance, plenty), and refers to the common occurrence of this species at sites characterised by high food availability on the continental slope of New Zealand (D. Leduc, unpublished data).

Description. Male Body relatively stout, cylindrical, tapering slightly towards both extremities. Cuticle with transverse rows of dots, lateral differentiation consisting of rows of slightly larger dots. Two dorso- and two ventrolateral rows of short, sparse somatic setae, some associated with rounded hypodermal glands ( Fig. 21 C). Head slightly set-off by depression at level of cephalic setae or slightly posterior to cephalic setae. Inner labial papillae indistinct, six outer labial papillae and four short cephalic setae. Anterior portion of buccal cavity small, cupshaped, lightly cuticularised and with minute teeth-like projection at base, posterior portion narrow. Fovea amphidialis spiral, 2.75–3.0 turns, located immediately posterior to cephalic setae. Marginal tubes arising from base of buccal cavity and extending to posterior end of pharynx. Pharynx gradually swelling towards posterior, not forming true bulb, cardia 15 µm long. Nerve ring at about middle of pharynx length. Secretory-excretory system present, with three glands situated just posterior to pharynx, one situated ventrally and two laterally, each with separate duct and opening through common pore situated 0.5–1.0 cbd posterior to nerve ring. Intestine wall with numerous small, colourless granules, with differentiation of rounded cells containing more densely packed granules in anterior portion.

Reproductive system diorchic with outstretched testes. Anterior testis on left of intestine, posterior testis on right of intestine. Mature sperm cells globular, 7–12 µm diameter by 15–20 µm long. Spicules paired, equal, arcuate, 1.0–1.4 abd long, without capitulum, and with central cuticularised projection (lamella) extending from proximal end over one half of spicule length. Distal tip of spicules swollen and more lightly cuticularised than distal portion ( Fig. 21 D). Velum present. Curved gubernaculum with pair of narrow, straight dorso-caudal apophyses. Rectal gland surrounds gubernaculum and spicules. Three pairs of ejaculatory glands situated anteriorly to spicules. Fourteen to eighteen tubular pre-cloacal supplements, one pre-cloacal seta. Pre-cloacal supplements are regularly spaced at 9–14 µm intervals, except for first two posterior supplements which are 7 µm apart. Tail conicocylindrical with several short caudal setae and three short terminal setae. Three small caudal glands and spinneret present.

Female Similar to male, but with slightly smaller fovea amphidialis, 2.5–2.75 turns. Reproductive system didelphic, opposed, outstretched, with anterior branch to the left of intestine and posterior branch to the right of intestine. Spermatheca present, oval-shaped or tapering distally. Vulva situated mid-body. Granular vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.

Diagnosis and relationships. Sabatieria bathycopia sp. n. is characterised by a combination of having a relatively stout body (a = 23–36), cuticle with lateral differentiation consisting of rows of larger dots, short cephalic setae (5–6 µm, 0.26–0.33 cbd), fovea amphidialis with 2.75–3.0 turns, curved gubernaculum, male secretoryexcretory system with three glands, spicules with swollen, lightly cuticularised distal tip, 14–18 pre-cloacal supplements, and tail length 2.6–3.0 abd.

Sabatieria bathycopia sp. n. belongs to the celtica group based on the presence of curved gubernaculum, and can be differentiated from most other species of the genus based on the structure of the spicules with a swollen, lightly cuticularised distal tip. The only other Sabatieria species with similar spicules is S. celtica . Sabatieria bathycopia sp. n. differs from the latter in body length (2028–2371 vs 2800–3120 µm), values of a (23–36 vs 52– 61), length of cephalic setae (0.26–0.33 vs ~1.0 cbd), number of fovea amphidialis turns (2.75–3.0 vs 2.0), and tail length (2.6–3.0 vs 3.5–4.0). Redescriptions of S. celtica by Lorenzen (1971), Boucher (1976), Platt (1984), Vincx (1986) and Chen and Vincx (1999) show spicules without the distinctive swollen distal tips; noting this discrepancy, Platt (1984, p.356–357) concluded that “Southern’s specimen was anomalous in this respect”. Whether the specimen described by Southern (1914) was indeed an anomaly or a different species to that described by other authors remains unclear, but the Chatham Rise specimens differ substantially from both the original description (as described above) and subsequent redescriptions (most notably in spicule shape and length of cephalic setae, 0.26–0.33 vs 0.45–1.2 cbd) and is therefore considered a distinct species.

Species Sabatieria pumila sp. n. Sabatieria bathycopia sp. n.

Males Females Males Females

Holotype Paratypes Paratypes Holotype Paratypes Paratypes

n 3 3 3 5 *at level of cephalic setae.

Figures

FIGURE 19. Sabatieria bathycopia sp. n. A: Male anterior region, showing position of one of the lateral S-E glands (dotted line); B: lateral view of male head; C: lateral view of female head; D: male posterior region; E: female tail. Scale bar: A = 70 µm; B and C = 30 µm; D = 60 µm; E = 70 µm.

FIGURE 20. Sabatieria bathycopia sp. n. A: entire male; B: male copulatory apparatus. Scale bar A = 160 µm; B = 50 µm.

FIGURE 21. Sabatieria bathycopia sp. n. Light micrographs. A: Lateral view of female mouth cavity; B: lateral view of female cuticle, mid-body region; C: lateral view of hypodermal glands, mid-body region; D: male intestine, anterior region; E: male copulatory apparatus; F: vagina. Scale bar: A = 10 µm; B = 16 µm; C and F = 32 µm; D = 45 µm; E = 24 µm.