Sabatieria parapraedatrix, 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 : 11-18

Sabatieria parapraedatrix sp. n.

( Figs 6–7 , Table 2)

Material examined. Holotype male (NIWA 865989), collected 6 April 2007, southern flank of 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. Two male and two female paratypes (NIWA 865990), same data as holotype.

Etymology. The species name refers to the species S. praedatrix , which is similar to the new species.

Description. Male Body cylindrical, slender, tapering slightly towards anterior extremity. Cuticle with transverse rows of dots, lateral differentiation consisting of rows of larger dots. Faint striations also present throughout body, situated 1.5 µm apart, most visible near head region. Striations appear restricted to epicuticle, are mostly visible in dorsal and ventral regions, and result from fusion of every second lateral row of dots. Two dorso- and two ventro-lateral rows of short, sparse somatic setae, some associated with inconspicuous, elongated hypodermal glands ( Fig. 7 A). Head slightly set-off by depression at level of cephalic setae. Six inner labial papillae, six outer labial papillae, and four short cephalic setae. Anterior portion of buccal cavity cup-shaped, posterior portion narrow. Fovea amphidialis spiral, 2.0–2.5 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 short, 5–8 µm long. Nerve ring near middle of pharynx. Secretory-excretory system present, cellular body of ventral gland at level of intestine, 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, nucleated, 4–6 µm diameter, 7–16 µm long. Spicules paired, equal, arcuate, 1.4–1.6 abd long, with distal hook and weak capitulum, and with central cuticularised projection (lamella) extending from proximal end over one third of spicule length. Velum present. Gubernaculum with pair of straight caudal apophyses. Rectal gland surrounds gubernacular apophyses and distal portion of spicules. Four to five pairs of large ejaculatory glands present anterior to spicules. Seven to twelve small tubular pre-cloacal supplements, one pre-cloacal seta. Tail short, conico-cylindrical with short cylindrical distal portion portion and slightly clavate tip in some specimens. Several short caudal setae and three short terminal setae. Three caudal glands and spinneret present.

Female Similar to male. Reproductive system didelphic, opposed, outstretched, with anterior branch to the left of intestine and posterior branch to the right of intestine. Oval-shaped spermatheca present. Vulva situated midbody. Granular vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.

Diagnosis and relationships. Sabatieria parapraedatrix sp. n. is characterised by a combination of having a slender body (a = 40–48), cuticle with lateral differentiation consisting of rows of larger dots and with striations resulting from fusion of every second lateral row of dots, fovea amphidialis with 2.0–2.5 turns, presence of hypodermal glands, spicules with distal hook, and short conico-cylindrical tail (3.0–3.6 abd).

Sabatieria parapraedatrix sp. n. belongs to the praedatrix group. It is similar to S. praedatrix , in having cuticle with transverse rows of dots and striations, fovea amphidialis with <2.5 turns, and spicules with distal projections (hooks). Sabatieria parapraedatrix sp. n. can be differentiated from the latter by its relatively short body (1562–1770 vs 1760–2900 µm), shorter cephalic setae (<20% cbd vs 40%), fewer pre-cloacal supplements (7–12 vs 13–17), and shorter tail (3.0–3.6 vs 4.0–4.5 abd). The two species also differ in the structure of the copulatory apparatus: the distal projections on the spicules of S. praedatrix have swollen and rounded distal ends, whereas the projections in S. parapraedatrix sp. n. do not have swollen distal ends (see Fig. 7 B). The gubernacular apophyses in S. praedatrix are triangular in shape and taper distally, whereas the gubernacular apophyses in S. parapraedatrix sp. n. are relatively thin and do not taper distally.

Within the praedatrix group, S. parapraedatrix sp. n. resembles S. granifer , S. paradoxa , S. paracupida , S. lyonessa , S. dodecaspapillata , and S. parabyssalis in the low number of amphid turns (<2.5 turns), but can be differentiated from all of these species by the presence of distal hooks on the spicules. Several other species of the genus possess spicules with distal hooks, viz., S. heipi , S. flecha , and S. bitumen . Sabatieria parapraedatrix sp. n. can be differentiated from S. heipi in the number of amphid turns (2.0–2.5 vs 4.0) and values of a (40–48 vs 29–34), from S. flecha by the position of the distal hook on the spicules (pointing anteriorly vs posteriorly in S. flecha ), and from S. bitumen by the shape of the tail (conico-cylindrical vs conical in S. bitumen ).

Sabatieria bubulba sp. n. ( Figs 8–10 , Table 2)

Material examined. Holotype male (NIWA 865991), collected 5 June 2007, western Challenger Plateau (532 m water depth), 40.8814°S, 170.8603°E. Characteristics of surface sediment layer (0–5 mm): mostly silt/clay (67.6%), with fine sand (15.1%), and very fine sand (11.4%); calcium carbonate content: 56.0%; total organic matter content: 2.1 %; chloroplastic pigment concentration: 1344 ng /gDW sediment. One male and one female paratype (NIWA 865992), same data as holotype. One male and one female paratype (NIWA 865993), collected 5 October 2001, Chatham Rise crest (350 m water depth), 43.4333°S, 178.5000°E. Characteristics of surface sediment layer (0–5 mm): mostly fine sand (35.7%), silt/clay (33.0%), and very fine sand (23.5%); calcium carbonate content: 40.5%; total organic matter content: 4.5%; chloroplastic pigment concentration: 3359 ng / gDW sediment. Two male paratypes (NIWA 865994), 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.

Etymology. The species name is derived from the latin prefix bu - (= large) and bulbus (= swelling), and refers to the large size of the pharyngeal bulb in this species relative to other species of the genus.

Description. Male Body cylindrical, slender, tapering slightly towards anterior extremity. Cuticle with transverse rows of dots, lateral differentiation consisting of rows of conspicuously larger dots ( Fig. 10 B). Two dorso- and two ventro-lateral rows of short, sparse somatic setae. Head slightly set-off by depression at level of, 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, cup-shaped, posterior portion narrow. Fovea amphidialis large, spiral, 3.0–3.5 turns, located immediately posterior to cephalic setae. Marginal tubes arising from base of buccal cavity and extending to posterior end of pharynx. Pharynx gradually widening from middle of region of pharynx towards posterior, forming an elongated, muscular basal bulb, 54–74 µm in length. Nerve ring at about one third of pharynx length from anterior. Secretory-excretory system present, cellular body of ventral gland large, up to 44 µm long and 20 µm diameter, at level of intestine, pore situated 0.5–1.0 cbd posterior to nerve ring, with lightly cuticularised opening ( Fig. 10 A). 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. One paratype specimen with opposite arrangement. Mature sperm cells globular to elongated, nucleated, 10–13 µm diameter, 14–18 µm long. Spicules paired, equal, arcuate, 1.4–1.7 abd long, pointed distally, without capitulum, and with central cuticularised projection (lamella) extending from proximal end over one half of spicule length. Velum absent. Gubernaculum with pair of straight dorso-caudal apophyses. Rectal gland surrounds gubernacular apophyses and distal portion of spicules. Three pairs of ejaculatory glands present anterior to spicules. Eight to eleven small tubular pre-cloacal supplements, one pre-cloacal seta. Tail conico-cylindrical with slightly clavate tip. Several short caudal setae and three short terminal setae. Three caudal glands and spinneret present.

Female Similar to male. Reproductive system didelphic, opposed, outstretched, with anterior branch to the left of intestine and posterior branch to the right of intestine. Elongated spermatheca present. Vulva situated mid-body. Granular vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.

Diagnosis and relationships. Sabatieria bubulba sp. n. is characterised by a combination of having cuticle with lateral differentiation of coarse dots, fovea amphidialis with 3.0–3.5 turns, presence of large muscular pharyngeal bulb, secretory-excretory system with large ventral gland at level of intestine and cuticularised pore opening, large nucleated sperm cells, and 8–11 small tubular pre-cloacal supplements. Sabatieria bubulba sp. n. belongs to the praedatrix group, and can easily be distinguished from all other species of the genus (except S. foetida ) by having a conspicuous pharyngeal bulb. Sabatieria bubulba sp. n. can be differentiated from S. foetida by the larger amphids (females: 70–75 vs 46–50% cbd; males: 62–73 vs 55–65% cbd), lower b ratio (7–8 vs 9–12), vulva located at 50% of body length (vulva at 43–47% of body length from anterior in S. foetida ), and lightly cuticularised opening of secretory-excretory pore (not cuticularised in S. foetida ). The two species also differ in the size and structure of the male copulatory apparatus. Spicules of S. foetida are longer than in S. bubulba sp. n. (50– 55 vs 41–44 µm), and are characterised by conspicuously thinner distal halves (vs uniform thickness along most of spicule length in S. bubulba sp. n.). In addition, S. foetida possess lateral guiding pieces near the distal end of spicules, but they are absent in S. bubulba sp. n.

Species Sabatieria parapraedatrix sp. n. Sabatieria bubulba sp. n.

Males Females Males Females

Holotype Paratypes Paratypes Holotype Paratypes Paratypes

n 2 2 4 2

L 1570 1562–1706 1730–1770 1608 1520–1750 1529–1540 a 46 40–46 47–48 47 48–59 38–46 b 8 7–9 8–9 8 7–8 7

c 16 17 18–19 16 14–16 13

Head diam.* 14 13 12 –14 11 9–10 10–11 Mouth diam. 3 3–4 3 2 2 2

Length of cephalic setae 2 2 2 3 3–4 3–4

Amphid height 7 7–8 6–7 8 7–8 8

Amphid width 8 8–9 8 9 8 8–9

Amphid width/cbd (%) 53 62–64 57–62 62 67–73 70–75 Amphid from anterior end 7 5–6 7 4 4–6 4

Nerve ring from anterior end 112 105 109–141 85 84–93 80–92 Nerve ring cbd 30 31 29–30 26 21–26 26–27 Excretory pore from anterior end 134 116–137 124–144 102 100–115 101–114 Pharynx length 201 190–211 194–227 206 194–228 219 Pharynx cbd 33 34 35 32 25–36 33–41 Pharyngeal bulb diam. 21 22 25–26 21 16–27 26–31 Max. body diam. 34 37–39 37 34 26–36 33–41 Spicule length 42 45–48 - 43 41–44 -

Gubernacular apophyses length 16 17 - 16 15–21 -

Anal body diam. 31 29–31 29–32 29 24–32 24–28 Tail length 100 94–103 89–100 102 105–111 114–117 Tail length/abd 3.2 3.0–3.6 3.1 3.5 3.4–4.4 4.2–4.8 V - - 826–905 - - 767–773 %V - - 48–51 - - 50

Vulval body diam. - - 35–36 - - 30–41

*at level of cephalic setae.

Figures

FIGURE 6. Sabatieria parapraedatrix sp. n. A: Male anterior region; B: lateral surface view of male head; C: lateral view of female head; D: male posterior body region showing reproductive system; E: female reproductive system; F: female tail; G: male posterior body region. Scale bar: A, B = 60 µm; C = 30 µm; D = 145 µm; E = 110 µm; F = 50 µm; G = 65 µm.

FIGURE 7. Sabatieria parapraedatrix sp. n. Light micrographs. A: Male mid-body region showing two hypodermal glands and associated somatic setae; B: copulatory apparatus. Scale bar: A = 14 µm; B = 10 µm.

FIGURE 8. Sabatieria bubulba sp. n. A: Female anterior region; B: male anterior region; C: lateral surface view of male head; D: female reproductive system. Scale bar: A, B = 30 µm; C = 14 µm; D = 75 µm.

FIGURE 9. Sabatieria bubulba sp. n. A: Male posterior body region showing reproductive system; B: mature sperm cells; C: female tail; D: male copulatory apparatus. Scale bar: A = 100 µm; B, C, and D = 35 µm.

FIGURE 10. Sabatieria bubulba sp. n. Light micrographs. Male anterior body region, showing pharyngeal bulb, ventral gland, and opening of secretory-excretory pore; B: male anterior body region showing cuticle ornamentation; C: male copulatory apparatus. Arrow points to opening of secretory-excretory pore. Scale bar: A = 20 µm; B = 12 µm; C = 10 µm.