Sabatieria balbutiens, 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 : 21-25

Sabatieria balbutiens sp. n.

( Figs 13–15 , Table 3)

Material examined. Holotype male (NIWA 865997), collected 5 April 2007, western Chatham Rise crest (478 m water depth), 43.8266°S, 176.7043°E. Characteristics of surface sediment layer (0–5 mm): medium sand (45.4%), with fine sand (43.9%), and silt/clay (6.6%); calcium carbonate content: 76.7%; total organic matter content: 1.0%; chloroplastic pigment concentration: 6233 ng /gDW sediment. Two male and one female paratypes (NIWA 865998), same data as holotype.

Etymology. The species name is the present participle of the latin verb balbutio (= stammer, stutter) and refers to the unusual position of the mouth opening in this species.

Description. Male Body cylindrical, slender, tapering slightly towards both extremities. Cuticle with transverse rows of dots, lateral differentiation consisting of larger, irregularly-spaced dots. Two dorso- and two ventro-lateral rows of short, sparse somatic setae. Head slightly set-off by depression at level of cephalic setae. Six minute inner labial papillae, six outer labial papillae, and four short cephalic setae. Ventral lip region extends further anteriorly than dorsal lip region, leading to asymmetry in position of head sensillae and mouth opening directed dorsally ( Figs 13 B, 15A). Buccal cavity small, cup-shaped, assymetrical, lightly cuticularised and with three minute tooth-like projections at base ( Fig. 15 A). Fovea amphidialis spiral, 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, 10 µm long. Nerve ring near middle of pharynx. Secretory-excretory system present, with three ventral glands situated close to each other at level of intestine, cardia, and basal portion of pharynx, each with separate duct and opening through common pore situated 0.5 cbd posterior to nerve ring. Intestine wall with numerous small, colourless granules.

Reproductive system diorchic with outstretched testes. Anterior testis to the left of intestine, posterior testis to the right of intestine. Mature sperm cells globular to elongated, nucleated, 8–11 µm diameter, 15–26 µm long. Spicules paired, equal, arcuate, 1.3–1.5 abd long, with thin distal hook (often difficult to observe) and weak capitulum, and with central cuticularised projection (lamella) extending from proximal end over one quarter of spicule length. Velum present. Gubernaculum with pair of caudal apophyses. Rectal gland surrounds gubernacular apophyses and distal portion of spicules. Four pairs of large ejaculatory glands present anterior to spicules. Fourteen or fifteen 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, but longer and wider body, and slightly smaller fovea amphidialis. Secretoryexcretory system with only one ventral gland at level of intestine. Reproductive system didelphic, opposed, outstretched, with anterior branch to the left of intestine and posterior branch to the right of intestine. Spermathecae present, irregular to tapering in shape. Vulva situated mid-body. Vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.

Diagnosis and relationships. Sabatieria balbutiens sp. n. is characterised by a combination of having cuticle with lateral differentiation consisting of larger, irregularly-spaced dots, dorsally-directed mouth opening and assymetrical mouth cavity, fovea amphidialis with 2.5 turns, males with secretory-excretory system with three glands opening through common pore, spicules with small distal hook, and 14–15 pre-cloacal supplements. Sabatieria balbutiens sp. n. belongs to the praedatrix group and can be differentiated from all other species of the genus by the dorsally-directed mouth opening and assymetrical mouth cavity.

A secretory excretory system with three cells (glands) was described in Sabatieria pulchra by Jensen (1979b) and S. celtica by Riemann (1977). Two of the glands are positioned further posteriorly (approx. two pharynx lengths from anterior) in the latter two species, whereas all three glands are situated close to each other near the level of the cardia in S. balbutiens sp. n. So far, the presence of additional cells in Sabatieria spp. has only been observed in males.

Species Sabatieria exculta sp. n. Sabatieria balbutiens sp. n.

Males Females Males Females

Holotype Paratypes Paratypes Holotype Paratypes Paratype

n 2 2 2 1

L 1696 1579–1619 1680–1848 1725 1601–1678 2030 a 58 54–56 58–60 24 24–25 20 b 9 8–9 9 8 7–8 8

c 20 18 16–17 12 11–15 14 Head diam.* 12 12–13 13 16 15–16 18 Mouth diam. 3 2–3 3 5 3–5 5

Length of cephalic setae 3 3 3 5 4–5 4

Amphid height 9 9–10 6 11 10–11 10 Amphid width 9 9–10 7 12 11–12 11 Amphid width/cbd (%) 75 75 54 67 61–65 58 Amphid from anterior end 6 6–7 6 8 8–9 8

Nerve ring from anterior end 101 102–103 100–103 129 116–122 134 Nerve ring cbd 25 25 25 52 46–48 62 Excretory pore from anterior end 119 124 120–131 145 137–140 158 Pharynx length 179 189 187–201 230 218–231 260 Pharynx cbd 28 28 28 66 60–62 75 Pharyngeal bulb diam. 18 17–19 18–21 37 33–36 51 Max. body diam. 29 28–30 29–31 72 67–68 103 Spicule length 37 38–39 - 74 68 -

Gubernacular apophyses length 18 18–21 - 24 22–26 -

Anal body diam. 27 27–29 22–25 49 46–52 65 Tail length 84 86 101–113 149 108–148 149 Tail length/abd 3.1 3.0–3.2 4.5–4.6 3.0 2.3–2.8 2.3 V - - 865–962 - - 1009 %V - - 51–52 - - 50 Vulval body diam. - - 28 - - 95

*at level of cephalic setae.

Figures

FIGURE 13. Sabatieria balbutiens sp. n. A: Male anterior region; B: lateral view of female head; C: lateral surface view of male head; D: female tail; E: male posterior region. Scale bar: A, B, and C = 30 µm; D and E = 50 µm.

FIGURE 14. Sabatieria balbutiens sp. n. A: Entire male; B: male copulatory apparatus and pre-cloacal supplements; C: female reproductive system. Scale bar: A = 100 µm; B = 45 µm; C = 130 µm.

FIGURE 15. Sabatieria balbutiens sp. n. Light micrographs. A: male head; B: distal end of spicules, showing hook. Scale bar = 10 µm.