Sabatieria exculta, 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 : 19

Sabatieria exculta sp. n.

( Figs 11–12 , Table 3)

Material examined. Holotype male (NIWA 865995), 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. Two male and two female paratypes (NIWA 865996), same data as holotype.

Etymology. The species name is derived from the latin excultus (= adorned, refined) and refers to the unusual ornamentation of the cuticle consisting of both punctations and annulations.

Description. Male Body slender, cylindrical, tapering slightly towards anterior extremity. Cuticle with transverse rows of dots, without lateral differentiation. Faint annulations (i.e., discontinuity running down entire thickness of cuticle) also present throughout body. Annulations result from fusion of every second or third transverse row of dots. Two dorso- and two ventro-lateral rows of short, sparse somatic setae, some associated with rounded hypodermal glands ( Fig. 12 A). Head slightly set-off by depression at level of fovea amphidialis. Six minute inner and outer labial papillae and four short cephalic setae. Anterior portion of buccal cavity small, cupshaped, posterior portion narrow. Fovea amphidialis spiral, 2.5 turns, located immediately posterior to cephalic setae. Marginal tubes not observed. Pharynx gradually widening towards posterior, not forming a true bulb. Nerve ring at about middle of pharynx length. Secretory-excretory system present, cellular body of ventral gland large, 19–20 µm by 25–28 µm, at level of intestine, pore situated 1.0 cbd posteriorly 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, 3 µm diameter by 4 µm long. Spicules paired, equal, arcuate, 1.3– 1.4 abd long, without capitulum, and with central cuticularised projection (lamella) extending from proximal end over one fifth of spicule length. Velum absent. Gubernaculum with pair of long, narrow, straight dorso-caudal apophyses, narrowest at base. Rectal gland surrounds gubernacular apophyses and distal portion of spicules. Ejaculatory glands not observed. Ten small tubular pre-cloacal supplements, one pre-cloacal seta. 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 and smaller ventral gland, 12–13 µm by 23–24 µm. Reproductive system didelphic, opposed, outstretched, with anterior branch to the left of intestine and posterior branch to the right of intestine. Spermatheca not observed. Vulva situated mid-body. Granular vaginal glands present, pars proximalis vaginae surrounded by constrictor muscle.

Diagnosis and relationships. Sabatieria exculta sp. n. is characterised by a combination of having a slender body (a = 54–60), cuticle with lateral rows of punctations without lateral differentiation, and faint annulations resulting from fusion of every second or third lateral row of dots, short cephalic setae (3 µm), fovea amphidialis with 2.5 turns, large ventral gland, and long, narrow gubernacular apophyses.

Sabatieria exculta sp. n. belongs to the praedatrix group and can be differentiated from most other species of the genus based on the combination of slender body shape, short cephalic setae, and annulated cuticle without lateral differentiation of larger dots. Sabatieria exculta sp. n. resembles S. ancudiana in body size and shape, cuticle without lateral differentiation, structure of fovea amphidialis, and size of gubernacular apophyses, but can be differentiated from the latter based on length of cephalic setae (3 µm in S. exculta sp. n. vs 9 µm in S. ancudiana ), number of pre-cloacal supplements (10 vs 16), and cuticle annulations (present vs absent in S. ancudiana ). S. exculta sp. n. also resembles S. intermissa and S. triplex in general body shape and structure of male copulatory apparatus, but differs in the length of cephalic setae (3 vs>6 µm in S. intermissa and S. triplex ), absence of lateral differentiation of the cuticle (vs present in S. intermissa and S. triplex ), and number of pre-cloacal supplements (10 vs>15). Sabatieria exculta sp. n. also resembles S. granifer , S. lawsi , and S. vasicola in having short cephalic setae, but can be differentiated from the latter in the more slender body shape (a = 54–60 vs 26–40), absence of lateral differentiation of the cuticle (vs present in the other three species), and ratio of head diameter to posterior pharynx body diameter (0.43–0.46 vs 0.26–0.33).

Figures

FIGURE 11. Sabatieria exculta sp. n. A: Entire male; B: male anterior region; C: lateral view of female head; D: ventral view of male head; E: female tail; F: male posterior body region. Scale bar: A = 135 µm; B = 50 µm; C and D = 20 µm; E = 40 µm; F = 35 µm.

FIGURE 12. Sabatieria exculta sp. n. Light micrographs. A: Lateral view of male cuticle, pharyngeal region; B: male copulatory apparatus; C: male intestine, mid-body region; D: hypodermal glands. Scale bar: A = 25 µm; B = 20 µm; C and D = 14 µm.