Vasostoma aurata, D, Leduc, K, Probert P. & D, Nodder S., 2012

D, Leduc, K, Probert P. & D, Nodder S., 2012, Two new free-living nematode species (Comesomatidae) from the continental slope of New Zealand, with keys and notes on distribution, Zootaxa 3348, pp. 40-55 : 43-48

Vasostoma aurata n. sp. ( Fig. 2–4 , Table 1 )

Material examined. Holotype Male, collected 6 April 2007, Chatham Rise (1240 m water depth), 44º29.1ʹS, 177º8.6ʹE. Characteristics of surface sediment layer (0–5 mm): mostly silt/clay (82.9%), with very fine sand (10.2%), and fine sand (8.4%); calcium carbonate content: 38.4%; total organic matter content: 1.91%; chloroplastic pigment concentration: 3501 ng /gDWsediment ( NNCNZ 272).

Paratypes Two males, three females, one J 4 juvenile, same data as holotype ( NNCNZ 2653-8); three males, three females, same data as holotype ( NIWA 71586-7).

Description. Males Body cylindrical, medium-sized, tapering towards both extremities. Cuticle with transverse rows of dots, no lateral differentiation. No somatic setae except on tail. Lateral, dorsal, and ventral chords conspicuous in most specimens, consisting of two bands of irregular cell bodies, <1−4 Μm in size, with outline often golden-coloured, fusing into single band near anterior and posterior ends of body ( Figure 4 ). Head distinctly set-off by constriction immediately posterior to cephalic setae. Six inner labial papillae, six outer setiform outer labial papillae, and four cephalic setae, the latter two very close to each other. Anteror portion of buccal cavity cupshaped. Posterior portion of buccal cavity cylindrical to conical, cuticularised, 13 Μm deep, with three cuticularised projections (teeth) at border with anterior portion. Amphid spiral, 4.5 turns. Pharynx gradually swelling, not forming true bulb. Cardia short. Nerve ring near one third of pharynx length from anterior. Cellular body of ventral gland at level of cardia, excretory pore near middle of pharynx.

Reproductive system diorchic, opposed, outstretched. Anterior testis to left of intestine, posterior testis to right of intestine. Spicules paired, equal, curved, 1.4–1.5 abd long, proximal end slightly enlarged, central lamella well developed. Gubernaculum with pair of straight caudal apophyses. Cloacal gland cells surround posterior portion of spicules and gubernaculum. Up to seven tubular pre-cloacal supplements, often difficult to distinguish, one pre-cloacal seta. Tail conico-cylindrical, with several short caudal setae and three short terminal setae. Three large caudal glands.

Females Similar to males, but with slightly larger maximum body diameter, amphid smaller, 3.5 turns. Reproductive system didelphic, opposed, outstretched. Anterior ovary to left of intestine, posterior ovary either to right or left of intestine. Vulva slightly post median. Granular vaginal glands present, vagina uterina surrounded by constrictor muscle.

Fourth stage juveniles Similar to adults but smaller body size, smaller amphid with 4.25 turns. Lateral chords conspicuous.

Diagnosis and relationships. V. a u r a t a n. sp. is characterised by a distinctly set-off head, amphid with 4.5 turns, conspicuous chords consisting of two bands of irregular, often golden-coloured cell bodies, short spicules, and faint tubular supplements.

V. aurata n. sp. is similar to the type species V. spiratum Wieser 1954 , but can be distinguished from the latter by its greater body length (2017–2432 vs 1370–1850 Μm), higher a values (41–47 vs 26–36), higher c values (14–19 vs 9–13), shorter tail (2.3–3.5 vs 4 abd), presence of conspicuous chords, and the presence of faint tubular supplements (as opposed to 11 well-developed supplements in V. s p ir a t um).

Etymology. The specific name (“gilded with gold”) refers to the intricate golden patterns of the chords.

Discussion. V. a ur a ta n. sp. specimens from the type locality were found exclusively in subsurface (1–5 cm) sediments. A study of the nematode community at the type locality found that V. aurata n. sp. (referred to as Vasostoma sp. A therein) was the fourth most common species at that site, and accounted for 3.6% of total nematode abundance ( Leduc et al. 2010a).

Figures

FIGURE 2. V. a u r a t a n. sp. Male. A. Lateral view of neck region. B. Lateral surface view of head. C. Ventral view of head showing buccal cavity and teeth. D. Entire body. Scale bar: A = 40 Μm; B, C = 25 Μm; D = 290 Μm.

FIGURE 3 V. a ur a t a n. sp. A. Male posterior body region showing copulatory apparatus B. Female posterior body region showing chords. C. Mid-region of female body showing vulva and genital branches. Scale bar: A, B = 50 Μm; C = 145 Μm.

FIGURE 4. V. a u r a t a n. sp. A. Lateral view of juvenile anterior body region. B. Lateral view of juvenile posterior body region showing chords. C. Lateral view of female anterior body region showing amphid and chords. D. Female mid-body region showing chords. Scale bars: A, B, C, D = 25 Μm.

Tables

TABLE 1. Morphometrics (Μm) of V. a ur at a n. sp. and S. conicauda n. sp. including mean values (range). (a, body length / maximum body diameter; abd, anal body diameter; b, body length / oesophagus length; c, body length / tail length; cbd, corresponding body diameter; % V, vulva distance from anterior end of body × 100 / total body length.)

Species	Vasostoma aurata n. sp. Males Females Holotype Paratypes Paratypes	J4 Paratype	Setosabatieria conicauda n. sp. Males Females Holotype Paratypes Paratypes
n L a	- 5 6 2057 2134 2292 (2017–2252) (2052–2432) 41 45 (42–48) 41 (39–45)	1 1040 35	- 4 5 1094 1257 1555 (1148–164) (1360–1807) 27 28 (25–30) 26 (23–28)
b c %V Head diam.	7 7 7 (7–8) 14 16 (15–16) 16 (15–19) - - 51 (48–54) 16 16 (15–16) 17 (15–18)	5 12 - 12	6 7 (6–8) 8 (7–10) 18 16 (15–18) 19 (16–21) - - 48 (44–50) 16 17 (16–17) 18 (17–19)
Mouth diam. Length of sub-cephalic setae Length of cephalic setae	5 4 (4–5) 5 (4–5) - - - 4 4 (3–4) 4 (3–4)	4 - 3	3 4 (3–4) 4 6 6 (5–7) 6 (6–7) 7 7 (6–8) 7 (6–8)
Amphid height Amphid width Amphid width/cbd (%) Amphid from anterior end Nerve ring from anterior end	10 11 (10–12) 9 (8–9) 10 10 (9–11) 9 (8–10) 63 65 (56–73) 53 (50–55) 6 7 (6–8) 7 (6–7) 115 122 (115–130) 105 (92–113)	7 7 58 7 89	13 13 (12–13) 11 (10–11) 12 12 (11–12) 11 75 68 (65–75) 57 (55–58) 8 7 (6–8) 8 (8–9) 114 104 (96–108) 114 (110–116)
Nerve ring cbd Excretory pore from anterior end	38 38 (37–39) 40 (38–41) 158 156 (156–157) 157	26 115	34 36 (34–38) 38 (35–39) 126 130 (126–133) 132 (130–134)
Pharynx length Pharynx cbd Pharyngeal bulb diam. Max. body diam. Spicule length	285 307 (300–314) 305 (274–342) 48 46 (45–47) 51 (48–54) 31 30 (29–31) 35 (32–36) 50 48 (47–50) 54 (51–56) 73 67 (64–69) -	199 31 21 30 -	174 178 (166–190) 196 (183–219) 38 40 (36–43) 46 (43–52) 24 26 (25–26) 31 (27–35) 40 46 (40–52) 61 (54–78) 59 55 (51–58) -
Gubernacular apophyses length Anal body diam. Tail length Tail length/abd	23 23 (21–24) - 44 43 (42–44) 45 (42–47) 148 137 (135–143) 145 (109–163) 3.4 3.2 (3.1–3.4) 3.2 (2.3–3.5)	- 25 84 3.4	11 12 (11–13) - 33 36 (33–39) 40 (35–48) 61 79 (71–93) 81 (69–90) 1.8 2.1 (1.9–2.4) 2.0 (1.8–2.4)
Vulva from anterior end Vulval body diam.	- - 1130 (1039–1225) - - 54 (51–56)	- -	- - 734 (675–830) - - 61 (54–77)