Sabatieria parvamphis, Yang & Guo & Chen & Lin, 2019

Yang, Peipei, Guo, Yuqing, Chen, Yuzhen & Lin, Rongcheng, 2019, Four new free-living marine nematode species (Sabatieria) from the Chukchi Sea, Zootaxa 4646 (1), pp. 31-54 : 39-45

Sabatieria parvamphis sp. n.

( Figures 5–7 , Tables 1 , 3 )

Type material. Five males and two females were collected from station CC 1.

Holotype: ♂ 1 on slide number Chukchi20100720 CC14206 . Paratypes: ♂ 2 on slide number Chukchi20100720 CC14206 , ♂ 3 on Chukchi20100720 CC14203 , ♂ 4 on Chukchi20100720 CC14210 , ♂ 5 on Chukchi20100720 CC14211 , ♀ 1 on Chukchi20100720 CC14212 , ♀ 2 on Chukchi20100720 CC12207 .

Type locality and habitat. All specimens were collected from the Chukchi Sea (52 m water depth). Station CC 1: 67.6722°N, 168.9562°W. Median grain diameter: 5.35 Md Φ, Sand: 33.34%, Silt: 58.02%, Clay: 8.63%.

Etymology. The species name is derived from the latin parvus (=small) and amphis (=amphid), and refers to the small amphid in this species relative to other species of the ornata group.

Measurements. Table 1 .

Description. Male. Body cylindrical, 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. Three crowns of anterior sensilla: six inner labial papillae, six short but distinct outer labial setae and four short cephalic setae. Buccal cavity cup-shaped. Amphideal fovea spiral with 3.25 turns, located immediately posterior to cephalic setae. Pharynx gradually swelling towards posterior, not forming true bulb. Nerve ring 143–157 µm from anterior end of body, at 52–57% of the pharyngeal region length. Excretory pore 161–193 µm from anterior end of body, at 59–66% of the pharyngeal region length. Tail 197–209 µm long, conico-cylindrical with four rows of sparse short caudal setae and three short terminal setae. Reproductive system diorchic, with outstretched testes. Anterior testis to the left of intestine, posterior testis to the right of intestine. Spicules paired, equal, arcuate, equal to 1.2–1.4 cloacal body diameters in length. Gubernaculum with 28–32 µm long, with paired, curved apophyses. Thirteen to fifteen prominent tubular pre-cloacal supplements with distance between adjacent supplements increasing towards anterior, followed by one pre-cloacal seta. Three caudal glands situated posterior to spicule. Spinneret present.

Female. Similar to male, except for longer total body length and longer tail length. Reproductive system didelphic, ovaries opposed, outstretched, with anterior branch to the left of intestine and posterior branch to the right of intestine. Mature eggs are oval-shaped. Spermatheca not observed. Vulva located at 46–49% of the body length. Vaginal glands not observed, pars proximalis vaginae surrounded by constrictor muscle. Three caudal glands situated posterior to anus. Spinneret present.

Diagnosis and relationships. Sabatieria parvamphis sp. n. is characterized by short cephalic setae (6–7 µm, equal to 31–38% of head diameter), small amphideal fovea (equal to 55–72% corresponding body diameter), amphideal fovea spiral with 3.25 turns, curved gubernacular apophyses, thirteen to fifteen prominent tubular precloacal supplements with distance between adjacent supplements increasing towards the anterior, tail length equal to 3.5–4.8 cloacal body diameters.

Sabatieria parvamphis sp. n. belongs to the ornata group based on the presence of curved gubernacular apophyses, and pre-cloacal supplements with distance between adjacent supplements increasing towards the anterior. There are five valid species in this group now. S. parvamphis sp. n. can be differentiated from all other species of the group by relatively small amphideal fovea (equal to 55–72% corresponding body diameter) and short cephalic setae (6–7 µm, equal to 31–38% of head diameter). Besides, S. parvamphis sp. n. can be differentiated from S. macramphis and S. longisetosa by the length of cephalic setae (equal to 31–38% vs 140–170%; 100% head diameter, respectively). S. parvamphis sp. n. can be differentiated from S. abyssalis in the number of pre-cloacal supplements (13–15 vs 10). S. parvamphis sp. n. and S. stenocephalus can be distinguished according to body shape – in S. stenocephalus anterior part of the body is very sharp-pointed ( Huang & Zhang, 2006). S. parvamphis sp. n. resembles S. ornata in the number of pre-cloacal supplements and tail shape, but differs from it in longer total body length (2180–2730 vs 1350–2240 µm) and shorter tail (c’=3.5–4.0 vs 3.8–4.6).

Figures

FIGURE 5. Sabatieria parvamphis sp. n. A: lateral view of male anterior part; B: lateral view of male tail and spicule; C: lateral view of female anterior part; D: lateral view of female tail. Scale bar = 20 µm.

FIGURE 6. Sabatieria parvamphis sp. n. A: lateral view of male head; B: lateral view of copulatory apparatus; C: lateral view of female reproductive system. Scale bar: A, B = 20 µm; C = 100 µm.

FIGURE 7. Sabatieria parvamphis sp. n. Male: (A) lateral surface view of head region (amphideal fovea; cephalic setae); (B) lateral surface view of head region (buccal cavity); (C) pre-cloacal supplements; (D, E) copulatory apparatus; (G) lateral differentiation (anterior body); (H) spicule and tail. Female: (F) vulva region; (I) rectal region and tail. Scale bar = 10 µm.

Tables

TABLE 1. Morphometrics (μm) of Sabatieria chukchensis sp. n. and Sabatieria parvamphis sp. n.

Characters		Sabatieria chukchensis sp. n.			Sabatieria parvamphis sp. n.
	Male	Males	Females	Male	Males	Females
	holotype	Paratypes	Paratypes	holotype	Paratypes	Paratypes
n	-	4	2	-	4	2
Total body length	2323	2144±76 (2052–2263)	2228–2326	2473	2293±72 (2180–2378)	2472–2730
a	26	27±2 (25–29)	23–29	26	28±1 (26–29)	31–32
b	10	10±1 (8–10)	9–10	8	9 (8–9)	9–10
c	14	14±1 (13–15)	13	12	11 (11–12)	11–12
Head diameter	17	16 (16–17)	17–18	18	18±1 (17–19)	17
Length of cephalic setae	5	5±1 (4–6)	6–7	6	6 (6–7)	6–7
Amphideal fovea from anterior end	7	7±1 (6–7)	5–6	8	9±1 (8–10)	8–9
Amphideal fovea diameter	11	11±1 (10–12)	10	13	13 ±1 (12–15)	11–12
Amphideal fovea diameter / corresponding body diameter (%)	61	62±4 (56–65)	53–55	69	66±5 (58–72)	55–62
Nerve ring from anterior end	136	113±7 (102–123)	130–138	157	149±5 (143–155)	147–153
Nerve ring / pharyngeal length (%)	59	51±5 (45–56)	55–56	52	56±2 (54–57)	54
Excretory pore from anterior end	142	130±6 (123–136)	141–147	193	168±5 (161–174)	172–177
Pharyngeal length	232	223±19 (205–254)	235–245	300	268±4 (264–273)	273–282
Pharyngeal end corresponding body diameter	62	65±5 (59–72)	59–80	77	69±1 (67–71)	64–65
Maximum body diameter	89	81±6 (73–89)	81–95	96	83±1(82–83)	81–86
Vulva from anterior end	-	-	1113–1178	-	-	1221–1253
V (%)	-	-	50–51	-	-	46–49
Spicule length along arc	73	70±1 (69–73)	-	72	71±3 (67–74)	-
Spicule length along chord	57	55±2 (52–58)	-	62	58±3 (54–62)	-
Gubernacular apophyses length	28	28±2 (25–30)	-	30	30±1 (28–32)	-
Number of pre-cloacal supplements	7	7	-	13	15	-
Anal or cloacal body diameter	55	52±5 (45–59)	47–58	58	54±4 (49–59)	47–50
Tail length	172	153±10 (142–164)	166–178	209	205±5 (197–209)	220–224
c’	3.1	3.0±0.1 (2.8–3.2)	2.8–3.8	3.6	3.8±0.2 (3.5–4.0)	4.4–4.8

TABLE 3. Diagnostic characters for males from Sabatieria ornata group of species (modified from Platt, 1985)

Species	Total body length	a	Amphideal fovea diameter / corresponding body diameter (%)	Cephalic setae length / head diameter (%)	Spicule arc length / cloacal body diameter	Number of pre-cloacal supplements	c’
S. parvamphis sp. n.	2180–2473	26–29	58–72	31–38	1.2–1.4	13–15	3.5–4.0
S. abyssalis	1650–1850	25–33	80	50–65	1.1–1.3	10	4.5
S. longisetosa	1310–1585	40	90	100	1.2–1.3	13–14	3.7–4.5
S. macramphis	1700–2120	52–61	84–93	140–170	1.0	18–21	4.5
S. ornata	1350–2080	35–47	78–98	40–57	1.0–1.3	10–18	4.6–5.9
S. stenocephalus	2162–2250	31–33	79–81	69–75	1.3–1.4	15	3.8–4.6