Parodontophora irregularis, Li, Yongxiang & Guo, Yuqing, 2016

Li, Yongxiang & Guo, Yuqing, 2016, Free living marine nematodes of the genus Parodontophora (Axonolaimidae) from the East China Sea, with descriptions of five new species and a pictorial key, Zootaxa 4109 (4), pp. 401-427 : 407-411

Parodontophora irregularis sp. nov.

( Figure 4 , Figure 5 , Table 3 , Table 4 )

Type material. Five males and two females were collected from Station ZZHS in September 2012.

Holotype: ♂1 on slide number ZZHS 201209 L3105. Paratypes: ♂2 on slide number ZZHS 201209 L3102, ♂3 and ♂4 on slide number ZZHS 201209 L3107, ♂5 on slide number ZZHS 201209 L3116, ♀1 on slide number ZZHS 201209 L3112, ♀2 on slide number ZZHS 201209 L3112. The holotype and paratypes are deposited in the Third Institute of Oceanography, State Oceanic Administration, Xiamen.

Type locality and habitat. All specimens were collected from intertidal sandy sediment at Huoshan Island, Zhangzhou City, East China Sea. Station ZZHS: 118.025°E, 24.213°N.

Etymology. This species is named irregularis (latin: irregularis , irregular) for its irregular opisthocephalic setae arranged.

Measurements. Table 3 .

Description. Body narrows gradually in the anterior region. Cuticle with faint outer striation discernible in the lateral field. Lip region more or less rounded, with six outer labial papillae. Four cephalic setae 4–5 µm, 31–42% of head diameter, 3–4 µm from the anterior end. Opisthocephalic setae 2–3 µm, arranged irregular. Among specimens collected, each specimens expresses different opisthocephalic setae arrangement, and both sides of buccal cavity inconsistent. Somatic setae scattered, length 2–3 µm. Buccal cavity 27–30 µm long and 4–6 µm wide, cylindrical with conspicuous sclerotized parallel walls and conoid posterior parts. Six bifurcate teeth at the tip of the buccal cavity with the anterior tip narrower than the posterior one. Armilliths absent. Amphid 2–3 µm from the anterior end, crook-shaped with the shorter dorsal branch and parallel much longer ventral branch reaching the base of buccal cavity. Length of the dorsal branch equals 0.33–0.41 of ventral branch length and the amphid length is 0.93–1.07 times the buccal cavity length. Pharynx starts at the base of buccal cavity, muscular, and gradually broadens to the base and forms a bulb. Cardia small, rounded-conoid, surrounded with intestinal tissue. Renette cell behind the base of pharynx, elongated oval, 46–63 µm, 32–42% of the pharynx length. Nerve ring at 64–67% of pharynx length. Excretory pore indistinct near cephalic setae at the anterior part of buccal cavity. Tail length 130–146 µm, conical anteriorly and cylindrical posteriorly without terminal setae. Three caudal glands open to the tail terminal.

Male: Several indistinct setae on the conical portion of the tail, length 4 µm. Due to the posterior part of body spiraling in all measured specimens, it is difficult to detect whether there are regular subventral setae. Reproductive system diorchic. Testes paired, opposed and outstretched. Anterior testis to the left and posterior testis to the right of the intestine. Vas deferens well developed. Spicules length 33–36 µm, paired, equal and arcuate, several slight thickened septa closes to dorsal sides, circle aperture in distal end and enlarged thickened proximal end with a front and dorsal constriction. Gubernaculum with dorsal-caudally directed apophysis 12–14 µm long, thickened rib-like ventral edge extended into two small points. About 9 fibriform precloacal supplements present, they extend 246–249 µm from cloaca to the anterior end, 19–23% of body length.

Female: Morphologically similar to the male. Unpaired setae on tail. Reproductive system ampdidelphic, ovaries outstretched. Anterior gonad to the right and posterior gonad to the left of the intestine. Vulva is at 49–51% of the total body length. Short vagina with thick walls is perpendicular to the longitudinal body axis. Vulval glands are present anterior and posterior to the vagina. No spermathecae and spermatozoa are found in uteris.

Diagnosis and relationships. Parodontophora irregularis sp. nov. is characterized by relatively short cephalic setae (0.31–0.42 h. d.); the positon of the posterior end of the amphid extending slightly beyond the base of the buccal cavity (0.93–1.07 times the length of the buccal cavity); opisthocephalic setae arranged irregular; excretory pore near cephalic setae at the anterior part of buccal cavity; armilliths absent; renette cell occupying 32–42% of the pharynx length; about 9 fibriform precloacal supplements present and extend 246–249 µm anteriad.

P. irregularis sp. nov. comes close to P. paragranulifera Timm, 1952 , P. deltensis Zhang, 2005 and P. chiliensis Murphy, 1966 in the ratio of dorsal branch length of the amphid to the ventral branch length, the ratio of ventral branch length of the amphid to buccal cavity length. The new species differs from P. paragranulifera and P. deltensis in having a more anterior position of the excretory pore (near cephalic setae at the anterior part of buccal cavity) and opisthocephalic setae arrangement ( Table 4 ). Although the opisthocephalic setae of P.chiliensis are simple in original description, we still can found opisthocephalic setae are present in the published pictures no matter whether irregular arranged, and we also know that about 15 precloacal supplements are present and extend about 300 µm anteriad. P. irregularis sp. nov. is also similar to P. chiliensis in relatively short cephalic setae (0.34 h. d. vs. 0.31–0.42 h. d.). However, it can be separated from P. chiliensis in shorter spicule length as arc (33–36 µm vs. 80 µm), the number of supplements (about 9 ind vs. about 15 ind) and the length of supplements field (246–249 µm vs. about 300 µm).

Notes: Base, at the base of buccal cavity; Middle, at the middle of buccal cavity; 1, excretory pore about at the level of cephalic setae; *, the data were calculated from original data or published pictures; -, no data; Y, present; N, absent.

Figures

FIGURE 4. Parodontophora irregularis sp. nov. A: lateral view of male anterior part; B: lateral view of female head; C: lateral view of copulatory apparatus; D: lateral view of male tail and spicule; E: lateral view of female tail; F: lateral view of female reproductive system. Scale bar: A, B, C, D, E = 20 Μm; F = 40 Μm.

FIGURE 5. Light micrographs of Parodontophora irregularis sp. nov. A: anterior body end of male, showing amphid, cephalic setae and opisthocephalic setae; B: anterior body end of female, showing buccal cavity; C: lateral view of male body part, showing copulatory apparatus; D: supplements in male; E: vulva region; F: posterior body end of female; G: ovary region; H: full view of male body. Scale bars: A, B, C, D = 10 Μm; E = 25 Μm; F, G = 50 Μm; H = 200 Μm.

Tables

TABLE 3. Individual measurement of Parodontophora irregularis sp. nov. (in µm).

Characteristics	Holotype	Paratypes
	♂1	♂2 ♂3	♂4	♂5	♀1	♀2
Total body length	1266	1334 1355	1281	1088	1266	1319
Head diameter	12	11 12	12	13	13	12
Cephalic setae	4	4 5	4	4	4	4
Opisthocephalic setae	2	2 3	2	2	2	2
Buccal cavity length	28	30 27	30	28	28	28
Buccal cavity diameter	5	5 4	6	5	5	5
Amphid from anterior end	3	3 2	3	3	3	3
Amphid c. b. d.	19	21 18	23	18	18	20
Amphid dorsal branch length	10	11 11	12	11	10	10
Amphid ventral branch length	30	29 29	29	30	26	28
Nerve ring from anterior end	100	108 105	101	98	102	103
Nerve ring c. b. d.	32	42 33	33	32	30	30
Pharynx length	149	163 165	148	146	159	158
Pharynx c. b. d.	35	50 39	39	37	37	37
Renette gland length	63	62 55	51	46	56	55
Maximum body diameter	48	61 58	53	46	46	50
a. b. d.	32	38 31	33	29	26	26
Tail length	131	140 134	136	135	130	146
c'	4.1	3.7 4.3	4.1	4.7	5.0	5.6
Spicule length as chord	28	26 25	26	25	-	-
Spicule length as arc	36	33 33	34	33	-	-
Gubernaculum length	7	9 9	9	8	-	-
Apophysis length	12	14 13	14	13	-	-
Vulva c. b. d.	-	- -	-	-	41	45
Vulva, %	-	- -	-	-	51.2	49.2
a	26.4	21.9 23.4	24.2	23.7	27.5	26.4
b	8.5	8.2 8.2	8.7	7.5	8.0	8.3
c	9.7	9.5 10.1	9.4	8.1	9.7	9.0

TABLE 4. Comparison of Parodontophora irregularis sp. nov. with allied species.

Species	P. chiliensis	P. deltensis	P. irregularis	P. paragranulifera
Buccal cavity length (Μm)	-	27–33	27–30	19
Cephalic setae length/head diameter	0.34*	0.33	0.31–0.42	0.5
Amphidael dorsal branch length/amphidael ventral branch (%)	40*	45	31–42	40*
Amphidael dorsal branch length/buccal cavity length	1	1.16	0.93–1.07	1.1–1.5
Opisthocephalic setae arrangement	-	(2D-2V)2 or (2D-1V)2	irregular	(4D-2V)2
Renette gland length/pharynx length (%)	-	37	32–42	40*
Position of excretory pore	Anterior1	Middle	Anterior1	Base
Spicule length as arc (Μm)	80	39	33–36	32
Supplements	Y	N	Y	N
Armilliths	N	N	N	N
Reference	Murphy 1966	Zhang 2005	Present sp. nov.	Timm 1952