Paracanthonchus multisupplementatus, Gagarin, Vladimir G., 2012

Gagarin, Vladimir G., 2012, Paracanthonchus multisupplementatus sp. n. and Cyatholaimus minor sp. n. (Nematoda) from the coast of Vietnam, Zootaxa 3392, pp. 60-68 : 61-64

Paracanthonchus multisupplementatus sp. n.

( Fig 1 , Table1 )

Type material. Holotype male, slide reference number 100/28, deposited in the collection of the Institute of Ecology and Evolution, Center for Parasitology, Russian Academy of Science, Moscow, Russia.

Paratypes. Ten males and five females deposited in the collection of the Institute of Ecology and Biological Resources, Vietnamese Academy of Sciences and Technology, Hanoi, Vietnam.

Measurements. Table 1 .

Type locality. South China Sea, Tra Co, Quang Ninh province, Vietnam, littoral zone. Latitude: 21º13'476" N, Longitude: 107º22'467'' E. Depth 2.0 m, sand, salinity 26.1‰. Collected in March 2010.

Etymology. The specific epithet means “with large number of supplementary organs”.

Description. Male. Body comparatively short and thin. Cuticle thin, annulated, about 1 µm thick at mid-body. Cuticular rings formed by transverse rows of small dots (punctations). Lateral fields present, 3.0–3.5 µm wide marked by two longitudinal rows of bigger dots. Cuticular pores distinct and comparatively large. Somatic setae scarce and short, 3.0–3.5 µm long. Lips poorly developed. Inner labial sensilla in the shape of small papillae. Outer labial and cephalic sensilla in the shape of thin setae and arranged in a single circle. Outer labial setae 8.0–8.5 µm long (30–39% of labial region width). Cephalic setae 4.5–5.0 µm long. Cheilostom spacious, its walls, reinforced by sclerotized rugae apparently twelve in number. Esophastom cup-shaped and armed with one large pointed tooth and two small denticles on both subventral walls. Total stoma length approximately equal to labial region width. Amphidial fovea large, round, multispirally coiled with 4.0–4.5 turns and deposed at the lips base. Amphidial fovea 10–13 µm in diameter, 50–55% of corresponding body diameter. Eyespots absent. Pharynx evenly muscular, widening at its base, forming an elongate bulb-shaped structure which is divided into two portions. Cardia and renette not observed. Excretory pore located 3.0–3.5 labial region diameters from anterior body end.

Diorchic; anterior testis outstretched, posterior testis reflexed. Anterior testis situated to the right of the intestine, posterior testis to the left of the intestine. Spicules thin, strongly curved with small, rounded capitulum and 1.4–1.6 times as long as cloacal body diameter. Gubernaculum paired, 1.6–1.7 times are shorter than spicules. Proximal portion of gubernaculum thin, distal portion expanded, thickened, with apex in the shape of plate with small denticles. Precloacal supplements in the shape of thin, short tubes, 57–62 in number. Supplement row 6.5–8.4 times as long as cloacal body diameter. Tail elongate-conical, slightly curved ventrally, gradually narrowing. Three caudal glands poorly visible. Spinneret in the shape of short tube. There are a 10–13 short lateroventral and laterodorsal setae.

Character Holotype male Paratype males Paratype females Female. General morphology is similar to that of males in structure of cuticle and anterior body end. Cuticle transversally annulated and punctated. Lateral fields present, marked by two longitudinal rows of larger dots. Somatic setae scarce and short. Cuticular pores distinct. Lips poorly developed. Inner labial sensilla in the shape of small papillae. Outer labial and cephalic sensilla in the shape of thin setae. Outer labia setae. 7.0–8.0 µm long cephalic setae 4.5–5.0 µm long. Cheilostom with walls reinforced by 12 sclerotized rugae. Esophastom cup-shaped and armed with one large dorsal tooth and small subventral denticles. Amphidial fovea large, round, multispirally coiled, with four turns. Amphidial fovea 8–11 µm diameter, 40–45% of corresponding body width. Pharynx evenly muscular, widening at its base, forming elongate bulb-shaped structure, divided into two portions.

Reproductive system didelphic, amphidelphic. Ovary bends comparatively short. Anterior ovary situated to the right of the intestine, posterior ovary to the left of the intestine. Vulva a transverse slit, equatorial. Vulval lips not sclerotized and not protruding outside the body contour. Vagina short, its walls thin. Uterus spacious, containing numerous spermatozoa. Tail elongate-conical, gradually narrowing, curved ventrally. Caudal glands and spinneret present.

Diagnosis. Body 1027–1365 µm long. Cuticle transversally annulated and punctated. Lateral fields formed by two longitudinal rows of larger dots. Cuticular pores distinct. Lips poorly developed. Inner labial sensilla in the shape of small papillae. Outer labial and cephalic and cephalic sensillae constitute a jointed circle of 6+4 setae. Amphidial fovea large, round, multispirally coated with 4.0–4.5 turns. Stoma with large dorsal tooth and small subventral denticles. Pharynx muscular, widening at its base, forming elongate bulb-shaped structure, divided into two portions. Didelphic, ovaries antidromously reflexed. Vulva a transverse slit, equatorial. Diorchic, anterior testis outstretched, posterior testis reflexed. Spicules thin, strongly curved, with small round capitulum. Gubernaculum paired, 1.6–1.7 times shorter than spicules. Proximal portion of gubernaculum thin, distal portion expanded and thickened, with apex in the shape of plate with small denticles. Precloacal supplements in the shape of thin and short tubes, 57–62 in number. Tail elongate-conical, gradually narrowing, curved ventrally. Caudal glands and spinneret present.

Differential diagnosis. Paracanthonchus multisupplementatus sp. n. is similar to P. multitubifer Timm, 1961 , but differs from it in the longer and more slender tail (c = 9.1–11.0, c’ = 3.0– 3.4 in males, c = 8.1–8.7, c’ = 3.6–4.1 in females versus c = 11.4–14.0, c’ = 2.3–2.8 in males, c = 10.2–10.4, c’ = 2.0– 2.8 in males in P. multitubifer ), larger dorsal tooth in stoma, larger diameter of amphidial fovea (40–55% of corresponding body width versus 15 % of corresponding body width in P. multitubifer ), longer spicules and gubernaculum (spicules 56–61 µm long, gubernaculum 36–43 µm long versus spicules 36 µm long, gubernaculum 36–43 µm long in P. multitubifer ) and greater number of preanal supplements (57–62 in number versus 21–22 in number in P. multitubifer ) ( Timm, 1961).

Figures

FIGURE 1. Paracanthonchus multisupplementatus sp. n., holotype male and paratype female. A: male, entire body; B: female, entire body; C: male, head; D: male, anterior body end; E: vulval region; F: male tail; G: spicule and gubernaculum. Scale bars: A, B = 150 µm; D, E = 70 µm; F = 60 µm; C = 25 µm; G = 20 µm.

Tables

TABLE 1. Morphometrics of Paracanthonchus multisupplementatus sp. n. (all measurements are given in µm unless otherwise stated, except for the rations a, b, c, c’, V, o. l .. s. r., spic. cl. and n. sup.)

n	1	10	5
L	1146	1172+(1027–1308)	1240+62 (1181–1365)
a	19	21+2 (19–23)	20+1 (19–22)
b	6.2	6.4+0.4 (6.0–7.0)	6.3+0.4 (6.1–7.0)
c	9.6	9.8+0.6 (9.1–11.0)	8.5+0.2 (8.1–8.7)
c’	3.1	3.2+0.2 (3.0–3.4)	3.8+0.2 (3.6–4.1)
V	–	–	49.6+0.6 (48.8–50.0)
diam.c.s.	21	21+1 (20–23)	24+1 (22–25)
diam.midb.	59	57+3 (52–62)	61+4 (56–65)
a.d.	38	37+2 (35–40)	36+1 (35–38)
o.l.s.	8.0	8.0+0.5 (7.0–8.5)	7.5+0.3 (7.0–8.0)
o.l.s.r.	36	36+2 (33–39)	35+2 (33–38)
st.l.	21	21+1 (20–22)	22+1 (21–23)
am.w.	11	12+1 (10–13)	10+1 (8–11)
dis.am.	3.5	4.0+0.5 (3.5–4.5)	6.0+0.5 (5.0–6.5)
ph.l.	185	183+6 (171–196)	197+2 (195–200)
dis.ph.cl.	842	870+81 (743–1006)	–
dis.ph.v.	–	–	415+40 (378–491)
dis.v.a.	–	–	481+20 (459–518)
spic.	60	58+3 (56–61)	–
spic.cl.	1.6	1.5+0.1 (1.4–1.6)	–
gub.l.	38	39+2 (36–43)	–
n.sup.	57	59+2 (57–62)	–
l.sup.r.	288	278+20 (240–311)	–
t.l.	119	119+6 (113–135)	147+7 (140–160)