Conilia sinensis , Chen, Yu Zhen & Guo, Yu Qing, 2015

Chen, Yu Zhen & Guo, Yu Qing, 2015, Three new and two known free-living marine nematode species of the family Ironidae from the East China Sea, Zootaxa 4018 (2), pp. 151-175: 152-156

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Conilia sinensis

sp. nov.

Conilia sinensis  sp. nov.

( Figure 1View FIGURE 1, Figure 2View FIGURE 2, Table 1)

Type material. Six males and two females were collected from Station ZZDS L 1, L 2 and L 3 in July 2012. Holotype: ♂ 1 on slide number ZZDS 20120707 L 1 U 123. Paratypes: ♂ 2 and ♀ 2 on slide number ZZDS 20120707 L 2 U003, and ♂ 3 on slide number ZZDS 20120707 L 2 U004, ♂ 4 on slide number ZZDS 20120707 L 3 U001, ♂ 5 and ♀ 1 on slide number ZZDS 20120707 L 2 U002, ♂ 6 on slide number ZZDS 20120707 L 4 D001.

Type locality and habitat. Intertidal sandy sediment at Dongshan Island, Zhangzhou City, East China Sea. Station ZZDS: 117.4836 °E, 23.7081 °N. Silt+clay: 3.27 %.

Etymology. The name of the species makes reference to the country of origin, China.

Measurements ( Table 1)

Description. Male. Body slender and cylindrical, maximum body diameter 33–36 µm. Head end blunt, lip region well developed and swelling, with several wrinkles on the outside wall of lips ( Figure 1View FIGURE 1 F. G). Six inner labial sensilla papilliform, six outer labial setae and four cephalic setae stout and blunt, arranged in a ring. Head diameter 25–26 µm. Head region set off from remaining body part by a strip, width about 4 µm. Buccal cavity consists of a cup-shaped anterior section length 5–12 µm, and a strong cuticularized posterior tube length 29–31 µm. Three solid curved claw-like teeth of almost equal size lie on the border of cup-shaped anterior section of buccal cavity, one of the teeth seems to be slightly double-tipped in two observed specimens. The anterior edges of cup-shaped section of buccal cavity bear a row of small cuticular denticles. Amphid not observed. Pharynx 0.18– 0.21 times of body length, with distinct anterior peribuccal swelling, posteriorly without obvious bulb. Nerve ring located at 37 %– 40 % of pharynx length. Tail conico-cylindrical, 4.5–5.7 abd long, obviously ventrally bent, one small ventro-median swelling occurred in the middle of tail. Three elongated caudal glands are precloacal. Terminal spinneret small. Cuticle smooth, almost all specimens are more or less adhered by rod-shaped bacteria, somatic setae cannot be accurately observed in most of specimens. While in one specimen, which is little adhered by bacteria can be observed several scattered ventro-sublateral somatic setae arranged in one row in each side, two are located near the cloaca.

Reproductive system diorchic with two testes arranged in tandem, situated to right of intestine. Spicule single and elongate, transversely or slightly obliquely striated, length 87–100 µm as arc, 3.5–4.2 abd. Telamons paired, length 25–28 µm, with thickened anterio-ventral and posterio-dorsal ribs which is bent distally with two strong hook-like structures, as well as rounded changeable proximal projection ( Figure 1View FIGURE 1 C. D. E; Figure 2View FIGURE 2 G. H. I. J). Gubernaculum is a slightly curved thin strip, length 18–22 µm. One precloacal supplement present as simple ventral swelling.

Female. Similar to male in general characteristics, but body plumper and slightly swollen at midbody, maximum body diameter 41–48 µm. Head diameter 29–33 µm; Head region continuous with body contour. The cuticularized posterior tube of buccal cavity longer, length 35–36 µm. Tail straight, without setae or swelling.

Reproductive system with two reflexed equally developed ovaries. Vulva at 53.9–56.7 % of body length.

Diagnosis and discussion. The genus Conilia  was established by Gerlach in 1956 with the type species Conilia divina Gerlach (Gerlach 1954)  . It belongs to Ironidae  with a cuticularized elongate-tubular buccal cavity and three claw-like teeth at anterior end of buccal cavity. It is a rare genus, with only two species described to date, and some diagnostic characters are still questionable ( Gerlach & Riemann 1974, Aryuthaka 1989, Platonova & Mokievsky 1994, Electronic database:; In general, it can be distinguished from other genera of Ironidae  by male copulatory apparatus. According to the original descriptions of this genus and the type species C. divina  , the male copulatory apparatus consists of three parts: the first part is short and paired, its proximal end expands to a funnel shape and distal end bends as two stout hooks; the second part is a narrow strip, longer than the first part; the third part is a very long obliquely striate sclerotized tube, which adjoins the first part and the second part ( Gerlach 1954). A structure similar to the third part was first found in Mesacanthion diplechma ( Southern, 1914) Filipjev, 1927  , which was described as a spicule ( Southern 1914); Schuurmans Stekhoven (1935) suspected that it might act as the ejaculatory duct. Gerlach (1954) regarded these three parts as spicules, gubernaculum and spicular accessory, respectively. Aryuthaka (1989) considered the third part to be a tubiform spicule and the first part to be the gubernaculum. Keppner & Tarjan (1989) regarded the first part and second part as asymmetrical spicules of different length (see also Platonova & Mokievsky 1994). In C. divina  , the third part of the copulatory apparatus may protrude up to two-thirds of its length from the cloaca ( Gerlach 1954). In Conilia sinensis  sp. nov., the third part of the copulatory apparatus may also protrude from the cloaca ( Figure 1View FIGURE 1 D; Figure 2View FIGURE 2 G), while the second part was never observed to protrude in all of our specimens. The former is more likely to act as the ejaculatory duct, so we describe the single striate sclerotized tube as a spicule and the short and paired structures as telamons in this paper. A pictorial key including C. divina  , C. monospiculata Aryuthaka, 1989  and the newly described species is given in Figure 3View FIGURE 3.

The new species is identified by its relatively large body size, well developed lips, single, striated and shorter spicule, fewer supplements, etc. It differs from C. divina  in the following characters: body (1883–2399 µm vs. 1535–1630 µm) and buccal cavity (37–45 µm vs. 36 µm) longer; length of cephalic setae smaller (17–22 µm vs. 25 µm); spicule (87–100 µm vs. 112 µm) shorter; telamons (25–28 µm vs. 12 µm) and buccal cavity (37–45 µm vs. 36 µm) longer; supplements fewer (1 vs. 4); male tail ventrally bent (straight in C. divina  ), relatively longer (4.5–5.7 abd vs. 4 abd) and with a small ventro-median swelling (absent in C. divina  ); female tail shorter (5.3–5.7 abd vs. 6 abd); lip well developed (lip region not particularly strengthened in C. divina  ). ( Gerlach 1954). It can be easily distinguished from C. monospiculata  by the absence of amphid (amphid present in C. monospiculata  ) and the presence of supplement (supplement absent in C. monospiculata  ); the striated and longer spicule (87–100 µ m vs. 60–64 µm); the longer male body length (1956–2399 µm vs. 1529–1990 µm) and telamon (25–28 µm vs. 15–20 µm); the posterior location of vulva (V 53.9 %– 56.7 % vs. 48 %); the bigger head diameter (♂: 25–26 µm vs. 17–22 µm; ♀: 29–33 µm vs. 21–22 µm) and male maximum body diameter (33–36 µm vs. 23–33 µm) ( Aryuthaka 1989).

TABLE 1. Individual measurements of Conilia sinensis sp. nov. (in µm).

    2399 2101 2141 2141 1956 2080 1883
Length of outer labial cephalic setae