Parodontophora wuleidaowanensis, Zhang, 2005

Zhang, Z. N., 2005, Three new species of free-living marine nematodes from the Bohai Sea and Yellow Sea, China, Journal of Natural History 39 (23), pp. 2109-2123 : 2118-2121

Parodontophora wuleidaowanensis sp. nov.

( Figure 5 )

Type material

Holotype: one male. Paratypes: two males, two females.

Type locality and habitat

Wuleidaowan Yellow Sea, 119 ° 599010E, 36 ° 589000N, water depth 1 m, silt-clay, two males and one female; one male and one female collected from the branchial filaments of mature female prawn Penaeus (Fenneropenaeus) chinensis (Osbeck) , in the spawning pond, 25 April 1992.

Etymology

Parodontophora waleidaowanensis is named after the sea area where the specimens were collected.

Measurements

Measurements are given in Table III.

Holotype male: 14 {46 170 53 M 1364 36 1553 mm; a533.8, b59.1, c58.2, Sc540

Paratype female: {15 167 50 M 62 1536 39 1768 mm; a528.5, b510.6, c57.6, V50.48%

Description

Body cylindrical, tapering toward extremeties. Cuticle with faint outer striation discernible in the lateral field. Six outer labial papillae around the lip region. Cephalic setae 4.0–5.0 mm long, 3.0–5.0 mm from the anterior end. Cervical setae 3 mm long, arranged as two subdorsal groups of two longitudinally arranged setae and single subventral seta, i.e. cervical seta formula: (2D-1V)2 both for males and females. There are irregular sublateral setae 3 mm long in the oesophageal region. Somatic setae scattered. There are six pairs of subventral setae on the conical portion of the tail and several irregular short setae on the cylindrical part of the tail. The mouth opens into a short vestibulum which links with the stoma, which has a slightly conical anterior part and a long posterior part with parallel highly cuticularized walls, equal in thickness, 21–25 mm long and 5.5–6.0 mm wide. There are six bifurcate teeth at the tip of the cylindrical stoma. Buccal cavity about 28.5–34 mm long from tip of teeth to the base of stoma. Oesophagus starting at the base of the stoma, widens gradually to the base and forms a bulb in the last quarter of oesophageal length. Amphids shaped like a shepherd’s crook, with a short dorsal arm, 8–10 mm, and a much longer ventral arm extending past the stoma, 72–106 mm long. Amphid length about 2.53– 3.12 times length of the buccal cavity. The renette cell is a long-oval 84–94 mm long, about 0.41–0.63 of the oesophageal length, just behind the small round cardia. Nerve ring is at 0.58–0.62 of the oesophageal length from the anterior. Excretory pore at middle level of the buccal cavity. Tail shape similar in both sexes, with the first half conical and the other half cylindrical. Three caudal gland cells open to the spinneret.

Males. Slightly smaller than females on average. Testes opposed and outstretched. Anterior testis to the right and posterior one to the left of the intestine. Spicules paired, arched with rounded proximal end and a slightly swollen sub-proximal part, about 9–10 mm from the proximal end. Spicules 39–49 mm long (arc). Gubernaculum with dorso-caudal directed apophysis 14 mm long, with the middle of its ventral side thickened. Caudal setae six pairs subventrally and a few unpaired dorsally.

Females. Two ovaries outstretched. Anterior ovary 398 mm long to the right and posterior one 368 mm long to the left of the intestine. Vulva slightly anterior to the mid-body. A pair of vulval glands present. Amphid ventral arm widens in the middle part, 4.5–5.5 mm wide, with fine striation. A few irregular setae on the tail.

Differential diagnosis

Parodontophora wuleidaowanensis sp. nov. may be separated from the close species P. danka Belogurov and Kartavtseva, 1975 , by regularly arranged cervical setae (2D-1V) 2 in both males and females (no description of cervical setae in P. danka ), much longer amphid, ventral arm 72–106 mm versus 59 mm, about 2.5–3.1 times versus 2.0 times the length of buccal cavity, and the distinct structure of the proximal ends of the spicules with no invaginated hole in the present new species.

Discussion

Since the establishment of the genus Parodontophora by Timm (1963), a total of 18 species are known in the genus, including the present two new species, P. deltensis and P. wuleidaowanensis . Among them there are six species in which the amphid length extends past the level of the base of the buccal cavity, which can be divided in to three groups: (1) amphids 1.1–1.5 times as long as buccal cavity, P. paragranulifera ( Timm, 1952) , P. deltensis sp. nov.; (2) amphids about two times as long as buccal cavity, P. danka ( Belogurov and Kartavtseva, 1975) ; (3) amphids more than two and half times as long as buccal cavity, including P. cobbi ( Timm, 1952) , length of amphids 80– 28 mm, buccal cavity 19–22 mm, P. polita (Gerlach, 1955) , length of amphids 125–150 mm, buccal cavity 35 mm. Length of amphids 72–106 mm and buccal cavity 29–34 mm in P. wuleidaowanensis sp. nov. A tabular key to the species of this last group is given in Table IV.

Figures

Figure 5. Parodontophora wuleidaowanensis sp. nov. (a) Lateral view of male head-end; (b) lateral view of female head-end; (c) tail of male; (d) tail of female. Scale bar: 20 mm.