Parodontophora deltensis, 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 : 2114-2118

Parodontophora deltensis sp. nov.

( Figures 3 , 4 )

Type material

Holotype: one male. Paratypes: 19 males, 10 females and five juveniles. Type locality and habitat

Laizhou Bay stations. DA2, 119 ° 459020E, 37 ° 599080N, water depth 20 m, poorly sorted clay-silt with MdØ 5.72, five males and six females, DA4, 119 ° 299050E, 37 ° 459070N, water depth 16 m, coarse silt with MdØ 4.93, 11 males and four females.

Submarine delta stations of Huanghe Estuary. E9, 119 ° 169070E, 37 ° 519000N, water depth 14 m, fine silt with MdØ 6.4, two males and three juveniles collected during July/ August 1986 cruise; E11, 119 ° 079300E, 37 ° 389030N, water depth 10 m, fine silt with MdØ 6.5, one male and two juveniles collected during July/ August 1986 cruise; E2, 119 ° 209000E, 37 ° 419030N, water depth 10 m, very poorly sorted clay-silt, with MdØ 7.86, QDØ 2.06, one male collected during October 1987 cruise.

Etymology

Parodontophora deltensis is named for its typical habitat, the submarine delta of the Huanghe River Estuary and adjacent Laizhou Bay.

Measurements

Measurements are given in Table II.

Holotype male: {13 146 35 M 36 954 25 1090 mm; a530.3, b57.5, c58.0, Sc541

Paratype female: 13 {182 39 M 41 1102 26 1270 mm; a531.0, b57.0, c57.6, V50.51% Description

Cuticle with faint outer striation discernible in the lateral field. Six outer labial papillae around the lip region. Cephalic setae 4.2 mm long, 4.2–5.0 mm from the anterior end. Cervical setae 3 mm long, arranged as two subdorsal groups of two longitudinally arranged setae and two subventral (or single) setae, i.e. (2D-2V)2 or (2D-1V)2 for most individuals. Somatic setae scattered. There are five 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 the stoma, consisting of a slightly conical anterior part and a cylindrical posterior part with highly cuticularized walls, equal in thickness, 23– 25 mm long and 4–5 mm wide. There are six bifurcate teeth at the tip of the cylindrical stoma. Buccal cavity about 27–33 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 fifth of oesophageal length (not illustrated in Figure 2 ). Amphid semi-looped with the shorter dorsal branch and parallel much longer ventral branch surpassing the base of the stoma. Generally, length of the dorsal branch equals about 0.45 of ventral length (0.36–0.55) and the amphid length is about 1.16 times the buccal cavity length (1.0–1.27 times). The renette cell is elongated oval or rectangular, 61 mm long (49–71 mm), about 0.37 of the oesophageal length (0.27–0.44), situated just behind the small conoid cardia. Nerve ring at the level of about 0.63 of the oesophageal length (0.58–0.67). Excretory pore indistinct at the middle level of buccal cavity.

Males. Slightly smaller than females on average. Testes paired, opposed and outstretched. Anterior testis to the right and posterior testis to the left of the intestine. Spicules paired, equal and arcuate, 38.9 mm long (1.10–1.76 a.b.d) as arc, pointed distally and enlarged proximal end with a front and dorsal constriction. Gubernaculum with dorsal-caudally directed apophyses, 11–15 mm long with the middle of their ventral sides extended into small points.

Females. Ovaries paired opposed and outstretched, anterior to the right and posterior to the left of the intestine, both equally developed with length 402–502 mm. Vulva transverse at the mid-body, vaginal length 11–13 mm, 0.21–0.25 of the corresponding body diameter. A pair of vulval glands present. Female differs from the male in having slightly longer tail (4.9–5.9 versus 4.6–5.3 a.b.d.), fewer subventral setae on the tail and slightly different arrangement of cervical setae. Among 10 female specimens examined, seven specimens had cervical setae formula: (2D-2 V)2 and another three specimens had (3D-1 V)2 .

Differential diagnosis

Parodontophora deltensis sp. nov. is characterized by the position of the posterior end of the amphid extending slightly beyond the base of the stoma (1.0–1.3 times the length of the buccal cavity). Slightly irregular cervical setae arranged as (2D-2V)2 for most males, females and all juveniles, with some exceptions (2D-1V)2 for a small number of males and (3D-1V)2 for some females.

Parodontophora deltensis sp. nov. is close to P. paragranulifera ( Timm, 1952) in the length of the amphid, with the ventral branch extending past the base of the stoma. However, P. delteusis sp. nov. may be separated from that species by the irregularly arranged cervical setae, (2D-2V)2 for the most males, females and juveniles, with some exceptions arranged as (2D-1V)2 for several males and (3D-1V)2 for some females. Cervical setae are arranged more irregularly in P. paragranulifera . The new species differs also from P. paragranulifera in the ratio of length of dorsal branch to ventral branch (0.36–0.55 versus 0.20–0.25) and anterior one-third of ventral branch running parallel to the dorsal branch, not looping.

Discussion

The genus Parodontophora was erected by Timm (1963) for Odontophora species with parallel rather than conical walls of the stoma. Parodontophora paragranulifera ( Timm, 1952) was chosen as the type species and many other species of Odontophora and Pseudolella were also included in this genus. Boucher (1973), Zhang (1991), and Smolyanko and Belogurov (1995) constructed a dichotomous and tabular key to the species, based on the following characters: length of ventral branch of amphids, position of the excretory pore from the anterior end, the arrangement of cervical setae, relative length of renette cell and presence or absence of armilliths in the endocapola, which was described as one stomatoidal ring in Paradontophora repens ( Smolyanko and Belogurov 1995) , but it was not found in our specimens. So far 17 species are known in the genus including P. limnophila ( Wu et al. 2000) , the only species found in freshwater habitats, and the present two new species, P. deltensis sp. nov and P. wuleidaowanensis sp. nov.

Figures

Figure 2. Paranticoma tricerviseta sp. nov. (a) Lateral view of male anterior end, showing cervical setae (1000×); (b) lateral view of spicules (400×); (c) lateral view of male tail (200×); (d) lateral view of conical part of male tail, showing subventral setae (400×).

Figure 3. Parodontophora deltensis sp. nov. (a) Lateral view of male head-end; (b) lateral view of male tail; (c) lateral view of male copulatory apparatus; (d) lateral view of female head-end; (e) tail of female. Scale bar: 20 mm (a, c, d); 50 mm (b, e).

Figure 4. Parodontophora deltensis sp. nov. (a) Lateral view of male buccal cavity (400×); (b) lateral view of male anterior end, showing amphids (400×); (c) lateral view of male tail, showing spicules and gubernacula with apophyses (200×).