Paranticoma tricerviseta, 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 : 2110-2113

Paranticoma tricerviseta sp. nov.

( Figures 1 , 2 )

Type material

Holotype: one male (Station B9761). Paratypes: six males (Stations B9761, B98D5), four females (Stations B9761), two juveniles (Stations B9761, B9805, B9765).

Type locality

Sublittoral in the Bohai Sea: B9761: 38 ° 299980N, 120 ° 299920E, water depth 29.8 m, MdØ 3.15, QDØ 0.94, silt-clay 27.97%; B9765: 39 ° 599980N, 121 ° 219630E, water depth 28 m,

MdØ 3.87, QDØ 1.67, silt-clay 44.16%; B98D5: 38 ° 309000N, 120 ° 009000E, water depth 35 m, MdØ 3.69, QDØ 1.82, silt-clay 28.05%.

Measurements

Measurements are given in Table I.

Holotype male 1: {15 610 58 M 65 2440 40 2730 mm; a542, b54.6, c59.4, Sc 553 Paratype female 1: {15 640 68 74 M 2420 37 2732 mm; a537, b54.3, c58.8, V553%

Description Head diameter 15.3 mm (14–17 mm) in male, 16.0 mm (15–18 mm) in female, equalling about 25.8% and 24.4% of diameter at end of oesophagus respectively. Six papillae distinct. Cephalic setae in one circle, 9.4 mm (9–11 mm) in male and 10.5 mm (9–12 mm) in females (about 61.4% and 65.6% of head diameter). The buccal cavity is a prominent rounded cup shape with three indistinct weakly sclerotized tooth-like cusps. Amphids indistinct, 5.1 mm in width (5–6 mm, 31% of c.d.) in male and 6.5 mm in width (6–7 mm, 37.6% of c.d.) in female. Amphids 6.8–7.3 mm from the anterior. Groups of three lateral cervical setae 56.9¡5.0 mm from anterior in male and 54.3¡ 7.8 mm in female. Excretory pore situated on a seta-like projection of the cuticle, 22.6¡ 1.6 mm from anterior in male and 25.3¡4.0 mm in female. Nerve ring situated at 48.9¡2.2% of oesophagus length in male and 49.5¡1.8% in female. Tail length about 7.1¡0.50 times a.b.d. in male and 8.2¡0.52 times in female.

Males. Spicules 52.1¡ 4.4 mm (cord) and 57.0¡ 6.4 mm (arc) about 1.12–1.34 times the a.b.d. with ventral side projection. Gubernaculum 20, 26 mm long, no apophyses. No supplements. Three cervical setae on each lateral side in all males examined. Two pairs of postanal subventral setae 4.5–6 mm long situated 59 and 69 mm from anus, respectively. Paired short subventral setae on distal half of tail.

Females. Two reflexed ovaries, the length of anterior one 362–382 mm and the posterior one 350–380 mm. Vulva situated at the 52.3¡6.4% of total length.

Discussion

The genus Paranticoma was established by Micoletzky and Kreis (1930) with the type species P. bandaensis . This genus can be distinguished from the closest genus Anticoma by the cup-shaped buccal cavity, excretory pore situated on a seta-like projection of the cuticle, single testis and supplementary organ reduced or vestigial. So far six species have been descrihed by Micoletzky and Kreis (1930), Wieser (1953), Mawson (1956), and Inglis (1967), respectively. All of these species are close to each other and can be distinguished by the structure of the spicules, the presence or absence of cervical setae and the relative position of such setae to the excretory pore, when present.

Differential diagnosis

Paranticoma tricerviseta sp. nov. is characterized by the presence of three cervical setae in male, female and juvenile, the relative position of cervical setae to the excretory pore, the structure of spicules and gubernacula and the presence of two pairs of post-anal subventral setae in the male. Paranticoma tricerviseta is close to P. bandaense Micoletzky and Kreis, 1930 and P. caledoniensis Inglis, 1967 in body size and spicule structure. However, it differs from P. bandaense in having a gubernaculum in the male, the presence of two pairs of postanal subventral setae and the higher value of De Man ratio ‘‘a’’, 37–44 versus 31–34 in the female and 39–43 versus 28–33 in the male. The present new species is distinguishable from P. caledoniensis in having three cervical setae in the male, the higher ‘‘a’’ value 39–43 versus 32–38 and by not having an enlarged distal end to the spicules.

Figures

Figure 1. Paranticoma tricerviseta sp. nov. (a) Lateral view of male head-end; (b) lateral view of female head-end; (c) lateral view of male copulatory apparatus and ventral-middle setae behind anus in the tail; (d) last part of the tail. Scale bar: 20 mm.

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×).