Amphimonhystera circula, Tchesunov & Mokievsky, 2005

Tchesunov, Alexei V. & Mokievsky, Vadim O., 2005, Three new species of free-living nematodes from the Bohai Sea, China, Journal of Natural History 35 (11), pp. 1575-1586 : 1579-1581

Amphimonhystera circula sp. nov.

(fi gure 3)

Type material Holotype: one male; paratypes: three males and several juveniles.

Type locality

Station A 4 in the Bohai sea, China (38 ° 24.8 ' N, 121 ° 35.15 ' E), wa ter depth 50.8 m, sand with MD 0.068 mm.

Etymology

Amphimonhystera circula is so-called because of the circular form of the amphids, as opposed to an elongated oval in the only other known species.

Measurements ( table 3 )

- 160 M 858 Holotype male: 970 µ m; a =44, b =6, c =9, Sc =32 10 20 22 19

- 142 M 530 Juvenile 1: 630 µ m; a =36, b =4.4, c=6.3 7 17 18 15

Description

Body slender. Cuticular striations, about 1.5 µ m apart. Large amount of granular material throughout epidermis, especially in oesophageal and cloacal areas. Coloration of preserved specimens yellow. Distinct hyaline lips with six 3.5–5 µ m labial setae; 14 cephalic setae, eight longer (18 µ m, 1.7–1.8 h.d.) and six shorter (13 µ m, 1.3 h.d.). Slender somatic setae very sparse, but more numerous near the cloacal area. Amphids circular, about one h.d. from anterior, 10 µ m in diameter, thick-walled with an internal cuticularized opening. Buccal cavity small with posterior chamber. Anterior oesophagus slightly swollen, no oesophageal bulbs present. Cardia triangular. N erve ring 85 –95 µ m behind anterior end (0.52–0.67 of oesophageal length). Tail 5.9–6.1 a.b.d., conico-cylindrical with three terminal setae 8–9 µ m long.

Males. Spicules paired, equal and arcuate, proximally cephalate and distally pointed, 30–32 µ m (1.52–1.78 a.b.d.) long as chord. G ubernuculum a simple tube.

No females found.

Differential diagnosis

So far only the type species A. anechma (Southern, 1914) has been described (R iemann, 1967; Lorenzen, 1977). Amphimonhystera circula sp. nov. can be distinguished from A. anechma by its size (910–970 µ m in the former, 1660–1860 µ m in the latter) and the shape of amphids in the male which are circular in the former compared to oval, 27 µ m long and 20 µ m wide, in the latter. The shape of the tail is also different (5.9–6.1 a.b.d. in A. sp. nov., 3.5–4.2 a.b.d. in A. anechma ), and the gubernaulum in A. anechma has a much more complicated structure.