Pingus sinensis Hsü, 1933

Moravec, František & Nagasawa, and Kazuya, 2018, Rhabdochona angusticaudata sp. n. (Nematoda: Rhabdochonidae) from the Japanese eel Anguilla japonica, and new records of some other nematodes from inland fishes in Japan, Folia Parasitologica (016) 65, pp. 1-22 : 6-7

Pingus sinensis Hsü, 1933

Description of gravid female (1 specimen). Length of body 5.40 mm, maximum width at region of oesophagus 135. Cephalic end rounded, bearing four submedian papillae and lateral amphids. Cephalic end forms two lateral lobes from which broad lateral alae extend posteriorly along body; alae broadest in oesophagus region. Oesophagus with short, slightly outlined pharynx 15 long and 36 wide; anterior portion of oesophagus (without pharynx) anterior to nerve ring muscular, 210 long and 48 wide; posterior muscular-glandular portion somewhat broader, 366 long and 84 wide; entire oesophagus including pharynx 591 long, representing 11% of body length. Nerve ring, deirids and excretory pore 218, 466 and 558, respectively, from anterior extremity. Vulva postequatorial, situated 3.26 mm from anterior end of body (at 60% of body length); anterior vulval lip somewhat elevated. Vagina directed anteriorly from vulva. Amphidelphic. Anterior ovary extending to short distance posterior to oesophagus, posterior ovary extends to mid-length of tail. Eggs in uterus arranged in one file. Eggs unembryonated, oval, smooth, size 66–81 × 39–51. Tail conical, 258 long, sharply pointed.

Host: Snakehead, Channa argus ( Channidae , Perciformes ).

Site of infection: Pyloric caeca.

Locality : Kamo River (a tributary of the Ashida River ), Fukuyama, Hiroshima Prefecture, Honshu, Japan (collected 26 November 2008) .

Prevalence and intensity: 1 fish infected, 61.5 cm TL/ 1fish examined; 1 nematode.

Deposition of voucher specimen: Not deposited (used for SEM).

Remarks. The morphology of the present nematode is in agreement with the redescription of P. sinensis by Shimazu et al. (2000), who also studied this species by SEM. Therefore, no illustrations of the present specimen are provided. This species was originally described by Hsü (1933) from C. argus in China, later it was recorded a few times from the same host species in China and eastern Russia (Amur River basin) (e.g. Wu 1956, Dogel and Akhmerov 1959, Wang et al. 1978, Moravec et al. 2003) and by Ky (1971) and Moravec and Sey (1988) from Channa maculata (Lacépède) from North Vietnam.

Shimazu et al. (2000) were the first to record and describe P. sinensis from C. argus in Japan (Imperial Palace in Tokyo). Later, this nematode was reported from the same host species in the Nagara River, Gifu Prefecture and from Lake Biwa, Shiga Prefecture ( Anonymous 2002, Grygier and Urabe 2003, Grygier and Hirasawa 2011). Although snakeheads ( Channidae ) were not naturally distributed in Japan ( Froese and Pauly 2018), C. argus was introduced from Korea as early as in 1923 and, most likely, the nematode also came to Japan from Korea ( Shimazu et al. 2000).