Hysterothylacium pseudotumbili n.sp. (Nematoda: Anisakidae) from the marine fishes of Visakhapatnam, Bay of Bengal.

Hysterothylacium pseudotumbili n.sp. from the stomach and body cavity of marine fishes. Chrorinemus tol Couvier. Saurida undosquamis (Richardson), Lutianus russelli (Bleeker), Rastrilliger kanagurta (Cuvier) and Saurida pseudotumbili Dutt and Vidyasagar collected from Visakhapatnam (Bay of Bengal) is described and figured. A detailed examination has allowed us to erect a new species of Hysterothylacium to accommodate the worm. It shows remarkable differences from other known species of Hysterothylacium in respect of body measurements, the papillae on the lips arrangement, location of nerve ring and excretory pore, long intestinal caecum, position of vulva, number and arrangement of caudal papillae and size of the spicules. The new species is designated as Hysterothylacium pseudotumbili. Saurida pseudotumbili is the new host record. This is the first report of the genus in this host. Visakhapatnam coast is the new locality record.     

Growth and emigration of third-stage larvae of Hysterothylacium aduncum (Nematoda: Anisakidae) in larval herring Clupea harengus

The growth and emigration of Hystherothylacium aduncum in laboratory-reared herring larvae Clupea harengus was studied. Experimental infections of 36-day-old herring larvae resulted in 126 hosts infected with 306 H. aduncum larvae. Regression analyses showed a significant worm emigration from the rectum to the head of the fish, accompanied by an increase in worm body length. The emigration was independent of worm intensity, which suggests an ontogenetic process. Some worms departed from this pattern by moving posteriorly or by penetrating into the muscle, and in 5 cases, the larvae were observed to leave living fish. This individual variation has not been observed in previous studies and might be explained by host signals related to condition or development stage. Indirect evidence suggested parasite-induced mortality in the tanks due to the emigrations because only 4 of the 126 infected fish survived 8 days postinfection; the emigration of H. aduncum affected vital organs, such as the heart and brain, and the larvae penetrating or leaving the host's tissues can cause extensive damage to the delicate herring larvae.     

Hysterothylacium patagonense n. sp. (Nematoda: Anisakidae) from freshwater fishes in Patagonia,Argentina, with a key to the species of Hysterothylacium in American freshwater fishes

A new anisakid nematode, Hysterothylacium patagonense n. sp., is described from the intestine of the temperate bass Percichthys trucha (Cuvier & Valenciennes), a freshwater fish from Lake Aluminé, Patagonia, Argentina. It is characterised mainly by the absence of lateral alae, the length ratio of the caecum and ventricular appendix (1:0.9–1.8), the length of the spicules (0.952–1.292 mm) and the presence of minute spines on the tip of the tail. In the same locality and in Lake Huechulafquen, advanced third-stage and fourth-stage larvae of this parasite were also recorded from the digestive tract of the introduced salmonids, Salvelinus fontinalis (Mitchell), Oncorhynchus mykiss (Walbaum) and Salmo trutta L. This is the second Hysterothylacium species described from freshwater fishes in South America. A key to Hysterothylacium species parasitising American freshwater fishes is provided.     

New records of Porrocaecum sp. and Hysterothylacium sp. (Nematoda: Anisakidae) from fishes of Bay of Bengal

The present paper deals with new records of nematoda of the family Anisakidae Railliet et Henry, 1912. During a study of the parasites of marine fishes (shark, ray and marine teleosts) of Bay of Bengal, females of interesting nematode parasites were found in stomach and body cavity of Chiloscyllium indicum (Gmelin), Torpedo panthera (Olfers), Pomadasys masculatus Bloch and Sphyraena obtusata Cuvier from Visakhapatnam, Bheemunipatnam and Yarada (Andhra Pradesh). Most of the characters tally with Porrocaecum galeocerdonis and Hysterothylacium engraulisi, except for minor variations. Because of the non-availability of the male, it is not possible to assign the present specimens to any of the known species of the genera Porrocaecum and Hysterothylacium. Hence these are referred as Porrocaecum sp. and Hysterothylacium sp. Chiloscyllium indicum and Torpedo panthera are new host records. Visakhapatnam, Bheemunipatnam and Yarada are the new locality records.     

Hysterothylacium simile n. sp. and H. aduncum (Rudolphi, 1802) (Nematoda: Raphidascarididae) from marine fishes in the Bohai and Yellow Sea, China, with comments on the record of H. paralichthydis (Yamaguti, 1941) from Chinese waters

Hysterothylacium simile n. sp., collected from the Japanese seabass Lateolabrax japonicus (Cuvier) (Perciformes: Lateolabracidae) in the Bohai Sea off China, is described using both light and scanning electron microscopy. The new species differs from its congeners in the presence of narrow lateral alae originating a short distance posterior to the base of the ventrolateral lips, a long intestinal caecum (60.4–79.1% of oesophageal length) and a relatively short ventricular appendix (intestinal caecum to ventricular appendix ratio 1:0.58–0.85), long spicules (2.11–2.99 mm, 4.25–7.83% of body length), the number and arrangement of the caudal papillae (32–36 pairs arranged as follows: 27–31 pairs precloacal, 1 pair paracloacal, and 4–5 pairs postcloacal with the second or third pair double) and the presence of a particular midventral precloacal papilla. Specimens originally identified as Contracaecum paralichthydis Yamaguti, 1941 [now H. paralichthydis (Yamaguti, 1941)] by Xü (1957), collected from the yellow striped flounder Pseudopleuronectes herzensteini (Jordan & Snyder) (Pleuronectiformes: Pleuronectidae) in the Yellow Sea off China, were also re-examined. Their morphology clearly revealed they belong to H. aduncum (Rudolphi, 1802), which is also redescribed based on Xü’s material. In addition, the morphological variation of caudal papillae in H. aduncum from P. herzensteini was compared, using scanning electron microscopy, with specimens collected from another three fish hosts, Lophius litulon (Jordan) (Lophiiformes: Lophiidae), Scomberomorus niphonius (Cuvier) (Perciformes: Scombridae) and Cleisthenes herzensteini (Schmidt) (Pleuronectiformes: Pleuronectidae), from the Yellow Sea off China.     

Life cycle of Hysterothylacium haze (Nematoda: Anisakidae: Raphidascaridinae)

Natural infections with Hysterothylacium haze in the Japanese common goby, Acanthogobius flavimanus, were observed in detail. In gobies in which no worm eggs were deposited, second-stage larvae were found in the digestive tract wall, and third-stage larvae occurred in the digestive tract wall, mesentery, and body cavity, whereas fourth-stage larvae and adults were found in the body cavity. This stage-habitat relationship demonstrates the infectivity of second-stage larvae to the goby and the larval migration. In heavily infected gobies, eggs and all worm stages, from hatched second-stage larvae to adults, often were found together in the body cavity of one individual host, suggesting that hatched second-stage larvae can develop in the body cavity. It was shown experimentally that H. haze develops to the second stage in the egg and does not hatch spontaneously. When a goby was fed the viscera of heavily infected gobies containing eggs and various stages of worms or artificially incubated eggs containing second-stage larvae, second- and third-stage larvae were recovered from the digestive tract wall, and fourth-stage larvae and adults were found in the body cavity. When polychaetes or crustaceans were placed in contact with infected goby viscera or incubated eggs, only second-stage larvae were recovered from the body cavity of the invertebrates. The experimental results were consistent with observations on natural infections and indicate that the direct life cycle of H. haze may involve invertebrates as transport hosts.     

Two new species of Ascarophis (Nematoda: Cystidicolidae) in marine fishes from Chile

In this study, we describe 2 new species of Ascarophis van Beneden, 1871 (Nematoda: Cystidicolidae), found in fishes from southern Chile. Ascarophis carvajali n. sp. was found in Austrolycus depressiceps and Patagonotothen cornucola, whereas Ascarophis draconi n. sp. was taken from Champsocephalus gunnari. These new Ascarophis species differ from other species in a combination of several morphometric and morphological characteristics. Although A. carvajali n. sp. was morphologically close to Ascarophis minuta, the new species has a larger ratio between glandular and muscular esophagus, filaments on both egg poles, and a shorter right spicule than A. minuta. Ascarophis draconi n. sp. was morphologically similar to Ascarophis adioryx and Ascarophisfiliformis. However, A. adioryx has eggs without filaments, a smaller ratio between glandular and muscular esophagus length, and a smaller ratio between left and right spicule lengths in contrast to A. draconi n. sp., whereas A. filiformis has a shorter glandular esophagus and left spicule length than A. draconi n. sp. Only 1 Ascarophis species has been recorded in a single fish from Chile (i.e., Ascarophis sebastodis in Sebastes capensis). Consequently, this study constitutes not only new species and records of Ascarophis in fishes from Chile, but also new records for the Pacific coast of South America.     

The morphology and differential diagnosis of parasitic larvae of Triodontophorus (Nematoda, Strongylidae)

356 parasitic larvae of the genus Triodontophorus from Equidae (two Equus hemionus and one E. grevyi) have been investigated. They belong to three phenons, which differ from each other by the shape and dimensions of a stoma, the structure of teeth and other signs. That phenons belong to three different species: T. serratus, T. tenuicollis and T. brevicauda. The differential diagnosis of L4 of that species of Triodontophorus are given.     

Two new species of Copepoda (Crustacea) parasitic on marine fishes

Two new species of parasitic Copepoda (Crustacea) are described and illustrated. Paeon australis n. sp. (Sphyriidae) is the first member of its genus discovered in Australian waters. It is parasitic on Rhinobates batillum, an elasmobranch fish. The other species, Lateracanthus curtus n. sp., is a parasite of an unspecified Macrourus, a deep-water teleost, taken in the northwestern Atlantic. The systematics of the genus Lateracanthus are discussed. Lateracanthus macrurus is relegated to the status of a species inquirenda.     

Morphology of the excretory system of Hysterothylacium haze (Nematoda: Anisakidae: Raphidascaridinae)

The morphology of the excretory system of Hysterothylacium haze was examined by serial histological sections. The excretory system was H-shaped and glandular, consisting of lateral filaments and a commissure, with the exretory pore opening posterior to the nerve ring. A large excretory nucleus was present in the left filament. The cuticularized excretory duct was confined to the left side of the commissure. The glandular excretory system is rare among the Raphidascaridinae.     

Trichodinid parasites (Ciliophora: Peritricha) from the gills of some Australian marine fishes

Three species of the genus Trichodina are reported from the gills of marine fishes in south-eastern Tasmania, Australia. Two of these species are new: T. australis n. sp. from five atherinid fish species, Atherinosoma microstoma, Leptatherina presbyteroides, Kestratherina brevirostris, K. esox and K. hepsetoides; and T. nesogobii n. sp. from Nesogobius sp. 1. One previously reported species, T. jadranica Raabe, 1958, was also found on Nesogobius sp. 1.