Life cycle of Coitocoecum plagiorchis (Trematoda: Digenea: Opecoelidae)

The life cycle of Coitocoecum plagiorchis Ozaki, 1926 (Coitocaecum is an incorrect subsequent spelling) was studied in the field and laboratory. The study was conducted at the Futatsu River and the Chikugo River, Kyushu, Japan. Adults of C. plagiorchis were obtained from fishes Coreoperca kawamebari, Rhinogobius spp. and Odontobutis obscura. Cotylomicrocercous cercariae with a two-point stylet (= Cercaria distyloides Faust, 1924) were detected in pleurocerid snails (Semisulcospira spp.). Metacercariae with a cyclocoel were obtained from shrimp (Neocaridina denticulata). The cercariae were experimentally exposed to the shrimp, and subsequently metacercariae with a cyclocoel were recovered from the shrimp within 24 days after exposure. These metacercariae were identified as C. plagiorchis. The sporocysts, cercariae, metacercariae and adults are briefly described.     

Opistholobetines (Digenea: Opecoelidae) in Australian tetraodontiform fishes

Opistholebetine opecoelids are reported following examination of 1,041 individual tetraodontiform fishes, comprising 60 species and seven families, collected in Australian waters between 1986 and 2018. Nine species consistent with Opistholebes Nicoll, 1915, Heterolebes Ozaki, 1935 or Maculifer Nicoll, 1915 were recovered. However, phylogenetic analysis of sequence data, generated for some of these species, suggested that five genera, not three, are required to adequately accommodate these taxa. Thus, the concept and composition for each is revised, Pseudoheterolebes Yamaguti, 1959 nec Gupta, 1968 is resurrected and Parallelolebes n. g. is proposed. Of the nine species examined, five are new. Four new species are from fishes endemic to subtropical and temperate Australian waters for which no trematodes have previously been reported: Pa. australis n. sp. and Ps. corazonae n. sp. from the slender-spined porcupinefish Diodon nicthemerus Cuvier (Diodontidae) off Stanley, Tasmania; Pa. virilis n. sp. from the horse-shoe leatherjacket Meuschenia hippocrepis (Quoy & Gaimard) (Monacanthidae) off Stanley; and Ps. stellaglobulus n. sp. from the threebar pocupinefish Dicotylichthys punctulatus Kaup (Diodontidae) in Moreton Bay, south-east Queensland. The fifth new species is M. diodontis n. sp., collected from the spotted porcupinefish Diodon hystrix Linnaeus and the blackblotched porcupinefish D. liturosus Shaw, in tropical waters on the Great Barrier Reef. Species reported previously include the type-species of Opistholebes, O. amplicoelus Nicoll, 1915 from the rough golden puffer Lagocephalus lunaris (Bloch & Schneider) (Tetraodontidae) and the common toadfish Tetractenos hamiltoni (Richardson) (Tetraodontidae) in Moreton Bay, and three species reported for the first time from fishes in Australian waters: H. maculosus Ozaki, 1935, Pa. elongatus Ozaki, 1937 n. comb. and Ps. diodontis (Cable, 1956) n. comb., each from both D. hystrix and D. liturosus on the Great Barrier Reef. Following the revisions, Opistholebes is recognised for two species, Heterolebes for five, Maculifer for eight, Pseudoheterolebes for five and Parallelolebes for three.     

Opecoelidae (Digenea) from western Mediterranean fishes: three rare species

Three little-known opecoelid digeneans from marine fishes off Corsica, France, are redescribed and their relationships discussed. Plagioporus novella Maillard & Lambert, 1978 from Conger conger is transferred to Podocotyle as P. novella (Maillard & Lambert, 1978) n. comb. The new combinations Podocotyle tohei (Yamaguti, 1970) and P. congeri (Yamaguti, 1970) are formed for species originally assigned to Plagioporus. Podocotyle temensis Fischthal & Thomas, 1970 from Epinephelus guaza is redescribed and compared with the other Podocotyle species reported from the Mediterranean. A third species, Pseudopecoeloides chloroscombri (Fischthal & Thomas, 1970) n. comb. (was Podocotyloides), is redescribed from three Trachurus species and a key to the species of this Pseudopecoeloides is given.     

The life cycle of Australapatemon magnacetabulum (Digenea: Strigeidae) from Northwestern Argentina

The life cycle of Australapatemon magnacetabulum Dubois, 1988 was resolved experimentally. Planorbid snails Biomphalaria tenagophila (d'Orbigny, 1835) collected in a small pond at the confluence of the San Lorenzo and Arias Rivers, near Salta City, Province of Salta, Argentina, were found to be shedding furcocercous cercariae possessing 4 pairs of penetration glands, 1 pair of unpigmented eyespots, 6 pairs of flame cells in the body, and 1 pair in the tail stem. Metacercariae were found encysted in naturally, and experimentally, exposed leeches Helobdella adiastola Ringuelet, 1972, Helobdella triserialis (Blanchard, 1849), Haementeria eichhorniae Ringuelet 1978, and Haementeria sp., and within their sporocysts in naturally infected planorbid intermediate hosts. Sexually mature adults were recovered from domestic chicks and a duck 8-28 days postexposure by metacercariae from leeches. The identification of the species was based upon the characteristic large ventral sucker and a genital cone, crossed by a hermaphroditic duct with internal folds, occupying approximately a 1/4 to 1/5 of the hindbody.     

The life-cycle of Helicometra gibsoni n. sp. (Digenea: Opecoelidae)

The life-cycle of Helicometra gibsoni n. sp., an opecoelid trematode of marine fishes, is elucidated and the life-history stages are described. Natural infections with the cercariae, which are typically opecoelid in many respects but characterised by having very long, extensile tails, were found in the intertidal snail Anachis terpsichore collected from the Lawson's Bay Coast, Bay of Bengal. Metacercariae were found in the thoracic muscles of the shooting shrimp Alphaeus malabaricus as prominent, reddish-brown, oval cysts. Laboratory experiments demonstrated that 14 days are required for the development of cercaria into the infective metacercarial stage in shrimps. Natural infections with the adult fluke were found in Scorpaenopsis cirrhosus. Therapon jarbua served as an experimental host. Fourteen-day-old metacercariae fed to T. jarbua developed into egg-producing adults in 40–43 days. Intra-specific variations noted in the flukes obtained from natural and experimental infections are presented. H. fasciata of Madhavi (1975) is regarded as a synonym of H. gibsoni.     

New plagioporines (Digenea: Opecoelidae) from deep-sea fishes of the North Atlantic Ocean

Three new species of digenean are described from demersal fishes taken in deep waters of the northwestern and northeastern Atlantic Ocean: Podocotyle schistotesticulata n. sp. from Antimora rostrata; P. harrisae n. sp. from Coryphaenoides (Lionurus) carapinus; and Gaevskajatrema halosauropsi n. sp. from Halosauropsis macrochir. The status of the nominal species of the genus Podocotyle Dujardin, 1845 is presented in annotated summary, along with a tabulation of the distinctive characteristics of recognised species of the genus. Gaevskajatrema Gibson & Bray, 1982 is discussed and its diagnosis amended.     

Clarification of Cercaria sevillana (Digenea: Microphallidae) life cycle using morphological and molecular data

Cercaria sevillana is the cercaria larval stage that infects the gonads and the digestive gland of its first intermediate host, Nassarius reticulatus. In this study the decapodous crustacean Carcinus maenas was used to determine if it would serve as second intermediate host in the parasite's life cycle. The latter hypothesis was based on the knowledge that C. maenas is the second intermediate host of several other digenean species. After dissection, it was possible to observe encysted metacercariae in the antennal glands of the green crab. After biochemical excystment, the metacercariae were processed for light and scanning electron microscopy. The morphological features observed led us to conclude that this species was a microphallid fluke, and it was identified as Gynaecotyla longiintestinata. To establish a possible relationship between C. sevillana and this metacercariae, the ITS1 region was analyzed. Thus, DNA was extracted from C. sevillana and from the cysts isolated from the antennal glands. The ITS1 region was amplified and sequenced, and the alignment clearly demonstrated that the cercaria and the metacercariae belonged to the same species, G. longiintestinata.     

Diplobulbus brayi n. sp. (Digenea: Opecoelidae) from Odax acroptilus (Perciformes: Odacidae) off Western Australia

Diplobulbus brayi n. sp. is described from the small intestine of Odax acroptilus (Perciformes: Odacidae) from Point Peron in southern Western Australia. One of the five previously described species of Diplobulbus, D. vitellosus Bilqees, 1972 from Tetraodon lunaris (now Lagocephalus lunaris), is synonymised with Alloheterolebes indicus (Gupta, 1968) Hafeezullah, 1971, which is known from the same host in the Indian Ocean. D. brayi n. sp. can be distinguished from the remaining four species of Diplobulbus by the distinct interruption of the vitelline follicles at the ventral sucker, its more elongate form and its long post-testicular space. Diplobulbus is so far restricted to the Indo-Pacific region and appears to be stenoxenic to labroid fishes. This is the first record of a trematode from an odacid fish.     

The life cycle of Monorchis parvus (Digenea: Monorchiidae) demonstrated by developmental and molecular data

Cercaria cerastodermae I, a digenean parasite of Cerastoderma edule, was recorded for the first time in the Atlantic Ocean off the Iberian peninsula. Sporocysts were present in the hemolymph of the digestive gland, gonad, gills, and foot of the mollusc. Most of the cercariae present within sporocysts were encysted as metacercariae. The corresponding adult stages were obtained after experimental infection of several Diplodus sargus artificially reared in fish farms and that had previously been protected against natural infections. Numerous adult specimens of Monorchis parvus were collected in Diplodus annularis along the French Mediterranean coast. Comparison of wild and experimental adults allowed the adult stage of Cercaria cerastodermae I to be identified as M. parvus. Another monorchid, Monorchis monorchis, a parasite of Spondyliosoma cantharus, was found in the same Mediterranean area and compared with M. parvus. Additionally, ITS1 nuclear ribosomal DNA sequences of C. cerastodermae I and of the adults collected in naturally infected D. annularis and S. cantharus were obtained. Sequence data indicate that C. cerastodermae I corresponds to the adult of M. parvus found in D. annularis and is clearly distinct from M. monorchis found in S. cantharus.     

A new species of Podocotyloides Yamaguti, 1934 (Digenea: Opecoelidae) from a Western Australian temperate marine fish

A new species of Podocotyloides is described from Sillago bassensis caught off the coast of Western Australia. This is the second report of a species of this genus from Australian waters but the first of a new species. P. victori n. sp. is one of four species whose vitelline follicles extend into the forebody. It is distinguished from the other three species with vitelline follicles in the forebody by its relatively shorter forebody, smaller eggs and bipartite seminal vesicle. Pedunculotrema Fischthal & Thomas, 1970 is reduced to synonymy with Podocotyloides Yamaguti, 1934.     

Chemical Nature and Mode of Stabilization of Egg-shell in Helicometra pulchella (Rudolphi, 1819) (Digenea: Opecoelidae)

The chemical nature and mode of stabilization of egg-shell protein in digenetic trematode Helicometra pulchella (Rudolphi, 1819) have been investigated using histochemical techniques. It was found that the egg-shell is stabilized by quinone-tanning together with dityrosine. Other structural proteins (elastin, collagen and keratin-like proteins), glycogen and acid mucopolysaccharides were absent in egg-shell. Tyrosine was present in vitelline cells and immature egg-shell indicating that the proteins involved in quinone-tanning were tyrosine rich and tyrosyl residues are modified to form dityrosine in mature egg-shell.     

The life cycle of Gyliauchen volubilis Nagaty, 1956 (Digenea: Gyliauchenidae) from the Red Sea

Although nothing is known about gyliauchenid life cycles, molecular phylogenetic studies have placed the Gyliauchenidae Fukui, 1929 close to the Lepocreadiidae Odhner, 1905. The gyliauchenid Gyliauchen volubilis Nagaty, 1956 was found in the intestine of its type-host, Siganus rivulatus, a siganid fish permanently resident in a lagoon within the mangrove swamps on the Egyptian coast of the Gulf of Aqaba. Larval forms of this trematode (mother sporocysts, rediae and cercariae) were found in the gonads and digestive gland of Clypeomorus clypeomorus (Gastropoda: Cerithiidae), a common snail in the same lagoon. So, this life cycle of G. volubilis was elucidated under natural conditions: eggs are directly ingested by the snail; mother sporocysts and rediae reach their maturity 3-6 and 11-13 weeks post-infection; rediae contain 23-29 developing cercariae; fully developed cercariae are gymnocephalus, without penetration glands, emerge from the snail during the night 16-18 weeks post-infection and rapidly encyst on aquatic vegetation (no second intermediate host); encysted metacercariae are not progenetic; 4-day-old metacercariae encysted on filamentous algae fed to S. rivulatus developed into fully mature worms 6-8 weeks post-infection. The cycle was completed in about 26 weeks and followed one of the three known patterns of lepocreadiid life cycles, and except for the gymnocephalus cercariae, the other larval stages are very similar to those of lepocreadiids. Generally, the life cycle of G. volubilis implicitly supports the phylogenetic relationship of Gyliauchenidae and Lepocreadiidae inferred from molecular phylogenetic studies.     

Macvicaria taksengi n. sp. (Digenea: Opecoelidae) in marine teleosts from Pinang,Malaysia

Summary A new species, Macvicaria taksengi (Opecoelidae: Plagioporinae), is described from the fishes Otolithes ruber and Sillago sihama from Pinang, Malaysia. It differs from most other members of the genus in the position of the ovary relative to the testes and the anterior position of the genital pore. A brief discussion on the Indo-West Pacific forms of the genus Macvicaria and related genera includes references to several new combinations: M. [Lebouria] isaitschikowi (Layman, 1930), M. [Plagioporus] sillagonis (Yamaguti, 1938), M. [Plagioporus] chrysophrys (Nagaty & Abdel Aal, 1969) and M. [Plagioporus (Plagioporus)] longisaccus (Fischthal & Kuntz, 1964).     

Two species ofCoitocaecum Nicoll, 1915 (Digenea: Opecoelidae) from Moreton Bay,Queensland, Australia

Two species ofCoitocaecum Nicoll, 1915,C. gymnophallum Nicoll, 1915 andC. michaeli n. sp., are recorded, described and figured from the intestine ofAcanthopagrus australis from Moreton Bay, off south east Queensland. The holotype ofC. gymnophallum Nicoll, 1915 is examined, measured and figured for comparison.C. glandulosum Yamaguti, 1934 andC. robustum Wang, 1984 are reduced to synonymy withC. gymnophallum. The host specificity ofCoitocaecum spp. is discussed.     

Effects of copper and zinc on the life cycle of Notocotylus attenuatus (Digenea: Notocotylidae)

Evans N. A. 1982. Effects of copper and zinc on the life cycle of Notocotylus attenuatus (Digenea: Notocotylidae). International Journal for Parasitology12: 363–369. The toxicity of copper and zinc to cercariae and metacercarial cysts of Notocotylus attenuatus was extremely low. The infectivity of cysts was not reduced even after exposure to high metal concentrations (10.0 p.p.m.) for six weeks whilst the encystment of cercariae was significantly impaired only by 10.0 p.p.m. of copper and by concentrations of zinc greater than 4.0 p.p.m. Metal-induced death of cercariae occurred most frequently during their attempts to encyst. Cercarial shedding from the first intermediate host Lymnaea peregra was, in contrast, substantially reduced by even low concentrations (0.1 p.p.m.) of both metals. Water hardness had a low influence on copper and zinc toxicity.