Academic literature on the topic 'Lepocreadiidae'

AbstractAlthough nothing is known about gyliauchenid life cycles, molecular phylogenetic studies have placed the Gyliauchenidae Fukui, 1929 close to the Lepocreadiidae Odhner, 1905. The gyliauchenidGyliauchen volubilisNagaty, 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 ofClypeomorus clypeomorus(Gastropoda: Cerithiidae), a common snail in the same lagoon. So, this life cycle ofG. volubiliswas 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 toS. rivulatusdeveloped 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 ofG. volubilisimplicitly supports the phylogenetic relationship of Gyliauchenidae and Lepocreadiidae inferred from molecular phylogenetic studies.

The monotypic genus Deraiotrema Machida, 1982 has only been reported once, from the orbicular batfish Platax orbicularis (Forsskål) in the waters around Palau in Micronesia (Machida, 1982). It has a body-shape similar to other lepocreadiids from batfishes, such as species of Bianium Stunkard, 1930 and Diploproctodaeum La Rue, 1926, but differs in having multiple testes in ventral and dorsal layers. Here we report Deraiotrema platacis Machida, 1982 for just the second time, infecting the dusky batfish Platax pinnatus (Linnaeus) from the waters off Lizard Island on the northern Great Barrier Reef. We present a molecular phylogenetic analysis of the position of this genus inferred from 28S rDNA sequences. Surprisingly, we find the species most closely related to Echeneidocoelium indicum despite the infection of completely unrelated hosts and the presence of two characters (lateral fold in the forebody and multiple testes) that are found elsewhere in the Lepocreadiidae. We conclude that homoplasy within the Lepocreadiidae is extensive and that morphology-based prediction of relationships has little prospect of success.

Metacercaria specimens of the genus Opechona (Trematoda: Digenea: Lepocreadiidae) are described parasitizing "coelenterates" (scyphomedusae and ctenophores) from Southeastern Brazil (São Paulo state). The worms are compared to other Opechona species occurring on the Brazilian coast, but no association has been made because only adult forms of these species have been described. Suppositions as to the possible transference of the parasites are made.

On the base of analysis of original and literature data four basic strategies were distinguished in host-search behaviour of trematode cercariae. There are active search (1), passive waiting (2), active waiting (3) and prey mimetism (4). Many of the Xiphidiocercaria, cercariae of some Echinostomatidae, Psilostomatidae, Acanthocolpidae and Lepocreadiidae as well as cercariae of Fasciolidae, Haploporidae, Notocotylidae, Pronocephalidae, Gladorchiidae and some Haplosplanchnidae encysting on surface of underwater substrates follow the first strategy. These cercariae demonstrate a continuous swimming and photo-, geo- and sometimes chemoreactivity. The second strategy is characteristic for cercariae of Microcerca group with ambuscade behaviour. These cercariae exhibit pronounced oscilloreactions whereas other orienting reactions are feebly marked or even absent. Cercariae of Bucephalidae and Hemiuroidea which float passively in the water column also follow the strategy of passive waiting. The strategy of active waiting is characteristic of cercariae (Furcocercaria, Pleurolophocerca, Parapleurolophocerca, etc.) with an intermittent type of locomotion, where periods of active movement alternate regularly with periods of repose. These cercariae demonstrate a wide range of orienting reactions. The pray mimetism strategy exhibit cercariae of some trematodes (Azygiidae, Bivesiculidae, some Echinostomatidae, Heterophyidae, Lepocreadiidae, Gyliauchinidae, etc.) infecting their hosts passively per os. The active searching cercariae (strategy 1) usually infect sedentary animals or mobile ones but during periods of their minimal locomotory activity. The cercariae exploiting strategies 2–4 predominantly infect mobile animals. It was emphasized that the model of foraging strategies produced by Schoener (1971) and Huey and Pianka (1981) for free-living animals could be applied to analysis of cercarial hostsearch behaviour.

Hypocreadium toombo n. sp. is described from the balistid Pseudobalistes fuscus from the waters off New Caledonia. It is distinguished by a series of characters shared by no other Hypocreadium species. The specimens are always slightly longer than wide, have a distinct anterior notch, have the vitelline fields confluent or nearly so in the forebody and have the terminal ends of the caeca pointing anteriorly. Other lepocreadiid species also recorded from New Caledonian waters are Lobatocreadium exiguum from P. fuscus, Intusatrium robustum from Bodianus perditio and B. loxozonus, Postlepidapedon secundum from Choerodon graphicus and Lepidapedoides angustus from Epinephelus fasciatus.

A checklist of cercariae parasitizing marine molluscs from Patagonian coast, Argentina, based on literature sources and new records here presented.In total, cercariae of 31 species of marine digeneans, including 11 new records here presented, are known to infect 20 species of molluscs (14 in nine gastropods species; 17 in 11 bivalve species). These records include two species of Aporocotylidae, four Bucephalidae, one Fellodistomidae, five Gymnophallidae, one Hemiuroidea, four Lepocreadiidae, two Microphallidae, five Monorchiidae, one Notocotylidae, one Philophthalmidae, two Renicolidae, one Schistosomatidae and two Zoogonidae. For each digenean species, their hosts, habitat type, localities, infection site, prevalence, life cycle advances, and access numbers in helminthological collections and GenBank, when available, are detailed. Regarding the life cycles, eight were completely elucidated and four were partially elucidated. Moreover, there are molecular data for 15 species. The data here presented constitutes an advance in the parasites biodiversity knowledge and their life cycles.

"The biodiversity and ecology of marine cercariae in Australia is poorly known. Although nassariid gastropods are widely distributed in Australia and are expected to have a diverse parasite fauna similar to that of other nassariids worldwide, their cercariae have not been characterised. Nassarius dorsatus, N. olivaceus and N. pullus were collected at three separate estuarine localities in central Queensland between August 2004 and August 2006 and their emergent cercariae characterised using morphological and molecular methods. Fifteen morphotypes of cercariae from six families that infect fishes and birds as definitive hosts were characterised. The highest richness was within the Acanthocolpidae (nine morphotypes) which comprised three cercariae interpreted as species of Stephanostomum and a complex of six unusual cercariae with a ventral keel. Molecular characterisation of these six cercariae supported their placement in the Acanthocolpidae and indicated that they comprised only three species, two of which displayed marked phenotypic plasticity. Molecular analysis supported the characterisation of the three species of Stephanostomum and suggested that one of the unusual cercariae was a species of Stephanostomoides. Dissection of fish from Sandy Point provided a single match; the sequence for a metacercaria in Valamugil buchanani, the blue-tail mullet, was identical to that of one of the species of Stephanostomum. There were two cercariae from the Echinostomatidae and one from each of the Lepocreadiidae, Microphallidae, Opecoelidae and Zoogonidae. Molecular analyses supported the placement of the cercariae from the Echinostomatidae, Lepocreadiidae, Opecoelidae and Zoogonidae within their respective families. The cercaria from the Lepocreadiidae was identified by comparison to known adult data and putatively corresponds to Prodistomum keyam, a parasite of Monodactylus argenteus, the silver moony or butter bream, common in the study region. Morphological analysis supported the characterisation of both of the Echinostomatidae as species of Himasthla. Although no other cercariae could be characterised to genus level, the opecoelid cercaria was determined to be in the subfamily Opecoelinae. Nassarius olivaceus was infected by three acanthocolpid cercariae and one cercaria from each of the other families. Nassarius dorsatus was infected by five acanthocolpid cercariae and one each from the Echinostomatidae and Lepocreadiidae. Nassarius pullus was infected by a single cercaria from the Echinostomatidae. Most cercariae were specific to a single species of gastropod; only four infected two species and none infected all three. Cercariae that infect fish as a definitive host were found at all three localities; but cercariae that infect birds were restricted to a single locality, Sandy Point at Corio Bay, important for domestic and migratory bird species. These results emphasise the relative significance of Sandy Point as an important bird habitat. In total, 126 infections were diagnosed (115 by cercarial emergence), with both the highest frequency of infection and number of infections in N. olivaceus (frequency 5.3%; n=102; 81% of infections), followed by N. dorsatus (1.1%; 20; 16%) and N. pullus (0.2%; 4; 3%). The highest number of infections occurred at Sandy Point (66; 52% of infections), followed by Cawarral Creek (38; 30%) and then Ross Creek (22; 17%). The highest number of infections was by the Acanthocolpidae (54; 43%). Diagnosis of infection by emergence was suitable for all cercariae except the opecoelid, which was underdiagnosed. Nassarius olivaceus had the longest survival in captivity (~4.5 y), followed by N. dorsatus (~0.8 y) and N. pullus (~0.3 y). Almost all infections remained patent for the life of the gastropod. Families commonly found in nassariids worldwide include Acanthocolpidae, Echinostomatidae, Lepocreadiidae and Zoogonidae. Nassariid gastropods are also the dominant marine first intermediate hosts for the Acanthocolpidae, Lepocreadiidae and Zoogonidae and one of the three most common first intermediate host families for species of marine Himasthla. Molecular relationships also indicate that the Acanthocolpidae and Brachycladiidae may actually be comprised of three discrete groups, the Stephanostomum + Monostephanostomum group, the Brachycladiidae, and a group of non-Stephanostomum species comprising Pleorchis, Tormopsolus and Stephanostomoides. This research adds information about the parasite assemblages of nassariid gastropods in Australia, adding 12 new cercarial species and 16 new host-parasite records. Cercarial reports for the Acanthocolpidae, Echinostomatidae, Lepocreadiidae, Opecoelidae and Zoogonidae have been comprehensively reviewed and patterns of association between nassariids and their common parasite families presented. As well, this research has provided a potential avenue for a review of the Acanthocolpidae, a family which is currently considered a ‘catch-all’ group."