Some rare larval trematodes of prosobranch snails, Semisulcospira spp., in the Lake Biwa drainage system, central Japan

A total of 17737 individuals of prosobranch snails, Semisulcospira spp., were collected from Lake Biwa and its tributaries, central Japan, from 1995 to 1999. They were examined for trematode larvae. One species of Aspidogastrea and 28 species of Digenea were detected. This paper briefly describes five of the 28 digeneans: a tetracotyle metacercaria from S. niponica, Cercaria A (cystophorous cercaria) from S. reticulata, Cercaria B (echinostomatid cercaria) from S. libertina, Cercaria C (magnacauda cercaria) from S. niponica and Cercaria D (mutabile cercarium) from S. nakasekoae. They were rare and every one of them was obtained from one snail only once.     

The sexual adult of Cercaria praecox Walker, 1971 (Digenea: Fellodistomidae), with the proposal of Oceroma n. g.

A sexual adult trematode that is considered to be conspecific with the distinctive larval trematode Cercaria praecox Walker, 1971 is reported from the kyphosid fish Scorpis lineolata Kner in Moreton Bay, Queensland, Australia. The sexual adult is consistent with the cercarial body of Cercaria praecox in having a single caecum with an asymmetrical appendix, symmetrical testes immediately posterior to the ventral sucker, and the ovary and vitellarium both well posterior to the testes. This combination of characters is distinct within the Fellodistomidae Nicoll, 1909 and requires the proposal of a new genus, Oceroma n. g. Analysis of 28S rDNA sequences demonstrates that this species forms a clade with Coomera Dove & Cribb, 1995 within the Fellodistomidae. The life-cycle of the species is predicted to require two hosts and to involve the direct ingestion of the cercaria.     

Studies on Cercariae from Kuwait Bay. XI. Description and surface topography of Cercaria kuwaitae XI sp.n. (Digenea: Echinostomatidae)

A new echinostome cercaria, Cercaria kuwaitae XI sp.n., from the prosobranch gastropod Cerithidea cingulata (Gmelin) from Kuwait Bay is described. The new cercaria is characterized by 23 collar spines and primary excretory tubules with distinct diverticula. The cercaria encysts in the snail host and is similar to those of Acanthoparyphium sp. The surface topography of the redia, cercaria and metacercarial cyst wall is studied by scanning electron microscopy. This is the first echinostome cercaria to be recorded in a gastropod from the Arabian Gulf region.     

长尾蚴吸虫幼虫在菲律宾蛤仔的寄生部位及其组织化学的研究

本文报道长尾蚴吸虫幼虫在菲律宾蛤仔的寄生部位及其组织化学的研究,长尾蚴吸虫幼虫主要寄生于哈仔的生殖腺组织中,仅少部分进入生殖腺附近的消化腺,鳃等。受感染严重的蛤仔,其生殖腺的滤泡等组织被虫体占满并被耗尽,长尾蚴吸虫子胞蚴的胞壁及尾蚴的皮导主要含碱性蛋白质和粘蛋白,子胞蚴的胚球,尾蚴的吸盘,生殖原基,单细胞腺体主要ＤＮＡ阳性物质,排泄囊含丰富的碱性蛋白质;尾蚴体的中部含有呈颗粒团的粘蛋白和抗淀粉酶的     

A review of the currently recognised opecoelid cercariae,including the identification and emergence ecology of Cercaria capricornia XII (Digenea: Opecoelidae) from Nassarius olivaceus (Gastropoda: Nassariidae) in Central Queensland,Australia

A new opecoelid cercaria, Cercaria capricornia XII, is reported from Nassarius olivaceus in Capricornia, Central Queensland, Australia. Combined molecular and morphological data indicate that this cercaria is a member of the subfamily Opecoelinae. Cercaria capricornia XII is the first known opecoeline cercaria reported from a nassariid gastropod. Cercaria capricornia XII can be distinguished from other opecoelid cercariae by the combination of the presence of a 2-pointed stylet, body length and width, and the size of the tail. The emergence pattern for C. capricornia XII in captivity was erratic; rapid emergences of thousands of cercariae were interspersed by periods that sometimes exceeded a month in which no emergence occurred. There was no detectable pattern to or stimulus of the emergence. The molluscan host range of opecoelids is analysed in detail. Gastropods from the Buccinoidea, Cerithioidea and Rissooidea are hosts to both opecoeline and plagioporine cercariae, but the dominant subfamily infecting the Cerithioidea and Rissooidea is the Plagioporinae. The dominant marine host gastropod superfamily for opecoeline cercariae is the Buccinoidea; the family Nassariidae is contained in the Buccinoidea. The range of gastropod superfamilies known as hosts of plagioporines is much broader than that for opecoelines, which may be explained by the relative size of the two opecoelid families and perhaps by indications that the Plagioporinae is polyphyletic.     

Cercaria orospinosa Encountered in the Snail Melanopsis praemorsa L. from a Mountain Stream in Turkey

Cercaria orospinosa is the only cercaria shed by Melanopsis praemorsa snails in Savanda stream, Turkey. Magnitude of infestation of snails by this cercaria was correlated with size of the snails and strength of the water current. The highest degree of infestation occurred in June, while in winter it was reduced to zero. The cercariae were released from rediae, which were found in the hepatopancreas of the snails.     

Magnibursatus caudofilamentosa (Reimer, 1971) n. comb. (Digenea: Derogenidae) from the stickleback Gasterosteus aculeatus L. in Danish waters: a zoogeographical anomaly?

The adult of Magnibursatus caudofilamentosa (Reimer, 1971) n. comb. is described from the stickleback Gasterosteus aculeatus in eastern Danish waters. Its larval form, Cercaria caudofilamentosa Reimer, 1971, develops in the prosobranch mollusc Rissoa membranacea. It is distinguished from its only congener, M. skrjabini (Vlasenko, 1931) from gobiids in the Black Sea, by several features, including the thick, heavily muscled nature of the wall of the sinus-sac. The zoogeography of halipegine derogenids in fishes is discussed. The group is considered to have a distribution which reflects the extent of the ancient Tethys Sea: in this respect, the finding of Magnibursatus in Danish waters is an anomaly.     

Method for the individual maintenance of mollusks infected with Schistosoma larvae in a thermostatic apparatus

A technique has been suggested for individual maintenance of intermediate hosts of Schistosoma mansoni, molluscs of the genus Biomphalaria, in thermostat water bath with thermoregulator in order to study the host-parasite relationships in the mollusc-trematode system. Advantages of the suggested technique have been shown for studying total production of Cercaria when estimating the compatibility degree of various strains of S. mansoni and races of molluscs of some species of the genus Biomphalaria.     

Black Sea mollusc, Cerithium vulgatum (Gastropoda, Cerithiidae), a new intermediate trematode host

The mollusc Cerithium vulgatum was first recorded as a new intermediate host of trematodes from the Black Sea. Two species of cercariae (Cercaria I and Ceracaria II) parasitizing this mollusc were found and described. The general infestation of molluscs was 7.54 per cent. Eight species of larval trematodes parasitzing 7 other species of sea molluscs were found.     

Experimental research on the biological cycle of Phyllodistomum elongatum Nybelin, 1926 (Digenea: Gorgoderidae Looss, 1901)]

Experimental infection of Tinca tinca and Carassius auratus have demonstrated that Cercaria duplicata von Baer, 1827 is the larval form of Phyllodistomum elongatum Nybelin, 1926 and that the life-cycle occurs between Anodonta cygnea (intermediate host) and Tinca tinca or Carassius auratus (final host) without a second intermediate host. The life-history experimentally completed in the laboratory occurs in the following way: -- adult in the ureters of Tinca tinca and Carassius auratus; -- mother sporocyst and daughter sporocyst of Phyllodistorum elongatum in Anodonta cygnea give rise to the large-tailed rhopalocercous cercaria; -- metacercaria encysted within transformed tail in water.     

Transversotrema Chackai sp. Nov,adult of Cercaria Chackai,from Fishes (Digenea: Transversotrematidae)

Transversotrema chackai sp. nov. adult of Cercaria chackai, is described. They are found as adults beneath the scales of three species of fishes, Macropodus cupanus (CUV & VAL), M. cupanus var. Dayi (DAY) and Barbus puntius (HAM & BUCH). This species is compared with other known adults of the genus Transversotrema and the creation of a new species is justified.     

Phenotypic plasticity of six unusual cercariae in nassariid gastropods and their relationships to the Acanthocolpidae and Brachycladiidae (Digenea)

Species-level relationships of a complex of six putative acanthocolpid cercariae with ventral keels from nassariid gastropods from Capricornia, Queensland (Cercaria capricornia I–VI) were explored using mitochondrial and nuclear DNA sequence data. Analysis of the large subunit of nuclear ribosomal DNA (rDNA), the internal transcribed spacer 2 rDNA and subunit 3 of the nicotinamide-adenine-dinucleotide dehydrogenase mitochondrial gene indicates that the six distinct morphotypes previously identified relate to only three discrete genotypes. Consequently, the six cercarial morphotypes that were inferred to represent six species and distinguished previously based on morphology and behaviour, are considered here to be comprised of three species (i.e. Cercaria capricornia I and II are considered the same species, C. capricornia types III to V are considered to belong to a second species and C. capricornia VI is considered to comprise the third species in this complex). This recognition of reduced diversity following molecular analysis runs contrary to the more frequently reported uncovering of cryptic diversity, especially when larval trematodes are examined. Phylogenetic analysis of these morphologically unusual cercariae supports their inclusion in the Acanthocolpidae. Bayesian inference analysis identifies three distinct clades: (a) Stephanostomum + Monostephanostomum; (b) the Brachycladiidae and Pleorchis; and (c) Tormopsolus and the present cercariae. Genus-level identification of these cercariae remains uncertain given the current lack of available comparative genetic data on nucleic acid databases.     

The Ultrastructure of the Daughter Sporocyst Tegument of Cercaria vaullegeardi Pelseneer (Digenea, Hemiuridae)

The body wall of the daughter sporocyst of Cercaria vaullegeardi Pelseneer, 1906 is unusual for a species without a birth pore in consisting of an outer anucleated, microvillous syncytial tegument and a cellular subtegument which lacks secretory cells. In contrast, most other known daughter sporocysts without birth pores have a nucleated region above the microvillous region of the tegument. The significance and functional aspects of this structure are discussed.     

Cercaria splendens Szidat--larva of the trematode Azygia lucii Looss]

The belonging of the only one "gigantic cercaria", Cercaria splendens, to the species Azygia lucii was proved experimentally. The geographic distribution of A. lucii is considerably wider than it has been indicated up to now. The distribution area of A. robusta is also confined not only to the Asiatic part of the USSR. The following characters are suggested for distinguishing the Azygia species: the shape and size of the pharynx, the spread of vitellaria beyond the posterior border of the testes and ratio between the sizes of suckers.