A revision of Petasiger Dietz, 1909 (Digenea: Echinostomatidae) and a key to its species

Petasiger Dietz, 1909 is revised, and a key to and lists of the records and hosts of the 18 recognised species are presented. The recognised species are: P. exaeretus Dietz, 1909, P. australis Johnston & Angel, 1941, P. combesi Zamparo, Overstreet & Brooks, 2005, P. floridus Premvati, 1968, P. grandivesicularis Ishii, 1935, P. islandicus Kostadinova & Skirnisson, 2007, P. johnstoni n. sp., P. megacanthus (Kotlán, 1922), P. minutissimus Gogate, 1934, P. neocomense Fuhrmann, 1927, P. nitidus Linton, 1928, P. novemdecim Lutz, 1928, P. oschmarini Kostadinova & Gibson, 1998, P. phalacrocoracis (Yamaguti, 1939), P. pseudoneocomense Bravo-Hollis, 1969, P. pungens (Linstow, 1894), P. soochowensis Ku, Chiu, Li & Zhu, 1977 and P. variospinosus (Odhner, 1910). Seven of these species are redescribed on the basis of type and newly collected material. P. laricola Ku, Chiu, Li & Zhu, 1977, Echinochasmus fotedari Chishti & Mir, 1989 and P. neocomense of Cankovi?, Kazi? & Milka (1983) are considered synonyms of P. pungens; P. longicirratus Ku, 1938, P. skrjabini Bashkirova, 1941 and P. nitidus of Chen et al. (1985) synonyms of P. neocomense; P. caribbensis Nassi, 1980 a synonym of P. novemdecim; and P. tientsinensis Ku, Chiu, Li & Zhu, 1977 a synonym of P. exaeretus. P. johnstoni n. sp. is described from Tachybaptus ruficollis novaehollandiae in Australia. It is readily distinguished from the most closely-related P. grandivesicularis Ishii, 1935 and P. australis Johnston & Angel, 1941 by the smaller size of the body and angle collar spines and differences in most other metrical characters. Species attributed to Petasiger which are here considered species inquirendae are: P. antigonus Nigam, 1944 sp. inq., P. chandleri Abdel-Malek, 1952 sp. inq., P. jubilarum Elperina in Skrjabin, Petrov & Bashkirova, 1947 sp. inq., P. nicolli Pande, 1939 sp. inq. and P. spasskyi Oshmarin in Skrjabin, Petrov & Bashkirova, 1947 sp. inq.; and Echinoparyphium inopinatum (Baer, 1959) n. comb. is a species previously attributed to Petasiger.     

A comparative study of cercarial chaetotaxy in two species of Petasiger Dietz, 1909 (Digenea: Echinostomatidae)

The chaetotaxy of two types of cercariae found in naturally infected Planorbis planorbis in a brackish water lake in Bulgaria is described. The comparison of the sensory patterns shows the distinct species status of the cercariae of P. grandivesicularis and Petasiger sp. The morphology of the cercaria of Petasiger sp. is described and compared with that of known large-tailed Petasiger cercariae from the Palaearctic. It is suggested that the unidentified species of cercaria is probably a larval stage of P. pungens.     

Redescriptions of two echinostomes from birds in Paraguay,with comments on Drepanocephalus Dietz, 1909 and Paryphostomum Dietz, 1909 (Digenea: Echinostomatidae)

Two species of echinostomatid trematodes from Paraguayan birds are redescribed: these are Drepanocephalus spathans Dietz, 1909 from Phalacrocorax olivaceus and Paryphostomum segregatum Dietz, 1909 from Coragyps atratus. The genera Drepanocephalus Dietz, 1909 and Paryphostomum Dietz, 1909 are redefined and the species previously assigned to them reviewed. Paryphostomum mexicanum (Lamothe-Argumedo &; Pérez-Ponce de León, 1989) n. comb. and P. parvicephalum (Rietschel &; Werding, 1978) n. comb. are transferred from Drepanocephalus to Paryphostomum. A key to the species of Paryphostomum is presented, and the nominal species of Echinostoma Rudolphi, 1809, Nephrostomum Dietz, 1909 and Artyfechinostomum Lane, 1915 previously ascribed to this genus are commented upon. New combinations for species previously attributed to Paryphostomum are: Echinostoma pentalobum (Verma, 1936) n. comb.; E. baiyangdienense (Ku, Pan, Chiu, Li &; Chu, 1973) n. comb.; Nephrostomum dollfusi (Agarwal, 1959) n. comb.; and Artyfechinostomum neotoma (Jain, 1953) n. comb. Species attributed to Paryphostomum which are here considered species inquirendae are: Paryphostomum (Lepustomum) mehrii Jain, 1953 sp. inq.; P. fragosum (Dietz, 1909) sp. inq.; P. horai Baugh, 1950 sp. inq.; P. huaccaci Ibáñez, 1974 sp. inq.; P. agrawali Gupta &; Singh, 1986 sp. inq.; P. siddiqui Gupta &; Singh, 1986 sp. inq.; P. durgensis Sapre, 1969 sp. inq.; and P. globorchum Oshmarin, 1970 sp. inq.     

Experimental data on the life-cycle of Petasiger grandivesicularis Ishii, 1935 (Trematoda: Echinostomatidae)

Larval stages of an echinostome were found in Planorbis planorbis in a brackish water lake on the Black Sea coast of Bulgaria. The cercaria is a large-tailed form with 19 collar spines. The life-cycle was completed in the laboratory using aquarium-reared fishes (Lebistes reticulatus, Puntius tetrazona tetrazona, P. pentazona pentazona, P. nigrofasciatus, Carassius auratus auratus and Xiphophorus helleri) as second intermediate hosts and canaries as definitive hosts. The redia, cercaria, metacercaria and experimentally reared adults are described. The species is determined as Petasiger grandivesicularis Ishii, 1935, and its cercaria is compared in detail with those of related forms. A key to the known large-tailed echinostome cercariae from the Palaearctic Region is presented.     

A revision of Patagifer Dietz, 1909 (Digenea: Echinostomatidae) and a key to its species

Patagifer Dietz, 1909 is revised and a key to the species is presented. P. oweni n. sp. is described from Threskiornis molucca (Cuvier) in the Western Province of Papua New Guinea and distinguished from the related P. chandrapuri Srivastava, 1952 by: the shape of the pair of large angle spines (cudgel-shaped vs sub-rectangular); pointed (vs rod-shaped) marginal spines; a smaller body and internal organs; more anteriorly located testes; and larger eggs. The new species differs from P. brygooi Richard, 1964 in its larger body, head collar, suckers, pharynx and eggs, longer oesophagus and testes, the latter being also more elongate and more anteriorly located, and a different number of collar spines (61-62 vs 59). P. bilobus (Rudolphi, 1819) (the type-species), P. parvispinosus Yamaguti, 1933, P. chandrapuri and P. vioscai Lumsden, 1962 are redescribed on the basis of museum and newly collected material. The variations in the number and size of the collar spines and other metrical characters of P. bilobus are studied in two different host species from Europe, Plegadis falcinellus and Platalea leucorodia. Other species considered valid are: Patagifer consimilis Dietz, 1909, P. acuminatus Johnston, 1917, P. fraternus Johnston, 1917, P. wesleyi Verma, 1936, P. brygooi and P. toki Onda, Imai & Ishii, 1983. P. plegadisi Sakla, Monib & Mandour, 1988 and P. simarai Nigam, 1944 are considered synonyms of P. bilobus, and P. sarai Saksena, 1957 is placed in synonymy with P. chandrapuri. Forms considered dubious are: P. bilobus of Machida et al. (Jpn J Parasitol 15:339, 1966) and Machida (Bull Natl Sci Mus Tokyo 11:157-160, 1968), P. simerai [sic] of Mehra (The fauna of India and adjacent countries. Platyhelminthes, 1980), P. skrjabini Hilmy, 1949 sp. inq. and P. srivastavai Peter, 1954 sp. inq. Lists of the records and hosts of the 11 valid species are included.     

Morphological and molecular data for larval stages of four species of Petasiger Dietz, 1909 (Digenea: Echinostomatidae) with an updated key to the known cercariae from the Palaearctic

Recent molecular phylogenetic studies on fish tapeworms of the genus Caryophyllaeus Gmelin, 1790 (Cestoda: Caryophyllidea), parasites of cyprinid fishes in the Palaearctic Region, have revealed unexpected phenotypic plasticity that seems to be related to definitive hosts. In the present paper, Caryophyllaeus brachycollis Janiszewska, 1953 is redescribed and its two morphotypes are circumscribed on the basis of newly-collected specimens. Morphotype 1 from barbels [Barbus spp. including the type-host Barbus barbus (L.); Barbinae] and chubs (Squalius spp.; Leuciscinae) is characterised by a more robust body with spatulate scolex, which is only slightly wider than a very short neck region, and the anterior position of the testes and vitelline follicles, which begin immediately posterior to the scolex. Specimens of Morphotype 2 from breams (Abramis spp., Ballerus spp. and Blicca spp.; Abraminae), which have been previously misidentifed as Caryophyllaeus laticeps (Pallas, 1781), possess a more slender body with a flabellate scolex, which is much wider than a long neck, and the first testes begin at a considerable distance posterior to the first vitelline follicles. Despite conspicuous differences in the scolex morphology and the anterior extent of the testes and vitelline follicles, both morphotypes are identical in the morphology of the posterior end of the body, in particular that of the cirrus-sac, which is large, thick-walled, elongate-pyriform, and contains a long cirrus, and in the distribution of the vitelline follicles, which surround medially vas deferens near the cirrus-sac. A specimen of Morphotype 1 from B. barbus from the Argens River, France, is designated as neotype of C. brachycollis. The presence of phenotypic plasticity in morphological characteristics previously used for differentiation of species of Caryophyllaeus may confound species identification, which is crucial for biodiversity, ecological and evolutionary studies. To avoid these potential problems, combination of morphological and molecular data is strongly recommended.     

Redescription of Echinostoma trivolvis (Cort, 1914) (Trematoda: Echinostomatidae) with a discussion on its identity

The life-cycle of Echinostoma trivolvis (Cort, 1914) has been completed experimentally and the validity and identity of this species are discussed. Synonyms for cercariae and adults of E. trivolvis are as follows: Cercaria trivolvis Cort, 1914, C. trisolenata Faust, 1917, C. acanthostoma Faust, 1918, C. complexa Faust, 1919; Distoma echinatum Zeder, 1803, of Leidy (1888, 1904) and Hassall (1896); E. echinatum (Zeder, 1803) of Hassall (1896), Stiles & Hassall (1895), Barker & Laughlin (1911), Barker (1916) and Swales (1933); E. revolutum (Frölich, 1802) Dietz, 1909 of Johnson (1920), Fallis (1934), Beaver (1937) and Fried & co-workers (1968–1989); E. armigerum Barker & Irvine, 1915; E. coalitum Barker & Beaver, 1915; E. callawayensis Barker & Noll, 1915; E. paraulum Dietz, 1909 of Miller (1937); E. multispinosum Vigueras, 1944; and Echinoparyphium contiguum Barker & Bastron, 1915. The first intermediate host is the planorbid snail Helisoma trivolvis. Second intermediate hosts are various pulmonate and prosobranch snails, mussels, planarians, fishes, frogs, tadpoles and freshwater turtles. Final hosts are various birds and mammals. E. trivolvis occurs only in North America.     

Life-cycle ofEchinochasmus macrocaudatus n. sp. (Trematoda: Echinostomatidae)

The life-cycle ofEchinochasmus macrocaudatus n. sp., from mother-sporocyst to adult, was studied under natural and experimental conditions. The aquatic snailsPyrgophorus coronatus (Prosobranchia: Hydrobiidae) from cenotes (sinkholes) of the Yucatan Peninsula, Mexico, served as the first intermediate host of this parasite, liberating cercariae possessing an extremely large tail (zygocercous cercaria). Metacercariae of the fluke were encysted on the gills of the characid fishAstyanax fasciatus (natural infection); the poeciliidsXiphophorus variatus andPoecilia velifera were suitable experimental hosts. Feeding experiments withE. macrocaudatus metacercariae resulted in finding adult trematodes, possessing 22 collar spines (with 2 angle spines on each side), in the intestine of chicks and ducks.E. macrocaudatus differs from the most closely related species,E. schwartzi Price, 1931, by its larger oral sucker (138–170×118–176 m) and by the position of the acetabulum which is situated at two-fifths of the body length.     

The life cycle of Echinochasmus bagulai (Trematoda: Echinostomatidae)

The life history of Echinochasmus bagulai, an echinostomatid trematode in birds, is reported and stages in the life cycle are described. Natural infections with cercariae, which are of the gymnocephalous type, were found in the thiarid snail Thiara tuberculata. Metacercarial cysts were found in the gills of Aplocheilus panchax, Oryzias melastigma, Gambusia affinis and Channa punctata. Adults were obtained in the small intestine of Ardeola grayi. In laboratory experiements development of cercariae into infective metacercariae took 10 days in the gills of A. panchax. Mature flukes were recovered in 10 days in the small intestine of experimentally infected 1-day-old leghorn chicks. The eggs collected from the faeces of these infected chicks were incubated at 39 degrees C. The free-swimming miracidia were found on the fifth day of incubation.     

Redescription of Hemiclepsis quadrata (Moore, 1939) n. comb. (Hirudinea: Glossiphoniidae)

Hemiclepsis quadrata, which is the only representative of the genus so far reported in Africa, is redescribed. Illustrations showing the diagnostic features of the taxon are provided for the first time. A thorough study of the holotype and one of the paratypes, as well as additional specimens, revealed that Moore overlooked certain important taxonomic features when he described the leech as a Batracobdella species. The transfer of this species to the genus Hemiclepsis is based on the following features exhibited by this leech: dilated head region, three pairs of eyes, central proboscis pore, ten pairs of crop caeca and small genital atria.     

Life-cycle,delimitation and redescription of Echinostoma revolutum (Froelich, 1802) (Trematoda: Echinostomatidae)

The life-cycle of Echinostoma revolutum (Froelich, 1802) Dietz, 1909 has been completed experimentally beginning with infected snails collected at the type-locality, near Erlangen, Germany. Based on the specimens obtained, each stage of the life-cycle has been redescribed. Important taxonomic features are discussed and hitherto unknown characteristics are described. Synonyms for E. revolutum are: Fasciola revoluta Froelich, 1802; Echinostoma paraulum Dietz, 1909; E. audyi Lie & Umathevy, 1965; and E. ivaniosi Mohandas, 1973. Adults and larvae described as E. revolutum in other works are found to be identical with Echinostoma echinatum (Zeder, 1803), E. trivolvis (Cort, 1914), E. jurini (Skvortsov, 1924), E. caproni Richard, 1964, Moliniella anceps (Molin, 1859), Echinochasmus beleocephalus (Linstow, 1873) and other echinostome species. For nearly a century, incorrect morphological, biological, life-cycle and host information has been attributed to E. revolutum, and at times these data have contributed to the diagnoses of the species. Occasionally, authors actually working with E. revolutum have ascribed their results to other species. Based on extensive experimental life-cycle studies beginning with infected snails from type-localities, it is shown that (1) the first intermediate host is a lymnaeid snail; (2) the second intermediate hosts are various pulmonate and prosobranch snails, mussels, frogs and freshwater turtles; (3) the final hosts are birds; (4) E. revolutum cercariae and adults have 37 collar spines; (5) the species occurs only in Europe and Asia; (6) Cercaria echinata Siebold, 1937, Echinostoma echinatum (Zeder, 1803) and E. jurini (Skvortsov, 1924) are the closely related 37-spined allies in Europe; and (7) species specific characteristics are expressed only in the larvae and the host-parasite relationships. The adults of E. revolutum cannot be identified using morphological criteria and it is proposed that worms with 37 collar spines belonging to the genus Echinostoma and occurring in naturally infected birds in Europe and Asia be referred to an “E. revolutum group.”     

Artyfechinostomum sufratyfex Lane, 1915 (Trematoda:Echinostomatidae), a parasite of mammals in Southern Vietnam

Trematoda Artyfechinostomumn sufratyfex Lane, 1915 was found in different mammal species of Southern Vietnam. Original measurements of this species from domestic pig, black rat, and Asian palm civet are given.     

Petasiger oschmarini n. sp. (Digenea: Echinostomatidae) in the grebes Podiceps grisegena (Bod.) and P. auritus (L.) (Aves: Podicipedidae) from Kamchatka,Russia

A re-examination of three sets of trematodes collected in two species of grebes, Podiceps grisegena and P. auritus, from the Kamchatka region of eastern Russia, previously identified as Petasiger neocomense, revealed that they actually represent a new species, which is named Petasiger oschmarini. Characteristic morphological features of the new species include: a head collar possessing a constant number of 19 spines; a large cirrus-sac comparable in size to the ventral sucker, containing a bipartite seminal vesicle and a well-developed pars prostatica; a large bulb-like cirrus similar in size to the testes; a long forebody; a long oesophagus; testes situated obliquely or symmetrically; and lateral vitelline fields which are not confluent in the forebody. The new species is distinguished from all Palaearctic and Nearctic members of Petasiger which possess 19 collar spines. The material described by Oschmarin (1950) as P. neocomense is considered to be conspecific.     

Development of mother sporocysts of Echinostoma caproni (Trematoda: Echinostomatidae)

New data on the migration and development of Echinostoma caproni mother sporocysts in two mollusk species of the genus Biomphalaria are obtained. It is confirmed, that the formation of primary and second generative cells takes place only as a result of undifferentiated cells' proliferation and following differentiation of some of them. These processes in miracidium, as well as in the parasitic stage of mother sporocyst, take place in a special organ, germinal mass, which occupies caudal position in both cases. The supposition of the role of germinal mass as the universal centre of multiplication and development of generative elements in all generations of Echinostoma caproni parthenites is confirmed. It is established, that mother sporocysts do not relize their reproductive potential completely, and the degree of its realization depends on the conditions arising in the host organism.     

Echinochasmus leopoldinae n. sp. (Trematoda: Echinostomatidae) and data on its life-cycle

The echinostomatid trematodeEchinochasmus leopoldinae n. sp. is described on the basis of adults found in the intestine of chicks and mice experimentally infected with metacercariae from the gills of the cichlid fishesCichlasoma urophthalmus andC. synspilum from the Peninsula of Yucatan.E. leopoldinae, which had previously been misidentified asE. zubedakhaname Nasir & Díaz, 1968, is characterised by the presence of 20 collar spines with one angular spine on each side and vitelline follicles confluent in the posterior part of the body. A differential diagnosis ofEchinochasmus species possessing 20 collar spines is provided, and the developmental stages (redia, cercaria, metacercaria and adult) ofE. leopoldinae are described.