Species of Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidae) from cyprinid fishes in North America

A taxonomic study of Proteocephalus species parasitizing cyprinid fishes in North America, namely Proteocephalus ptychocheilus Faust, 1920 and Proteocephalus cobraeformis Haderlie, 1953, has demonstrated their conspecificity with Proteocephalus torulosus (Batsch, 1786), a common parasite of cypriniform fishes (Cyprinidae and Cobitidae) in the Palaearctic Region. Proteocephalus ptychocheilus and P. cobraeformis are considered junior synonyms of P. torulosus.     

The developmental cycle of Proteocephalus thymalli (Cestoda, Proteocephalidae)--a parasite of the Arctic grayling from Lake Baikal

The life cycle of Proteocephalus thymalli (Cestoda, Proteocephalidae), a parasite of Siberian glame (Thymallus arcticus), was repeated under experimental conditions. The first intermediate hosts, the copepods Epischura baicalensis, Cyclops kolensis and C. vicinus, were determined. The developmental time of P. thymalli in the first intermediate host was determined and the morphology of the larval and adult phases was described.     

Redescription of Proteocephalus glanduligerus (Cestoda: Proteocephalidea), a parasite of clariid catfishes in Africa with a unique glandular apical organ

The tapeworm Proteocephalus glanduligerus (Janicki, 1928) Fuhrmann, 1933 (Cestoda: Proteocephalidea), a parasite of clariid catfishes (Clarias spp.) in Africa, is redescribed on the basis of an evaluation of voucher material and newly collected specimens from Clarias gariepinus and C. cf. anguillaris from the Sudan, Ethiopia, and South Africa. The most typical characteristic of P. glanduligerus (previously misspelled as P. glanduligera or P. glanduliger) is the presence of an extremely large glandular apical organ, the size of which is 1.6-3.5 times larger than that of the suckers. In addition, other morphological characteristics unreported in previous accounts are provided, such as an unusual position of osmoregulatory canals (situated close to each other, with the dorsal canal latero-ventral to testes), the presence of a vaginal sphincter, several (usually 3-5) uterine pores, and eggs with paired lateral auricular swellings (extensions) of the outer envelope.     

The morphological variability of a population of Proteocephalus percae (Cestoda: Proteocephalidea) in Lake Rindozero]

The morphology of the cestode Proteocephalus percae, a typical parasite of Perca fluviatilis, from Lake Rindozero has been studied. The variability of 8 age groupings has been revealed and the connection of their morphological parameters with the specificity of host-parasite relationships at different developmental stages of the population has been shown.     

Description of a new species of Proteocephalus pronini sp.n. (Cestoda: proteocephalidae)--a parasite of grayling from lake Hovsgol

A new cestode species, Proteocephalus pronini sp. n., is described from the Lake Hovsgol Grayling Thymallus arcticus nigrescens (Mongolia, Hovsgol Lake). The new species differs from P. thymalli from the Baikal Lake by the length of strobile, number of proglottids, form of mature proglottids, and number of diverticles of uterus.     

Distribution and ultrastructure of two types of scolex gland cells in adult Proteocephalus macrocephalus (Cestoda, Proteocephalidea)

In the scolex-neck region of the adult Proteocephalus macrocephalus two types of eccrine gland cells are present. The first type of gland cells, localized in the frontal part of the scolex only, contains large, more or less round electron lucid granules. The second type of unicellular glands produces large electron dense granules. These electron dense granular gland cells are localized primarily in the neck region, only few are present in the scolex apex. The secretion of both types of gland cells is concentrated in the ducts opening to the exterior. The ducts are fixed to the plasmalemma of the tegument by septate junctions. The function of both types of gland cells is discussed.     

Phylogenetic analysis of European species of Proteocephalus (Cestoda: Proteocephalidea): compatibility of molecular and morphological data, and parasite-host coevolution.

The phylogeny of European species of the tapeworm genus Proteocephalus was studied, based on partial 18S rDNA and morphological data. The group was found to be monophyletic. The analysis showed a low informative value of available morphological characters in comparison with molecular data. The morphological matrix resulted in a poorly resolved tree which is, however, compatible with the topology (Proteocephalus osculatus (Proteocephalus torulosus (Proteocephalus macrocephalus, Proteocephalus filicollis) (Proteocephalus tetrastomus, Proteocephalus percae, Proteocephalus longicollis))) based on the 18S rDNA data. A comparison performed by the program TreeMap showed a lack of significant congruency between parasite and host phylogenies. Therefore, the distribution of species in their hosts appears to be independent of the phylogeny and it is likely to be a result of host-switching, rather than co-speciation events.     

Occurrence of Proteocephalus tetrastomus (Rudolphi, 1810) (Cestoda: Proteocephalidea) in larval rainbow smelt (Osmerus mordax) in North America: identification of a potential pathogen confirmed

A morphological evaluation and genetic analysis (sequencing of ITS2 region of rDNA) of proteocephalidean cestodes from rainbow smelt (Osmerus mordax) in the Saint Lawrence Estuary, Canada, has shown their conspecificity with Proteocephalus tetrastomus, a specific parasite of smelt (Osmeridae), previously known only from northern Europe, Russia, and Japan. The parasite occurs only in larval, but not adult, smelt in the Saint Lawrence Estuary. Prevalence of larval smelt infection was 42% (n = 50), mean intensity 2.1 +/- 2.4 and mean abundance 1.1 +/- 1.0.     

Species of Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidae), parasites of coregonid and salmonid fishes from North America: taxonomic reappraisal

A taxonomic study of species of Proteocephalus Weinland, 1858 (Cestoda: Proteocephalidae), from coregonid and salmonid fishes in North America, based largely on their type specimens, was carried out. None of the taxa studied possesses obvious autapomorphies that would justify its validity. On the contrary, all species share the following diagnostic features typical of Proteocephalus longicollis (Zeder, 1800) (syn. Proteocephalus exiguus La Rue, 1911), a polymorphic and widely distributed parasite in the Holarctic: (1) a spherical or club-shaped scolex, with sublaterally situated suckers and a vestigial but distinct and relatively large apical sucker; (2) the vagina possessing a well-developed vaginal sphincter and crossing mostly ventrally the proximal part of the cirrus sac; and (3) a long, thick-walled cirrus sac, overlapping vitelline follicles medially by more than its proximal half. Accordingly, Proteocephalus pusillus Ward, 1910; P. laruei Faust, 1920; "P. obtundus" La Rue, 1920 (nomen nudum); P. arcticus Cooper, 1921; P. wickliffi Hunter and Bangham, 1933; P. parallacticus MacLulich, 1943; P. californicus Haderlie, 1950; P. salmonidicola Alexander, 1951; and P. primaverus Neiland, 1952 are considered junior synonyms of P. longicollis.     

Successional features of the dynamics of abundance and population structure of the cestode Proteocephalus longicollis (Zeder, 1800) (Cestoda: Proteocephalidae)

Dynamics of abundance and changes of populations structure were investigated in a host-specific parasite of salmonids, cestode Proteocephalus longicollis from the vendace Coregonus albula L. of the Syamozero Lake during the period of more than forty years. A relative stability of the values of infestation indices independently of significant changes in the abundance and population structure of the vendace is established. Changes in the distribution of abundance and population structure of P. longicollis are shown to be connected with the change of the water body's status resulting from eutrophication. These changes can be considered as reliable indices of the succession in freshwater bodies.     

Fine Structure of the Cellular Parenchyma and Extracellular Matrix of Ophiotaenia loennbergii (Cestoda: Proteocephalidea)

The cellular parenchyma and extracellular matrix (ECM) of Ophiotaenia loennbergii were studied by light and transmission electron microscopy. The parenchyma consists primarily of muscle cells divided into three compartments that maintain some cytoplasmic continuity: (1) myofibrils; (2) broadly lobate nucleated myocytons (muscle cell perikarya) with the perinuclear cytoplasm dominated by greatly dilated cisternae of granular endoplasmic reticulum: (3) thin anucleated sarcoplasmic extensions formed in sheets with abundant glycogen and extremely large lipid droplets, which cause the cytoplasmic sheets to bulge. These cellular compartments are separated from each other by abundant ECM, which consists primarily of an electron-lucent amorphous ground substance. Filaments are scarce in all ECM except the tegumental basement lamella. This is the first report of parenchyma and ECM fine structure in the Proteocephalidea. The results provide additional evidence that cestode parenchyma is formed from similar cells, but is subject to substantial variability between different species.     

An annotated list of species of the Proteocephalus Weinland, 1858 aggregate sensu de Chambrier et al. (2004) (Cestoda: Proteocephalidea), parasites of fishes in the Palaearctic Region, their phylogenetic relationships and a key to their identification

A list and key to the identification of valid species of tapeworms of the Proteocephalus Weinland, 1858 aggregate sensu de Chambrier et al. (2004), i.e. species of the genus occurring in fresh- and brackish-water fishes in the Palaearctic Region, are provided, with data on their hosts and geographical distribution. Instead of 32 taxa listed by Schmidt (1986) and subsequent authors, only the following 14 species are considered to be valid: P. ambiguus (Dujardin, 1845) (type-species); P. cernuae (Gmelin, 1790); P. filicollis (Rudolphi, 1802); P. fluviatilis Bangham, 1925; P. gobiorum Dogiel & Bychowsky, 1939; P. longicollis (Zeder, 1800); P. macrocephalus (Creplin, 1825); P. midoriensis Shimazu, 1990; P. percae (Müller, 1780); P. plecoglossi Yamaguti, 1934; P. sagittus (Grimm, 1872); P. tetrastomus (Rudolphi, 1810); P. thymalli (Annenkova-Chlopina, 1923); and P. torulosus (Batsch, 1786). An analysis of sequences of the nuclear genes (ITS2 and V4 region of 18S rDNA) revealed the following phylogenetic relationships for these taxa: P. torulosus ((P. midoriensis, P. sagittus) (P. fluviatilis (P. filicollis, P. gobiorum, P. macrocephalus)) (P. cernuae, P. plecoglossi, P. tetrastomus ((P. longicollis, P. percae) (P. ambiguus, P. thymalli)))). P. pronini Rusinek, 2001 from grayling Thymallus arcticus nigrescens is synonymised with P. thymalli. P. esocis La Rue, 1911 is apparently invalid but its conspecificity with either P. percae or P. longicollis could not be confirmed due to the absence of the scolex in the holotype and the unavailability of other material for morphological and molecular studies. P. osculatus (Goeze, 1782) has recently been transferred to Glanitaenia de Chambrier, Mariaux, Vaucher & Zehnder, 2004. The validity of the genus is supported by the position of G. osculata within the Proteocephalidea, based on molecular data, as well as its morphology and nature of the definitive host (the European wels Silurus glanis). P. hemispherous Rahemo & Al-Niaeemi, 2001, described from S. glanis in Iraq, is transferred to Postgangesia Akhmerov, 1960 as Postgangesia hemispherous (Rahemo & Al-Niaeemi, 2001) n. comb.     

Redescription de Proteocephalus paraguayensis (Rudin, 1917) (Cestoda: Proteocephalidae) parasite de Hydrodynastes gigas (Dum., Bibr. & Dum., 1854) du Paraguay

Redescripción de Proteocephalus paraguayensis (Rudin, 1917) (Cestoda: Proteocephalidae), parásito de Hydrodynastes gigas (Dum., Bibr. & Dum., 1854) de Paraguay. Se describe esta especie notable, considerada por Freze (1965) como species inquirenda. Si comparamos esta especie con otras especies de Proteocephalidea, veremos que ella presenta caracteres anatomo-morfológicos propios. Esta especie se caracteriza por: vitelógenos de posición dorsal, adosados a la musculatura interna longitudinal, desbordando en parte sobre el córtex y la médula; formación particular del útero; posición cortical del tronco uterino y medular de los divertículos uterinos; esfínter vaginal proximal; cirro muy alargado; glándula de Mehlis muy desarrollada. Consideramos P. paraguayensis como una especie válida y presumimos que el huesped-tipo es Hydrodynastes gigas (Dum., Bibr. & Dum., 1854). A pesar de las características que posee P. paraguayensis, pensamos que no es oportuno clasificar esta especie en un nuevo género monotípico. Proteocephalus paraguayensis, considered by Freze (1965) as a species inquirenda, is redescribed and figured. When compared with other members of the Proteocephalidea, the species shows the following morpho-anatomical characters: the vitelline follicles in a dorsal position, attached to the internal longitudinal musculature and extending into both the cortex and medulla; a characteristic formation of the uterus; the uterine stem in a cortical position and uterine branches in a medullary position; a proximal vaginal sphincter; a very elongate cirrus; and very large Mehlis' glands. The specific status of Proteocephalus paraguayensis is confirmed. Our specimens were taken from Hydrodynastes gigas (the host according to Rudin was Coluber sp.). Even though the species differs significantly from other proteocephalideans, its systematic and phylogenetic position is not yet clearly demonstrated, and it is decided to refrain from attributing it to a new genus.     

A multidisciplinary approach to the systematics of Proteocephalus macrocephalus (Creplin, 1825) (Cestoda: Proteocephalidae)

The tapeworm Proteocephalus macrocephalus (Creplin, 1825), a parasite of the eel Anguilla anguilla, was characterised using morphological and genetic characters. The species is morphologically typified mainly by features of the scolex (i.e. shape and size of an apical organ which is formed early during the development in an intermediate host) and strobila (i.e. regularly rectangular proglottides, morphology of the vagina and anterior position of the seminal receptacle). Genetically, P. macrocephalus was compared with two congeners, P. percae and P. exiguus. Characters enabling differentiation of P. macrocephalus were as follows: fixed allelic differences at Got, Pgm and Gapdh loci, metrical features of chromosomes Nos 1, 2 and 7, and species-specific fragments obtained by RAPD method using 13 random primers.     

Polymorphism and structure of the population of Proteocephalus longicollis Zeder, 1800 (Cestoda: Proteocephalidae) in the vendace Coregonus albula L

Polymorphism and phenotypic diversity of a hostal ecoform of Proteocephalus longicollis from its typical host, the vendace, Coregonus albula L., were studied. A complex phenotypic structure of the parasite population and presence of morphologically different groupings were revealed. We distinguished four groupings based on the external characters and three groupings based on the feed and reproduction features; among latter groupings one has very specific variations of features. We conclude that P. longicollis has high intraspecific and intrapopulation heterogeneity, and the host plays a stabilising role in the parasite species formation.     

Comparative morphological and gene systematics analysis of the Proteocephalus thymalli (Cestoda: Proteocephalidae), a parasite of graylings in lakes Hovsogol and Baikal

Results of comparative morphological and gene analyses of the cestode Proteocephalus thymalli, an intestine parasite of the lakes Hovsogol (Thymallus arcticus nigrescens) and Lake Baikal graylings (Thymallus arcticus baicalensis) are presented for the first time. The results indicate that representatives of the P. thymalli from these fishes are really two different species.     

Phylogenetic analysis on genera of Corallobothriinae (Cestoda: Proteocephalidea) from North American ictalurid fishes, using partial sequences of the 28s ribosomal gene

Partial sequences of the 28S rDNA (ribosomal gene) were obtained from a total of 11 populations of 5 species (in 3 genera) of North American corallobothriine proteocephalideans. These included Corallobothrium fimbriatum (3 populations), Corallobothrium parafimbriatum (1 population), Corallotaenia minutia (1 population), Megathylacoides giganteum (2 populations), and Megathylacoides lamothei (4 populations). These sequences were used in a phylogenetic analysis to test the monophyly of Corallobothriinae and to investigate the interrelationships of the North American species. The results indicate that Corallobothriinae, as conventionally understood, is not monophyletic and that only the North American corallobothriines, parasites of ictalurid catfishes, form a monophyletic group. Corallobothrium parafimbriatum is sister taxon to a clade that includes Corallotaenia intermedia and C. minutia and not to its congener C. fimbriatum. Also, M. giganteum from Mexico appears to be more closely related to M. lamothei than to its conspecific in Canada. This and the amount of sequence divergence indicate possible cryptic speciation in its endemic host, the Lerma catfish, Ictalurus dugesi.