Redescription of Corallobothrium solidum (Cestoda: Proteocephalidea) and erection of a new genus, Essexiella, for tapeworms from channel catfishes (Ictaluridae)

The proteocephalidean tapeworm, Corallobothrium solidum, type species of the genus, is redescribed on the basis of the examination of its type specimens and extensive material recently collected from Malapterurus electricus (type host). Some morphological characteristics of taxonomic importance are reported for the first time, such as the presence of semispherical (U-shaped) sphincters on the external (outer) margin of the suckers, a vaginal sphincter, a well-developed seminal receptacle, and a unique morphology of the eggs. Corallobothrium solidum differs from the 2 remaining species of the genus, both parasitic in channel catfishes (Ictaluridae), in its scolex shape, morphology of its suckers, presence of longitudinal and transverse grooves on the body surface, dense network of excretory canals in the apical part of the scolex, morphology of the eggs, and uterine development. The non-monophyletic nature of Corallobothrium is further supported by molecular data (partial sequences of the 28S rRNA gene) because C. solidum and the 2 remaining species from ictalurids do not form a monophyletic assemblage. Therefore, Essexiella n. gen. is proposed to accommodate Essexiella fimbriatum new comb. (type and only species; syn. Corallobothrium fimbriatum) from channel catfish. Essexiella n. gen. differs from Corallobothrium, Megathylacoides, and Megathylacus by the absence of a sphincter in the suckers, from Corallotaenia by the shape of the scolex and the number and shape of proglottids, and from Paraproteocephalus by the structure of the uterus. The diagnosis of Corallobothrium, which becomes monotypic and restricted to electric catfishes in Africa, is emended. The remaining species of Corallobothrium, Corallobothrium parafimbriatum, is tentatively transferred to Corallotaenia as Corallotaenia parafimbriata n. comb., based on molecular data, small size of the strobila, and shape of the scolex.     

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.     

A new genus and species of proteocephalidean tapeworm (Cestoda) from Pangasius larnaudii (Siluriformes: Pangasiidae) in Southeast Asia

A new proteocephalidean cestode is described from spot pangasius, Pangasius larnaudii (Siluriformes: Pangasiidae), from Tonle Sap Lake in Cambodia and a new genus, Pangasiocestus , is proposed to accommodate it. The genus is placed in the Gangesiinae because its scolex possesses a large rostellum-like apical organ and its genital organs (testes, ovary, vitellarium, and uterus) are situated in the medulla, with some vitelline follicles paramuscular. Pangasiocestus romani n. gen. and n. sp., the type and only species of the new genus, is characterized mainly by its rosette-like scolex composed of 4 lobes bearing a small sucker in their center, and the apical part with a large, discoidal, rostellum-like apical organ devoid of hooks, by weakly developed inner longitudinal musculature formed by very few isolated muscle fibers, uneven size of testes in immature and mature proglottids, with lateral testes smaller and more dense than median ones, by very narrow lateral bands of vitelline follicles, formed usually by single follicles, and by the vagina anterior to the cirrus sac. This is the first proteocephalidean cestode from a pangasiid catfish identified to the species level (proteocephalidean cestodes from 3 Pangasius spp. reported in an unpublished account from Vietnam, misidentified as Proteocephalus osculatus (Goeze, 1782) [?= Glanitaenia osculata ], are not considered).     

Morphological and ultrastructural aspects of Branchiobdella pentodonta Whit. (Annelida,oligochaeta) suckers

The muscular system in the posterior sucker of Branchiobdella pentodonta Whit. has circular, longitudinal and radial fibers. In the anterior sucker, which has circular and longitudinal fibers, the muscle system is scarce. Concentric fibers are found around the mouth. In both suckers the glandular elements form voluminous complexes secreting mucus for attachment to the substrate. Suckers show neuromuscular junctions and three distinct types of neuroglandular junctions: one with typical neurosecretory granules, one with larger neurosecretory granules produced by cells located at the origin of the segmental nerves, and one with presynaptic vesicles. The second type is peculiar to the posterior sucker. A comparison is made between suckers of Branchiobdella and those of leeches.     

Nomimoscolex semenasae n sp (proteocephalidea: Monticelliidae), a cestode parasite of Diplomystes viedmensis (Pisces: Siluriformes) from the Patagonian region of Argentina

Nomimoscolex semenasae n. sp. is described from the primitive fish Diplomystes viedmensis (Siluriformes) from the Patagonian region of Argentina. The new species is placed in Nomimoscolex because of the cortical position of the vitelline follicles, medullary position of the testes, ovary and uterus, and having a scolex with four uniloculate suckers. N. semenasae differs from all other species in the genus by the following combination of characters: (1) apical organ absent; (2) strobila acraspedote; (3) vagina anterior or posterior to cirrus-sac and lacking a sphincter; (4) testes in one irregular layer and in two fields connected anteriorly; (5) uterine stem cortical in immature proglottides, growing from cortical stem into medullary region in mature proglottides; (6) long uteroduct; and (7) presence of spiniform microtriches on all regions of the scolex, proliferation zone and immature proglottis. This is the first record of a proteocephalidean tapeworm in D. viedmensis and in the family Diplomystidae.     

Nomimoscolex pertierrae n. sp. (Eucestoda: Proteocephalidea), a parasite of Pseudoplatystoma corruscans (Siluriformes: Pimelodidae) in Brazil and redescription of N. sudobim Woodland, 1935, a parasite of P. fasciatum

The cestode Nomimoscolex sudobim Woodland, 1935 (Proteocephalidea) is redescribed on the basis of its type-specimens and recently collected material found in the intestine of the 'sudobim' Pseudoplatystoma fasciatum (Siluriformes: Pimelodidae) (type-host), from the Amazon River (near the type-locality). Nomimoscolex pertierrae n. sp. is described from the 'surubi' Pseudoplatystoma corruscans from the Paraná River around Porto Rico. Among fifteen known Nomimoscolex species, only N. sudobim possess a cortical uterus in combination with osmoregulatory canals some distance internal to the proglottis margins, as in N. pertierrae n. sp. N. pertierrae differs from N. sudobim, which exhibits the most similarity with the former species, in the morphology of the scolex, the size and unusual shape of microtriches (slender digitiform) on the internal and marginal regions of the suckers, and in the lower mean number of testes [(114 in N. pertierrae, ranging between 216 (recently collected material) and 240 (type-material) in N. sudobim)]. The material described as N. sudobim by Pavanelli & Rego (1992) from the intestine of P. corruscans is considered to be N. pertierrae. The utility of microtriches as characters for distinguishing between species is demonstrated in the clear differences in the shape of those of N. pertierrae and N. sudobim. The morphology of microtriches warrants more attention in future studies on the taxonomy of proteocephalidean cestodes.     

Redescription of Testudotaenia testudo (Magath, 1924) (Eucestoda: Proteocephalidea), a parasite of Apalone spinifera (Le Sueur) (Reptilia: Trionychidae) and Amia calva L. (Pisces: Amiidae) in North America and erection of the Testudotaeniinae n. subfam.

Testudotaenia testudo (Magath, 1924) is redescribed from the intestine of the softshell turtle Apalone spinifera (Le Sueur) (Trionychidae) and the bowfin Amia calva Linnaeus (Amiidae) from Reelfoot Lake, Tennessee, United States. A new subfamily, the Testudotaeniinae, is erected. The new taxon differs from all proteocephalidean subfamilies in the position of the genital organs in relation to the longitudinal internal musculature, i.e. the testes are cortical, rarely medullary; the ovary is partly medullary, with cortical lobes; the vitelline follicles are mainly medullary, with some follicles in the cortex; and the uterus is cortical. A key to the subfamilies of the order Proteocephalidea Mola, 1928 is provided. The most characteristic features of T. testudo are the precocious uterine aperture, the presence of internal uterine pores (as previously described for Proteocephalus paraguayensis (Rudin, 1917)), the eggs laid unripe, the very long strobila (up to 970 mm), and the presence of an anterior circular musculature in the suckers, which is considered as a good differential character. Three other species were found in Amia calva: Proteocephalus perplexus La Rue, 1911, P. ambloplitis (Leidy, 1887) and a new, undescribed form. Sequences of the partial nuclear 28S rRNA gene of specimens of T. testudo from Apalone spinulifera and Amia calva confirm the conspecificity of samples from these two very distinct hosts, which may represent a capture phenomenon. As the subfamily Adenobrechmoinae Bursey, Goldberg & Kraus, 2006 and the genus Adenobrechmos Bursey, Goldberg & Kraus, 2006 are based on the presence of an apical organ, a character which reflects a rather common convergence, we consider the Adenobrechmoinae to be a junior synonym of the Proteocephalinae La Rue, 1911 and Adenobrechmos a junior synonym of Ophiotaenia La Rue, 1911. Adenobrechmos greeri Bursey, Goldberg & Kraus, 2006 thus becomes Ophiotaenia greeri (Bursey, Goldberg & Kraus, 2006) n. comb.     

Phyllobothrium squali Yamaguti, 1952 (Tetraphyllidea,Phyllobothriidae): redescription and first record in the Black Sea

Phyllobothrium squali Yamaguti, 1952 is redescribed and illustrated on the basis of the holotype from Squalus acanthias from Japanese waters and specimens from the same host off the Bulgarian Black Sea coast (new geographical record). The species is characterised by: a scolex diameter of 2.9-4.3 mm, a glandular apical organ, foliose bothridia with folded and posteriorly bifid margins, accessory suckers of 286-367 micro m in diameter, 222-373 testes per proglottis, an oval cirrus-sac with a length of 354-655 micro m, the vagina opening anteriorly to the cirrus-sac, and the terminal part of vagina with a circular musculature. Specimens from Etmopterus spinax off Naples, Mediterranean Sea, recorded by Euzet (1959) as Crossobothrium squali, are redescribed and their identification not confirmed. P. squali is recognised as a specific parasite of S. acanthias; it is presently known only from Japanese waters, the Black Sea and the Irish Sea. Changes to the generic diagnosis of Phyllobothrium, as given by Ruhnke (1996a), are proposed in order to include the characters of P. squali.     

Mariauxiella pimelodi n. g., n. sp. (Cestoda: Monticelliidae): a parasite of pimelodid siluroid fishes from South America

Mariauxiella pimelodi n. g., n. sp. (Cestoda, Monticelliidae, Othinoscolecinae) is described from the South American siluriform fishes Pimelodus ornatus and Pimelodus sp. caught in Brazil and Paraguay. When compared with other genera of South American monticelliids, the new genus exhibits the following morpho-anatomical characters: the particular development of the distal circular musculature of the suckers acting as a sphincter; the medullar ovary projecting numerous lobules into the dorsal cortex; and the uterus situated in the ventral cortex but with numerous outgrowths penetrating the medulla and reaching the dorsal cortex in pregravid proglottids. The new species is the fourth monticelliid cestode recorded from Pimelodus.     

Brachylepis gen. n.--a new genus of cestodes (Cyclophyllidea: Hymenolepididae) from shrews in Siberia and the Far East

A new genus Brachylepis gen. n. hymenolepididean cestodes associated with common shrews (Sorex) in Siberia and Russian Far East is created. These genus includes three species removed from the genus Mathevolepis: Brachylepis morosovi (Karpenko, 1994) comb. n. (type species), B. sorextscherskii (Morosov, 1957) comb. n. and B. triovaria Karpenko, 1990) comb. n. The new genus is characterized by the gradual strobila with a little number of segments, unarmed scolex with apical glandular organ, by lack of internal seminal vesicle and differential seminal receptacle, by form of uterus as horse shoe in young worms and buble-like in mature worms. A tendency of inverse proportional dependence between the number of uterus segments in the strobila and the number of hexacanths in the uterus has been noticed. The table of differential characters for the species of the genus Brachylepis is proposed.     

Spatial organization of musculature in the Himasthla elongata cercaria (Trematoda: Echinostomatidae)

Somatic muscles (body-wall and "parenchyma" musculature), muscles of suckers, alimentary tract and excretory bladder of Himasthla elongata cercaria were investigated using fluorescent phalloidin labelling and confocal microscopy. The arrangement of body-wall muscles differs between the certain parts of cercarial body and appears to be the most complicated in the collar district. Among the body-wall musculature, we described U-shaped muscles, which have never been found previously in trematodes. Muscles of oral and ventral suckers are grouped into 6-7 independent layers. In some of those layers, they are arranged bilaterally, which contradicts the tradition to consider the sucker as radially symmetric.     

Cestodes of cestodes of Peruvian freshwater stingrays

Adult tetraphyllidean tapeworms (Platyhelminthes: Eucestoda) from the spiral intestines of 3 species of potamotrygonid stingrays (Paratrygon aiereba, Potamotrygon castexi, and Portamotrygon motoro) in the Madre de Dios river in Peru were found to host numerous cysts embedded in their parenchymal tissues. Histological sections of the cysts revealed the presence of a scolex bearing 4 suckers and an unarmed apical organ consistent with larval stages of both Cyclophyllidea and Proteocephalidea. To further elucidate their identities, partial 28S ribosomal DNA (rDNA) sequences were characterized from 3 cysts and 4 adult Rhinebothrium spp. 'host' worms and screened against all available cestode 28S rDNA data. Initial BLAST screening and subsequent alignment ruled out the possibility that the cysts were cyclophyllidean, and the cyst and adult sequences were thus aligned together with all available lecanicephalidean, litobothriidean, proteocephalidean, and tetraphyllidean sequences. Sequences from all 3 cysts were identical, and phylogenetic analysis clearly placed them among derived members of the Proteocephalidea, although no exact match was found. Sequences from the adult host worms formed 2 identical pairs and grouped together with other tetraphyllidean species from rays. These results are compared with records of hyperparasites of South American catfish cestodes. This is the first confirmed record of a proteocephalidean cestode parasitizing a tetraphyllidean cestode.     

Redescription of Electrotaenia Malopteruri (Fritsch, 1886) (Cestoda: Proteocephalidae), a Parasite of Malapterurus Electricus (Siluriformes: Malapteruridae) from Egypt

The proteocephalidean cestode Electrotaenia malopteruri (Fritsch, 1886) (Proteocephalidae: Gangesiinae), the type- and only species of Electrotaenia Nybelin, 1942 and specific to the electric catfish Malapterurus electricus Gmelin (Siluriformes: Malapteruridae), is redescribed on the basis of freshly collected material from the River Nile in Egypt. The validity of Electrotaenia is confirmed and some unique characters of this genus, observed in extensive material from different host specimens from Egypt, Sudan, Sierra Leone and Nigeria are first reported or described in detail. Such details include the internal morphology of a rostellum-like apical organ which is disc-shaped with a flat or slightly concave apex, the structure of the ovary which is follicular to reticulate, the structure of the cirrus-sac, the presence of a medio-dorsal band of muscle fibres, and the morphology of the vagina and eggs.     

A large 28S rDNA-based phylogeny confirms the limitations of established morphological characters for classification of proteocephalidean tapeworms (Platyhelminthes,Cestoda)

Proteocephalidean tapeworms form a diverse group of parasites currently known from 315 valid species. Most of the diversity of adult proteocephalideans can be found in freshwater fishes (predominantly catfishes), a large proportion infects reptiles, but only a few infect amphibians, and a single species has been found to parasitize possums. Although they have a cosmopolitan distribution, a large proportion of taxa are exclusively found in South America. We analyzed the largest proteocephalidean cestode molecular dataset to date comprising more than 100 species (30 new), including representatives from 54 genera (80%) and all subfamilies, thus significantly improving upon previous works to develop a molecular phylogeny for the group. The Old World origin of proteocephalideans is confirmed, with their more recent expansion in South America. The earliest diverging lineages are composed of Acanthotaeniinae and Gangesiinae but most of the presently recognized subfamilies (and genera) appear not to be monophyletic; a deep systematic reorganization of the order is thus needed and the present subfamilial system should be abandoned. The main characters on which the classical systematics of the group has been built, such as scolex morphology or relative position of genital organs in relation to the longitudinal musculature, are of limited value, as demonstrated by the very weak support for morphologically-defined subfamilies. However, new characters, such as the pattern of uterus development, relative ovary size, and egg structure have been identified, which may be useful in defining phylogenetically well-supported subgroups. A strongly supported lineage infecting various snakes from a wide geographical distribution was found. Although several improvements over previous works regarding phylogenetic resolution and taxon coverage were achieved in this study, the major polytomy in our tree, composed largely of siluriform parasites from the Neotropics, remained unresolved and possibly reflects a rapid radiation. The genus Spasskyellina Freze, 1965 is resurrected for three species of Monticellia bearing spinitriches on the margins of their suckers.     

The structure and adhesive mechanism of octopus suckers

Octopus suckers consist of a tightly packed three-dimensionalarray of muscle with three major muscle fiber orientations:1) radial muscles that traverse the wall; 2) circular musclesarranged circumferentially around the sucker; and 3) meridionalmuscles oriented perpendicular to the circular and radial muscles.The sucker also includes inner and outer fibrous connectivetissue layers and an array of crossed connective tissue fibersembedded in the musculature. Adhesion results from reducingthe pressure inside the sucker cavity. This can be achievedby the three-dimensional array of muscle functioning as a muscular-hydrostat.Contraction of the radial muscles thins the wall, thereby increasingthe enclosed volume of the sucker. If the sucker is sealed toa surface the cohesiveness of water resists this expansion.Thus, the pressure of the enclosed water decreases instead.The meridional and circular muscles antagonize the radial muscles.The crossed connective tissue fibers may store elastic energy,providing an economical mechanism for maintaining attachmentfor extended periods. Measurements using miniature flush-mountedpressure transducers show that suckers can generate hydrostaticpressures below 0 kPa on wettable surfaces but cannot do soon non-wettable surfaces. Thus, cavitation, the failure of waterin tension, may limit the attachment force of suckers. As depthincreases, however, cavitation will cease to be limiting becauseambient pressure increases with depth while the cavitation thresholdis unchanged. Structural differences between suckers will thendetermine the attachment force.     

The genus Biuterina Fuhrmann, 1902 (Cestoda,Paruterinidae) in the Old World: redescriptions of four species from Afrotropical Passeriformes

Four species of Biuterina Fuhrmann, 1902 (Cestoda, Cyclophyllidea, Paruterinidae), originally described from Afrotropical passeriform birds, are redescribed and figured on the basis of their type-specimens. These are B. pentamyzos (Mettrick, 1960) from Prionops plumata (Laniidae) in Zimbabwe, B. quelea (Mettrick, 1963) from Quelea quelea (Ploceidae) in Zimbabwe, B. ugandae Baylis, 1919 from Chalcomitra senegalensis (Nectariniidae) in Uganda and B. zambiensis (Mettrick, 1960) from Campephaga flava (Campephagidae) in Zimbabwe. The rostellum of B. quelea is a spherical structure filled with strongly-developed glandular tissue and possessing a weak musculature. The remaining three species have a sucker-like rostellar apparatus with moderately developed glandular tissue in the rostellum and around it. It is considered that the glandular elements are an inherent part of the rostellar apparatus of the paruterinids. An armament consisting of fine, punctiform, spine-like structures arranged in transverse rows on the inner surface of suckers is observed in B. pentamyzos. This is the first record of sucker armature in the Paruterinidae.