A key to three species of larval Diphyllobothrium Cobbold, 1858 (Cestoda: Pseudophyllidea) occurring in European and North American freshwater fishes

A key is presented to the plerocercoids of the three species of Diphyllobothrium frequently occurring in fishes of Europe and North America. The key is intended for use by both helminthologists and fish biologists. It is designed in four parts: readily visible features of gross-morphology; body-size and site data; features of gross-morphology more clearly seen under the scanning electron microscope; and features visible in histological sections.     

Stomach contents of long-finned pilot whales (Globicephala melas) from southern Chile

The widely distributed long-finned pilot whale (Globicephala melas) has been reported off the Chilean coast, from Iquique (20°12′S) south to Navarino Island (55°15′S; 67°30′W), but little is known about its biology or ecology in the region. Here, we report on the prey of this species, identified by stomach content analyses from animals stranded on Holget Islets, Beagle Channel, southern Chile in August 2006. The stomachs of seven individuals (six females and one male) contained cephalopod remains. The prey composition found in these southern Chilean pilot whales was similar to that described in other parts of the world and the Southern Ocean. This is the first report on the feeding habits of this species from Chile.     

Major Histocompatibility Complex (MHC) class II sequence polymorphism in long-finned pilot whale (Globicephala melas) from the North Atlantic

Determining how intra-specific genetic diversity is apportioned among natural populations is essential for detecting local adaptation and identifying populations with inherently low levels of extant diversity which may become a conservation concern. Sequence polymorphism at two adaptive loci (MHC DRA and DQB) was investigated in long-finned pilot whales (Globicephala melas) from four regions in the North Atlantic and compared with previous data from New Zealand (South Pacific). Three alleles were resolved at each locus, with trans-species allele sharing and higher levels of non-synonymous to synonymous substitution, especially in the DQB locus. Overall nucleotide diversities of 0.49?±?0.38% and 4.60?±?2.39% were identified for the DRA and DQB loci, respectively, which are relatively low for MHC loci in the North Atlantic, but comparable to levels previously described in New Zealand (South Pacific). There were significant differences in allele frequencies within the North Atlantic and between the North Atlantic and New Zealand. Patterns of diversity and divergence are consistent with the long-term effects of balancing selection operating on the MHC loci, potentially mediated through the effects of host-parasite coevolution. Differences in allele frequency may reflect variation in pathogen communities, coupled with the effects of differential drift and gene flow.     

Characterizing alloparental care in the pilot whale (Globicephala melas) population that summers off Cape Breton,Nova Scotia,Canada

Alloparental care happens when a calf is cared for by an adult that is not their parent. Although alloparental care is common in social mammals, its prevalence is difficult to assess in cetaceans, and has not been studied in Globicephala melas. A population off Cape Breton, Nova Scotia, has been studied from whale‐watching vessels since 1998, during July and August each year. From 2009 to 2011, we collected photo identifications of calves and the adults accompanying them. Alloparental care was considered to be occurring when a calf was identified with more than one companion. We found that 85.7% of calves in 2009, 80.6% of calves in 2010 and 63% of calves in 2011 had alloparents. Mothers were difficult to identify. Nevertheless, none of the other companions of calves were assigned to the same unit as the mother. Five carers were sexed, four of them males. There were no cases of within‐ or between‐year alloparental care reciprocity. It is possible that delayed reciprocity is happening on a larger time scale in this population, but the most likely explanation is that alloparental care is a byproduct of this species’ social structure, with a very small cost to the alloparent's fitness.     

Spondylitic changes in long-finned pilot whales (Globicephala melas) stranded on Cape Cod, Massachusetts, USA, between 1982 and 2000

The primary bone pathology diagnoses recognized in cetacea are osteomyelitis and spondylosis deformans. In this study, we determined the prevalence, type, and severity of vertebral pathology in 52 pilot whales, a mass stranding species that stranded on Cape Cod, Massachusetts, between 1982 and 2000. Eleven whales (21%) had hyperostosis and ossification of tendon insertion points on and between vertebrae, chevron bones, and costovertebral joints, with multiple fused blocks of vertebrae. These lesions are typical of a group of interrelated diseases described in humans as spondyloarthropathies, specifically ankylosing spondylitis, which has not been fully described in cetacea. In severe cases, ankylosing spondylitis in humans can inhibit mobility. If the lesions described here negatively affect the overall health of the whale, these lesions may be a contributing factor in stranding of this highly sociable species.     

On the Procercoid Protonephridial Systems of Three Diphyllobothrium Species (Cestoda, Pseudophyllidea) and Janicki's Cercomer Theory

Because the types of hooks are so similar in the oncosphacra/procercoid ef cestodes and in several groups of monogenclic trcmatodes and because the exterior of a procercoid with the hooks in a cercomer is so suggestive of a monogenetic nematode, the development of the procercoids of three Diphyllobothrium species was studied. The intention was to determine whether or not the procercoid protonephridial system would have a developmental stage when its type is similar to, or identical with that type which characterizes the monogeneans. Such a conformity would greatly support the theory of a common origin of monogeneans and ceslodes. However, it has emerged that no similar developmental stage exists. The ontogeny revealed a thorough metamorphosis from a very simple primary protonephridial system (identical with that of the miracidium larva in digeneans) to a secondary system, which develops into the system of the adult tapeworm. This fact may be interpreted as an argument against the supposed inter-relalionships between monogeneans and cestodes. However, the type of hooks and the procercoid cercomer still indicate common ancestors. An analysis of the miracidium, the oncosphaera and the oncomiracidium (the monogenean larva) with reference to their different developmental stages when hatching, gave rise to my interpretation of the fundamental structure of both the miracidium and the oncosphaera as primitively simple and not reduced, Especially the identical type of protonephridial system indicates. in my view, that digeneans and ceslodes originally had a common larva type. If the ceslodes and the monogeneans have common ancestors, then the procercoid may be interpreted as the ontogenetic recapitulation of a common hook-armed ancestor, here named hexucanthoid. This rhabdocoelan creature with six hooks in the cercomer and adapted to an ectocommensalic/ectoparasitic mode of life, is thought to have given rise to the monogeneans, the gyrocotylideans, the amphilinideans and the cestodes. The monogeneans were found to have two fundamentally different types of marginal hooks, and on this basis ihe existence of two different lines of evolution in Monogenea is indicated.     

A comparative study of the egg morphology in four species of Eubothrium (Cestoda: Pseudophyllidea) with comments on their early development

Abstract. Freshly released eggs from four species of the cestode Eubothrium ( Eubothrium crassum, Eubothrium fragile, Eubothrium rugosum , and Eubothrium salvelini ) were subjected to morphological and morphometric analysis. The eggs of the two freshwater species, E. rugosum and E. salvelini , were ovoid with a lobed embryophore whereas the eggs of the two marine species, E. crassum and E. fragile , were more circular with a smooth embryophore. However, the morphological differences between species were not readily evident to permit their clear distinction from one another. To discriminate species, a forward stepwise linear discriminant analysis, using six of the seven measured metric characters made on the eggs, was used, which gave 100% correct classification of two species, E. rugosum and E. salvelini , and a high proportion of correct classification for E. crassum (98%) and E. fragile (83%). Of the latter two species, one specimen of E . crassum and five specimens of E. fragile were misclassified between the respective groups. The principal characters used in the classification of the species were the width of the egg, the length of the mediolateral hooks, and the width of the oncosphere. To provide more information on the life cycle of each species, the eggs were used in a series of infection trials to identify appropriate intermediate hosts. Experimental infections with freshwater copepods were successful when exposed to the eggs of E . salvelini , partially successful when exposed to the eggs of marine E. crassum with 10% of the copepods becoming infected, but no infections were obtained when the eggs of E. fragile were used.     

Comparative karyological studies on the species of Eubothrium Nybelin, 1922 (Cestoda: Pseudophyllidea)

Karyotypes of Eubothrium salvelini, E. crassum and Eubothrium sp. were studied using conventional Giemsa staining and comparative karyometric analysis. The karyotypes, reported here for the first time, consist of eight chromosome pairs. The two first pairs of homologues are metacentric and markedly larger than the remaining elements. The obvious similarity in karyotype structure does not exclude the possibility of discriminating E. salvelini and E. crassum using karyotypic characters. The best cytogenetic marker is the last pair of chromosomes, which is acrocentric in the karyotype of E. salvelini and metacentric in that ofE. crassum. Karyological observations provide strong evidence for assigning Eubothrium sp. from Clupea harengus membras to E. crassum. Comments are made on the karyotypes of these and related species with respect to their phylogenetic links.     

On the Early Development of the Protonephridial Systems in Some Species Belonging to the Genera Diphyllobothrium, Triaenophorus and Schistocephalus (Cestoda, Pseudophyllidea)

Malmberg, G. {Department of Zoology, University of Stockholm, Stockholm, Sweden.) On the early development of the protonephridial systems in some species belonging to the genera Diphyllobothrium, Triaenophorus and Schistocephalus {Cestoda, Pseudophyllidea). Zool. Scripta 1 (5): 227–228, 1972.–The protonephridial systems of coracidia (oncospheres) and procercoids of four Diphyllobothrium species, of Triaenophorus nodulosus (Pallas) and of Schistocephalus solidus (Muller) were studied. In the oncospheres of Diphyllobothrium and Schistocephalus the two flame bulbs of the primary protonephridial system were present, but not in the oncospheres of Triaenophorus. In Schistocephalus the two flame bulbs were found to be inactive in the oncosphere (studied inside the coracidium), but very active in the youngest procercoids, which may imply that the primary protonephridial system does not start its function until the oncosphere has entered the copepod body cavity. The primary protonephridial system of the Triaenophorus procercoids was totally (most specimens) or partly reduced. The secondary protonephridial system, however, began developing more or less simultaneously with the integumental hooklets, the cercomer and the first calcareous bodies, which is in accordance with what is described concerning Diphyllobothrium. The ciliated, excretory bladder described by Rosen in 1919 was found to be a posteriorly open invagination, surrounding the “cercomer shaft”. Reverse bends of the posterior main canals of the secondary system are located closely around the wall of, though very likely not emptying into this invagination.     

A revision of the species of Bothriocephalus Rudolphi, 1808 (Cestoda: Pseudophyllidea) parasitic in American freshwater fishes

The species of the pseudophyllidean genus Bothriocephalus Rudolphi, 1808 parasitising freshwater fishes in America are revised, based on the examination of type and voucher specimens of seven taxa. There are five valid species: Bothriocephalus claviceps (Goeze, 1782), B. cuspidatus Cooper, 1917, B. formosus Mueller & Van Cleave, 1932, B. acheilognathi Yamaguti, 1934, and B. pearsei Scholz, Vargas-Vázquez & Moravec, 1996. B. texomensis Self, 1954 from Hiodon alosoides in the USA, and B. musculosus Baer, 1937 from a cichlid Cichlasoma biocellatum (= C. octofasciatum) which died in an aquarium in Switzerland, are synonymised with B. cuspidatus. B. schilbeodis Cheng & James, 1960 from Schilbeodes insignis in the USA, B. speciosus (Leidy, 1858) Leidy, 1872 from Boleostoma olmstedi in the USA, and B. cestus Leidy, 1885 from Salvelinus sp. in Canada are considered to be species inquirendae until new material for the evaluation of their taxonomic status is available. B. cordiceps (Leidy, 1872) from Salmo (= Salvelinus) fontinalis in North America is in fact a larva (plerocercoid) of a Diphyllobothrium species. The study showed that there have been many misidentifications, mostly of B. cuspidatus erroneously designated as B. formosus or B. claviceps. The five valid species are redescribed and illustrated, with emphasis on scolex morphology. The distribution of individual taxa and the spectrum of their definitive hosts are briefly reviewed and a key facilitating identification of individual species is also provided.     

The functional morphology of the scolex of Diphyllobothrium Cobbold (Cestoda, Pseudophyllidea). A scanning electron and light microscopical study on scoleces of adult D. dendriticum (Nitzsch), D. latum (L). and D. ditremum (Creplin).

Scoleces of adult D. dendriticum, D. latum and D. ditremum were studied using scanning electron and light microscopy. In D. dendriticum and D. latum the transverse bar between the bothria at the scolex apex always possessed a frontal pit while in D. ditremum no such invagination was seen. The scoleces attach to the host intestine by taking a firm grip with each bothrium around one or two intestinal villi. In D. ditremum and D. latum a layer of secreted substance is present between the scolex apex and the host intestine and between the inner bothrium surface and the host intestinal villi. In D. dendriticum, however, such a secreted layer was only observed at the scolex apex. A general account of the musculature and nervous and excretory systems of a Diphyllobothrium scolex is given.     

Nematops nanosquama, a new species of righteye flounder (Pleuronectiformes: Poecilopsettidae) from off the Marquesas Islands

A new poecilopsettid flounder, Nematops nanosquama, is described from 10 specimens (4 males, 6 females) collected from deep waters (96–650 m) off Hiva Oa, Marquesas Islands. This species is easily separated from the three recognized species of the genus Nematops by having large numbers of dorsal fin rays, anal fin rays, lateral line scales, and vertebrae, five dark transverse broad bands on the body, and a black blotch on the distal area of the pectoral fin. N.nanosquama shows the easternmost record of this genus from the Pacific Ocean.     

Ultrastructural studies on Diphyllobothrium ditremum and D. dendriticum (Cestoda, Pseudophyllidea), with emphasis on the scolex tegument and the tegument in the area around the genital atrium.

The scolices of D. ditremum and D. dendriticum are similar in regard to general morphology and ultrastructure of the tegument. At the scolex apex and along the upper bothrial edges sensory endings are numerous. The inner bothrium surface of D. ditremum appears to be plain or smooth, the distal cytoplasm is only about 0.6 mum thick and covered with long and slender microtriches. When D. ditremum is attached to the host gut an adhesive layer of secreted substance exists between the inner bothrium surface and the host intestinal villi. In D. dendriticum, however, no secreted layer exists between the inner bothrium surface and the host intestinal villi and the inner bothrium surface of this species appears to be lobed or lappet formed. The lobes are protrusions of the distal cytoplasm and are covered with long and slender microtriches. Large conglomerations of secretion globules appearing to be enclosed by a double membrane, are observed in the scolices of D. dendriticum and D. ditremum, although more frequent in the latter. Differences existing between the distal cytoplasm of the scolex and the gravid proglottid are described. The papillae around the genital atrium in mature and gravid segments were studied. Each papilla appears as a thickening of the distal cytoplasm, which in this region is 10-12 mum thick, when studied with transmission electron microscope. From the area between the papillae sensory endings appearing in sections to be either single, double or triple are described.     

Onchobothrium malakhovi n. sp. (Cestoda: Onchoproteocephalidea) ex Bathyraja (Arctoraja) sexoculata (Rajiformes: Arhynchobatidae) from Kuril Islands (Russia), with comments on the status of the genus Onchobothrium

Onchobothrium malakhovi n. sp. was found in the spiral valve of the softnose skate Bathyraja (Arctoraja) sexoculata off the Simushir Island (Kuril Islands, Russia). The new species has bothridia with three loculi and no additional suckers on bothridia, single-toothed hooks unconnected by their bases, no spines at the bases of the hooks, dense matrix around the hook bases shaped as an unpaired butterfly wing, and a short and wide ovary. Onchobothrium malakhovi n. sp. differs from O. antarcticum and O. magnum in having a smaller total length, cirrus sac and ovary, smaller testes and eggs. Additionally, the new species differs from O. antarcticum by the absence of a vaginal sphincter and shorter bothridia; differs from O. magnum in having fewer proglottids and smaller vitelline follicles. It differs from O. farmeri, O. convolutum, and O. pseudouncinatum, by the absence of a small spine at the base of the hooks and the absence of accessory suckers on bothridia; from O. pseudouncinatum, additionally, by unconnected hooks; from O. schizacanthium, by the number of testes and by the presence of a postvaginal group of testes. Onchobothrium malakhovi n. sp. was placed among other members of the Onchoproteocephalidea with a high support based on the sequence data for the D1-D3 region of the 28S rDNA and cox1 gene. The phylogenetic position of the genus Onchobothrium sensu lato remains ambiguous. We suggest that Onchobothrium sensu lato is a complex genus containing at least two morphologically different groups of species. Onchobothrium farmer, O. convolutum, O. schizacanthium, and O. pseudouncinatum, for which there are no molecular genetic data, are considerably different morphologically from O. malakhovi n. sp., O. antarcticum, and O. magnum. A new genus might have to be established for the latter three species after the accumulation of genetic data.