The phylogenetic position of the Loimoidae Price, 1936 (Monogenoidea: Monocotylidea) based on analyses of partial rDNA sequences and morphological data.

Phylogenetic analyses of partial sequences of 18S and 28S rDNA of some monogenoids, including monocotylids and a specimen of Loimosina sp. collected from a hammerhead shark off Brazil, indicated that the Loimoidae (as represented by the specimen of Loimosina sp.) represents an in-group taxon of the Monocotylidae. In all analyses, the Loimoidae fell within a major monocotylid clade including species of the Heterocotylinae, Decacotylinae, and Monocotylinae. The Loimoidae formed a terminal clade with two heterocotyline species, Troglocephalus rhinobatidis and Neoheterocotyle rhinobatis, for which it represented the sister taxon. The following morphological characters supported the clade comprising the Loimoidae, Heterocotylinae, Decacotylinae and Monocotylinae: single vagina present, presence of a narrow deep anchor root, and presence of a marginal haptoral membrane. The presence of cephalic pits was identified as a putative synapomorphy for the clade (Loimoidae (T. rhinobatidis, N. rhinobatis)). Although rDNA sequence data support the rejection of the Loimoidae and incorporating its species into the Monocotylidae, this action was not recommended pending a full phylogenetic analysis of morphological data.

Neotropical Monogenoidea. 46. Three new species from the gills of introduced aquarium fishes in India, the proposal of Heterotylus n. g. and Diaphorocleidus n. g., and the reassignment of some previously described species of Urocleidoides Mizelle & Price, 1964 (Polyonchoinea: Dactylogyridae).

Three new species of the Dactylogyridae are described from aquarium fishes collected in India and two new genera are proposed: Heterotylus heterotylus n. g., n. sp. from Hypostomus sp. (Loricariidae), Diaphorocleidus armillatus n. g., n. sp. from Gymnocorymbus ternetzi (Characidae) and Urocleidoides vaginoclaustrum n. sp. from Xiphophorus helleri (Poeciliidae). Heterotylus n. g. is characterised by species having overlapping gonads (testis posterodorsal to the ovary), a mid-ventral vaginal aperture, a copulatory complex consisting of a relatively straight copulatory organ unarticulated to a complex accessory piece, erect acute hook thumbs, unexpanded hook shanks, dorsal and ventral anchor/bar complexes and absence of well-defined basal roots of the ventral anchors. Diaphorocleidus n. g. includes species with overlapping gonads (testis posterodorsal to the ovary), submarginal sinistral vaginal pore, a copulatory complex comprising a coiled (counterclockwise) copulatory organ unarticulated to an accessory piece, protruding depressed hook thumb, hook shank with two subunits (proximal subunit expanded), dorsal and ventral anchor/bar complexes and V-shaped bars. The following new combinations are proposed: D. affinis (Mizelle, Kritsky & Crane, 1968) n. comb. (syn. U. affinis Mizelle, Kritsky & Crane, 1968), D. kabatai (Molnar, Hanek & Fernando, 1974) n. comb. (syn. U. kabatai Molnar, Hanek & Fernando, 1974) and D. microstomus (Mizelle, Kritsky & Crane, 1968) n. comb. (syn. U. microstomus Mizelle, Kritsky & Crane, 1968).

Haliotrema abaddon n. sp. (Monogenoidea: Dactylogyridae) from the gills of wild and maricultured West Australian dhufish Glaucosoma hebraicum (teleostei: Glaucosomatidae), in Australia.

Haliotrema abaddon n. sp. (Dactylogyridae) is described from the gills of West Australian dhufish Glaucosoma hebraicum (Teleostei: Glaucosomatidae), from the Indian Ocean near Fremantle, Western Australia. The parasite is recorded from cultured dhufish and from a major portion of the known geographic distribution of its host. In cultured dhufish, H. abaddon causes branchitis and hyperplasia and metaplasia of the lamellar epithelial cells and may be a limiting factor in the development of an economically feasible mariculture industry. Comparable prevalences and densities of the parasite on wild and cultured dhufish were observed. In heavily infested captive fish, clusters of eggs (egg strands) appear to restrict blood flow to localized regions of the gills as a result of entanglement of egg filaments with secondary gill lamellae. Hatching of oncomiracidia occurs in 7-10 days at 20-25 C.

Calicobenedenia Polyprioni n. gen., n. sp. (Monogenoidea: Capsalidae) from the external surfaces of wreckfish, Polyprion americanus (Teleostei: Polyprionidae), in the north Atlantic.

Calicobenedenia polyprioni n. sp. (Capsalidae) is described from the external surfaces (skin and eye) of wreckfish, Polyprion americanus (Teleostei, Perciformes, Polyprionidae), from the north Atlantic Ocean. The monotypic Calicobenedenia n. gen. is proposed for this species and is characterized, in part, by its members possessing an aseptate haptor armed with 14 submarginal hooks and 1 pair of anchors, a common genital pore opening marginally immediately posterior to the left cephalic lobe, 2 testes juxtaposed near the body midlength, and by lacking cephalic suckers or adhesive discs, accessory haptoral sclerites, and a uterine valve. The new genus most closely resembles Entobdella, which differs from Calicobenedenia by having an aseptate haptor armed with 14 submarginal hooks, 2 pairs of anchors, and a pair of accessary sclerites.

Coevolution of the Monogenoidea (Platyhelminthes) based on a revised hypothesis of parasite phylogeny.

A revised hypothesis for the phylogeny of the Subclass Polyonchoinea (Monogenoidea) was constructed employing phylogenetic systematics. The Acanthocotylidae (formerly of the Order Capsalidea) is transferred to the Order Gyrodactylidea based on this analysis. The new phylogeny is used to determine coevolutionary relationships of the familial taxa of Monogenoidea with their hosts. The coevolutionary analysis suggests that the Monogenoidea apparently underwent sympatric speciation or dispersal while parasitic on ancestral Gnathostomata, resulting in two primary clades: the Polyonchoinea and the Oligonchoinea + Polystomatoinea. The two parasite clades apparently cospeciated independently with divergence of the Chondrichthyes and Osteichthyes. In the Polyonchoinea, the clade associated with Chondrichthyes experienced primary extinction within the Holocephala, but coevolved into the Loimoidae and Monocotylidae in the Galeomorphii and Squalea (Elasmobranchii), respectively. Within the Osteichthyes, polyonchoineans experienced primary extinction with the divergence of Sarcopterygii, Polypteriformes and Acipenseriformes. They demonstrate primary dispersal from the Neopterygii into the Squalea (as Amphibdellatinea), Actinistia (as Neodactylodiscinea) and Urodela (as Lagarocotylidea). Secondary dispersals of polyonchoineans occurred in the Gyrodactylidae to the Polypteriformes, Urodela and Anura; in the Acanthocotylidae to the Myxinoidea and Squalea; in the Capsalidae to the Acipenseriformes and Elasmobranchii; and in the Monocotylidae to the Holocephala. The Oligonchoinea and Polystomatoinea developed upon divergence of the Chondrichthyes and Osteichthyes. Oligonchoineans cospeciated within the Chondrichthyes, with the Chimaericolidea developing within the Holocephala and the ancestor of the Diclybothriidea + Mazocraeidea within the Elasmobranchii. Two cases of primary dispersal occurred within this clade: the Diclybothriidae to the Acipenseriformes and the ancestor of mazocraeidean families to the Neopterygii (both Osteichthyes). Secondary dispersal within the Oligonchoinea includes host switching of the common ancestor of Callorhynchocotyle (Hexabothriidae) to the Holocephala. Polystomatoineans coevolved within the Osteichthyes, but experienced primary extinctions in the Actinopterygii, Actinistia, Dipnoi and Amniota. Coevolution of the Sphyranuridae and Polystomatidae occurred with divergence of the Urodela and Anura, respectively. Secondary dispersal of Polystomatids to the Urodela, Dipnoi and Amniota is suggested. A preliminary phylogenetic analysis of the Polystomatoinea suggests that primary extinction with secondary dispersal of polystomatids to the Dipnoi may not be necessary to explain extant parasite distributions, since Concinnocotyla (Concinnocotylinae) appears to represent the sister taxon of the remaining Polystomatidae + Sphyranuridae.

Spermatogenesis in Octomacrum lanceatum (Monogenoidea, oligonchoinea, mazocraeidea).

Ultrastructural aspects of spermatozoon development and morphology in Octomacrum lanceatum are presented. Spermiogenesis involves development of zones of differentiation from the surface of cytophores followed by formation of a middle cytoplasmic process and 2 free flagella whose axonemes form from basal bodies located within each zone of differentiation. The mitochondrion and nucleus penetrate through the zone of differentiation into the middle cytoplasmic process. An intercentriolar body is present. Initially the axes of the basal bodies are perpendicular to that of the intercentriolar body but subsequently rotate about 90 degrees to parallel positions as the flagella develop. Flagella are initially free, but eventually fuse with the middle cytoplasmic process from the proximal to distal end (proximodistal fusion). Subsurface microtubules occur within the zone of differentiation but are lacking from the lateral regions of the middle cytoplasmic process. The mature sperm possesses two axonemes, one mitochondrion, and a complete ring of cortical microtubules (sperm pattern 1). The finding of sperm pattern 1 in the Octomacridae suggests that many features of the spermatozoon of the Diplozoidae are autapomorphic.

The phylogenetic status of the Ancyrocephalidae Bychowsky, 1937 (Monogenea: Dactylogyroidea).

Phylogenetic analysis of selected subfamily and family taxa within the Dactylogyroidea indicates that the Ancyrocephalidae Bychowsky, 1937, is unnatural. The family contains both poly- and paraphyletic features. The analysis supports the previous elevation of the Pseudomurraytrematinae to family status and suggests that revision of the Ancyrocephalidae is necessary. Two options for revision are provided; that of returning the taxon to subfamily status within the Dactylogyridae is preferred, requiring a change in status of the Heterotesiidae to a subfamily within the Dactylogyridae.

Neotropical monogenea. 13. Rhinonastes pseuodocapsaloideum n. gen., n. sp. (Dactylogyridae, Ancyrocephalinae), a nasal parasite of curimatã, Prochilodus nigricans Agassiz (Cypriniformes, Prochilodontidae), in Brazil.

Rhinonastes pseudocapsaloideum n. sp. (Dactylogyridae, Ancyrocephalinae) is described from the nasal cavity of Prochilodus nigricans Agassiz (Cypriniformes, Prochilodontidae) in Brazil. Rhinonastes n. gen. is proposed for species possessing a dextroventral genital pore, a bilobed testis, a ventral C-shaped ovary lying between the 2 testicular lobes, and a disc-shaped haptor armed with a ventral anchor-bar complex and 14 hooks.

Studies on sylvatic echinococcosis. V. Factors influencing prevalence of Echinococcus multilocularis Leuckart 1863, in red foxes from North Dakota, 1965--1972.

A total of 1,153 red foxes, Vulpes vulpes, was examined for strobilae of Echinococcus multilocularis from 2 geographic regions in North Dakota during 1965 through 1972. Echinococcus multilocularis was found in 184 (16%) of these foxes. The data including date and location of collection, age and sex of the host, and presence or absence of the cestode were used to assess the relative influence of collection interval (sampling period), climatic season, geographic location, and age and sex of the host on the prevalence of the adult cestode. The rate of infection varied significantly with collection interval, which was probably attributable to annual changes in the overall environment. Seasonally, the highest prevalences were observed during summer (32.4%) followed by spring (25.3%), autumn (13.7%) and winter (6.4%). Differences in prevalence between adult and juvenile foxes and that between male and female foxes were not significant. A 3-factor analysis of variance showed the order of importance of the significant variables to be collection interval, season, and the interaction of collection interval and season. A 4-factor ANOVA, which in addition to the above variables included geographic location, showed that the collection interval-location interaction had significant effects on prevalence. Also, evidence is presented that suggests that density of the definitive host may in part be responsible for annual fluctuation in prevalence.

Allencotyla pricei sp. n. (Microcotyloidea: Heteraxinidae) from the gills of the pile surfperch, Damalichthys vacca (Girard), in southern California.

Allencotyla pricei sp. n. (Monogenea: Heteraxinidae) from the gills of pile surfperch, Damalichthys vacca (Girard), from Redondo Beach, California is described. This species is distinguished primarily by the prebifurcal position of the genital atrium and vagina, and by possessing an elongate esophagus. The systematic arrangement of microcotyloid forms characterized by an asymmetric haptor is discussed.

The natural occurrence of Echinococcus multilocularis in the bushy-tailed woodrat, Neotoma cinerea rupicola, in Wyoming.

Echinococcus multilocularis Leuckart, 1863, is reported from Neotoma cinerea rupicola Allen in Wyoming. This report represents new host and locality records for the cestode. The larva had undergone active multilocular vesiculation in the liver with minimal host-tissue reaction. Protoscolices and calcareous corpuscles were absent.