Volume 51, Issue 4

A species of Sarcocystis is reported from two naturally infected Buffon’s macaws (Ara ambigua) from Costa Rica. Only mature sarcocysts, measuring up to 950 μm in length and up to 75 μm in width, were observed. By light microscopy the sarcocyst wall was thin (< 1 μm thick) and smooth. The villar protrusions on the sarcocyst wall were up to 4.0 μm long and up to 0.6 μm wide; they were folded over the sarcocyst wall giving a thin-walled appearance. The microtubules in villar protrusions were smooth and confined to villar protrusions. Bradyzoites in sections were 4.0–5.9 × 0.8–1.8 μm in size. Structurally, sarcocysts from the macaw appeared different from sarcocysts of other avian species. This is the first report of Sarcocystis infection in this host.

The type material of Polylekithum ictaluri, P. halli, and Maculifer chandleri was examined from the United States National Parasite Museum, and we determined that the material was conspecific, making P. halli and M. chandleri junior subjective synonyms of P. ictaluri. Polylekithum catahoulensis sp. nov. was described from material collected from catfishes at the Catahoula Wildlife Refuge, LaSalle Parish, Louisiana, USA, and compared with P. ictaluri collected from catfishes in Reelfoot Lake, Obion County, Tennessee, USA, and the Pearl River, Hancock County, Mississippi, USA. Polylekithum catahoulensis had smaller eggs (77–88 μm long by 51–63 μm wide vs. 94–108 μm by 52–76 μm) and a longer forebody (35–41% of overall body length vs. 29–34%). Comparison of more than 2,400 bp long fragments of nuclear ribosomal DNA (complete ITS and partial 28S regions) strongly supported the status of P. catahoulensis as a new species. Molecular phylogenetic analysis of 28S rDNA gene sequences from Polylekithum as well as representative species from Allocreadiidae, Atractotrematidae, Brachycoeliidae, Callodistomidae, Dicrocoeliidae, Encyclometridae, Gorgoderidae, Haploporidae, Opecoelidae, Plagiorchiidae, and Telorchiidae rooted by Monorchiidae and Lissorchiidae demonstrated that of the families tested, Polylekithum was most closely related to Encyclometridae as a gorgoderoid and not to Allocreadiidae as previously reported. Morphological features of three South American allocreadiids, Allocreadium patagonicum, P. percai, and A. pichi were inconsistent with generic diagnoses of Allocreadium and Polylekithum, so we suggested they belonged in a single unnamed genus similar to Creptotrema. Polylekithum catlai from India was assessed from the description and failed to conform to the generic diagnosis of Polylekithum. Morphology of Caudouterina suggested a close relationship with Polylekithum and not Allocreadiidae.

Specimens of the fishes Pterois volitans Linnaeus (Scorpaenidae) and Chaetodon auriga Forsskål (Chaetodontidae) were caught in the Red Sea off the coast of Sharm El-Sheikh, South Sinai, Egypt. Five (20%) and 20 (44%) of these fishes, respectively, were found to harbour intestinal trematodes. P. volitans was parasitised by Proneohelicometra aegyptensis gen. nov., sp. nov. (Opecoelidae) and C. auriga by Neohypocreadium gibsoni sp. nov. (Lepocreadiidae). Proneohelicometra gen. nov. is similar to Neohelicometra Siddiqi et Cable, 1960 which is the only opecoelid genus having caeca opening with separate ani and eggs with unipolar filaments, but differs significantly from it in having two lateral folds of body wall extending along the posterior third of body, an oral sucker smaller than the ventral sucker, a median cirrus sac not reaching the ventral sucker posteriorly and a median genital pore situating immediately posterior to the intestinal bifurcation. Neohypocreadium gibsoni sp. nov. is similar to the other four species of the genus, but is unique in having a distinctly pear-shaped body and a much smaller egg size, and differs significantly from each in several other characters: from N. longisaccatum, it differs in having a cirrus sac not reaching the testes and a pretesticular ovary; from N. dorsoporum in having an external seminal vesicle much shorter than the cirrus sac, a longer cirrus sac extending posteriorly to the level of the posterior margin of the ventral sucker and a pretesticular ovary; from N. chaetodoni in having a smaller body size, symmetrical testes, a longer cirrus sac extending posteriorly to the level of the posterior margin of the ventral sucker and a trilobed ovary; and from N. aegyptense in having a smaller body size, symmetrical testes, a longer cirrus sac extending posteriorly to the level of the posterior margin of the ventral sucker, a trilobed ovary and vitelline follicles terminating anteriorly at the level of oesophagus. Neohypocreadium Machida et Uchida, 1987 is briefly reviewed.

In the spathebothriidean tapeworm Didymobothrium rudolphii (Monticelli, 1890) the fine structure of the vitellocytes at different stages of their development within the vitelline follicles, vitelline ducts and uterus was studied for the first time using transmission electron microscopy. The vitellocyte inclusions of D. rudolphii are shell globule clusters containing tightly packed shell globules associated with a matrix of moderate electron density, glycogen granules, large electron-lucent lipid droplets (up to 3 μm in diameter), and, occasionally, a lipid droplet may occur in the nucleus of the vitellocytes. The diameter of the clusters ranges from 0.4 to 2.5 μm, the number of shell globules in the clusters varies from 8 to 45, and the size of the globules ranges from 0.12 to 0.25 μm and they are of approximately homogeneous sizes within a cluster. Most vitellocyte lipid droplets have a heterogeneous configuration with a ‘cavity’ inside them when they are within vitelline ducts and intrauterine eggs. Vitellocytes of the eggs contain dark concentric bodies and lipid droplets. The interstitial tissue has a syncytial structure. The morphological parameters of the diameter and shape of shell globule clusters, arrangement of shell globules in clusters, number and diameter of globules within clusters, types of lipid droplets and presence of dark concentric bodies are compared with those of two other spathebothriidean genera, Cyathocephalus and Diplocotyle. The comparative data demonstrate that vitelline material morphology has unique features in three spathenothriidean genera and may be used as evidence for the recognition of separate taxa.

The ultrastructure of the spermiogenesis of a dilepidid cestode species is described for the first time. The spermiogenesis of Angularella beema is characterised by absence of both flagellar rotation and proximodistal fusion. The differentiation zone is surrounded by cortical microtubules and is delimited by a ring of arching membranes. It contains two centrioles, one of which develops the axoneme that grows directly into the elongating cytoplasmic protrusion. This pattern of spermiogenesis was described as the Type IV spermiogenesis of cestodes. Among cestodes, similar pattern of spermiogenesis is known in the family Hymenolepididae and in some representatives of the family Anoplocephalidae. The mature spermatozoon of A. beema consists of five regions differing in their ultrastructural characteristics. It is characterised by the presence of cortical microtubules (spirally arranged at angle of 30–40° to the spermatozoon axis) and a single crested body. There is a periaxonemal sheath in certain parts of the spermatozoon as well as glycogen-like granules between the periaxonemal sheath and the cortical microtubules. The comparisons of the mature spermatozoon of A. beema with those of other two dilepidid species (Dilepis undula and Molluscotaenia crassiscolex) demonstrate some variation within the family: presence of periaxonemal sheath in A. beema and D. undula and its absence in M. crassiscolex; presence of electron-dense rods in D. undula and their absence in A. beema.

Scanning electron microscopy examination of male and female specimens of Micropleura australiensis Moravec, Kay et Hobbs, 2004 (Nematoda, Dracunculoidea) from the peritoneal cavity of the freshwater crocodile Crocodylus johnsoni of the Ord River in Western Australia revealed some previously unreported morphological features. The male, first studied by SEM, possesses the same number (14) of cephalic papillae as the gravid female, but these are comparatively larger and somewhat differently arranged; four slit-like depressions located near the inner base of male dorsolateral and ventrolateral cephalic papillae of the external circle are present. The inner margin of the female oral aperture is smooth, without papilla-like formations. The male caudal end is provided with a right-side ventral ala. The transverse cuticular striae on the male ventral surface bear minute ornamentations (rows of papilla-like formations) in the pre-and postcloacal region. For the first time, M. australiensis is reported from wild and farmed Crocodylus johnsoni and saltwater crocodile C. porosus (new host record) from four localities in the Northern Territory, Australia.

Female specimens of a little-known philometrid nematode, Nilonema senticosum (Baylis, 1927), were collected from the swimbladder of the arapaima, Arapaima gigas, from the Amazon River basin (Iquitos, Loreto District) in Peru. Scanning electron microscopical (SEM) examination, used for the first time in this species, made it possible to reveal some taxonomically important, previously unreported features of N. senticosum, such as the presence of minute cephalic papillae (10 papillae in 2 circles) and amphids surrounding the small oral aperture, and to confirm the absence of an anal opening in this species. Males and females of another philometrid, Alinema amazonicum (Travassos, 1960), were recovered from the body cavity of the pimelodid catfishes Calophysus macropterus and Brachyplatystoma juruense (a new host record) from the Amazon River basin (fish market in Iquitos, Loreto District) in Peru. SEM examination, not previously used in the male of A. amazonicum, enabled to study in detail the male cephalic and caudal structures.

A new nematode species, Trichostrongylus duretteae sp. nov., found in the small intestine of Ctenomys talarum from Argentina is described. The new species more closely resembles T. suis lwanitsky, 1930 a parasite of Sus scrofa in the USSR. However, the new species can be distinguished by the morphology of male genital bursa: Rays 6 distant from rays 8 and a larger dorsal ray in relation to the length of rays 2 to 8. The present finding is the first record of the genus Trichostronglyus in rodents of the family Octodontidae.

Neobrachiella spinicephala (Ringuelet, 1945) (Copepoda, Siphonostomatoida, Lernaeopodidae) is redescribed based on newly collected material from the Brazilian sandperch, Pinguipes brasilianus Cuvier, 1829, (the type host) from Mar del Plata, Argentina (the type locality). A description of the male is given for the first time. Although some differences were observed between the original description and the specimens examined in this study, these differences do not warrant a change in the taxonomic status of this species. Indeed, the generic status of the species is confirmed, especially based on characteristics of the male.

A total of 36 adult individuals of Leptodactylus latinasus were collected near the city of Corrientes, Province of Corrientes in Argentina. The main goals of this study were: (1) to determine the helminth parasite fauna of L. latinasus; (2) to determine the richness and diversity of parasites at the component and infracommunity levels; (3) to analyze the relationships between helminth, frog body size and sex, and (4) to identify and examine species affinity of helminth communities. The helminth component community of this frog’s population consisted of 17 species. The predominant groups of parasites were the trematodes (adults: Glypthelmins repandum, Catadiscus inopinatus and Haematoloechus longiplexus; larvae: Travtrema aff. stenocotyle, Bursotrema aff. tetracotyloides, Styphlodora sp., unknown opisthogonimid species, Petasiger sp. and unknown strigeid species), followed by the nematodes (Cosmocerca podicipinus, C. parva, C. rara, C. cruzi, Schrankiana schranki and Aplectana hylambatis); other groups of parasites were represented by only one species (unknown larval cestode species and Centrorhynchus sp.). All parasite helminth species showed an aggregated pattern of distribution. The most infected organs were kidneys, small intestine, large intestine and pharyngeal zone. The host body size was important in determining the parasites abundance of G. repandum. At the level of component community G. repandum was the species with highest prevalence of infection and Bursotrema aff. tetracotyloides was the dominant species. Helminth species showed four significant pairs of covariation and two significant pairs of association in the infracommunities of Leptodactylus latinasus.

This paper presents the first extensive data on the helminth community of the wood mouse Apodemus sylvaticus in a coastal sand dune area in Portugal. The 557 hosts analysed in this study were trapped seasonally between autumn 2002 and summer 2005 across 6 habitat types. Twelve helminth species were detected among which, Taenia parva larvae, Angiostrongylus dujardini, Heligmosomoides polygyrus, Syphacia stroma and S. frederici constitute the component species, accounting for 98.7% of all worms. H. polygyrus was the most prevalent helminth parasite. Species richness varied according to habitat and season. The highest species richness was found in sand dunes during winter whereas the lowest was detected along lake margins also during the winter. Some differences in prevalence and mean intensity values were found in relation to year (T. parva larvae and H. polygyrus), habitat (A. dujardini), season (T. parva larvae, H. polygyrus, A. dujardini and S. stroma) and host sex (T. parva larvae and S. stroma). These differences are discussed both in view of the host’s biology and habitat characteristics.