Zdzisław Laskowski

Intermediate and paratenic hosts in the life cycle of Aelurostrongylus abstrusus in natural environment

The cat lungworm Aelurostrongylus abstrusus affects the domestic cats and other felids all over the world. Feline aelurostrongylosis is of importance in clinical feline medicine. Snails and slugs are the intermediate hosts, but the cat is probably infected by eating paratenic hosts, e.g., rodents, birds, amphibians and reptiles. Herein we present the first finding of A. abstrusus in a naturally infected invasive synantropic slugs Arion lusitanicus (intermediate host) and wild living rodents Apodemus agrarius (paratenic host). The results confirm the usefulness of molecular approaches for investigating the biology, ecology and epidemiology of A. abstrusus, the agent of feline aelurostrongylosis.

New data on the occurrence of Acanthocephala in Antarctic Amphipoda

In total, 6401 amphipods, including 5707 Cheirimedon femoratus, caught at the Galindez Island (Argentine Islands, Western Antarctica) were examined for the presence of cystacanths and advanced acanthellae of Acanthocephala. Two parasite species, Corynosoma pseudohamanni Zdzitowiecki, 1984 and Metacanthocephalus johnstoni Zdzitowiecki, 1983, were found in the haemocoeloma of C. femoratus. Total prevalence was 1.19%, that of C. pseudohamanni 0.68% and of M. johnstoni 0.51%. Additionally, 8 of 1416 C. femoratus caught in the Admiralty Bay (South Shetland Islands) were found to be infected with C. pseudohamanni and free of M. johnstoni. The representative of the genus Metacanthocephalus was found in the intermediate host for the first time. C. pseudohamanni was more abundant at the Galindez Island (prevalence 0.68%) than in the Admiralty Bay (prevalence 0.42% in previous investigations and 0.56% in present ones). Amphipods harboured usually one or rarely two acanthocephalans of one species. Both parasites were more abundant in amphipods caught in the polluted water closely to the Vernadsky Station than in the Mick Channel, farther from the station (prevalence 0.77% vs. 0.51% for C. pseudohamanni and 0.64% vs. 0.26% for M. johnstoni).

Description of a New Digenean (Zoogonidae) Genus and Species from Sub-Antarctic Fish Patagonotothen tessellata

Abstract Whitegonimus ozoufae n. gen., n. sp. (Digenea: Zoogonidae) is reported from the stomach of Patagonotothen tessellata in the harbor of Ushuaia in the Beagle Channel (Tierra del Fuego, Argentina) at a depth of 7–9 m. The female genital system structure indicates the new taxon belongs in the subfamily Lepidophyllinae (Zoogonidae). None of the genera previously described is similar to the new genus. The most important taxonomic features are the spined tegument, lack of enlarged circumoral spines, gonads arranged in tandem, long caeca, vitelline follicles extending from the level of the ventral sucker to the posterior end of anterior testis, and a Y-shaped excretory vesicle. Only 3 genera, Overstreetia, Anarhichotrema, and Pseudopalaeorchis, have testes arranged in tandem, but they differ from the new genus in possessing enlarged circumoral spines, oral sucker size, esophagus length, length of caeca, vitellaria restricted to hindbody, the form of the ovary, and an I-shaped excretory vesicle.

Description of a New Opecoelid Trematode Species from Nototheniid Fish in the Beagle Channel (Sub-Antarctica)

Abstract: Macvicaria magellanica n. sp. (Digenea: Opecoelidae) is the third representative of this genus occurring in fish in the Magellanic sub-region of sub-Antarctica and the first one found in sub-coastal waters in this area (the Beagle Channel). Its main taxonomic features include an elongate body, oral:ventral sucker ratio based on widths of 1.0:1.52–1.98, cirrus sac reaching to level of posterior half of the ventral sucker, testes arranged in tandem, numerous vitelline follicles divided into 2 groups separated by a gap parallel to the ventral sucker, vitelline follicles dorsally not confluent at the uterus and gonads, and egg dimensions of 40–51 × 25–32 μm. The most similar species is Macvicaria antarctica, but it differs from the newly described species in having vitelline follicles dorsally confluent at the level of the uterus and by occurring in fish associated with the Falkland–Patagonian shelf at greater depths (at the North Scotia Ridge, 300–500 m). A key to 9 Antarctic and sub-Antarctic species of Macvicaria is included.

Molecular identification larvae of Onchobothrium antarcticum (Cestoda: Tetraphyllidea) from marbled rockcod, Notothenia rossii, in Admiralty Bay (King George Island, Antarctica)

Antarctic bony fishes are infected with cestode larvae belonging to the order Tetraphyllidea (parasites as adults in chondrichthyans). Larvae of the Tetraphyllidea differ from each other in the morphology of their scoleces and represent five forms. There are larvae with bothridia subdivided into one, two and three loculi, bothridia sac-like in shape and bothridia undivided with hook-like projections. Only one species of the family Onchobothriidae, Onchobothrium antarcticum, has been described from Antarctica and larvae with trilocular bothridia were assigned to this cestode species. In this study, ten larvae obtained from Notothenia rossii and three adult specimens of Onchobothrium antarcticum isolated from Bathyraja eatonii were examined. A partial sequence of cytochrome c oxidase subunit 1 of three adult specimens and four larvae was identical. The remaining six larval sequences differed from the sequences obtained from adult cestodes. Partial sequences of lsrDNA of all analyzed larvae were identical. These results confirm the taxonomic affiliation of the larvae with trilocular bothridia parasitizing marbled rockcod in Antarctica as Onchobothrium antarcticum.

Interrelationships of Dictyocaulus spp. in Wild Ruminants with Morphological Description of Dictyocaulus cervi n. sp. (Nematoda: Trichostrongyloidea) from Red Deer, Cervus elaphus

Abstract Lungworms from the genus Dictyocaulus cause parasitic bronchitis (dictyocaulosis) characterized by coughing and severe lung pathology in both domestic and wild ruminants. In this study we investigated the interrelationships of Dictyocaulus spp. from European bison (Bison bonasus L.), roe deer (Capreolus capreolus), and red deer (Cervus elaphus) by nucleotide sequence analysis spanning the 18S RNA gene (small subunit [SSU]) and internal transcribed spacer 2 (ITS2) regions of the ribosomal gene array as well as the mitochondrial cytochrome c oxidase subunit 1 (cox1). Molecular analyses of sequence data obtained partly with novel primers from between 10 and 50 specimens from each host were carried out. Bayesian inference analysis revealed that each host species was infected with different genotypes. Analysis of cox1 sequence data showed a diverse genetic background and high evolutionary potential of Dictyocaulus taxa. Data from lungworms of European bison revealed a distinct genotype of Dictyocaulus viviparus, whereas Dictyocaulus capreolus was only found in roe deer. In contrast, red deer were infected with a taxon with unique SSU, ITS2, and cox1 sequences. These results indicate the occurrence of a novel genotype from red deer, which differs significantly from the National Center for Biotechnology Information reference sequence of Dictyocaulus eckerti. The molecular evidence was consistent with a morphological study with description and imaging of Dictyocaulus cervi n. sp. recovered from red deer. Dictyocaulus cervi n. sp. can be distinguished from D. eckerti on the basis of the absence of cervical papillae, the occurrence of a single ring of 4 symmetrical submedian cephalic papillae, length of the tail in females, morphometry of the female reproductive system, and measurements of gubernacula in males. In conclusion, our findings further strengthen the idea that the genetic complexity and diversity among Dictyocaulus lungworms infecting wildlife ruminants is larger than previously believed and warrants further investigation.

Host-dependent morphology of Isthmiophora melis (Schrank, 1788) Luhe, 1909 (Digenea, Echinostomatinae) – morphological variation vs. molecular stability

BackgroundEchinostomes are cosmopolitan digenean parasites which infect many different warm-blooded hosts. Their classification is extremely confused; the host spectrum is wide, and morphological similarities often result in misidentification. During our long-term studies on the helminth fauna of rodents and carnivores we have collected 27 collar-spined echinostomes which differ in morphology to an extent that suggests the presence of more than one species. Here, we describe this material, and the extent of host-related variation in this parasite.MethodsSpecimens of Isthmiophora isolated from four host species (badger, American mink, hedgehog, striped field mouse) were subject to morphological and molecular examination; the data were statistically analysed.ResultsOur results show that genetically all the Isthmiophora specimens obtained from all the examined hosts are conspecific and represent I. melis. On the other hand, the individuals isolated from Apodemus agrarius are morphologically distinct and, based on this criterion alone, should be described as a new species.ConclusionsThe morphological traits of Isthmiophora melis are much variable and host-dependent; without molecular analysis they would suggest a necessity to describe a new species or even genus. Such a high level of intraspecific variability may be affected by the host’s longevity.

Digenea in notothenioid fish in the Beagle Channel (Magellanic sub-region, sub-Antarctica)

Fish of five species of Notothenioidei (104 specimens), Cottoperca trigloides, Patagonotothen brevicauda, P. longipes, P. tessellata and Champsocephalus esox, caught in the Beagle Channel (Magellanic sub-region, sub-Antarctica) were infected with Digenea of nine species (1130 specimens). Faunistic data on the occurrence of all nine parasites are provided. The most abundant digenean species was Macvicaria magellanica found in the intestine of three host species of the genus Patagonotothen. The second most abundant digenean species was Elytrophalloides oatesi found in the stomach of four host species, with exception of P. brevicauda. Three digenean species: Stenakron kerguelense, Whitegonimus ozoufae and Genolinea bowersi, were more abundant in fish caught at the harbor of Ushuaia (depth 7–9 m), remaining six species: M. magellanica, Neolepidapedoides subantarcticus, Postmonorchis variabilis, Derogenes varicus, E. oatesi and Lecithaster macrocotyle, in the eastern mouth of the Beagle Channel (depth 30 m).

Description of Neolepidapedoides subantarcticus sp. nov. (Digenea, Lepocreadiidae) from sub-Antarctic notothenioid fishes

Neolepidapedoides subantarcticus sp. nov. (Digenea, Lepocreadiidae) is reported from the intestine, mainly the jejunum, of fishes in the eastern mouth of the Beagle Channel and in the harbour of Ushuaia in the Beagle Channel (Tierra del Fuego, Argentina) at a depth 7–30 m. The typical host is Patagonotothen longipes, other hosts are P. tessellata, P. brevicauda and Champsocephalus esox. The male terminal genitalia indicates that the new species belongs to the genus Neolepidapedoides (Lepocreadiidae, Lepocreadiinae). The most important taxonomic features are the presence of eye-spots, the spined tegument, the “Opechona-type” cirrus-sac, the external seminal vesicle free in the parenchyma, the gonads arranged in tandem, the vitelline follicles extending from the level of the oesophagus in the forebody to the posterior end of the body and an I-shaped excretory vesicle reaching to the intestinal bifurcation and the absence of a pseudoesophagus. Ten previously described species differ from the N. subantarcticus sp. nov. mainly in the extent of the vitelline fields and length of the excretory vesicle which reaches into forebody.

New morphological data on the acanthocephalan Hypoechinorhynchus magellanicus Szidat, 1950 (Palaeacanthocephala: Arhythmacanthidae)

Hypoechinorhynchus magellanicus Szidat, 1950 (Acanthocephala: Arhythmacanthidae) is redescribed based on specimens collected from a sub-Antarctic notothenioid fish, Champsocephalus esox (Günther). The host was caught in the Beagle Channel (Magellanic sub-region). H. magellanicus has a trunk with an antero-dorsal curvature, a spherical proboscis, spines on the anterior region of the trunk, narrow lemnisci which are considerably longer than the proboscis receptacle, six cement glands and a single vaginal sphincter. The proboscis is armed with 40 hooks, including 15 large hooks with roots and 25 rootless basal spines. The large hooks are arranged in 10 alternate rows of one and two hooks. Each single large hook is followed by two spines, and pairs of large hooks are followed by single spines. Ten single spines are also present at the base of the proboscis between the rows. The eggs have polar prolongations of the middle envelope.