Biochemical differentiation in bile duct cestodes and their marsupial hosts

Revision of the Progamotaenia zschokkei (Janicki, 1905) complex (Cestoda: Anoplocephalidae), with the description of six new species

A review of cestodes currently attributed to Progamotaenia zschokkei (Janicki, 1905) (Cestoda: Anoplocephalidae) suggests that six additional species are present: Pr. tenuis n. sp. found in Thylogale stigmatica (Gould) and T. thetis (Lesson), Pr. lomatosoma n. sp.from Macropus agilis (Gould), Pr. petrogale n. sp. from Petrogale spp. and Macropus dorsalis(Grey), Pr. fimbriata n.s p. from Lagorchestes conspicillatus Gould and L. hirsutus Gould, Pr. obesa n. sp. from Onychogalea fraenata (Gould) and O. unguifera (Gould) in north-eastern Australia and Pr. kellerae n. sp. from O. unguifera in north-western Australia. The new species are differentiated by a combination of characters: prominence of scolex lobes, number of lobes in the fimbriated velum, testis number and distribution, size of the cirrus-sac, morphology of the uterus and presence or absence of a pyriform apparatus in eggs from terminal segments. The morphological differences found support earlier molecular studies, in that cestodes within each host genus are distinct, with the exception that considerable morphological variation exists within Pr. petrogale. Principal components analysis suggested that most of the cestodes from Petrogale spp. belonged to Pr. petrogale. The status of specimens from Pe. lateralis is unclear. More detailed molecular studies are required to determine the significance of the morphological variation within this taxon. A key is provided to species within the complex and the related species Pr. villosa (Lewis, 1914).

Allozyme analysis of genetic variation and polymorphism in Eubothrium salvelini and E. crassum (Cestoda: Pseudophyllidea) from alpine lakes

The genetic structure of the most abundant species in the genus Eubothrium, E. crassum and E. salvelini, was studied by allozyme analysis in order to provide a consistent diagnosis for these morphologically similar species, as well as to assess their genetic relatedness. The proportion of fixed allelic differences (56.3%, 9 of 16 loci) between the species falls within the range accepted for valid species. A strict host specificity of E. crassum and E. salvelini for their typical host (lake trout, Arctic charr, respectively) was found in the French localities examined (Lake Annecy, Lake Bourget). For E. salvelini, polymorphism with the established allelic profile was found in the acid phosphatase (ACP) system. No significant deviation from the Hardy-Weinberg equilibrium expectations for ACP were found in either of the E. salvelini populations, which suggests predominantly cross-fertilization of these hermaphrodites. Analysis of the standardized variance in allelic frequencies demonstrated almost no among population differentiation (estimator theta of Fst = -0.03) between E. salvelini populations.

What is Paranoplocephala macrocephala (Douthitt, 1915) (Cestoda: Anoplocephalidae)?

We present a redescription for Paranoplocephala macrocephala (Douthitt, 1915) in the type host, Geomys bursarius (Shaw) (hereafter PMG), and compare it with a P. macrocephala-like taxon in Microtus pennsylvanicus (Ord) (hereafter PMM) and P. kalelai (Tenora, Haukisalmi & Henttonen, 1985) in Clethrionomys rufocanus (Sundevall) using uni- and multivariate (discriminant analysis) morphometric methods. P. kalelai was found to be most divergent among these three taxa using both uni- and multivariate analyses, supporting its status as an independent species. Most of the observed metrical differences between PMG and PMM were found to reflect the larger body size of PMM; the relative size of organs (ratios) did not usually differ significantly between these taxa. The length/width ratio of mature segments was found to be the only size-independent feature that reliably separates PMG and PMM. Since PMM and PMG are also qualitatively very similar, e.g. with respect to the distribution of testes and morphology of the terminal genital ducts, the present analysis could not provide conclusive evidence against their conspecificity. However, the morphological variability and wide host and geographical distribution of P. macrocephala-like cestodes in North American voles of the genus Microtus, and the patterns of host-specificity within Paranoplocephala, suggest that this complex probably includes several species.

Biogeography of helminth parasitism in Lemmus Link (Arvicolinae), with the description of Paranoplocephala fellmani n. sp. (Cestoda: Anoplocephalidae) from the Norwegian lemming L. lemmus (Linnaeus)

We describe the gastrointestinal helminth fauna of true lemmings (Lemmus spp., Arvicolinae) based on published and original material throughout the Holarctic range of these hosts. According to the existing data, the helminth fauna of true lemmings consists of three widespread and/or locally common taxa: Hymenolepis horrida (sensu lato) (Hymenolepididae), Anoplocephaloides lemmi (Anoplocephalidae) and Heligmosomoides spp. (Heligmosomidae). Despite the taxonomic boundaries and ancient phylogenetic splits in the hosts, there are no major faunistic differences for parasites within western (Siberian) L. sibiricus and L. bungei, and eastern (North American) L. trimucronatus throughout their distribution range. In contrast, the Norwegian lemming L. lemmus, which is a Fennoscandian endemic and closely related to the western populations of L. sibiricus, has only a single host-specific helminth, the cestode Paranoplocephala fellmani n. sp. (Anoplocephalidae). We describe the new species and show that it differs consistently from related species by its long and slender cirrus-sac. However, there are also a number of other significant differences, e.g., P. fellmani n. sp. and Andrya primordialis in Tamiasciurus hudsonicus (Sciuridae) evidently have a unique (sub)type of uterine development among Andrya/Paranoplocephala spp. Because P. fellmani n. sp. was also found to occur in Alaska (host L. trimucronatus), this species seems to follow the same biogeographical pattern as the other specialist helminths of Lemmus. We suggest alternative explanations for the absence of three major helminth taxa in the Norwegian lemming in Fennoscandia.