Antechinus Swainsonii Research Articles

Strzeleckia major n. g., n. sp. and S. minor n. sp. (Digenea: Hasstilesiidae) from Antechinus swainsonii (Marsupialia: Dasyuridae) in Australia

Strzeleckia major n. g., n. sp. and S. minor n. sp. are described from the dusky antechinus Antechinus swainsonii (Marsupialia: Dasyuridae) from the Kosciusko National Park in southern New South Wales, Australia. The two species were found together in the same individual host animals but occupy different sites in the intestine. The new genus is placed within the Hasstilesiidae, where it differs from the only other genus, Hasstilesia, by being more elongate and in having larger suckers, tandem testes, the ovary between rather than opposite the testes, and in having the caeca not reaching the posterior end of the body. It is suggested that the life-cycles of these species are similar to those of other hasstilesiids. Pupillid snails may act as sole intermediate hosts.

A physiological profile of male dusky Antechinuses, Antechinus swainsonii (Marsupialia: Dasyuridae) surviving the post-mating mortality.

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Diet of the Mountain Pygmy-possum, Burramys parvus (Marsupialia: Burramyidae) and other small mamma ls in the alpine environment at Mt Higginbotham, Victoria.

The diets of Burramys parvus, Rattus fuscipes and Antechinus swainsonii in Podocarpus lawrencei heathland in alpine Victoria during the non-winter period were determined from analysis of 264 faecal pellets. Both frequency of occurrence and mean percentage composition of dietary items in the samples were determined; the Iatter being used to assess the diet. We found B. parvus to be an omnivore concentrating on insec ts. It eats a variety of foods but the Bogong Moth (Agrolis infusa) is heavily exploited (31 % of the composition of faecal samples) especially by females during the breeding season (46 %). Other components of the diet are other invertebrates, predominantly insects (32 %) and vegetative material (16 %). Seasonal differences in the composition of the diet of B. parvus were due to the exploitation of fruit in the non-breeding season. No differences in diet were observed between age-classes and the sexes but females are sedentary in food resource-rich habitats, whilst when not breeding, males occur in areas of poorer food resources. Circumstantial evidence suggests that during facultative hibernation a major dietary component of B. parvus may be seeds, cached from the previous summer-autumn. The diet of R. fuscipes consists mainly of insects (12 %) and the largest vegetative component was seeds (10.1 %). Fungi were found in 53 % of faecal samples of R. fuscipes but could not be quantified as a percentage composition of diet. The species is classified as a selective omnivore. The diet of A. swainsonii consisted of 68 % in sec ts, 10.4 % of insect setae and worms with the major vegetative component (5.2 %) being soft fruits. Burramys parvus, relative to the other small mammals with which it cohabits, has become a specialist in exploiting the abundant and rich food resource of Bogong moths.

Helminth communities in small mammals in southeastern new south wales

1. 1. Changes in the composition and abundance of 5 marsupial and 3 eutherian mammal species, and of their helminth communities pre- and post-perturbation by wildfire at Nadgee and Timbillica State Forests in southeastern coastal New South Wales during the period September 1977 to September 1985 are reported. 2. 2.Dasyurid marsupials ( Antechinus stuartii, Antechinus swainsonii and Sminthopsis leucopus), peramelid marsupials ( Perameles nasuta and Isoodon obesulus) and native eutherian rodents ( Rattus fuscipes and Rattus lutreolus) occurred pre-fire. These species and the introduced house mouse ( Mus musculus) occurred post-fire. 3. 3. All host taxa harboured a diverse helminth fauna dominated by nematodes. The helminth communities in A. stuartii, A. swainsonii, S. leucopus and R. lutreolus represented more than 70%, those in P. nasuta, R. fuscipes and M. musculus represented more than 50% and that in I. obesulus represented less than 40% of the total helminth faunas known to occur in these hosts throughout their geographic ranges in Australia. 4. 4. Adult nematodes of Capillaria sp. 11 and Tetrabothriostrongylus mackerrasae occurred in all host groups, those of Peramelistrongylus skedastos occurred in both marsupial groups but not in rodents, larval stages of the ascaridoid nematode Ophidascaris robertsi occurred in all host groups and physalopterid nematode larvae believed to be Abbreviata spp. occurred in dasyurid marsupials and in rodents but not in peramelid marsupials. 5. 5. Four helminth communities were recognised: one in the dasyurid marsupials, a second in the peramelid marsupials, a third in the native rodents and a fourth in the introduced house mouse. 6. 6. Differences in the helminth communities in host taxa pre- and post-wildfire were associated with the ecological strategies of the hosts and their roles as opportunistic invaders ( M. musculus), fire-enhanced species ( S. leucopus) or slow recolonisers ( P. nasuta) post-perturbation by wildfire.

Failure of glucocorticoid feedback in males of a population of small marsupials (Antechinus swainsonii) during the period of mating.

In an investigation of the factors leading to the increase in the concentration of plasma free glucocorticoid, which results in immunosuppression and death after mating of all males in natural populations of a small shrew-like marsupial, the dusky antechinus (Antechinus swainsonii), the integrity of the glucocorticoid feedback control of the concentration of plasma cortisol was examined by use of dexamethasone-suppression tests. Injection of 0.2 mg dexamethasone/kg i.m. caused a marked fall in the concentration of plasma cortisol 17 h later, approximately 2 months and 2 weeks before the annual mating period in mid-July. However, the same dose had no significant effect on the increased concentration of plasma cortisol characteristic of the mid- to late July mating period. Injection of 100 i.u. ACTH/kg i.m. caused a significant increase in the concentration of plasma cortisol 6-7 h later on all occasions, indicating that the responsiveness of the adrenal cortex to ACTH did not change. Pretreatment with dexamethasone had no effect on the ACTH-stimulated cortisol concentration, ruling out a possible direct effect of dexamethasone on adrenocortical secretion in this species. Dexamethasone also reduced the concentration of plasma testosterone when the level was low, before the mating period, but not when the level was high, at the beginning of the mating period. It is concluded that, in association with a rapid increase in the concentration of plasma testosterone, an increase in aggression and intense mating activity, glucocorticoid feedback control of ACTH secretion is impaired.(ABSTRACT TRUNCATED AT 250 WORDS)

A novel structure in the stomach and intestine of two species of Australian marsupial mice

A tubular or sac-like structure with a well defined lumen which occasionally contained parasites was found in the outer muscle wall of the small and large intestine in 32 out of 40 male and 35 of 40 female marsupial mice of the two species, Antechinus swainsonii and Antechinus stuartii (Macleay). A similar structure was also found in the muscle layers of the stomach in 5 marsupial mice of both species. The cellular matrix of the structure appeared to be composed of randomly organized macrophage-like cells and in one case there was evidence of an inflammatory reaction to parasites within the lumen. The origin of this tube is either vestigial or the result of reactive changes.

Stress Related Involution of Lymphoid Tissues in Australian Marsupial Mice

Involution of the thoracic thymus in two species of marsupial mouse, Antechinus swainsonii(Waterhouse) and Antechinus stuartii (Macleay) was shown to be unrelated to corticosteroid action and to be complete before puberty. A stress response in male marsupial rice is caused by an androgen related drop in the plasma corticosteroid binding globulin concentration which gives rise to an increase in the plasma free glucocorticoid concentration. The high concentrations of free glucocorticoids in the plasma just prior to the breeding season causes a rapid involution of the spleen and lymph nodes while the gut associated lymphoid tissues remain unaffected. The concentration of free glucocorticoids also rises in females, but it never attains the high concentrations observed in males. Nevertheless, the spleen and lymph nodes do involute to some extent in some females and the degree of involution appears to be related to the relative concentration of plasma free glucocorticoids. At the conclusion of the breeding season, there is a complete mortality in males of thepopulation, due to a stress response in which the compromised immune system clearly plays a role.

Cytomegalic lesions in Australian marsupials.

Cytomegalic lesions were detected in nine dusky antechinus (Antechinus swainsonii), three bettongs (Bettongia gaimardi) and two little pygmy possums (Cercartetus lepidus). Virus particles were demonstrated in inclusions in A. swainsonii and B. gaimardi, but electron microscopy was not performed on tissues from C. lepidus.

Anatrichosoma haycocki sp. n. (Nematoda: Trichuridae) from the paracloacal glands of Antechinus spp. With notes on Skrjabinocapillaria skarbilovitsch.

Anatrichosoma haycocki sp. n. (Nematoda: Trichuridae) is described from the paracloacal glands of Antechinus swainsonii (Waterhouse, 1840) and A. stuartii Macleay, 1841 (Marsupialia: Dasyuridae) from Nadgee State Forest, New South Wales, Australia. Immature male and female worms occur free in the intestine. A. haycocki is distinguished from other species of Anatrichosoma by the following suite of morphological characters: small size, absence of longitudinal cuticular striations in both sexes, subterminal constriction of male tail bearing 14 minute papillae and inflation of posterior portion of mature female giving Trichuris-like appearance. It is also characterised by its occurrence in paracloacal glands in a genus of small carnivorous dasyurid marsupial restricted to Australia and New Guinea. Skrjabinocapillaria rodentium Wertheim and Chabaud, 1979 is recognised as a synonym of Anatrichosoma gerbillis (Bernard, 1964). The genus Skrjabinocapillaria Skarbilovitsch, 1946 is placed as a synonym of Capillaria Zeder, 1800, resulting in the new combination for the type species: C. eubarsata (Skarbilovitsch, 1946) comb. nov. It is suggested that deep penetration of the female uterus by the male at insemination is a behavioural feature common to members of the Trichinelloidea and that the morphology of the male reproductive tract reflects the mechanisms of penetration employed by members of each genus.

Population regulation and dispersion of the smoky mouse, Pseudomys fumeus I. Dietary determinants of microhabitat preference

Habitat preferences of four species of small mammals were studied on a 7.5-hectare trapping grid in a subalpine heathland/woodland complex on Mt William, western Victoria. Animals did not show strong spatial separation and differences in dispersion appeared to represent response to some feature of habitat. Floristic cues were good predictors of preference for Rattus lutreolus, Antechinus swainsonii and Pseudomys fumeus. Structural factors might also be important for R. lutreolus and A. swainsonii. The entire grid was suboptimal for Antechinus stuartii. Pseudomys fumeus was mycophagous during winter and, in the summer breeding season, principally ate seeds and bogong moths. Habitat preferences appear to reflect selection for those areas providing a year round source of high quality food rich in nitrogen. The transition period between the end of production of fungal sporocarps and prolific subalpine flower and seed production during summer may be particularly important as preferred areas provide fungi and seeds over longer periods, and food for bogong moths during their annual migration.

Endocrine changes in dasyurid marsupials with differing mortality patterns

A comparison was made between the breeding-related endocrine changes in two species of dasyurid marsupial ( Antechinus swainsonii and A. flavipes), which exhibit a catastrophic male mortality after a brief mating period; and those of another dasyurid species ( Sminthopsis crassicaudata), the males of which survive an extended breeding period. In the males of both Antechinus species, the mating period was preceded by a rapid rinse in plasma androgen concentration and accompanied by a marked fall in plasma corticosteroid-binding globulin (CBG) concentration, to less than the total glucocorticoid concentration, which itself rose. As a consequence plasma free glucocorticoid concentration rose approximately 10-fold just before the males disappeared from the populations. Severe hemorrhagic ulceration of the upper digestive tract was consistently found soon after capture near the time of mating. In females, CBG concentration was always well in excess of total glucocorticoid concentration and free glucocorticoid concentration remained low. There was a significant negative correlation between plasma androgen and CBG concentrations in male Antechinus species from the natural populations. In laboratory-held castrate male A. swainsonii, injection of either testosterone or dihydrotestosterone caused a dose-related fall in CBG. In contrast to the above, the CBG concentration was always well in excess of total glucocorticoid concentration in the plasma of male S. crassicaudata and there was no evidence of interaction between plasma androgen and CBG concentration. These findings support the hypothesis that, in those species with a breeding-related mortality of males, an androgen-dependent fall in plasma CBG concentration and a stressful mating period result in death from adrenocortical suppression of the immune and inflammatory responses.

Trapping Success in Relation to Trap Placement with Three Species of Small Mammals, Rattus fuscipes, Antechinus swainsonii and A.stuartii

The effect of trap placement on trapping success was investigated with the small mammals Rattus fuscipes, Antechinus swainsonii and A. stuartii. Trapping success for A. stuartii was not affected by density of ground cover (measured qualitatively and by the penetration of light), type of ground cover, presence of logs or presence of runways (either small natural openings in the ground cover or wombat pathways). R. fuscipes and A. swainsonii were caught more frequently in areas of good cover, in fishbone water-fern Blechnum nudum and on runways. The two indices of cover gave similar results. A. swainsonii was often caught on wombat pathways but not often on small natural runways; preference for wombat pathways increased in winter. Logs were not preferred by any of the species. Some latitude may be desirable in trap placement within a predetermined trapping configuration, especially when small mammals are sparsely distributed.

THE SPINOSA SPECIES-GROUP, GENUS BOOPIA PIAGET (PHTHIRAPTERA: BOOPIIDAE)*

Four new species belonging to the Boopia spinosa species-group parasitic on Australian Dasyuridae are described: B. greeni, type-host Antechinus minimus (Geoffroy); B. murrayi, type-host Antechinus swainsonii (Waterhouse); B. aquilonia, type-host Antechinus bellus (Thomas); and B. lukoschusi, type-host Sminthopsis murina (Waterhouse). The characters within the group are considered and some remarks included on the possible relationships of the species and their hosts. The correct interpretation of Harrison and Johnston's original description of B. brevispinosa is discussed.

A brachylaimid trematode from marsupial mice with observations on its life cycle

A species of digenetic trematode, Brachylaime antechini (Family Brachylaimidae), is described from adult worms recovered from the intestine and rectum of two species of marsupial mice, Antechinus stuartii(10 of 56 infected) and Antechinus swainsonii (2 of 5 infected). On experimental evidence unencysted metacercariae from the kidney of a terrestrial gastropod, Strangesta capillacea, are considered to be larval stages of Brachylaime antechini. Miracidia, sporocysts and cercariae have not been recovered, but circumstantial evidence suggests that Strangesta capillacea fulfils the role of first intermediate host. Brachylaime antechini most closely resembles Brachylaime chiapensis, a parasite of deer mice in Mexico.

Energy requirements of the dasyurid marsupial mouse Antechinus swainsonii (Waterhouse).

The requirements of the marsupial "mouse" Antechinus swainsonii for energy and water have been investigated using five individuals. The rate of food passage is recorded. Apparent digestible energy requirement for normal activity, determined by the equation, food energy less fecal energy, averages 23.3 kcal per day for 50-g animals. This is close to 4 times the calculated basal metabolic energy requirement. The equation relating water intake to apparent digestible energy (ADE) is y = 0.299x1,2. Rate of food passage is such that 90% of the residues are eliminated in 12 h, and 99% in 18 h. Among eutherian mammals, Antechinus most closely resembles the short-tailed shrew Blarina brevicauda.