Hydromys

Abstract: The interrelationships of 19 genera and 28 species of New Guinean rodents representing 80% of the currently recognised New Guinean genera, were studied using microcomplement fixation of albumin to measure immunological distances among genera. The phylogenetic distinctiveness of Rattus and the closely related Stenomys from all other genera was confirmed. The remaining genera fall into three groups: (i) Lorentzimys; (ii) Anisomys, Coccymys, Chiruromys, Hyomys, Macruromys, Mallomys and Pogonomys; and (iii) Crossomys, Hydromys, Leptomys, Mayermys, Melomys, Neohydromys, Parahydromys, Pseudohydromys and Uromys. Solomys, from the Solomon islands, and Leggadina, Mesembriomys and Xeromys, from Australia, were shown to belong to this latter group. Groups (i) and (ii) are essentially endemic to New Guinea, while the third shares genera and species with Australia.

Abstract: A systematic review is given of a collection of over 57,000 parasitic mites collected from 1370 small mammals taken in the Innisfail area, north Queensland. The laelaptids comprised 46% of the total, the trombiculids 41%, and six other families (mainly Listrophoridae) 13%. Sixty-four species and 30 genera were represented as follows : Laelaptidae 11 genera 21 spp. Trombiculidae 7 genera 26 spp. Spinturnicidae 2 genera 2 spp. Teinocoptidae 1 genus 1 sp. Speleognathidae 1 genus 1 sp. Psoroptidae 1 genus 1 sp. Myobiidae 2 genera 3 spp. Listrophoridae 5 genera 9 spp. Twenty-two host species were examined, comprising 1 monotreme (Tachyglossus), 1 marsupial mouse (Antechinus), 2 bandicoots (Perameles and Isoodon), 3 rat-kangaroos and pademelons (Hypsiprymnodon, Aepyprymnus, and Thylogale), 9 rats and mice (Hydromys, Uromys, Melomys (2 spp.), Rattus (4 spp.), and Mus), and 6 bats (Rhinolophus, Hipposideros, Miniopterus (2 spp.) , and Pteropus (2 spp.)). Almost all of the 21 species of Laelaptidae are clearly dependent on host, and not on habitat. In a single habitat such as rain-forest, the species are confined to one host - e.g. four species of Laelaps are restricted to Ratrus ussimilis, but L. southcotti is always found on Uromys. Further, hosts with a broad habitat range are infested by the same parasite over their entire range Australolaelaps to Thylogale, Peramelaelups to Perameles, and Ichoronyssus, Spinolaelaps, and Neolaelaps to bats. Two species of Haemolaelaps and Mesolaelaps anomalus are found only on bandicoots, while M. sminthopsis is a parasite of marsupial mice alone of the several small mammals characteristic of rain-forest. Seven of the eight species of Laelaps are also host specific, four to Rattus assirnilis, one to Melomys, one to Uromys, and one to Hydromys.

Abstract: A new species of the murid Hydromys is named and described, based on skins, skulls and denti tions. The sample comes from the Wissel Lakes region in the Indonesian half of New Guinea (Irian Jaya). In many features, the new species is a miniature version of Hydromys chrysogaster and may be more closely related to that large water rat than to H. habbema. Nothing is known about habits or habitat of the new rat, and it has not yet been collected elsewhere in Irian Jaya or in the eastern half of New Guinea (Papua).

Abstract: From a survey of the intestinal helminths of 8 common water rats, Hydromys chrysogaster, and 1 Shaw Mayer’s water rat, Hydromys shawmayeri, from Papua New Guinea and 1 H. chrysogaster from Papua Indonesia, an acanthocephalan, Porrorchis hydromuris, a cestode Hymenolepis diminuta, a notocotylid and a psilostomid trematode and the nematodes Heterakis fieldingi, Subulura sp., Toxocara mackerrasae, Trichuris sp., Uncinaria hydromyos were found, all being new records for Hydromys in the Island of New Guinea. Tikusnema intersedis sp. nov. (Acuariidae), differing from its congenors in the number of teeth on the leaves of the pseudolabia and the length and morphology of the left spicule, was described from H. chrysogaster. Similar life styles and diets provide a common link between the rodents hosts of Tikusnema spp. The commonalities between the helminth communities of H. chrysogaster in northern Australia and New Guinea support the hypothesis that H. chrysogaster originated in New Guinea and subsequently migrated south.