Endemic Murids Research Articles

Morphological diversity of the spermatozoon and male reproductive tract in Australian Hopping mice, genus Notomys – is it determined by sexual selection?

AbstractHopping mice (Genus Notomys) are a monophyletic group of Australian Old Endemic murid rodents in the Tribe Hydromyini four of which, Notomys alexis, N. mitchellii, N. fuscus and N cervinus, occur in arid or semiarid environments. Here, we compare the size and morphology of their testes, spermatozoa, accessory sex glands and external genitalia across the species, and from these data, we draw conclusions as to their likely breeding systems. We show that both wild caught and laboratory bred adult N. alexis, N. fuscus and N. mitchellii individuals have extremely small testes, but their spermatozoa vary in morphology across the species. The ventral prostate is the only large accessory sex gland present, and their glans penis has very large spines. By contrast N. cervinus individuals have significantly larger testes with their spermatozoa being less variable but generally more complex in morphology, their seminal vesicles and coagulating glands are much larger, whereas the glans penis has only small spines. Since these reproductive traits in N. cervinus are more similar to those of most other hydromyine rodents in the genus Pseudomys, they are likely to reflect the retention of the ancestral condition within the Notomys lineage whereas the divergent reproductive traits of the other species of tiny testes, variable sperm, small seminal vesicles and coagulating glands and large penile spines are probably more recently derived traits. It is suggested that N. cervinus with its relatively larger testes mass and greater abundance of sperm of more consistent morphology has retained a mating system that may potentially involve some intermale sperm competition whereas, by contrast, the reproductive anatomy of the other three Notomys species suggests that these species exhibit monogamy.

Short-tailed mice with a long fossil record: the genus Leggadina (Rodentia: Muridae) from the Quaternary of Queensland, Australia.

The genus Leggadina (colloquially known as ‘short-tailed mice’) is a common component of Quaternary faunas of northeastern Australia. They represent a member of the Australian old endemic murid radiation that arrived on the continent sometime during the late Cenozoic. Here we describe two new species of extinct Leggadina from Quaternary cave deposits as well as additional material of the extinct Leggadina macrodonta. Leggadina irvini sp. nov. recovered from Middle-Upper (late) Pleistocene cave deposits near Chillagoe, northeastern Queensland, is the biggest member of the genus, being substantially larger than any other species so far described. Leggadina webbi sp. nov. from Middle Pleistocene cave deposits at Mount Etna, central eastern Queensland, shares features with the oldest species of the genus, the Early Pleistocene L. gregoriensis. Based on the current palaeoecological interpretation of the type locality, L. webbi, represents the only member of the genus that inhabited rainforest. The succession of Leggadina species through the late Quaternary suggests an ecological replacement of the extinct large-bodied L. irvini with the extant, small-bodied L. lakedownesis at Chillagoe. At Mt. Etna, the extinct rainforest species L. webbi is replaced with the extant xeric-adapted L. forresti during the latest Middle Pleistocene. This replacement is associated with a mid-Pleistocene shift towards progressive intensifying seasonal and arid climates. Our study adds to the growing list of small-bodied faunal extinctions during the late Quaternary of northern Australia.

The gastrointestinal helminths of Rattus verucundus (Rodentia: Muridae) with the description of a new species (Heligmonellidae: Nematoda) from Papua New Guinea and a comment on the Rictulariidae (Nematoda) from the Sahul Region

ABSTRACTCestodes, including Hymenolepis cf diminuta, the acanthocephalan Moniliformis moniliformis and 13 species of nematode, were collected from the digestive tracts of 22 individuals of Rattus verucundus (Murinae: Rattini) from Papua New Guinea. Missimstrongylus oweni n. gen., n. sp. differs from all other genera in the Heligmonellidae in the characters of the synlophe. Nippostrongylinae sp. 1 differs from all other Heligmonellidae and may have been previously reported as Nippostrongylinae sp. 1 from R. niobe. The capillariids Capillaria s. l., and Eucoleus sp., the chabertiid Cyclodontostomum purvisi, the heterakids Heterakis sirawii and H. spumosa, the oxyurid Syphacia niobe, the spirurids Protospirura kaindiensis and P. muricola, the sublurid Subulura andersoni and the trichurid Trichuris muris, have been reported previously from endemic murids. The rictulariid Pterygodermatites whartoni has not been reported previously from New Guinea. Examination of the three species of Australian Rictularia resulted in the reassignment of two to the genus Pterygodermatites. Species richness of the nematode assemblage, as indicated by bootstrap estimates, was similar to those reported from R. niobe, R. giluwensis and R. steini and those individuals of R. leucopus examined from Papua New Guinea. Of the species recovered only Missimstrongylus oweni was unique to R. verucundus.

Two new species of Trichuris (Nematoda: Trichuridae) collected from endemic murines of Indonesia.

Two new species of the genus Trichuris (Nematoda: Trichuridae) parasitic in the old endemic murids of Indonesia are described: T. musseri sp. nov. from Echiothrix centrosa (Murinae: Rattini) in Sulawesi and T. mallomyos sp. nov. from Mallomys rothschildi (Murinae: Hydromyini) in Papua Indonesia. Both species are characterized by having a gradually tapered and sharply pointed distal end of the spicule, being readily distinguished from most of the congeners known from murid rodents. Trichuris musseri is readily distinguished from T. mallomyos by having a much smaller body and large number of nuclei per subdivision of stichosome. The resemblance in spicule morphology between the two new species is of special interest because both hosts belong to different tribes and have different habitats and habits. It remains to be elucidated whether the resemblance is merely homoplasy or actually reflects close phylogenetic relationship of the parasites.

Why are there no giants at the dwarves feet? Insular micromammals in the eastern Mediterranean

The eastern Mediterranean has yielded some textbook examples of insular evolution among large mammals such as the world's smallest hippopotamus and mammoth. By contrast, gigantism among small mammals is limited, with the exception of the early Pleistocene murid Kritimys from Crete. The large body size of insular rodents can be related to an energetically advantageous position at the slow end of the mammalian fast–slow continuum. In order to test the hypothesis that the development of gigantism was hampered by the harsher climatic conditions of the middle and late Pleistocene, we constructed a dataset of endemic murids and cricetids from islands all over the world. Upto the middle Pleistocene, giant rodents can be found all over the world. However, in the later part of the Pleistocene and Holocene, these are only found at lower latitudes, suggesting that indeed the harsher conditions of the north no longer allowed insular rodents to develop the slow life-strategy that previously could still be achieved at these latitudes.

Musserellusgen. nov., and Five New Species of Fleas (Siphonaptera: Stivaliidae) From Murid Rodents in Sulawesi and West Papua, Indonesia

A new stivaliid flea genus, Musserellus, and five new species are described. The new genus is compared with its closest morphological relatives, the genera Rectidigitus Holland and Metastivalius Holland. Musserellus vanpeeneni sp. nov., Musserellus wattsi sp. nov., Musserellus whitei sp. nov., and Musserellus marshalli sp. nov. are described from endemic murid rodents in Sulawesi, Indonesia, while Musserellus dunneti sp. nov. is described from Rattus rattus in West Papua, Indonesia. Host associations and the biogeographical relevance of the faunal connection between Sulawesi and New Guinea shown by Musserellus are briefly discussed.

Gastrointestinal helminths (Cestoda, Chabertiidae and Heligmonellidae)of Pogonomys loriae and Pogonomys macrourus (Rodentia: Muridae) from Papua Indonesia and Papua New Guinea with the description of a new genus and two new species.

Pieces of cestode, not indentified further, and 12 species of nematode including 1 new genus, 3 new species and 7 putative new species from the Families Chabertiidae and Heligmonellidae were collected from the digestive tracts of 16 Pogonomys loriae and 19 P. macrurous (Murinae: Hydromyini) from Papua, Indonesia and Papua New Guinea. The chabertiid Cyclodontostomum purvisi and the heligmonellid Odilia mackerrasae have been described previously from endemic murids. Hasanuddinia pogonomyos n. sp. can be distinguished from its congeners by the number of ridges in the synlophe, length of spicules and having a vagina with a dorsal diverticulum. Odilia dividua n. sp. is larger than its congeners, has a longer oesophagus, relatively shorter spicules and larger eggs. Pogonomystrongylus domaensis n. gen., n. sp. differs from all other genera in the Heligmonellidae in the characters of the synlophe, 7-10 ridges oriented sub frontally with a single left ventral ridge hypertrophied. Species richness of the nematode assemblages of P. loriae and P. macrourus are comparable to those of Abeomelomys sevia, Chiruromys vates and Coccymys rummleri when numbers of hosts examined are considered. Species composition was distinctive with 12, including the 7 putative species, of 14 species presently known only from species of Pogonomys. Similarities between the nematode fauna of endemic rodent hosts from Indonesia and Papua New Guinea were noted.

Musserakis sulawesiensis gen. et sp. n. (Nematoda: Heterakidae) collected from Echiothrix centrosa (Rodentia: Muridae), an old endemic rat of Sulawesi, Indonesia.

Musserakis sulawesiensis gen. et sp. n. (Nematoda: Heterakidae) is described from the large-bodied shrew rat, Echiothrix centrosa, one of the old endemic rats of Sulawesi, Indonesia. Musserakis is readily distinguished from other heterakid genera by having non-recurrent and non-anastomosing cephalic cordons, by lacking papillae between papillae groups around precloacal sucker and cloacal aperture and by lacking teeth in the pharyngeal portion. The spicules are equal but with marked dimorphism among individuals. Heterakids collected from other old endemic murids examined, i.e., Crunomys celebensis, Tateomys macrocercus and Tateomys rhinogradoides, and the new endemic rats of Sulawesi, were Heterakis spumosa Schneider, 1866, a cosmopolitan nematode of various murids. It is suggested that M. sulawesiensis is specific to Echiothrix.

The Namaqua rock mouse (Micaelamys namaquensis) as a potential reservoir and host of arthropod vectors of diseases of medical and veterinary importance in South Africa.

BackgroundThe role of endemic murid rodents as hosts of arthropod vectors of diseases of medical and veterinary significance is well established in the northern hemisphere. In contrast, endemic murids are comparatively understudied as vector hosts in Africa, particularly in South Africa. Considering the great rodent diversity in South Africa, many of which may occur as human commensals, this is unwarranted.MethodsIn the current study we assessed the ectoparasite community of a widespread southern African endemic, the Namaqua rock mouse (Micaelamys namaquensis), that is known to carry Bartonella spp. and may attain pest status. We aimed to identify possible vectors of medical and/or veterinary importance which this species may harbour and explore the contributions of habitat type, season, host sex and body size on ectoparasite prevalence and abundance.ResultsSmall mammal abundance was substantially lower in grasslands compared to rocky outcrops. Although the small mammal community comprised of different species in the two habitats, M. namaquensis was the most abundant species in both habitat types. From these 23 ectoparasite species from four taxa (fleas, ticks, mites and lice) were collected. However, only one flea (Xenopsylla brasiliensis) and one tick species (Haemaphysalis elliptica) have a high zoonotic potential and have been implicated as vectors for Yersinia pestis and Bartonella spp. and Rickettsia conorii, respectively. The disease status of the most commonly collected tick (Rhipicephalus distinctus) is currently unknown. Only flea burdens differed markedly between habitat types and increased with body size. With the exception of lice, all parasite taxa exhibited seasonal peaks in abundance during spring and summer.ConclusionM. namaquensis is the dominant small mammal species irrespective of habitat type. Despite the great ectoparasite diversity harboured by M. namaquensis, only a small number of these are known as vectors of diseases of medical and/or veterinary importance but occur at high prevalence and/or abundance. This raises concern regarding the potential of this host as an endemic reservoir for zoonotic diseases. Consequently, additional sampling throughout its distributional range and research addressing the role of M. namaquensis as a reservoir for zoonotic diseases in southern Africa is urgently needed.

Morphological and Geographic Definitions of the Sulawesian Shrew RatsEchiothrix leucura and E. centrosa(Muridae, Murinae), and Description of a New Species of Sucking Louse (Phthiraptera: Anoplura)

Among the 15 known genera of murine rodents endemic to the island of Sulawesi, is the shrew rat genus Echiothrix. Physically large (length of head and body = 182–235 mm; weight = 215–310 g) with a bicolored tail typically longer than head and body (100%–135% of head and body length), elongate hind feet (48–55 mm), large ears (31–35 mm), long and thin muzzle, spinous fur, and tiny molars relative to size of skull (length of molar row = 12%–13% of occipitonasal length), Echiothrix was named and described in 1867 and through the years has been treated as monotypic or containing up to three species. Results from analyses of morphometric traits derived primarily from cranial and dental measurements document the presence of two species. Echiothrix leucura (Gray, 1867) is restricted to the northern peninsular mainland east of the Gorontalo region (00°31′ N, 123° 03′ E). This distribution is concordant with that of four other murids endemic to the northeastern tip of the northern peninsula: Bunomys fratrorum, Taeromys taerae, Rattus xanthurus, and R. marmosurus. Echiothrix centrosa Miller and Hollister, 1921 (Echiothix brevicula Miller and Hollister, 1921, is a synonym), is documented by specimens from the northern peninsula west of the Gorontalo region and in the central portion of the island; 19 other murine species are also known only from the core of Sulawesi. Whether the range of E. centrosa extends to the eastern, southeastern, and southwestern peninsulas is at present unknown. Echiothrix leucura has a more elongate skull compared with E. centrosa (greater lengths of skull, rostrum, diastema, and bony palate), a wider interorbital region, larger braincase, narrower bony palate and mesopterygoid fossa, shorter incisive foramina, and appreciably larger molars; the two species also differ in frequencies of particular molar cusps and cusplets. Both species of Echiothrix are nocturnal, terrestrial, and occupy habitats in tropical lowland evergreen rain forest. Natural history observations made in the field for Echiothrix centrosa show it to be primarily vermivorous; other natural history observations derived from field work in central Sulawesi are provided. One aspect of that natural history is the ectoparasitic load borne by E. centrosa. This shrew rat is host to at least four species of ticks (Haemaphysalis kadarsani, Haemaphysalis hystricis, Haemaphysalis sp. and Amblyomma sp.), a tiny fur mite (Listrophoroides echiothrix), mesostigmatid mites belonging to the genus Laelaps, currently undetermined chiggers, a flea (Farhangia quattuordecimdentata), and a new species of sucking louse described herein as Polyplax beaucournui. This louse has tibiotarsal claws adapted for grasping slender soft hairs in the pelage and not the wide host spines; female lice also attach their eggs only to these slender hairs. The closest relative of Echiothrix is probably Paucidentomys vermidax, another Sulawesian endemic shrew rat that is also vermivorous but lacks molars and has been collected only in montane forests. The present report documents morphological and distributional limits of species in Echiothrix, places one of those species in an ecological and parasitological landscape, and generally contributes to knowledge covering endemic murid species diversity and identifying unique zoogeographical areas on Sulawesi.

Evolutionary trends in arvicolids and the endemic murid Mikrotia – New data and a critical overview

The study of evolutionary rates dates back to the work of Simpson and Haldane in the 1940s. Small mammals, especially Plio-Pleistocene arvicolids (voles and lemmings), are particularly suited for such studies because they have an unusually complete fossil record and exhibit significant evolutionary change through time. In recent decades, arvicolids have been the focus of intensive research devoted to the tempo and mode of evolutionary change and the identification of trends in dental evolution that can be used to correlate and date fossil sites. These studies have raised interesting questions about whether voles and lemmings had unique evolutionary trajectories, or show convergent evolutionary patterns with other hypsodont rodents. Here we review evolutionary patterns in selected arvicolid lineages and endemic Messinian murids (Mikrotia spp.) and discuss reasons for convergence in dental morphology in these two groups of hypsodont rodents. The results substantiate previously detected patterns, but the larger dataset shows that some trends are less regular than previous studies have suggested. With the exception of a pervasive and sustained trend towards increased hypsodonty, our results show that other features do not follow consistent patterns in all lineages, exhibiting a mosaic pattern comprising stasis, variable rate evolution and gradual unidirectional change through time. Evidence for higher evolutionary rates is found in lineages apparently undergoing adaptations to new ecological niches. In the case of Mikrotia, Microtus voles and the water vole (Mimomys–Arvicola) lineage, a shift to a fossorial lifestyle appears to have been an important driving force in their evolution. For other characters, different causes can be invoked; for example a shift to a semi-aquatic lifestyle may be responsible for the trend towards increasing size in Arvicola. Biochronological application of the data should take into account the complexity and biases of the data.

Two new species ofSyphacia(Nematoda: Oxyuridae) in endemic murid rodents from Sulawesi, Indonesia

Two new species of Syphacia (Nematoda: Oxyuridae) are described from endemic murids of Sulawesi, Indonesia: Syphacia (Syphacia) taeromyos sp. n. and S. (S.) paruromyos sp. n. parasitic in the caecum of Taeromys celebensis and Paruromys dominator, respectively. They are readily distinguished from all of the congeners recorded from Indonesia-Australian regions by having a round cephalic plate, vesicular lateral alae in the male, posteriorly positioned excretory pore in the male, and/or lacking cervical alae. Syphacia (S.) paruromyos differs from S. (S.) taeromyos by having a whip-like tail appendage in the male, longer relative distance between excretory pore and vulva, and larger eggs. The round cephalic plate in both sexes and developed vesicular lateral alae in the male are morphological traits common in endemic Syphacia species hitherto known from Sulawesi murids, suggesting that they have derived from a common ancestor and evolved with their hosts in the isolated insular environment.

Reproductive biology of an old endemic murid rodent of Australia, the Spinifex hopping mouse, Notomys alexis: adaptations for life in the arid zone

The Spinifex hopping mouse (Notomys alexis Thomas, 1922) is an arid adapted Australo-Papuan old endemic rodent that undergoes boom and bust population cycles. In this communication, we review our findings on the timing of reproduction and the potential reproductive rate of this species. To investigate the first question, the reproductive condition of adult females, and occurrence of immatures, in a population on a cattle station in central Australia was determined and, for the second, data from a laboratory colony compared to those previously published on closely related species in other environments. The findings show that, at least in the population at the times that monitoring was performed, reproductive activity was only taking place in spring and early summer, whereas the laboratory study indicates that females have a similar gestation length and litter size to those of most close relatives occurring in other environments. Males have extremely small testes and store relatively few sperm. The findings suggest that Notomys alexis might show some seasonality of reproduction at least in this region of central Australia and that this species does not have a higher reproductive rate than that of related species in other, more predictable, environments.

The first fossil record of endemic murid rodents from the Philippines: A late Pleistocene cave fauna from northern Luzon

Excavations in Callao Cave, in the lowland (ca. 85 m elevation) Cagayan River Valley of northeastern Luzon, Philippines, have produced the first fossils of any endemic genera of Philippine murid rodents. Three dentaries dated to the Late Pleistocene, between ca. 50,000 and 68,000 BP, are referred to the genera Batomys and Apomys; the former is a member of the endemic “Phloeomys Division” of Philippine murids, and the latter of the “Chrotomys Division,” also endemic to the Philippines. Batomys is currently known from five extant species from Luzon, Mindanao, and Dinagat islands; the two species known from Luzon differ in size and dental and mandibular morphology from the two fossil mandibles, and both occur only at elevations above 1350 m. Apomys is currently known from two subgenera on Luzon; the fossil is a member of the nominate subgenus, which contains two species on Luzon, one of which, Apomys microdon, is conspecific with one fossil. We hypothesize that the Batomys fossils represent a different species from the living taxa, but we do not name it due to the fragmentary nature of the specimens. These Apomys and Batomys represent the first fossil small mammals from the main body of the Philippine archipelago (east of Huxley's Line), and the Batomys are the first suspected extinct Pleistocene small mammal from the Philippines. The fossils indicate greater species richness and broader distributions than at present within this distinctive and diverse endemic radiation of mammals.

Late Miocene insular mice from the Tusco-Sardinian palaeobioprovince provide new insights on the palaeoecology of the Oreopithecus faunas

Oreopithecus bambolii is one of the few hominoids that evolved under insular conditions, resulting in the development of unique adaptations that have fueled an intensive debate. The palaeoenvironment associated with this great ape has been the subject of great controversy as well. On the one hand, palaeobotanical data indicate that Oreopithecus likely inhabited mixed mesophytic forests interrupted by swamps; on the other hand, an abundance of hypsodont bovids points towards the existence of dry and open environments. Here, we provide a new approach based on the ecomorphology of the extinct endemic Muridae (rats and mice) of the so-called Oreopithecus faunas. Our results show that the successive species of endemic insular murids ( Huerzelerimys and Anthracomys) evolved a number of adaptations observed only in extant family members that include significant proportions of grass in their diet. While this fits the pattern exhibited by large mammals, it contrasts with the available palaeobotanical information, which indicates that grasses were minor components of the vegetation. This contradiction may be explained because these endemic murids may have been adapted to the consumption of particular food items such as hard parts of aquatic plants (as shown by some extant murid species). However, because it is unlikely that the remaining herbivore mammals were adapted to this diet as well, we favour an alternative hypothesis that takes into account the peculiar ecological conditions of insular ecosystems leading to a density-dependent selective regime with strong competition. Such a regime would promote the selection of dental adaptations to increase feeding efficiency and durability of the dentition (such as hypsodonty) as seen in some fossil insular ruminants. This hypothesis requires further testing, but may partly account for parallel evolution of dental traits in phylogenetically unrelated insular mammals.

Novel Persectives of GM Plants

The eastern Mediterranean has yielded some textbook examples of insular evolution among large mammals such as the world's smallest hippopotamus and mammoth. By contrast, gigantism among small mammals is limited, with the exception of the early Pleistocene murid Kritimys from Crete. The large body size of insular rodents can be related to an energetically advantageous position at the slow end of the mammalian fast–slow continuum. In order to test the hypothesis that the development of gigantism was hampered by the harsher climatic conditions of the middle and late Pleistocene, we constructed a dataset of endemic murids and cricetids from islands all over the world. Upto the middle Pleistocene, giant rodents can be found all over the world. However, in the later part of the Pleistocene and Holocene, these are only found at lower latitudes, suggesting that indeed the harsher conditions of the north no longer allowed insular rodents to develop the slow life-strategy that previously could still be achieved at these latitudes.

Neopsylla musseri n. sp. (Siphonaptera-Ctenophthalmidiae), a new flea from central Sulawesi (Indonesia)

This flea is a montane flea, known from elevations of 1,700-2,300 m, that parasitizes endemic murid rodents. It represents a newly recorded genus and family of fleas for Sulawesi. Morphologically, the closest taxon to N. musseri n. sp. is N. sondaica Jordan, 1931 from Java; it is not closely related to N. luma Traub, 1954 from Borneo.

Evolutionary patterns in the first lower molar of the endemic murid Microtia

The morphology of the first lower molars of the Microtia species found in eight samples collected in the ‘terre rosse’ fillings of the karst fissure network of Gargano (Puglia, Italy) have been studied through bivariate and principal component analyses. The data fall into seven systematic units that indicate that at least four phyletic lineages were present in the Gargano area. The evolutionary modifications of the characteristics of the various lineages are discussed.

A COLLECTION OF TICKS (IXODIDAE) FROM SULAWESI UTARA, INDONESIA

Ixodid ticks were collected from seven species of endemic murid rodents and from vegetation in Sulawesi Utara, Indonesia. Adult ticks belonging to the species, Amblyomma babirussae, A. cyprium and Dermacentor (Indocentor) steini were taken from the vegetation. Immature ticks assignable to the genera, Haemaphysalis, Amblyomma and Ixodes infested the murids with Parauromys dominator and Maxomys musschenbroekii being the two most heavily tick-infested host species. The data are compared to other tick records from Sulawesi.

Comparative studies on the reproductive biology of three species of laboratory bred Australian conilurine rodents (Muridae: Hydromyinae)

The reproductive biological parameters of laboratory bred and maintained individuals from three species of Australian conilurine rodents, Notomys alexis, Pseudomys australis and P. nanus were determined. Considerable' divergence was found in interbirth intervals (indicative of gestation length) in nonsuckling and suckling mothers, litter size, growth rate of pups, age at weaning, and time of sexual maturity in both males and females. It is concluded that selection has been for rapid production and development of young in P. nanus, whereas in P. australis and, especially N. alexis, litter size has been maximized within the constraints of the mammary formula. These data further emphasize the high degree of plasticity of the reproductive system in this assemblage of old endemic murid rodents of Australasia.