Search

Une population de Ctenomys talarum a fait l'objet de captures-recaptures et de collecte sur un terrain d'etude a Mar del Cobo (Argentine) de juin 1985 a aout 1986. L'activite reproductrice commence en juin et se poursuit jusqu'en fevrier. Bien qu'il n'y ait pas eu de periode de pullulation nette, un pic de reproduction a ete constate depuis aout jusqu'a novembre. Les femelles nees au debut de la saison de reproduction ont atteint la maturite sexuelle au cours de cette meme periode, mais les mâles ne se sont pas reproduits avant la saison de reproduction suivante. Les femelles ont eu jusqu'a deux portees par cycle de reproduction. La moyenne des portees a ete de 4,09±0,18. Il y a eu plus de femelles que de mâles. Le degre d'ossification des epiphyses des humerus a ete utilise comme critere pour distinguer les classes d'âge

Previous studies of the visual cortical organization in the rat and other rodent species have raised the possibility that the visual cortical plan in the rat is common to a large number of species within the order. We have tested this idea by comparing the visual plan in the rat to cortical subdivision schemes obtained from five native Chilean rodent species, including members of the Cricetidae family within the Miomorph group, as well as from the Octodontidae family within the Caviomorph group. Cortical subdivision schemes were inferred from the analysis of the patterns of callosal connections revealed following multiple injections of HRP contralaterally, as well as from ipsilateral cortico-cortical connections observed after small injections of horseradish peroxidase conjugated with wheat germ agglutinin (WGA-HRP) into striate cortex. As in the rat, callosal connections in the native rodents concentrate at the border between cytoarchitectonic areas 17 and 18a, and along the borders of discrete, sparsely callosal islands of cortex in lateral peristriate cortex. Furthermore, single injections of WGA-HRP into striate cortex produce multiple, separate fields of labeled cells and terminations in the cortex surrounding area 17. Together, our data supports the idea of a common plan of visual cortical organization among rodents by providing evidence that the visual cortex in the native species is subdivided into multiple visual areas in a manner that resembles the rat cortical plan.

New World hystricognath rodents (parvorder Caviida) easily qualify as the most diversified members of the nonvolant Quaternary land mammal fauna of the West Indies. This paper describes three intriguing but problematic representatives of this group from Jamaican cave deposits. The first is the holotype (and still the only) specimen of Alterodon major from Wallingford Roadside Cave, a taxon that continues to generate controversy because specialists disagree as to its placement within Caviida. We reject the argument that it should be placed in Octodontidae and reaffirm the high probability that it is a clidomyine. The second fossil is a large proximal femur, apparently recovered from Sheep Pen locality near Windsor (Trelawney Parish) in the 1960s. Much larger than the femur of Clidomys (previously thought to be Jamaica's largest Quaternary mammal), in size and morphology the new fossil somewhat resembles femora of the eastern Caribbean heptaxodontine Amblyrhiza. Although firm allocation is not poss...

Subterranean rodents have been used frequently as examples of explosive speciation in mammals. We tested for differential rates of diversification by using information from molecular phylogenies to focus primarily on tuco-tucos (Rodentia: Octodontidae), the most speciose lineage of subterranean rodents. Tuco-tucos were not significantly more diverse than their sister taxon (octodontines); however, a lineages-through-time analysis suggests an increase in diversification at the base of the tuco-tuco clade.

Predation is often implicated as the most important factor determining differential microhabitat use by small mammals, particularly in desert ecosystems. This generalization, however, is based primarily on observational and correlational approaches and only a few field experimental studies. In a large-scale, long-term experimental manipulation of predators in semiarid north-central Chile, we studied the effects of excluding vertebrate predators on the space use of a small mammal species. We used three different techniques to determine space use under and away from shrubs by the diurnal, herbivorous rodent Octodon degus. These included smoked tiles, fluorescent pigment tracking, and tabulation of numbers of runways among shrubs. Results show that O. degus used spaces away from shrubs more often, made more (and less straight) runways between shrubs and had smaller daily home ranges in grids where predators were excluded. Thus, besides the well known predator effects of density depression and survival reduction of their prey, our study demonstrates experimentally that prey respond behaviorally to perceived predation risks.

ROBERTSHAW, J. D., AND R. H. HARDEN. 1986. The ecology of the dingo in northeastern New South Wales. IV. Prey selection and its effect on the major prey species, the swamp wallaby Wallabia bicolor (Desmarest). Australian Wildl. Res., 13:141-164. RUSSELL, E. M. 1982. Patterns of parental care and parental investment in marsupials. Biol. Rev., 57: 423-486. SCHLAGER, F. 1981. The distribution, status and ecology of the rufous rat-kangaroo, Aepyprymnus rufescens, in northern New South Wales. Unpubl. M. Nat. Res. thesis, Univ. New England, Armidale, New South Wales, 190 pp.

We studied the glans penis of Ctenomys from 8 localities in western and southern Uruguay. Three of them, representing C. rionegrensis , are characterized by a trilobed bacular tip and a pair of spikes (length = 2.412 ± 0.093 mm, mean ± SD ) within the intromittent sac. Five samples representing the C. pearsoni complex exhibit a paddle-shaped baculum with a simple, rounded tip, and peculiar spiny bulbs. These paired structures consist of an evagination of the dorsolateral inner surface of the intromittent sac, and bear a large number of spines. A variable number of small spikes (length = 0.861 ± 0.034) may be present at the base of the spiny bulbs. The spikes may be absent, present only on one side or on both. Phallic structural variation is congruent with cranial morphology and karyotypes. The observed variation in pattern of spikes, as well as the striking differences between the species considered, suggest that penial structures of caviomorph rodents might be useful for diagnosing species as well as for tracing macroevo-lutionary relationships.

NEVO, E. 1979. Adaptative convergence and divergence of subterranean mammals. Ann. Rev. Ecol. Syst., 10:269-308. 1982. Speciation in subterranean mammals. Pp. 191-218, in Mechanisms of speciation (C. Barigozzi, G. Montalenti, and M. J. D. White, eds.). Liss Publ., New York, 546 pp. PEARSON, O. P. 1959. Biology of subterranean rodents, Ctenomys, in Perui. Mem. Mus. Hist. Nat. "Javier Prado," 9:1-56. PEARSON, O. P. ET AL. 1968. Estructura social, distribuci6n espacial y composicion por edades de una poblaci6n de tuco-tucos (Ctenomys talarum). Invest. Zool. Chilenas, 13:47-80. PETRUSEWICZ, K. 1983. Numbers: the concept and definitions. Acta Theriol., 28:89-101. REIG, O. A., AND P. KIBLISKY. 1969. Chromosome multiformity in the genus Ctenomys (Rodentia, Octodontidae). Chromosoma, 28:211-244. SMOLEN, M. J., H. H. GENOWAYS, AND R. J. BAKER. 1980. Demographic and reproductive parameters of the yellow-che ked pocket gopher (Pappogeomys castanops). J. Mamm., 61:224-236. WEIR, B. J. 1974. Reproductive characteristics of hystricomorph rodents. Symp. Zool. Soc. London, 34:265-301. WILSON, A. C., G. L. BUSCH, S. M. CASE, AND M. C. KING. 1975. Social structuring of mammalian populations and rate of chromosomal evolution. Proc. Natl. Acad. Sci., 72:5061-5065.

La morphologie du penis chez le genre Ctenomys est examinee en relation avec les hypotheses de Patterson (1983) sur l'evolution du penis, et la signification et l'utilisation des caracteres phalliques en systematique

Two chromosomal forms of Ctenomys torquatus are found in southern Brasil: 2n = 44 and 2n = 46, both showing AN = 72. The patterns of the G and C bands and the nucleolar organizer regions are presented. The two chromosomal forms do not show important differences in their morphology.

SUMMARYChromosome polymorphisms involving shortening or total absence of short arms in several chromosome pairs were found to occur in different populations of the burrowing rodent Ctenomys talarum. In one population (2n = 48) G-bands showed dimorphic pairs having deletions varying in size from one band to a whole short arm. C-banding analysis confirmed the heterochromatic nature of the chromosome regions involved in the polymorphisms. Diploid number variations between populations were furnished by three populations which showed 2n = 46.

Additions to the knowledge on fossil rodents of Uruguay (Mammalia: Rodentia). — This paper brings new information on fossil rodents of Uruguay. Four new species are described:Microcavia (M.) aua n. sp. (Caviidae),Ctenomys mesorhinus n. sp. (Octodontidae),Isostylomys intermedius n. sp. andIsostylomys magnus n. sp. (Dinomyidae), the latter from Argentina. Apart from this,Palmiramys waltheri Kraglievich, 1932, illustrated here for the first time, is considered a Lower Oligocene (Deseadan) ?Dasyproctidae. The first records for Uruguay ofEucardiodon cf.marshi (Ameghino) (Hydrochoeridae), and +Holochilus brasiliensis (Desmarest) are reported.

1. 1. Serological relationship among eight species of the burrowing octodont rodent Ctenomys investigated using the precipitin test proved to be consistent with distribution and chromosomes data. 2. 2. This rapidly evolving and highly diversified genus seems to have reached during the Pleistocene a great amount of biochemical and therefore genetic differentiation, which agrees with the classical taxonomic distinction of many nominal species. 3. 3. Serological information seems also to give a relevant basis for the definition of species groups within the genus.M

Chromosomes obtained from bone-marrow, spleen and testes were studied in samples from five populations of Spalacopus cyanus of Central Chile. Animals of four low-land coastal localities and animals of a high Andean valley showed a karyotype of 2n = 58 chromosomes, with almost no variation, either in number or in structure, both within each population or among the various populations. This karyotype was found to be very similar to that of Octodon degus, but very different to those in species of Ctenomys. The evolutionary and systematic significance of these results is discussed. The lack of karyotypic variation found in Spalacopus is correlated with its taxonomic uniformity, and both could be the result of the high vagility of the populations of this rodent, suggested by previous studies. This high capacity of dispersal is supposed to have enhanced gene flow, and therewith chromosome uniformity and low taxonomic diversification. The occurrence of a case of dimorphism for the presence of a secondary constriction in one of the autosome pairs is reported and discussed.

The ultrastructural changes observed during the growth phase of oocytes of Ctenomys torquatus (Rodentia, Octodontidae) are reported. Interest was particularly centered on the transformation and/or distribution of the components of the endoplasmic reticulum. According to the observations made it is suggested that the endoplasmic reticulum stores some kind of material which may support early stages of development.

Les chromosomes de 4 especes de rongeurs fouisseurs du genreCtenomys de la Province de Tucuman, Argentine, ont ete etudies dans des cellules somatiques de la moelle osseuse. Le nombre diploide est de 22 chromosomes dansC. occultus, de 28 dansC. tucumanus et de 42 dansC. latro. Un seul individu mâle deC. tucunax a presente un complement de 2N=61.

Spalacopus cyanus (Molina, 1782). Sagg. Stor. Nat. Chile, p. 300. TYPE LOCALITY: Chile, Valparaiso Prov. DISTRIBUTION: Chile, west of the Andes. COMMENT: Includes tabanus; see Cabrera, 1961:517. ISIS NUMBER: 5301410026005002001 as S. cyanus. 5301410026005001001 as S. tabanus., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 582, DOI: 10.5281/zenodo.7353039

Octodon bridgesi Waterhouse, 1845. Proc. Zool. Soc. Lond., 1844:155. TYPE LOCALITY: Chile, Curico Prov., Rio Teno. DISTRIBUTION: Andes, in Colchagua, Curico, and Concepcion Provs. (Chile). COMMENT: Massoia, 1979, Neotropica, 25:36, reported Octodon, perhaps bridgesi, from S. Argentina. ISIS NUMBER: 5301410026002001001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 581, DOI: 10.5281/zenodo.7353039

As well as in the economy of several countries the wealth is unevenly distributed among individual people, there is a notorious inequality in the distribution of richness in species among different taxa of organisms in nature. In the economy of nature there are a few privileged taxa sharing most of the richness in species, and a reduced middle class including a much lesser number, whereas the great majority of taxa is extremely poor.

Family Octodontidae REVIEWED BY: M. A. Mares (MAM); C. A. Woods (CAW). ISIS NUMBER: 5301410026000000000., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 581, DOI: 10.5281/zenodo.7353039

Octomys mimax Thomas, 1920. Ann. Mag. Nat. Hist., ser. 9, 6: 118. TYPE LOCALITY: Argentina, Catamarca Prov., La Puntilia. DISTRIBUTION: Foothills and lower montane slopes of the Andes, and portions of the Monte desert of Catamarca, La Rioja, San Juan, and N. Mendoza Provs. (W. Argentina). ISIS NUMBER: 5301410026004002001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 582, DOI: 10.5281/zenodo.7353039

Octodon lunatus Osgood, 1943. Field Mus. Nat. Hist. Publ. Zool. Ser., 30: 110. TYPE LOCALITY: Chile, Valparaiso Prov., Olmue. DISTRIBUTION: Coastal mountains of Valparaiso, Aconcagua, and Coquimbo Provs. (Chile). COMMENT: Probably a subspecies of bridgesi (CAW). ISIS NUMBER: 5301410026002003001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 581, DOI: 10.5281/zenodo.7353039

1. 1. Resting metabolic rate and body temperature in function of ambient temperature were determined for two species of Ctenomys. 2. 2. Oxygen consumption was lowest between 25 and 30°C and was 0.946 ± 0.030 and 0.968 ± 0.022 in Ctenomys talarum (from Mar de Cobo and Necochea, respectively). Resting metabolic rate was 0.343 ± 0.053 at 30°C in C. australis. 3. 3. Mean rectal temperature at thermoneutrality was 36.1 ± 0.13 and 37.3 ± 0.17 in C. talarum and C. australis, respectively. 4. 4. Limited thermoregulation occurred in C. talarum down to 20°C but C. australis maintained body temperature down to 10°C. 5. 5. Both species of tuco-tucos became hyperthermic at ambient temperatures above thermoneutrality.

James H. Honacki, Kenneth E. Kinman, James W. Koeppl (1982): Order Rodentia (Part 6). In: James H. Honacki, Kenneth E. Kinman, James W. Koeppl (Eds): Mammal Species of the World (1st Edition). Lawrence, Kansas, USA: Alien Press, Inc. & The Association of Systematics Collections: 560-594, ISBN: 0-89327-235-3, DOI: http://doi.org/10.5281/zenodo.7353039

Octodontomys gliroides (Gervais and d'Orbigny, 1844). Bull. Sei. Soc. Philom. Paris, p. 22. TYPE LOCALITY: Bolivia, La Paz Dept., near La Paz. DISTRIBUTION: Andes of N. Chile, S.W. Bolivia, and N.W. Argentina. ISIS NUMBER: 5301410026003001001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 582, DOI: 10.5281/zenodo.7353039

Spalacopus Wagler, 1832. Isis, 25: 1219. ISIS NUMBER: 5301410026005000000., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 582, DOI: 10.5281/zenodo.7353039

Octodon degus (Molina, 1782). Sagg. Stor. Nat. Chile, p. 303. TYPE LOCALITY: Chile, Santiago Prov., Santiago. DISTRIBUTION: Chile, west slope of the Andes between Vallenar and Curico, to 1200 m. COMMENT: Reviewed by Woods and Boraker, 1975, Mamm. Species, 67:1-5. ISIS NUMBER: 5301410026002002001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 581, DOI: 10.5281/zenodo.7353039, {"references":["Woods, C. A., and D. Boraker. 1975. Octodon degus. Mammalian Species, 67: 1 - 5."]}

Octomys barrerae Lawrence, 1941. Proc. N. Engl. Zool. Club, 18:43. TYPE LOCALITY: Argentina, Mendoza Prov., La Paz. DISTRIBUTION: Arid plains of Mendoza Prov. (Argentina). COMMENT: Formerly placed in a separate genus, Tympanoctomys, by Yepes, 1940, Rev. Inst. Bact., 9: 569, and Cabrera, 1961:516, but Packard, 1967, in Anderson and Jones, p. 278, considered it congeneric with Octomys. ISIS NUMBER: 5301410026004001001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 582, DOI: 10.5281/zenodo.7353039

Octodon Bennett, 1832. Proc. Zool. Soc. Lond., 1832:46. ISIS NUMBER: 5301410026002000000., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 581, DOI: 10.5281/zenodo.7353039

Aconaemys Ameghino, 1891. Rev. Argent. Hist. Nat., 1:245. ISIS NUMBER: 5301410026001000000., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 581, DOI: 10.5281/zenodo.7353039

Octodontomys Palmer, 1903. Science, n.s., 17: 873. ISIS NUMBER: 5301410026003000000., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Rodentia (Part 6), pp. 560-594 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 582, DOI: 10.5281/zenodo.7353039

Primitive species in the differentiation of the subfamily Ctenomyinae are revisited, and, on molar evidence, a new interpretation of the evolutionary pattern of these earliest members of the group is proposed. The octodontid Phtoramys is rejected as possible ancestor, whereas the genus Chasichimys (including Pattersomys), previously included in the family Echimyidae, is transferred to the Octodontidae as a primitive member of the ctenomyine radiation. During the Chasicoan and Huayquerian Ages (Late Miocene), an anagenetic event represented by an increase of hypsodonty in Chasichimys, may have led to the differentiation of the primitive euhypsodont ctenomyines of the genus Xenodontomys. Coeval cladogenetic processes, occurring during the protohypsodont evolutionary stage of the group, would have resulted in the separation of the genus Palaeoctodon from the lineage Chasichimys-Xenodontomys. These ancient representatives of the subfamily would have differentiated in central Argentine pampas. The recognition of such evolutionary events and concordant evidence from other octodontoid rodents suggest temporal differences among the outcroppings of the Cerro Azul Formation in central Argentina.

South American octodontid rodents of the subfamily Octodontinae currently show low species richness but great morphological and chromosomal diversity. This diversity is interpreted alternatively as the remnant of a wider past radiation or as the result of saltational evolution. These hypotheses are discussed in relation to a phylogenetic analysis of the Late Pliocene octodontineAbalosia castellanosi. My results suggest thatAbalosia, together withTympanoctomys andOctomys, is part of a clade of desert specialist propalinal octodontids, which would have differentiated east of the Andes in the emergent semi-deserts of western Argentina. The presence ofAbalosia in the coastal region of central Argentina during the Upper Marplatan Age (Late Pliocene) suggests a pulse of expansion of such arid environments, probably coeval with the global climatic deterioration detected around the transition Gauss-Matuyama magnetic ages. The phylogenetic position ofA. castellanosi suggests that extinction events affected the clade of the octodontine desert specialists. Accordingly, regardless of how rough or gradual the differentiation of the octodontine’s diversity has been, the living representatives seem to be remnants of a wider radiation.

A morphometric study of the sperm ofCtenomys maulinus Philippi 1872 was carried out. A process of the postacrosomic region that probably correponds to a permanent structure in the sperms of these rodents, and is characteristic of the genus, was observed.

In the coastal region of central Chile the coruro, Spalacopus cyanus, lives in large populations consisting of many small, nomadic colonies. One colony contained 15 members belonging to no less than three generations. A colony of coruros occupies a common burrow system and apparently wanders continuously in search of food. Coruros feed primarily, if not exclusively, on the tubers and underground stems of the lily, Leucoryne ixiodes. S. cyanus has a higher metabolic rate than similar-sized fossorial species of Ctenomys. In February, adult males were sexually active and two of six adult females were pregnant, each bearing three small fetuses.

Allusions appear frequently in the literature to the idea that a special relationship exists between the African hystricomorph rodents Petromys and Thry-onomys and the Octodontidae and Myocastoridae (Capromyidae auct .), respectively, of South America. I have elsewhere ( In press ) reviewed the history of this arrangement and attempted to show that few positive reasons for classifying these two genera with South American families have ever been advanced. The idea derives ultimately from the unsupported assertion of Waterhouse (1839). Ellerman (1940) classified both Petromys and Thryonomys as sole representatives of the subfamilies Petromurinae and Thryonomyinae of the Echimyidae. This “Echimyidae” is roughly the equivalent of Simpson's (1945) “Octodontoidea,” so these two authors really classified Petromys and Thryonomys in the same way, as Simpson lists them under Petromyidae and Thryonomyidae of the Octodontoidea, stating (p. 212), “… Thryonomys and Petromys are morphologically octodontoid and it has been common practice to refer them to neotropical families and subfamilies, for instance, placing Petromys with Octodon and Thryonomys with Capromys .” Wood (1955) separates Thryonomys and Petromys from the South American hystricomorphs in his splitting apart of the suborder Hystricomorpha. He divides the hystricomorphs into two suborders: Hystricomorpha (Old World forms) and Caviomorpha (New World forms). He still asserts, however, that there is “morphological similarity” between Petromys and Thryonomys and New World families. He says (p. 184), “There are many obvious similarities to the Octodontidae and Echimyidae respectively. These are so great that formerly the African genera were placed in South American families. This is still done sometimes, the latest example being Ellerman, Morrison-Scott and Hayman (1953: 237–239) who consider the Thryonomyinae, Petromurinae and Echi-myinae to be subfamilies of the Octodontidae.” As a matter of fact, Ellerman, Morrison-Scott and Hayman (1953) concede that there may be some doubt about the classification of Thryonomys , …