Pampa De Achala Research Articles

A new peculiar species of the subterranean rodent Ctenomys (Rodentia, Ctenomyidae) from the Holocene of central Argentina

The subterranean rodent Ctenomys is the single living representative of the family Ctenomyidae, and the most diverse genus within Hystricomorpha. Its fossil record begins in the late Pliocene and shows an increase in diversity since the Pleistocene. Here we describe a new middle-sized Ctenomys species from a large cranial sample collected at the archaeological site Quebrada del Real 1 in the high plains of the Pampa de Achala (Córdoba, Argentina). For this goal, we analyzed the cranial and mandibular shape variation through a geometric morphometric approach, and performed a comparative morphological analysis in the context of the living Ctenomys. The new species is characterized by having a wide rostrum with a deep rostral fossa, strong temporal fossa in the frontal, upper incisors strongly procumbent and with grooved enamel, and mandible with low corpus, long procumbent diastema and descending masseteric crest. A phylogenetic analysis demonstrated its close affinity with Ctenomys osvaldoreigi, an extant species from a nearby area. The new species represents the first notice of an extinct Ctenomys species from the Holocene. Given its peculiar morphology, the extinction of this species would have resulted in significant loss of morphological diversity, thus constraining the current boundaries of variation of the genus. The last record of the new species occurs in a period characterized by marked extinction of small mammals in southern South America mainly due to anthropogenic causes.

Physiognomic changes in response to herbivory increase carbon allocation to roots in a temperate grassland of central Argentina

In most temperate grasslands, cattle grazing can promote physiognomic changes on plant communities, as well as changes in species growth patterns. Through these changes in vegetation, cattle grazing can generate changes in allocation to total, fine and coarse root biomass, which can further affect ecosystem processes. The objective of this work was to evaluate differences in root biomass, in the proportions of fine and coarse root biomass and in root C:N ratio across physiognomies from 0 to 30 cm. We selected plots of grazing lawns (associated to relatively high stocking rates), and plots of thin and thick tussock grasslands (associated to relatively low stocking rates) within the Pampa de Achala system in central Argentina. We found that total, coarse, and fine root biomass were highest in grazing lawns, intermediate in thin tussock grasslands, and lowest in thick tussock grasslands. Thick tussock grasslands showed the highest relative proportion of fine roots while root C:N ratio did not vary among physiognomies. Higher root biomass in lawns was probably caused by the dominance of species that allocate more biomass to roots than to shoots, as well as by the complementarity of soil resource extraction and by compensatory root growth in response to herbivory. In addition, and contrary to what was expected based on their above-ground attributes, thick tussock grasslands presented higher proportion of fine roots, which suggests a more acquisitive resource use strategy. However, root C:N from thick tussock grasslands did not differ from other physiognomies which might indicate there are not clear differences in below-ground resource use strategies. Our results show that grassland root biomass in this study system can increase in patches associated to higher cattle grazing due to changes in plant composition and physiognomy, while changes in root quality seem to be uncoupled from the above-ground traits.

Revision of "Aemilia" pagana Species-Group (Lepidoptera: Erebidae: Arctiinae), with a Description of a New Endemic Species and Comments on the Conservation Status.

A taxonomical rearrangement of "Aemilia" pagana species-group is proposed: Leucanopsis pagana (Schaus in Proc Zool Soc London 1894:225-243, 1894) comb. nov. and L. ninae (Orfila in Rev Soc Entomol Argent 21:67-70, 1959) comb. nov. A new endemic species from Pampa de Achala, Córdoba, Argentina, closer to both species, is described: Leucanopsis navarroi sp. nov. These three species can be recognized because the color pattern is the darkest among species of Leucanopsis. Characteristics of male genitalia suggest the nomenclatural rearrangement proposed. Leucanopsis pagana comb. nov. has a wide distribution from the center of Brazil to northeastern Argentina, including southern Paraguay. The known distribution and geospatial analysis suggest that this species is not in danger. Leucanopsis ninae comb. nov. is restricted to only one known locality (Villa Gesell, Buenos Aires). The restricted known distribution, the different land use practices, and geospatial analysis suggest that this species could be endangered. Leucanopsis navarroi sp. nov. is endemic to the high plateau present in the center of Argentina called Pampa de Achala. The known distribution and geospatial analysis suggest that this species could be endangered. Further studies are necessary to determine effectively the conservation status of these three species.

A redescription of the chigger Hannemania achalai Alzuet and Mauri, 1987 (Acariformes: Prostigmata: Leeuwenhoekiidae) in frogs from Sierra Grande, Cordoba, Argentina

We redescribe the endoparasitic chigger Hannemania achalai based on specimens collected from the type frog host (Pleurodema kriegi) and an additional host (P. cordobae) in the type locality of this mite (Pampa de Achala, Córdoba province, Argentina). Hannemania achalai is diagnosed by the following characters: palpal setal formula B/B/BBB/5B, palpal claw trifurcate, galeal seta B, parasubterminala I N, 2–4 genualae I, 1 genuala II–III, femorala III absent and coxa III with 1B. This redescription is accompanied by micrographs with scanning electronic microscopy and drawings.

Geastrum minutisporum sp. nov. from Polylepis australis woodlands in central Argentina

Geastrum minutisporum is characterized by a basidioma up to 25 mm wide, exoperidium saccate to planar, non-hygroscopic; a globose to subglobose, sessile and greyish brown endoperidium; a silky fibrillose peristoma, lighter or darker than the endoperidium and with globose, slightly asperulate basidiospores, 2–2.5–3 μm in diam, with a short apiculus up to 0.5 μm long. Specimens were collected at the Reserva Hídrica Provincial Pampa de Achala located in the upper portion of Sierras Grandes from Córdoba, central Argentina. Morphology and phylogenetic analysis based on sequences of the ribosomal DNA internal transcribed spacer region support Geastrum minutisporum as a new species.

Morphological diversity displayed by high altitude Branchinecta papillata (Anostraca) and additional morphological comparisons with Branchinecta achalensis

ABSTRACT Populations of the high altitude anostracan Branchinecta papillota from the type locality in the Atacama Altiplano (Iquique province, Chile) and from the Cumbres Calchaquies (Tucuman province, Argentina) and specimens of B. achalensis from the type locality (La Posta, Pampa de Achala, Cordoba province, Argentina) were compared and new observations on the morphological diversity of the species were made. A basal branching in the male antenna 2 distal article, only observed in one branchinectid to date, was found in the Argentinean populations of both species.

Distribution patterns and trophic characteristics of salmonids and native species inhabiting high altitude rivers of Pampa de Achala region, Argentina

The Pampa de Achala in central Argentina is an area with low fish species richness where salmonids were first introduced at the beginning of the twentieth century. A total of 19 rivers of different order were sampled during the low water period by using portable electrofishing equipment. We covered different identified macrohabitats (pools, riffles, glides and cascades) in reaches of 300-500 m length. The native species Trichomycterus corduvensis and two exotic salmonids such as Salvelinus fontinalis and Oncorhynchus mykiss represented the most common species, showing allopatric and sympatric distribution in some streams. Stomach contents and diet overlapping were also analyzed. Cluster results showed a first main group comprised those streams with high diet similitude between T. corduvensis and O. mykiss whereas a second main group consisted of streams with high diet similitude between O. mykiss and S. fontinalis. Mean niche width was similar among all these species but T. corduvensis showed that widest range whereas S. fontinalis exhibited the narrowest trophic niche. We were able to document a direct predation on T. corduvensis by O. mykiss in two stream although distribution overlapping among native and exotic species were low. In turn diet overlapping among species were negligible. Trophic niche amplitude of S. fontinalis was inversely related to stream order, providing clues that geomorphology and hydrology may exert also influence of trophic characteristics and can be used for predicting the potential for food competition with native species. Analysis by Tokeshi plot revealed that T. corduvensis ranged from specialist to generalist whereas both salmonids showed generalist feeding habits with a heterogeneous and homogeneous diet.

Déficit de vitamina D y osteoporosis en una población rural de montaña en Córdoba – Argentina

Introduction: Vitamin D deficiency is defined when blood levels of 25-hydroxyvitamin D (25 (OH) D) is less than 20 ng / mmol/L. The status of Vitamin D level is associated with clinical, pathological and physiological changes as increased of parathyroid hormone, bone remodeling, osteoporosis and increased risk of fractures. Moreover, vitamin D and its metabolites are known to be associated with multiple chronic diseases as diabetes mellitus, autoimmune, cardiovascular and neoplasia diseases. Objective: To assess the vitamin D status in a rural population of Córdoba Province in Argentina and its relation with bone mineral density. Material and Methods: We prospectively studied 31 patients over 50 years old who live in a rural population of Pampa de Achala in Córdoba Province, Argentina. This city is located in Córdoba High mountains. Blood vitamin D levels were tested in 24 patients and Bone mineral density in 31 patients. Vitamin D level was determined by HPLC. The vitamin D level were considered normal between 20-50 ng/ml in the winter season and 20-80 ng/ml in the summer season. Bone mineral density of lumbar spine and femoral neck was measured by DXA GE LUNAR DPX-L, according to World Health organization classification (37). The data were analyzed by Spearman coeficient and Chi cuadrado.Results: The vitamin D levels samples were avaliable in 24 patients. Mean blood Vitamin D level was 24.54 ng /ml. 8 of them (33%) had vitamin D level less than 20ng/ ml. 83% (20) of the analysed patients had vitamin D level less than 30 ng/ml and only 4 patients has vitamin D level more than 30 ng/ml.Low bone mineral density of lumbar spine and femoral neck was found in 66 % of the patients. 19 % of the patients were diagnosed of lumbar spine and femoral neck osteoporosis and 29% of them had lumbar spine meanwhile 25% had femoral neck. There was not statistically significant associaton between vitamin D level and bone mineral density analysed by Chi Cuadrado (p<0.07). A significant association was found between blood vitamin D level and low bone mineral density of femoral neck (Spearman 0.51) Conclusions: Vitamin D insufficiency is high in the rural adult population of Pampa de Achala in Córdoba and it could be a major health problem in this population.

A new species of <I>Schendylops</I> Cook, 1899 from a high plateau of the Córdoba mountains (central Argentina), with notes on other Neotropical members of the genus (Myriapoda: Chilopoda: Geophilomorpha)

Schendylops achalensis sp. n. (Chilopoda: Geophilomorpha: Schendylidae) is here described and illustrated from a female (holotype) and a male (paratype) from Pampa de Achala plateau, Cordoba mountains (central Argentina). The new species is characterized by having well defined pore fields on the sterna of the anterior and posterior region of the body, but totally absent on the intermediate ones, this character being shared by only four other Neotropical species of the genus, i.e., Schendylops demangei (Pereira, 1981), Schendylops demartini (Pereira & Minelli, 1996), and Schendylops placcii (Pereira & Minelli, 1996) from Argentina, and Schendylops minutus (Pereira & Minelli, 1993) from Venezuela, with which it is here compared in detail. New diagnoses for these latter species are also given.

Habitat selection in the Pampa de Achala toad, Bufo achalensis

AbstractHabitat selection in adult and juvenile Bufo achalensis was studied at La Ciénaga Stream, Pampa de Achala, Central Argentina from December 1998 to October 2001. Habitat preference was evaluated by comparing the observed use of each habitat type with its availability. Juveniles were surveyed on 32 occasions between January 1999 and March 2001 using 13 permanent transects. The effect of cattle on larval survivorship was also evaluated. Most adult and juvenile B. achalensis occurred within 300 m of each side of the breeding site stream. No correlation was found between body size and distances moved. Juveniles and adults selected granite outcrops after the breeding season and avoided the heavily grazed areas. Adults also selected the stream and used tall tussock grassland in proportion to its availability. Juveniles used loose, flat, relatively small stones as shelters whilst adults used larger rocks. The presence of cattle at the breeding sites directly reduced larval survivorship by trampling, and indirectly through sediment deposition at the breeding sites resulting from increased stream bank erosion. The habitat preferences of B. achalensis suggest that long term cattle grazing also affects them adversely through deterioration of their transition habitat from tall tussock grassland to short sward. Future conservation management plans for B. achalensis must include the protection of the breeding sites and the surrounding terrestrial area if they are to be effective.

A NEW SPECIES OF TRICHURIS (NEMATODA: TRICHURIDAE) FROM PHYLLOTINI RODENTS IN ARGENTINA

A new species of Trichuris is described. Trichuris pardinasi n. sp. was recovered from Phyllotis xanthopygus Waterhouse (Rodentia: Muridae: Phyllotini) in Sierra de la Ventana, Buenos Aires Province, and Pampa de Achala, Córdoba Province (Argentina). This is the first record of Trichuris parasitizing Phyllotini rodents. The new species can be differentiated from the other 10 species parasitizing rodents from South America by the absence of the spicular tube, spicular sheath with spines uniformly distributed, the length of spicule, the J-shaped proximal cloacal tube, and the nonprotrusive vulva. Also, a description of the bacillary band is provided. The present and the future findings of shared parasite fauna from both populations of P. xanthopygus in these disjunct areas will support the hypothesis of a continuous distribution of this host species at a past time.

Sensitivity of wildlife to spatial patterns of recreationist behavior: A critical assessment of minimum approaching distances and buffer areas for grassland birds

A major goal of protected area management is to promote coexistence between wildlife and people and managers may restrict human activity by creating buffer zones. There are a number of assumptions implicit in establishing buffer zones that are typically based on how animals respond to approaching humans. Conventional wisdom suggests that animals will be more sensitive to directly approaching humans than humans approaching tangentially. Visibility and detectability are important factors influencing a species’ response to an approaching threat. Grasslands are an ideal system to study the different approach types because visibility is similar in all directions. We focused on five species of birds, four of them endemic, in the high Pampa de Achala mountain grassland of Argentina to study the effects of direct and tangential approaches on disturbance, and to evaluate five methods typically used to estimate buffer areas considering their sensitivity to the type of approach and their ability to estimate areas large enough to ensure the protection of the target species. We found that, contrary to conventional wisdom, four out of the five species showed greater flight initiation distance response to tangential rather than direct approaches, and that the minimum approach distance and buffer area estimates for these species varied significantly (in some cases an order of magnitude) between methods. Variability in the estimates between methods could be related to their different assumptions, which are not typically evaluated. More generally, we should be cautious when asserting that a buffer area calculated from direct approaches necessarily eliminates human disturbance.

Breeding behaviour and reproduction in the Pampa de Achala toad, Bufo achalensis

AbstractDuring 1999 and 2000 the reproductive behaviour, breeding site characteristics and reproduction of Bufo achalensis were studied mainly at La Ciénaga stream, Pampa de Achala, Argentina, using capture-recapture and skeletochronology methods. Breeding activity occurred from mid-August to mid-September and was explosive. Males and females congregated at night at selected, but scarce, breeding sites, resulting in a patchy distribution of small breeding populations near to the stream source. The sex ratio (♂ : ♀) of the breeding population ranged between 0.65 : 1 and 1.16 : 1. On average, breeding males were larger and older than breeding females. Although most females and males reached sexual maturity at four and five years of age, some bred for the first time at the ages of three and four years respectively. Neither size dependent nor size assortative pairings were found. Male reproductive success was not related to body size (SVL) but was related to the number of nights spent at a breeding site. Females laid between 700-2,390 eggs. Eggs hatched approximately nine days after deposition and larval development was completed in about two months.

Uroleucon bereticum (E.E. Blanchard) (Hemiptera: Aphididae) and its new endemic parasitoid species (Hymenoptera: Braconidae, Aphidiinae) in Argentina

Collections of Uroleucon bereticum (E.E. Blanchard) on Conyza bonariensis (L.) Cronquist were made throughout the National Park Quebrada del Condorito at Pampa de Achala, province of Cordoba, Argentina. This aphid species was described as Macrosiphoniella beretica by Blanchard (1922) from apterous viviparous female and the alate viviparous female were unknown. Morphological characteristics of U. bereticum presented in this paper include the re-description of the apterous viviparous female as well as a new description of the alate viviparous female. Very little is known about the aphid parasitoids in Argentina and material of the indigenous endemic aphid species has not been collected up to now. Binodoxys achalensis Starý, sp.n. is described as a new endemic parasitoid species associated with U. bereticum and its seems to indicate the occurrence of new and more numerous oligophagous parasitoid guild in the target area.

Longevity and sexual size dimorphism of the Pampa de Achala copper lizard Pristidactylus achalensis (Gallardo, 1964)

AbstractLongevity and sex-specific growth of the neotropical lizard Pristidactylus achalensis was studied from 1993 to 1998 in a population inhabiting the Pampa de Achala, Sierras Grandes de Cordoba, Argentina, at an elevation of 2,000 m. Capture effort concentrated on the territorial adults which were detected while basking. Each of the 149 individuals studied was sexed, morphometrically described and toe-clipped. The second phalanx was used for skeletochronological age estimation and retrospective growth reconstruction, in some voucher specimens additionally the humerus to validate LAG counts in the phalanx cross sections. Longevity was about the same in males (9 LAGs) and females (10 LAGs) but may be even larger in non-territorial individuals. Sexual maturity was usually attained at an age of 3 LAGs, only occasionally one year earlier. With respect to snout-cloaca length, females were always significantly smaller than males of the same age. Bone growth (increase of LAG diameter) revealed that the sexual size dimorphism was related to a significantly lower growth rate of females following hatching. Age and size were correlated (rs = 0.564, n = 149, P << 0.001), but still most of the total size variance remained unexplained by age. Maximum size was approached asymptotically with more than 90% of size increase occuring during the first three years of life: 46.0 ± 1.7 mm (1 LAG), 81.3 ± 5.6 mm (2 LAG), 100.1 ± 0.7 mm (3 LAGs). Territorial individuals rarely were successful to defend a territory more than one activity period, as evidenced by a low recapture probability and a stable between-years age structure of this group.

Longevity, Demography and Sex-Specific Growth of the Pampa de Achala Toad, Bufo achalensis CEI, 1972

The demography and life history parameters of the neotropical Bufo achalensis, an endemic toad of the Pampa de Achala, Sierras Grandes de Cordoba, Argentina, were studied in 13 activity periods between 1970/71 and 1998/99. We used phalange bones for skeletochronological age estimation and to assess annual growth rates in 243 individuals. Maximum longevity was 11 years, and sexual maturity was attained at an age of 2–4 years. Reproductive females were on average 4–8 mm smaller than males of the same age. There is no indication that the population of B. achalensis is declining as observed in several neotropical amphibian species.

Distribution and ecological observations of wild rodents in Pampa de Achala, Córdoba, Argentina

This study lists the species of rodents living in the Pampa de Achala, a high plain in the Sierras de Cordoba, and analyses their habitat preferences and their Zoogeographic relationships. Five cricetine rodents in order of numbers captured were Akodon sp., Phyllotis darwinii, Oxymycterus paramensis, Reithrodon auritus, and Oligoryzomys flavescens, and one caviomorph rodent, Galea sp. Each of the seven habitats sampled supported a characteristic mixture of species. Range extensions were documented for several species, and the first records for the Province for some of them. The population of Akodon appears to be endemic. The composition of the rodent fauna confirms that the Pampa should be considered a distinct Sector within the Southeastern District of the Subandean Dominion, without close faunal connections with the rest of the Province.

Plant Communities and Associated Soil Types in a High Plateau of the Cordoba Mountains, Central Argentina

The Pampa de Achala, a high plateau located in Cordoba Province, central Argentina, is the major catchment area of the region and exhibits some biogeographic peculiarities. However, little information is available on vegetation-soil relationships, considered to be of great importance for the conservation of the bio-geo-edaphic stability. This paper discusses plant communities and their associated soil conditions in a mountainous ecosystem. Seven plant communities are distinguished and the range of soil types on which they occur is described. A physiographic map gives a general idea of the spatial distribution of landforms with their corresponding soil and vegetation associations. From the analysis of the soil-vegetation relationships, it is concluded that the soil moisture regime is the principal environmental factor determining the type of vegetation community present at one particular place. This factor is a complex of variables of which soil texture, soil depth, and the hydrological position in the landscape are the most important. These variables can be arranged in an environmental gradient, ranging from shallow, sandy/rocky, dry places to deep, silty-to-clayey, wet places, in which all plant communities can be exactly situated. Successional features related to plant communities within that gradient are inferred and some conclusions drawn on the landscape stability of the area in relation to the gully erosion affecting the bottomlands.

Observations on Tuberculosis in the City of Cordoba and Pampa De Achala, Argentina, and Minneapolis, Minnesota

SUMMARY The tuberculin test was administered to six groups of children in the Province of Cordoba, Argentina, and to a group of Minneapolis, Minnesota, children. Twelve hundred eighty-eight Argentina children and 2881 Minneapolis children were tested. In the Argentina group Koch's Old Tuberculin was used with the initial dose of 0.1 cc. of a dilution of 1:1000. For those who did not react, a second dose consisted of 0.1 cc. of a dilution of 1:100, and for those who still did not react, a third dose consisting of 0.1 cc. of a dilution of 1:10 was administered. In the Minneapolis group, the same procedure was employed except that the third dose was omitted. Among the Cordoba children the percentage of reactors to tuberculin ranged from 12.7 to 58.6, the average being 51.1. The low percentage of 12.7 was obtained among seventy-one children ranging from six to fifteen years of age, who resided in Pampa De Achala, where there is little contact with large centers of population. In the remainder of the Cordoba group the lowest percentage of reactors was 43.5. In the Minneapolis group of 2881 children, 23.1 per cent reacted definitely, and 0.6 per cent questionably to tuberculin. Among the 1288 Cordoba children, 741 had x-ray film inspection of the chest. Although no attempt was made to determine etiology from x-ray shadows, the films presented evidence of disease which was determined to be the first infection type of tuberculosis in the pneumonic stage in 6.9 per cent, and the reinfection type of pulmonary tuberculosis was diagnosed in 1.7. In 17.6 per cent, small, sharply outlined, dense shadows were seen in the pulmonary parenchyma, the hilum region, or both, which were thought to represent depositions of calcium, bone, or dense fibrous tissue. Among the 648 tuberculin reactors in the Minneapolis group the first infection type of tuberculosis in the pneumonic stage was found in 2.3 per cent. On the first examination the reinfection type of pulmonary tuberculosis was found in 0.2 per cent; however, on subsequent examinations this type of disease appeared in 1.1 per cent. Sharply outlined, small densities were seen in 21.1 per cent. Apparently the disease has the same characteristics among the children of the two nations, as they tolerate the first infection type of tuberculosis in the same manner and the reinfection type of disease is rare in this age group. The Pampa De Achala observations are unique. Here is an isolated community of families devoting their lives for the most part to the raising of sheep at an altitude of about eight thousand feet. Of 183 persons tested with tuberculin, the incidence of reactors was only 12.2 per cent among those of sixteen to twenty-five years of age. However, in the older age group, the incidence was 65.2 per cent, while the average for all ages was 32.2 per cent. Of the 116 persons in this group who had x-ray film inspection of their chests there was evidence of first infection type of tuberculosis in the pneumonic stage in 0.8 per cent, but in no individual was there any evidence whatsoever of the reinfection type of tuberculosis. Small, dense, sharply outlined shadows were present in 22.4 per cent.