Showing papers in "Studies on Neotropical Fauna and Environment in 1991"
TL;DR: Habitat, activity period, food, predators, and defensive behavior are briefly described for five species of snakes with coral‐snake pattern, sympatric in southeastern Brazil: Micrurus frontalis, M. lemniscatus, Erythrolamprus aesculapii, Oxyrhopus guibei, and Simophis rhinostoma.
Abstract: Habitat, activity period, food, predators, and defensive behavior are briefly described for five species of snakes with coral‐snake pattern, sympatric in southeastern Brazil: Micrurus frontalis, M. lemniscatus, Erythrolamprus aesculapii, Oxyrhopus guibei, and Simophis rhinostoma. Defensive behaviors were analyzed by numerical methods in order to evaluate the degree of similarity between these species. The similarity between defensive displays is supposed to be due either to phylogenetic affinity or to mimetic convergence.
69 citations
TL;DR: In this paper, the authors studied the behavior of a spectacled bear (Tremarctos ornatus) on cattle in the Venezuelan Andes from February 1986 to November 1988.
Abstract: Spectacled bear (Tremarctos ornatus) predatory behavior on cattle was studied in the Venezuelan Andes from February 1986 to November 1988. Only 12 of the 140 localities surveyed reported spectacled bear predation. Sixteen recent claims of predation were investigated, and predation by spectacled bear confirmed. Herding practices used in the Venezuelan Andes may increase the probability of predation and the subsequent persecution and killing of bears.
47 citations
TL;DR: Twenty one species of lizards (four families) were found in the region of Balbina Hydroelectric Station, Uatuma river, 60 km east of Presidente Figueiredo, Amazonas State, Brazil, and it is shown that most lizards are exclusive forest dwellers exploring horizontal, vertical, or both spaces.
Abstract: Twenty one species of lizards (four families) were found in the region of Balbina Hydroelectric Station, Uatuma river, 60 km east of Presidente Figueiredo, Amazonas State, Brazil. Most lizards are exclusive forest dwellers exploring horizontal, vertical, or both spaces. Twenty species are diurnal and one is nocturnal; no marked seasonal difference in activity was observed. Except for the known food specialists Iguana iguana (leaves) and Plica umbra (ants), and the omnivorous Tupinambis nigropunctatus, all other species seem to be arthropod generalists. Three guilds with widely overlapping resource utilization are evident. These patterns are very similar to those found in other localities in the Amazon Basin, probably because of the similarity among their herpetofaunas and structural habitats. A brief review of the hypothesis that tries to explain how the members of these complex assemblages coexist shows that, although some authors suggest that competition is weak or inexists in these assemblages, there i...
46 citations
TL;DR: In this paper, three oceanic sandy beaches, covering a full range of dissipative-reflective categories were sampled at southern Chile (ca. 39'S) during the summer of 1990.
Abstract: Three oceanic sandy beaches, covering a full range of dissipative‐reflective categories were sampled at southern Chile (ca. 39'S) during the summer of 1990. The purpose of this study was to analyse...
27 citations
TL;DR: It is concluded that the mara preferencially selects habitats with large representation of bare ground, which results in its increased presence in grazed areas.
Abstract: The mara Dolichotis patagonum is a cursorial rodent typical of savannas, steppes and grasslands. In the Monte of Argentina, where the typical vegetation is an open scrub with a ground layer of scarce herbs and unvegetated spaces of sandy soil, difference in mara abundance between protected and grazed areas suggest a preference for open areas. The main purpose of this paper is to assess how D. patagonum uses the habitat, especially with reference to the vegetation structure. The abundance of mara feces was considered as a measure of its spatial activity and was correlated with cover of three vegetational strata in two study sites: one in Nacunan Ecological Reserve and another in a contiguous grazed area. Significant correlationas were obtained with percent bare ground (positive) and percent shrub cover (negative). It is concluded that the mara preferencially selects habitats with large representation of bare ground. This results in its increased presence in grazed areas. In contrast, mara abundance is mark...
25 citations
TL;DR: The tadpoles of Hyla armata (Hylidae) and Bufo veraguensis (Bufonidae) from the Amazonian slopes of the Andes in southern Peru and Bolivia are described, with modifications reflecting adaptations to stream life.
Abstract: The tadpoles of Hyla armata (Hylidae) and Bufo veraguensis (Bufonidae) from the Amazonian slopes of the Andes in southern Peru and Bolivia are described These tadpoles, collected from streams draining the Cordillera Oriental in southern Peru, have modifications reflecting adaptations to stream life These include, in Hyla armata, an enlarged oral disc with numerous labial tooth rows and complete marginal papillae and, in Bufo veraguensis, a belly sucker, unique within the genus but similar to the more fully‐developed sucker of Atelopus tadpoles In addition, Bufo veraguensis tadpoles are unusual for Bufo in having a dextral vent, high density of labial teeth with no unbroken rows, and small external nares The morphology of the tadpoles of Hyla armata and Bufo veraguensis is as yet uninformative regarding the relationships to these two unusual frogs The advertisement call of Hyla armata consists of a single, high‐pitched note with a dominant frequency of 47 KHz
22 citations
TL;DR: It is shown in this report that two species live sympatrically at two localities in Chile and two in Argentina, and the genus Euneomys thus comprises at least two species.
Abstract: A recent review lists all forms of Euneomys as a single species. We show in this report that two species live sympatrically at two localities in Chile and two in Argentina. The grooves on the anterior surfaces of the upper incisors are centrally positioned in one of the species and laterally positioned in the other. The species with central grooves has a larger head and body, larger hind foot, wider interorbital constriction, wider rostrum, longer molar toothrow, larger claws on the front feet, and lives in deep soils. The smaller species lives in bare, rocky habitat. The genus Euneomys thus comprises at least two species. The names mordax and chinchilloides are appropriate for the large and the small species, respectively.
22 citations
TL;DR: Six species and subspecies of Bulimulus are represented in the Republic of Argentina and their variations and geographic distribution are discussed, their spermatophores described.
Abstract: Six species and subspecies of Bulimulus are represented in the Republic of Argentina: B. apodemetes, B. bonariensis bonariensis, B. bonariensis sporadicus, B. prosopidis, B. rushii and B. vesicalis vesicalis. Their variations and geographic distribution are discussed, their spermatophores described. B. sporadicus gracilis, B. jorgenseni and B. jujuvensis are species which do not belong to the genus.
17 citations
TL;DR: The results of a comparative study of a trophic spectre of three species of shorebirds (Tringaflavipes) show the mechanisms of isolation despite sharing the same source of food.
Abstract: The results of a comparative study of a trophic spectre of three species of shorebirds (Tringaflavipes. Calidrisfuscicollis and Charadrius collaris), are given in this contribution. They show the mechanisms of isolation despite sharing the same source of food. Considering the diversity of food, the mechanisms of isolation can be shown in the trophic as well as in special dimension of the ecological niche. Specialization on certain types of food and different types of habitat use are the prevalent strategies to avoid competitive exclusion.
14 citations
TL;DR: It is suggested that censuses for establishing harvest quotas avoid resting periods because important proportions of Capybaras may be hidden in thickets or aquatic vegetation.
Abstract: A study of the 24‐hour cycle of activity in Capybaras in the llanos of Venezuela was made using visible red light for nocturnal activity. Observations were made during both the dry and rainy season. In both cases Capybaras showed 4 peaks of activity during the 24‐hour cycle, but in the dry season 3 peaks were after dark while in the wet season 2 peaks were by day and 2 by night. By night groups of Capybaras moved rapidly to grazing sites keeping together by low volume vocal communication. Experimentation showed that visible red light permits close approach to Capybaras because it hides the observer. Coprophagy was frequently observed, almost exclusively during the morning resting period. Copulations were observed mostly in May (dry season), all but one in water, and most between 08.00 to 13.00. It is suggested that censuses for establishing harvest quotas avoid resting periods because important proportions of Capybaras may be hidden in thickets or aquatic vegetation.
13 citations
TL;DR: These findings are unexpected considering that Sphiggurus and Coendou resemble morphologically more to each other than either of them to Erethizon, and are most parsimoniously explained by retaining the hypothesis of a closer cladistic relationship between Sphigguru and Coendschildi and by proposing the 2n‐74 and FN=82 karyotype to be autapomorphic.
Abstract: Sphiggurus vestitus pruinosus, a porcupine from western Venezuela, has a karyotype with a diploid number (2n) of 42, and a fundamental number (FN) of 76. The autosomes consist of 34 metacentric and submetacentric, 2 subacrocentric, and 4 acrocentric chromosomes. The X‐chromosome is submetacentric, and the Y‐chromosome is acrocentric. This karyotype is identical in gross morphology to that of the North American porcupine, Erethizon dorsatum, but differs markedly from the 2n=74 and FN=82 karyotype of the Panamanian porcupine, Coendou rothschildi. These findings are unexpected considering that Sphiggurus and Coendou resemble morphologically more to each other than either of them to Erethizon, and are most parsimoniously explained by retaining the hypothesis of a closer cladistic relationship between Sphiggurus and Coendou and by proposing the 2n‐74 and FN=82 karyotype to be autapomorphic. The karyological information is complemented with observations on cranial and external characters. The results support re...
TL;DR: A new species of Biomphalaria found in Andean swamps close to Isluga, Tarapaca Region, north of Chile, is described.
Abstract: A new species of Biomphalaria found in Andean swamps close to Isluga, Tarapaca Region, north of Chile, is described. The study of its anatomy, particularly of those structures which have been assigned taxonomic and phylogenetic value, allows both its comparison and evaluation to establish relationships and differences with other species of the High Andes plateau.
TL;DR: The macrobenthic fauna of lago Escondido (Rio Negro, Argentina) has been sampled from May to November, 1987, along four transects with an 1 meter depth interval.
Abstract: The macrobenthic fauna of lago Escondido (Rio Negro, Argentina) has been sampled from May to November, 1987. Samples were collected with an Ekman‐Birge dredge (263 cm2), along four transects with an 1 meter depth interval. Some physical and chemical parameters were also taken. From the 28 identified taxa, chironomid larvae exhibited the highest values both in species richness and abundance. The most abundant chironomids were Polypedilum sp. (3354 ind./m2) and Nimbocera sp. (2312 ind./m2) in the 0–1 m interval. The higest density was observed in the littoral zone (0–5 m), where Schaenoplectus californicus and Potamogeton linguatus grow; in which the maximum value was 8224 ind./m2 between 0 and 1 m. The lowest density (303 ind./m2) was detected in the zone without vegetation (7–8 m). The faunistic composition of lake Escondido showed some differences with similar temperate lakes in the Northern hemisphere and Australia, e.g. it lacks the predaceous chaoborid larvae; and similarities with the New Zealand lak...
TL;DR: Bertalanffy's model was applied for the study of growth, which showed an effective fitness to the data obtained from the samples.
Abstract: Leptodactylus latinasus Jimenez de la Espada, 1875 at Punta Lara, Province of Buenos Aires, Argentina, was assigned to cohorts on the basis of snout‐vent length, development, and reproductive condition. Frogs were sampled by pitfall traps during December 1985 to November 1986. Two age‐classes were observed during this period. Bertalanffy's model was applied for the study of growth, which showed an effective fitness to the data obtained from the samples.
TL;DR: Variations of density and of population structure of Octodon degus in the area of National Park “La Campana”, two habitats with different grade of intervention during the time of breeding in two consecutive years, are shown.
Abstract: Variations of density and of population structure of Octodon degus in the area of National Park “La Campana”, two habitats with different grade of intervention during the time of breeding in two consecutive years, are shown. The density of this rodent is in inverse relation to the degree of alteration of the habitat, showing its sensibility to the changes of the habitat. At the end of winter (August/September) the population would have its lowest density. Its maximun expression is obtained at the beginning of summer (December) coinciding with the breeding period. The relationship between immature adult from one year to the other shows a close relation. However, the variations observed during the same year are due to the recruit of the immature of the two offsprings that the rodent produces. When demand is greatly reduced from February to May, the palm fruit is an important nutricional help. But it has not been well defined quantitatively. The other members of the community of micro‐mammals show the same t...
TL;DR: Five species of the antlike jumping spider Synemosyna were collected in northern Colombia and a key to the species is provided.
Abstract: Five species of the antlike jumping spider Synemosyna were collected in northern Colombia: S. americana (Peckham and Peckham), 5. ankeli n, sp., S. aurantiaca (Mello Leitao), S. invernar n. sp. and S. lucasi (Taczanowski). A key to the species is provided.
TL;DR: Three cases of hybridization obtained in laboratory conditions between Centruroides gracilis and Centruoides margaritatus bring some evidence on the genetic relationship between these two species.
Abstract: Three cases of hybridization obtained in laboratory conditions between Centruroides gracilis and Centruroides margaritatus bring some evidence on the genetic relationship between these two species. The experiments were done with specimens collected in Florida (USA), Mexico and Colombia.
TL;DR: Oxygen uptake was lower for dormant groups at high temperature, and a lack of response to temperature was reported between 20–25C in the dormant group of both species.
Abstract: In southeastern Brazil the leptodactylid frogs Leptodactylus fuscus and Physalaemus fuscomaculatus enter dormancy during the dry season. Oxygen uptake was measured in awake and dormant groups of both species in a temperature range at which these frogs are usually exposed throughout the year. Oxygen uptake was lower for dormant groups at high temperature, and a lack of response to temperature was reported between 20–25C in the dormant group of both species. This temperature‐intensitive range can be considered an adaptive feature to save fat reserves during dormancy.
TL;DR: It is proposed that in the new species described seasonality of tropical rain forest environment may have represented the constraint which selected the displacement of the gizzard.
Abstract: Lavellodrilus ilkus and L. bonampakensis are described from two Mexican tropical rain forests. Some ecological observations are also discussed. Despite the presence of an intestinal gizzard, these species are placed in the genus Lavellodrilus (where this character is absent) because they present sexual characters diagnostic of this genus and by the close association of this feature with a certain ecological niche. The adaptive nature of intestinal gizzards in non‐moniligastid genera is discussed in terms of: their repeated appearence, Bouche's hypothesis of functional constraints and the suggested adaptive function. It is proposed that in the new species described seasonality of tropical rain forest environment may have represented the constraint which selected the displacement of the gizzard.
TL;DR: The specimen of M. brevipes, a juvenile female, is declared as a species “incertae sedis” since the specimen doesn't present sufficient characteristics which allow a secure identification of the genera and species.
Abstract: After the examination of the types of Mygalarachne brevipes Ausserer, 1871, and Sericopelma rubronitens Ausserer, 1875, we declare M. brevipes, a juvenile female, as a species “incertae sedis” since the specimen doesn't present sufficient characteristics which allow a secure identification of the genera and species.
TL;DR: The taxonomy of the Neotropical genus Sampsonius Eggers is reviewed and a key to all species is included and each species is redescribed.
Abstract: The taxonomy of the Neotropical genus Sampsonius Eggers is reviewed. Fourteen species (2 new) are included in the genus. The genus is redescribed, a key to all species is included and each species is redescribed. All available data on distribution is included. New species are: alvarengai (Brazil) and mexicanus (Mexico). Illustrations of most species are included.
TL;DR: The survivorship curve indicates that the experimental population was affected by mortality since age 4 to 9 being this a critical period because the nymphs moult from I to II and from II to III instars, and the curve shows another critical period when the population moults to adult stage.
Abstract: This paper completes the study of the life cycle of Steatoda retorta, which was published before (Gonzalez, 1987). The dates given in this paper were obtained from specimens reared in laboratory. Variations of mortality, survivorship and mean life expectation were studied. The survivorship curve indicates that the experimental population was affected by mortality since age 4 to 9 being this a critical period because the nymphs moult from I to II and from II to III instars. The curve shows another critical period when the population moults to adult stage. The mean life time of the cohort was 37.09 weeks. These results were compared with the data recorded for L. mirabilis, L. antheratus, L. corallinus, L. diaguita and Tidarren sisyphiodes. This analysis showed differences as: a) The survivorship curve of Steatoda retorta is more convex than the others because there is no differential mortality between males and females, b) The higher value of the mean life expectation in Steatoda retorta occurs when the fir...
TL;DR: Immature stages of Rogenhofera bonaerensis (Del Ponte, 1939) are described and illustrated and seasonality data of each stages are included.
Abstract: Immature stages of Rogenhofera bonaerensis (Del Ponte, 1939) are described and illustrated. Seasonality data of each stages are included.
TL;DR: Neosanfilippia zoiai, new species of terrestrial Isopod from Ecuador is described and the diagnostic characters between the new species and the only current species of the genus are discussed.
Abstract: Neosanfilippia zoiai, new species of terrestrial Isopod from Ecuador is described. The diagnostic characters between the new species and the only current species of the genus, Neosanfilippia venezuelana Brian, 1957, are discussed. The relationships between the genus Neosanfilippia and the genus Amazoniscus Lemos de Castro, 1967, are discussed. For scanning electron miscroscopy, specimens were fixed in 70% ethanol, dried by air, coated with gold, and studied in a Cambridge Stereoscan 200.
TL;DR: The authors describe and illustrate the preimaginal stages, male and female adults of Sennertia (A.) splendidulae Alzuet y Abrahamovich, 1989, found in nests of Xylocopa (S.) splendidula splendidula Lepeletier, 1841.
Abstract: The authors describe and illustrate the preimaginal stages, male and female adults of Sennertia (A.) splendidulae Alzuet y Abrahamovich, 1989. found in nests of Xylocopa (S.) splendidula splendidula Lepeletier, 1841.
TL;DR: The systematic position of the mollusc Castalia orinocensis Morrison, 1943, is clarified by comparing it with the holotype of Castalia multisulcata Hupe, 1857, which was suggested to be lost, but was refound in the collection of the Natural History Museum in Paris.
Abstract: The systematic position of‐the mollusc Castalia orinocensis Morrison, 1943, is clarified by comparing it with the holotype of Castalia multisulcata Hupe, 1857. The latter was suggested to be lost, but was refound in the collection of the Natural History Museum in Paris. The differences between the two species are described, and C. orinocensis is revalidated by this means.
TL;DR: Psocoptera were collected from soil (by Kempson extraction) and from tree trunks (by arboreal photoeclectors) at two contrasting sites near Manaus, Brazil, for one year and about 81 per cent of the psocids were immature stages.
Abstract: Psocoptera were collected from soil (by Kempson extraction) and from tree trunks (by arboreal photoeclectors) at two contrasting sites near Manaus, Brazil, for one year. The predominant soil taxa were Epipsocetae, especially Isthmopsocus, and a number of minor constituents are probably casual litter‐frequenters. Tree trunks yielded several taxa absent from soil. Soil in a secondary forest site yielded about four times as many psocids as a primary forest site and psocids were more abundant in the dry season than in the rainy season. Arboreal photoeclectors collected more psocids in the primary forest, but catches at both sites were larger in the dry season than in the rainy season. About 81 per cent of the psocids were immature stages.
TL;DR: An illustrated key is given in Portuguese and German for the orders of neotropical Myriapoda (Arthropoda).
Abstract: An illustrated key is given in Portuguese and German for the orders of neotropical Myriapoda (Arthropoda).
TL;DR: From the six previously in Colombia reported Andogyrus species, A. buqueti (Aube, 1838) was proved and details to the habitat and remarks on the behaviour of the egg‐morphology and on socialization with other streamdwellers are announced.
Abstract: From the six previously in Colombia reported Andogyrus species, A. buqueti (Aube, 1838) was proved. For this species details to the habitat and remarks on the behaviour of the egg‐morphology and on socialization with other streamdwellers are announced.