Taxonomic and evolutionary analysis of Zaprionus indianus and its colonization of Palearctic and Neotropical regions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Gill chemoreceptors and cardio-respiratory reflexes in the neotropical teleost pacu, Piaractus mesopotamicus

This study examined the location and distribution of O-2 chemoreceptors involved in cardio-respiratory responses to hypoxia in the neotropical teleost, the pacu (Piaractus mesopotamicus). Intact fish and fish experiencing progressive gill denervation by selective transection of cranial nerves IX and X were exposed to gradual hypoxia and submitted to intrabuccal and intravenous injections of NaCN while their heart rate, ventilation rate and ventilation amplitude were measured. The chemoreceptors producing reflex bradycardia were confined to, but distributed along all gill arches, and were sensitive to O-2 levels in the water and the blood. Ventilatory responses to all stimuli, though modified, continued following gill denervation, however, indicating the presence of internally and externally oriented receptors along all gill arches and either in the pseudobranch or at extra-branchial sites. Chemoreceptors located on the first pair of gill arches and innervated by the glossopharyngeal nerve appeared to attenuate the cardiac and respiratory responses to hypoxia. The data indicate that the location and distribution of cardio-respiratory O-2 receptors are not identical to those in tambaqui (Colossoma macropomum) despite their similar habitats and close phylogenetic lineage, although the differences between the two species could reduce to nothing more than the presence or absence of the pseudobranch.

An analysis of the floristic composition and diversity of Amazonian forests including those of the Guiana Shield

A large number of newly published and unpublished hectare plots in Amazonia and the Guiana Shield area allow an analysis of family composition and testing of hypotheses concerning alpha-diversity in the south American rain forest. Using data from 94 plots the family-level floristic patterns in wet tropical South America are described. To test diversity patterns, 268 plots are used in this large area. Contrary to a widely held belief, western Amazonian plots are not necessarily the most diverse. Several central Amazonian plots have equal or even higher tree diversity. Annual rainfall is not a good estimator for tree diversity in the Amazonia area and Guiana shield. Plots in the Guiana Shield area (and eastern Amazonia) usually have lower diversity than those in central or western Amazonia. It is argued that this is not because of low rainfall or low nutrient status of the soil but because of the small area of the relatively isolated rain forest area in eastern Amazonia and the Guiana Shield. The low diversity on nutrient-poor white sand soils in the Amazon basin is not necessarily due to their Low nutrient status but is, at least partly, caused by their small extent and fragmented nature.

The role of branchial and orobranchial O-2 chemoreceptors in the control of aquatic surface respiration in the neotropical fish tambaqui (Colossoma macropomum): progressive responses to prolonged hypoxia

The present study examined the role of branchial and orobranchial O-2 chemoreceptors in the cardiorespiratory responses, aquatic surface respiration (ASR), and the development of inferior lip swelling in tambaqui during prolonged (6 h) exposure to hypoxia. Intact fish (control) and three groups of denervated fish (bilateral denervation of cranial nerves IX+X (to the gills), of cranial nerves V+VII (to the orobranchial cavity) or of cranial nerves V alone), were exposed to severe hypoxia (Pw(O2) = 10 mmHg) for 360 min. Respiratory frequency (fR) and heart rate (fH) were recorded simultaneously with ASR. Intact (control) fish increased fR, ventilation amplitude (V-AMP) and developed hypoxic bradycardia in the first 60 min of hypoxia. The bradycardia, however, abated progressively and had returned to normoxic levels by the last hour of exposure to hypoxia. The changes in respiratory frequency and the hypoxic bradycardia were eliminated by denervation of cranial nerves IX and X but were not affected by denervation of cranial nerves V or V+VII. The VAMP was not abolished by the various denervation protocols. The fH in fish with denervation of cranial nerves V or V+VII, however, did not recover to control values as in intact fish. After 360 min of exposure to hypoxia only the intact and IX+X denervated fish performed ASR. Denervation of cranial nerve V abolished the ASR behavior. However, all (control and denervated (IX+X, V and V+VII) fish developed inferior lip swelling. These results indicate that ASR is triggered by O-2 chemoreceptors innervated by cranial nerve V but that other mechanisms, such as a direct effect of hypoxia on the lip tissue, trigger lip swelling.

Phylogenetic analysis of the neotropical pseudopolybia de saussure, 1863, with description of the male genitalia of pseudopolybia vespiceps (Hymenoptera : Vespidae, epiponini)

The male genitalia of Pseudopolybia vespiceps are described and compared to congeners. Characters of the male genitalia are combined with morphological characters of the females and nests and used in a phylogenetic analysis. The single cladogram resulting supports monophyly of the genus Pseudopolybia and interrelationships among the species as: P. langi + (P. difficilis + (P. compressa + P. vespiceps)). A new, illustrated identification key is presented.

Neotropical Monogenoidea .25. Anacanthorus penilabiatus n sp (Dadylogyridae, Anacanthorinae) from Piaractus mesopotamicus (Osteichthyes, Serrasalmidae), cultivated in the State of São Paulo, Brazil

Anacanthorus penilabiatus n. sp. is described from the serrasalmid fish, Piaractus mesopotamicus (Holmberg, 1887), cultivated in the Centro de Aquicultura, Universidade Estadual Paulista. The new species is characterized by having a relatively straight copulatory organ with a long ''lip'' on the distal margin and a median longitudinal flap, and a copulatory ligament. The large size of the infrapopulations of this species of parasite indicates that it should be considered a potential agent causing losses in aquaculture of the fish host.

Two new genera of neotropical Chrysopini (Neuroptera : Chrysopidae)

Two new genera and two new spec ies of Chrysopini (Neuroptera: Chrysopidae) are described from Brazil. The main characteristics of Cryptochrysa chloros are: a sheath of long setae in the oral cavity; slender forewing; triangular intramedian cell; antennal scape longer than wide; and lines of strong setae ventral to the arcessus. Characteristics of Furcochrysa allata are: large gonocornua; presence of a pseudopenis; arcessus absent; and basal marginal vein of forewing forked.

2 PERMANENT LINEAR-CHAINS OF SEX-CHROMOSOMES IN NEOTERMES-FULVESCENS AND KARYOTYPES OF 2 OTHER NEOTROPICAL KALOTERMITIDAE SPECIES (INSECTA, ISOPTERA)

Meiosis and (or) mitosis of males and females of Cryptotermes brevis, Eucryptotermes wheeleri, and Neotermes fulvescens, all of them from the neotropical region, were analyzed. Cryptotermes brevis showed a similar karyotype to that obtained by other authors for specimens of the neartic and Australian regions (2n = 36 for females and 2n = 37 for males, with XX and XYY sex mechanisms, respectively). Eucryptotermes wheeleri, the only species that has been described in this genus, showed the lowest number of chromosomes reported for Isoptera (2n = 22) until now. The male meiosis of this species presents a linear chain of six sex chromosomes, three of them being X and three of them Y chromosomes. Neotermes fulvescens showed a diploid number of 40 for males and 42 for females and, in the first male meiosis, two linear chains of chromosomes, both related to sex. One of the chains, named A, presented nine chromosomes and the other, named B, seven chromosomes. Hypotheses to explain these mechanisms are formulated in this paper and putative ancestral relationships with other species of Kalotermitidae are presented.

Reproductive biology of the neotropical superfetaceous Pamphorichthys hollandi (Cyprinodontiformes : Poeciliidae)

We investigated sex ratio, reproductive period, fecundity, and sexual dimorphism of Pamphorichthys hollandi in southeastern Brazil. Reproductive status was identified according to a female's gonads/embryos development scale. of the 613 collected specimens, 373 (60 %) were females and 240 (40 %) males giving a sex ratio of I male: 1.6 female. Sexual dimorphism was evident in respect to body size, body coloration, and anal and pelvic-fin morphologies. The highest proportion of reproductive females was registered in January and February, which represent wet and hot periods. The simultaneous presence of more than one litter at different stages of development within a single female characterized this species as superfetaceous.

Biology and behaviour of the neotropical ant-mimicking spider Aphantochilus rogersi (Araneae: Aphantochilidae): nesting, maternal care and ontogeny of ant-hunting techniques

Aphantochilus rogersi is an ant-mimicking spider that preys exclusively on cephalotine ants. The spiders oviposit in close proximity to nests of the model ant Zacryptocerus pusillus, and emergent spiderlings tend to remain in the vicinity of natal egg sacs. Females of A. rogersi actively defend their egg sacs against approaching workers of Z. pusillus, but the latter may sometimes destroy the eggs. Feeding specialization on these ants is confirmed by more than 300 observations of young and adult A. rogersi carrying ant corpses in the held. Although A. rogersi possesses several behavioural traits which may reduce the risk of being injured by ants during subjugation, field and laboratory observations showed that social defence by Z. pusillus may cause mutilation to the spiders. Tests in captivity revealed an ontogenetic change in the prey-capture techniques employed by A. rogersi. Early-instar spiderlings can apparently only seize the ant's petiole tightly if they are able to approach the ant from the front. As the ant is paralysed, the spiderling positions itself vertically in relation to the substratum. Larger spiders, on the other hand, attack ants most frequently from behind, and seem better equipped to seize the ant's petiole firmly with their larger chelicerae. Owing to their greater strength, late-instar spiders are able to Lift the struggling ant aloft. The selection of a suitable oviposition site, the mother's ability to defend herself and the eggs from nearby ants, and the capacity to capture and subdue ants safely from emergence to maturity, are regarded as crucial traits inherent in the mimetic and feeding specialization by A. rogersi.

Evolution of caste in neotropical swarm-founding wasps (Hymenoptera : Vespidae; Epiponini)

Reproductive castes are compared in species of swarming wasps representing all currently recognized genera of Epiponini (Polistinae). New morphometric data for nine measures of body parts and ovarian data are presented for 13 species. These are integrated with all similarly conducted available studies, giving a total of 30 species. Analysis reveals several syndromes relating reproductive and nonreproductive individuals: no meaningful distinction, physiological differences only, reproductives larger than nonreproductives with intermediate individuals present, reproductives different in shape from nonreproductives with no intermediates, and reproductives smaller in some aspects than nonreproductives. Distribution of these syndromes among species is consistent with phylogenetic relationships derived from other data. Optimizing these syndromes on the cladogram indicates that the basal condition of Epiponini is a casteless society that is not comparable to the primitively social genus Polistes where dominant queens control reproduction. Castes originate several times in Epiponini, with different results in different lineages. The best documented evolutionary sequence passes from casteless societies, to those with reproductives larger, to those with reproductives differing in shape from nonreproductives, to those with reproductives smaller in some measures. This sequence is consistent with Wheeler's theory of the origin of caste through developmental switches, and represents the most thorough test of that theory to date.