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O Parque Estadual do Cantão é uma área protegida no rio Araguaia. Em um inventário realizado durante um ciclo hidrológico completo, foram capturadas 271 espécies de peixes, pertencentes a 183 gêneros, 41 famílias e 12 ordens. Characidae foi a família mais diversa com 89 espécies (32,6% do total), seguida por Loricariidae com 23 espécies (8,4%) e Cichlidae com 21 espécies (7,7%), dez famílias foram representadas por uma única espécie. Os resultados mostraram que o PE Cantão é uma área com alta diversidade de espécies de peixes, e que as assembleias ainda estão bem preservadas, de modo que a existência e manutenção deste Parque é de alto interesse para a preservação da fauna de peixes do rio Araguaia. The Parque Estadual do Cantão is a protected area in the Araguaia River. In a survey carried out during a complete hydrological cycle, 271 species of fish, belonging to 183 genera, 41 families and 12 orders were captured. Characidae was the most diverse family with 89 species (32.6% of the total), followed by Loricariidae with 23 species (8.4%) and Cichlidae with 21 species (7.7%), ten families were represented by only one species. The results showed that the PE Cantão is an area with high diversity of fish species, and that the assemblies are still well preserved, so the existence and maintenance of this Park is of high interest for the preservation of the Araguaia River fish fauna.

The loricariid genus Peckoltia currently encompasses 13 valid species ranging throughout the Amazon basin in Brazil, Venezuela, Colombia, Peru, and Guyanas. Peckoltia is included in the tribe Ancistrini, but its relationships with other taxa within the tribe are not well established. In this paper we describe a new species of Peckoltia from the rio Tapajos drainage, Para State, Brazil. Peckoltia compta, new species, is characterized by a bold color pattern consisting of large dark transversal bars on body and thick longitudinal dark stripes on snout and head. The new species is most similar in color pattern to P. vittata but can be distinguished from all its congeners by the presence of a pale line inside each dark stripe running from the snout tip to anterior margin of eyes (vs. absence of such clear lines and a mottled appearance in P. vittata, and a mix of vermiculations and spots on the head of the remaining congeners). A brief discussion on the taxonomic status of the nominal species Peckoltia vittata is also presented.

Ancistrus is the most speciose genus of the tribe Ancistrini, with 58 valid species and many yet to be described. Cytogenetic studies were conducted on five apparently undescribed species from the Amazon basin, which showed different diploid numbers: Ancistrus sp. Purus (2n = 34); Ancistrus sp. Macoari (2n = 46); Ancistrus sp. Dimona (2n = 52); Ancistrus sp. Vermelho (2n = 42) and Ancistrus sp. Trombetas (2n = 38). All species possessed only one pair of NOR-carrying chromosomes, but with extensive variation in both the location on the chromosome as well as in the position of the ribosomal sites on the karyotype. The karyotypic evolution of Ancistrus species seems to be based on chromosomal rearrangements, with a tendency to a reduction of the diploid number. Two new instances of XX/XY sex chromosomes for Ancistrus species, based on the heteromorphism in the male karyotype, were also recorded. The large karyotypic diversity among Ancistrus species may be related to biological and behavioural characteristics of these fish that include microhabitat preferences, territoriality and specialized reproductive tactics. These characteristics may lead to a fast rate of fixation of chromosomal mutations and eventually speciation across the basin.

The relationship between the distribution of the lateral line canals and their functionality has not been well examined in elasmobranchs, especially among Neotropical freshwater stingrays of the family Potamotrygonidae. The spatial distribution of the canals and their tubules and the quantification of the neuromasts were analyzed in preserved specimens of Potamotrygon motoro, P. orbignyi, Potamotrygon sp. "cururu", and Paratrygon aiereba from the middle Negro River, Amazonas, Brazil. The hyomandibular, infraorbital, posterior lateral line, mandibular, nasal and supraorbital canals were characterized and their pores and neuromasts quantified. The ventral canals are known to facilitate the accurate localization of prey items under the body, and our results indicate that the dorsal canals may be employed in identifying the presence of predators or potential prey positioned above the stingray's body. The presence of non-pored canals in the ventral region may be compensated by the high concentration of neuromasts found in the same area, which possibly allow the accurate detection of mechanical stimuli. The concentration of non-pored canals near the mouth indicates their importance in locating and capturing prey buried in the bottom substrate, possibly aided by the presence of vesicles of Savi. A relação entre a distribuição dos canais da linha lateral e a sua funcionalidade é pouco conhecida para os elasmobrânquios, especialmente para as raias neotropicais da família Potamotrygonidae. A distribuição espacial dos canais e seus túbulos e a quantificação dos neuromastos foram analisadas em exemplares preservados das raias Potamotrygon motoro, P. orbignyi, Potamotrygon sp. "cururu" e Paratrygon aiereba, provenientes do médio rio Negro, Amazonas, Brasil. Foram identificados os canais hiomandibular, infra-orbital, linha lateral posterior, mandibular, nasal e supra-orbital, e os poros e neuromastos de cada um foram quantificados. Nossos resultados mostram que os canais dorsais podem ter a função de identificar a presença de predadores ou presas posicionadas acima do corpo da raia, enquanto os canais ventrais provavelmente permitem uma localização precisa da posição de presas sob o corpo. A existência de canais sem poros na região ventral pode estar relacionada com a alta concentração de neuromastos, que compensaria a falta de contato direto dos neuromastos com o meio externo na detecção de estímulos mecânicos. A concentração dos canais sem poros na proximidade da boca indica sua importância para a localização e captura de presas enterradas no substrato, possivelmente auxiliadas pela presença das vesículas de Savi.

This study aimed to identify the diet of giant otters, Pteronura brasiliensis (Zimmermann, 1780) in the Balbina reservoir (01°55'S, 59°29'W), to compare it with literature data on the diet of giant otters from non-dammed areas, and to verify the effects of the seasonal changes in water levels on the feeding habits of Balbina otters. A total of 254 feces samples were collected and identified according to the lowest possible taxonomic level. Teleostei fish were present in 100% of the samples; two samples also presented monkey fur (n = 1) and sloth fur (n = 1), suggesting that the diet of P. brasiliensis, in the reservoir, is almost exclusively based on fish. Ten fish families were identified in our samples, six of which were exclusive to the Balbina Lake (not present in the diet of giant otters from non-dammed areas). These six fish families, however, were present in less than 3% of the samples. The fish families with highest representation in the diet of giant otters from non-dammed areas also appeared with higher frequencies in the Balbina Lake, suggesting that the otters have not changed their diet substantially after the implementation of the reservoir. During the high-water period, when the fish are dispersed into the flooded forest and are not very easy to catch, the otters seem to have an opportunistic feeding habit. By contrast, during the low-water period, when prey items are widely available and easier to catch in the reservoir, their feeding habits are more selective. © 2010 Sociedade Brasileira de Zoologia.

The ornamental discus fish Symphysodon aequifasciatus Pellegrin, 1904, is a popular endemic cichlid species from the Amazon basin, however scientific information concerning biology and ecology in its natural habitat is scarce despite its importance on the international aquarium trade. In this study we evaluated reproductive parameters of S. aequifasciatus in natural habitat in Piagaçu-Purus Sustainable Development Reserve (RDS-PP), lower Purus River, Brazilian Amazon. Males are more frequent in the larger size classes and this might be related to the complex breeding behavior known for S. aequifasciatus. Values of L50 for both sexes corresponded to more than 60% of the maximum attained length which may indicate that energy allocation for somatic growth takes longer in S. aequifasciatus than in other species. Average fecundity for female discus was 1490, ranging from 950 to 1892 oocytes and its correlations with standard length and total weight were very low, probably due to the highly compressed discus ́ body shape. Egg size distribution showed four types of patterns, indicating one to four modes besides the reserve oocytes group. Our results indicate that S. aequifasciatus shows total spawning, in the beginning of flooding period, with the peculiar capacity of releasing multiple egg batches as a strategy that potentially enhances reproductive success. © 2010 Sociedade Brasileira de Ictiologia.

In Amazonia reduced-impact logging, which is meant to reduce environmental disturbance by controlling stem-fall directions and minimizing construction of access roads, has been applied to large areas containing thousands of streams. We investigated the effects of reduced-impact logging on environmental variables and the composition of fish in forest streams in a commercial logging concession in central Amazonia, Amazonas State, Brazil. To evaluate short-term effects, we sampled 11 streams before and after logging in one harvest area. We evaluated medium-term effects by comparing streams in 11 harvest areas logged 1-8 years before the study with control streams in adjacent areas. Each sampling unit was a 50-m stream section. The tetras Pyrrhulina brevis and Hemigrammus cf. pretoensis had higher abundances in plots logged > or =3 years before compared with plots logged

The feeding habits of Pellona flavipinnis (Valenciennes, 1836) at Catalão, a floodplain area on the Brazilian Central Amazon was studied. Data was obtained during three hydrological cycles, between September 1999 and September 2003. Diet composition, daily and seasonal variation in the feeding activity and the relationship between predator's size and its prey were analyzed. Almost 80% of the food consumed has autochthonous origin and diet was composed basically by insects and fish. Juvenile fish predominated in the stomach contents of all size classes but there was no significant relationship between predator's size and its prey. Pellona flavipinnis may be considered a carnivorous species which feeds mainly on juvenile (young-of-the-year) specimens of other fish. More intense feeding activity occurred at night and in the high water period. Os hábitos alimentares de Pellona flavipinnis (Valenciennes, 1836) de uma área de várzea na Amazônia Central, Catalão, foram estudados. Foram utilizados dados referentes a três ciclos hidrológicos, entre setembro de 1999 e setembro de 2003. Foram analisados a dieta, a atividade alimentar diária e sazonal e a relação entre o comprimento da presa e o do predador. Cerca de 80% dos alimentos consumidos eram de origem autóctone e a dieta composta basicamente de insetos e peixes. Peixes juvenis predominaram nos conteúdos estomacais de exemplares de todas as classes de tamanho, mas não houve relação significativa entre o tamanho do predador e o das presas consumidas. Pellona flavipinnis pode ser considerada uma espécie carnívora que se alimenta principalmente de indivíduos juvenis de outras espécies de peixes. A atividade alimentar foi maior durante a noite e no período da cheia.

This study was conducted in an Amazonas state conservation unit, the Catuá-Ipixuna Extractive Reserve (Catuá-Ipixuna RESEX). The main purpose was to provide an ichthyological survey of its small streams, all them tributaries of the Solimões River. Nine small streams (up to 4 m width and 1 m depth) were sampled in September 2006. A total of 1,525 specimens were captured, belonging to 78 species, 24 families and eight orders. Eight species had higher abundances and represented altogether 61.4 % of all collected specimens (Hemigrammus belotii, Microphilypnus amazonicus, Physopyxis ananas, Apistogramma agassizii, Elachocharax pulcher, Apistogramma cf. cruzi, Gladioglanis conquistador and Copella nigrofasciata). Based on the high number of singletons and doubletons present in our samples, as well as the estimated number of species for those streams (106 spp.), we believe that the total fish species richness present in the Catuá-Ipixuna Extractive Reserve may be considerably higher than indicated by our samples. This seems especially true when considering the dimensions of the Catuá-Ipixuna RESEX and the dense hydrographic network present in the area.

Animal coloration has many functions, and fishes are noted among vertebrates for presenting a wide variety of color patterns. Although in marine fishes the relationship between body coloration and behavioral context is well documented, there’s not much information about freshwater fishes. Here we describe color patterns displayed by the dwarf cichlid Apistogramma hippolytae and suggest that these patterns are dependent on different social and behavioral settings. Field observations were conducted underwater in a pond in Central Amazonia, Brazil. We recorded six body coloration patterns related to seven different kinds of behavioral activities: foraging, resting, reproductive and agonistic displays, aggression (attacking and fleeing) and parental care. Changes in coloration occur rapidly and take only a few seconds. Females on parental care exhibited a unique pattern that are more persistent and probably manifests more slowly. In the shallow and clear waters of the natural environment of this dwarf cichlid, color communication seems to constitute an efficient way to display information about individual mood, social status and reproductive readiness, contributing to minimize loss of energy in unnecessary interactions. Coloracao animal tem diferentes funcoes, e os peixes se destacam entre os vertebrados por apresentarem uma grande diversidade de padroes de cores. Embora se conheca relativamente bem a relacao entre coloracao e contexto comportamental para peixes marinhos, pouco se sabe para os peixes de agua doce. Nos descrevemos os padroes de coloracao de um ciclideo amazonico, Apistogramma hippolytae, e sugerimos como esses padroes sao dependentes das caracteristicas sociais e comportamentais. Realizamos observacoes subaquaticas utilizando mergulho livre em campo durante o dia em uma lagoa na Amazonia Central. Nos caracterizamos seis padroes de coloracao associados a sete comportamentos diferentes: alimentacao, repouso, displays sexual e agonistico, agressao (ataque e fuga) e cuidado parental. As mudancas de coloracao levam apenas alguns segundos. Femeas em cuidado parental exibem um padrao exclusivo, cuja mudanca e mais lenta. No ambiente natural desse ciclideo, locais rasos com aguas claras, a comunicacao por coloracao pode ser um sistema eficiente de comunicar o estado motivacional individual, status social e disposicao para reproducao, possivelmente contribuindo para minimizar a perda de energia com interacoes desnecessarias.

The distribution and composition of aquatic insect communities in streams at a local scale are considered to be primarily determined by environmental factors and interactive relationships within the system. Here, we evaluated the effects of forest fragmentation and forest cover changes on habitat characteristics of streamlets (igarapes) in Amazonian forests and on the aquatic insect communities found there. We also developed a habitat integrity index (HII) based on Petersen’s protocol (1992) to evaluate physical integrity of these streamlets and to determine its efficiency to interpret the environmental impacts on this system. We studied 20 small streams at the Biological Dynamics of Forest Fragments Project (BDFFP INPA/SI) study areas, Central Amazonia, 80 km north of Manaus, Amazonas State, Brazil. The vegetation cover was estimated by using LANDSAT images and classified in the following categories: exposed soil, pastures, secondary forests (capoeiras), and primary forests. Stream habitat features were evaluated by using a HII based on visual assessment of local characteristics. Aquatic insects were sampled in four major stream substrates: litter deposited in pools or backwaters, litter retained in riffles, sand, and marginal banks. Stream habitat characteristics were significantly correlated to land use and riparian forest condition. Overall aquatic insect richness and Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness were significantly lower in pasture streams, and their taxonomic composition differed significantly from streams in forested areas. However, these metrics were not significantly correlated to the stream HII. Taxonomic composition of bank insect assemblages changed significantly between streams with low and high values of HII. There was no significant relationship between the proportion of primary forest cover and the faunal metrics. Only drastic changes in the vegetal cover seem to induce significant changes in the aquatic insect community. Matrix habitat heterogeneity, distance to forest fragments, the presence of areas of secondary forest, and the intrinsic capacity to disperse in many of the insect groups may have contributed to attenuate the effects of habitat disturbance on aquatic insect assemblages in streamlets.

Loricariid catfishes show a predominance of homomorphism in sex chromosomes, but cases of simple and multiple systems were also found. Here we describe two cases of multiple sex chromosome systems in loricariids from Brazilian Amazonia. Males of Ancistrus sp.1 "Balbina" have a modal number of 2n = 39 chromosomes, fundamental number (FN) of 78, and karyotypic formula of 27 m + 10 sm + 2 st; females have 2n = 38 chromosomes, FN = 76, and 26 m + 10 sm + 2 st. Ancistrus sp.2 "Barcelos" has 2n = 52 chromosomes for both sexes, FN = 80 for males and FN = 79 for females. Karyotypic formula is 12 m + 12 sm + 4 st + 24a for males and 11 m + 12 sm + 4st + 25a for females. The two species show different arrangements of constitutive heterochromatin blocks, which are coincident with NORs and absent in sex chromosomes. We suggest a XX/XY(1)Y(2) mechanism for Ancistrus sp.1 "Balbina", and a Z(1)Z(1)Z(2)Z(2)/Z(1)Z(2)W(1)W(2) mechanism for Ancistrus sp.2 "Barcelos". The XX/XY(1)Y(2) mechanism here reported is the second known occurrence of this type of multiple sex chromosomes for Loricariidae and the third for Neotropical fishes; the mechanism Z(1)Z(1)Z(2)Z(2)/Z(1)Z(2)W(1)W(2) represents the first record among fishes. The presence of different sex chromosome systems in Ancistrus indicates a probable independent origin and suggests that the differentiation of sex chromosomes is evolutionarily recent among species in this genus.

[[Anostomoides]] Identification key for species of Anostomoides 1. Body without black bands or blotches; anal fin with 10 branched rays...... A. atrianalis - Body with black bands or blotches on the side; anal fin with 8-9 branched rays........ 2 2. Lateral line scales 39-41; three transverse dark bands on the side; fins hyaline to light gray........................................................................................................ A. laticeps - Lateral line scales 38-39; two round- to heart-shaped dark blotches on the side; deep red fins................................................................................................ A. passionis n. sp., Published as part of Geraldo Mendes dos Santos & Jansen Zuanon, 2006, Anostomoides passionis, a new fish species from rio Xingu, Brasil (Characiformes: Anostomidae)., pp. 59-68 in Zootaxa 1168 on page 67

[[Anostomoides]] Anostomidae currently includes 12 genera and approximately 140 species. It includes small fishes of less than 100 mm standard length and larger species up to 400 mm SL, the latter usually included in commercial and subsistence fisheries (Géry, 1977; Garavello & Britski, 2003). The genus Anostomoides has only two valid species: A. atrianalis, of small adult size (~200 mm SL), and so far recorded only from río Orinoco, and A. laticeps, a larger species that attains ca. 400 mm SL of wide distribution in the Amazon Basin. During ecological studies conducted by one of the authors (JZ) in the lower rio Xingu rapids, Pará State, several specimens of an undescribed species of Anostomoides were collected. The fish were readily distinguished by their conspicuous color pattern and are herein described as a new species.

Anostomoides laticeps: INPA 20204, 1 ex., rio Araguaia, State of Tocantins, 18 Feb 2000. INPA 10991, 1 ex., rio Aripuan��, State of Mato Grosso, 01 Aug 1976. INPA 15182, 1 ex., rio Jamari, State of Rond��nia, 05 Apr 1986. INPA 15185, 1 ex., rio Jamari, State of Rond��nia, 18 Jun 1985. INPA 1190, 1 ex., rio Negro, State of Amazonas, 31 Jul 1979. INPA 1191, 2 ex., rio Negro, State of Amazonas, 27 Jun 1980. INPA 3210, 1 ex., rio Pitinga, State of Amazonas, 11 Oct 1989. INPA 17277, 1 ex., rio Purus, State of Amazonas, 03 Jun 2001. INPA 7106, 1 ex., rio Tapaj��s, State of Par��, 27 Oct 1991. INPA 1609, 3 ex., rio Tocantins, State of Par��, 10 Nov 1981. INPA 20553, 1 ex., rio Tocantins, State of Par��, 31 Aug 2000. INPA 20554, 1 ex., rio Tocantins, State of Par��, 5 May 2001. INPA 10091, 1 ex., rio Uatum��, State of Amazonas, Feb 1985. INPA 15577, 1 ex., rio Uatum��, State of Amazonas, May 1988, Published as part of Geraldo Mendes dos Santos & Jansen Zuanon, 2006, Anostomoides passionis, a new fish species from rio Xingu, Brasil (Characiformes: Anostomidae)., pp. 59-68 in Zootaxa 1168 on page 60

[[Anostomoides passionis, new species (continued)]] Diagnosis Anostomoides passionis n. sp. is distinguished from the other two congeneric species by the lower lateral line scale count (38-39 versus 39-41 in A. atrianalis and 42-44 in A. laticeps); premaxillary teeth with straight and smooth borders, without cusps (vs. bicuspidate to somewhat tricuspid in the other two species); and by the color pattern (brownish-grey with two round to heart-shaped dark blotches on the side and deep red fins, vs. three transverse dark bands on the side in A. laticeps and absence of dark blotches or bands on the side in A. atrianalis). Description Refer to Figs. 1 and 2 for a general view of the holotype and one of the paratypes, and to Table 1 for measurements and body proportions. Body deep and laterally compressed. Dorsal profile gently sloped from snout to dorsal fin base; slightly slanted posteroventrally at dorsal fin base, slightly convex between end of dorsal fin base and origin of adipose fin, then gently concave to caudal fin base. Ventral body profile gently curved from tip of lower jaw to pectoral fin insertion, slightly convex to almost straight to anal opening, slanted posterodorsally at anal fin base and somewhat concave at caudal peduncle. Caudal peduncle almost rectangular, slightly longer than high. Post pelvic region compressed but without forming keel. Dorsal fin with upper margin slightly convex when fully spread; median dorsal fin rays approximately two times longer than first and last rays. Dorsal and adipose fins well separated, anterior portion of adipose fin base partially covered with scales. Pectoral fin wide, with convex margin, its tip reaching midway to base of pelvic fin. Pelvic fins wide with round edges, located slightly in advance of mid-body, and well separated from each other when spread. Anal fin with border slanted posterodorsally, its tip surpassing level of hypural joint when adpressed. Caudal fin deeply forked with long and wide lobes with rounded tips. Dorsal fin ii, 10; pectoral fin i, 15-16; pelvic fin i, 8 and anal fin ii, 8-9. Head stout and approximately conical, laterally compressed and covered with thick skin. Snout conical and relatively long with nasal openings set close together and separated by thin fold of skin. Anterior nare a short tube with posterior flap; posterior nare round with lamellae clearly visible inside. Interorbital distance large (ca. 2.4 times in head length). Eye with free orbital rim, relatively small (contained ca. 5.2 times in head length) and placed low on side of head (orbit���s lower edge located below main longitudinal body axis). Mouth terminal to slightly upturned, with lips fleshy and thick, covered internally with numerous papillae. Lower jaw shorter and set behind anterior margin of upper jaw with mouth closed. Gill rakers short and fleshy, numbering 17-20 on first branchial arch, of which 7-8 are located on epibranchial and 10-12 on hypobranchial. Teeth incisiform, with borders almost straight, excavated on the inner (lingual) side. Symphyseal teeth larger, wider and showing a slightly convex border, the following ones becoming smaller posteriorly, with truncate border and sometimes with small lateral saliencies forming incipient cusps (Fig. 3). Four teeth in each premaxillary and four in each dentary. Scales large and cycloid. Lateral line straight with 38-39 perforated scales, the pores ramified and composed of 2-4 divergent, usually independent rami. Six to 6.5 series of scales between the dorsal fin origin and the lateral line and 5.5-6.0 series to the pelvic fin origin. Sixteen series of scales around caudal peduncle; 11-13 irregularly set scales along the space between the dorsal and adipose fins. Color pattern in alcohol. Background color brownish grey, slightly darker at dorsum. Scales with dark edges and central portion yellowish, forming an incipient reticulate pattern on the body. Two dark blotches on the side, round to heart-shaped, over the lateral line series of scales (one, more conspicuously located at the level of posterior half of dorsal fin, and another at anal fin level); these blotches occupy 2-3 scales horizontally as well as vertically. Caudal fin uniformly yellowish to light grey; anal fin grayish with darker interradial membrane; adipose fin with central portion dark grey, base and free edge yellowish; pelvic fin grey with yellowish edges; dorsal and pectoral fins uniformly light grey. Live color pattern. Dorsal area olive grey, ventral portion lighter and yellowish. Two black, round to heart-shaped blotches over the lateral line scales, one placed at the level of the anterior portion of dorsal fin, and another at anal fin level. Scales with base and free edge darker than the central area, producing a conspicuous reticulated pattern. Fins red to dark orange, suffused with dark melanophores at the base of dorsal and caudal fins, tip of anal fin and central portion of adipose fin (Fig. 2). Distribution Presently known only from rio Xingu, State of Par��. Ecological notes All specimens of A. passionis collected in rio Xingu were found in areas with moderate to strong current (up to 0.80 m*sec-1) and bottom substrate composed of sand, pebbles and scattered rocks of various sizes. Partially submerged boulders composed the main landscape at all collecting sites (Fig. 3). On one occasion two specimens were collected side-by-side in a gill net, which suggests that this species may form small groups, at least during the dry season. Local fishermen say that A. passionis may form groups of up to a hundred individuals during the early rainy season, when ripe females are commonly caught. During snorkeling sessions conducted in the dry season, one of us (JZ) observed a single large specimen of A. passionis swimming among dark recesses among submerged boulders, at a depth up to 2 m. The fish moved slowly among the rocks, foraging in feeding bouts of three to four bites directed to the ceilings of small caves under the boulders or at crevices among rocks. The biting produced a loud rasping sound, clearly audible underwater. Stomach contents of two specimens of A. passionis caught during the low water season were composed mainly of fragments of sponges. On another occasion, one fish was observed in a mixed group of several anostomid species (Leporinus tigrinus Borodin, L. julii Santos, J��gu & Lima, L. brunneus Myers, L. friderici (Bloch) and Leporellus vittatus (Valenciennes)). Other anostomid fishes observed occupying the large spaces under and among boulders were Leporinus megalepis G��nther, Sartor respectus Myers & Carvalho, Pseudanos sp., Anostomus ternetzi Fern��ndez-Y��pez and Synaptolaemus cingulatus Myers & Fern��ndez-Y��pez. Smaller fishes, mainly individuals of the tetragonopterin Astyanax dnophos Lima & Zuanon, pike cichlids (Crenicichla spp.) and armored suckermouth catfishes (Loricariidae) also shared the rocky shelters in the rapids. Anostomoides passionis is locally known as ���piau do sar��o.��� Piau is a common popular name for anostomids, and ��� sar��o ��� is the vernacular name of a plant species of the family Mirtaceae, common in the seasonally flooded margins of small rocky islands in rio Xingu. According to the local fishermen, A. passionis feeds on the fruit of these plants during the early flooding season. Etymology From the Latin passio, meaning a feeling, in allusion to the round to heart-shaped dark blotches on the side of the fish, as well as the deep red color of its fins. Discussion The genus Anostomoides was proposed by Pellegrin (1908) based on the type species A. atrianalis, described from three specimens collected in 1887 by Chaffanjon in the r��o Orinoco, Venezuela. Later, Eigenmann (1912) described Schizodontopsis laticeps, based on four specimens collected in British Guiana (Crab Falls and Gluck Island), included subsequently in Anostomoides as A. laticeps. According to Pellegrin���s (1908), Anostomoides is an intermediate genus between Leporinus and Anostomus with a distinct dentition: the upper jaw bears compressed teeth, the median ones bicuspidate and the lateral ones somewhat tricuspid; lower jaw teeth also compressed with straight cutting edges, truncate, not denticulate, as in Leporinus. The teeth in Anostomus are aligned sideto-side, whereas in Leporinus the teeth are arranged in a ���stair-like��� pattern, with the second tooth placed slightly under the anterior one and so on. Anostomoides presents a ���reversed��� pattern of teeth arrangement, where each tooth partially covers the anterior one (G��ry, 1961). Myers (1950) proposed a diagnostic key for the genera of Anostomidae but did not include the genus Anostomoides, arguing that the data supplied by Pellegrin did not present relevant information, despite concluding that the genus proposed by that author was distinct enough to be considered valid. G��ry (1961) considered Myers���s (1950) work to be a useful contribution to the knowledge of the anostomids, rendering it one of the best-known fish taxa among South American characins at the time, although the omission of the genus Anostomoides in the identification key was pointed out as a problem. From this standpoint, and based on the three specimens analyzed by Pellegrin, G��ry (1961) redescribed Anostomoides atrianalis Pellegrin, 1908, considering Anostomoides a valid genus after comparing it to Leporinus, Anostomus, Synaptolaemus, and Laemolyta. According to Mago Leccia (1970), A. atrianalis is one of the 27 anostomid species occurring in Venezuela and in the Orinoco basin. The species is considered rare both in collections and in nature. Anostomoides atrianalis is known only from r��o Orinoco, in Venezuela, while A. laticeps has been reported in British Guiana (Eigenmann, 1912) and various rivers of the Amazon basin such as the Tocantins (Santos et. al, 1984; Santos & J��gu, 1989), Uatum�� (Santos & J��gu, 1996), Jamari (Santos, 1991), Xingu (Zuanon, 1999), Araguaia, Negro, Purus, and Tapaj��s (pers. obs.). These records indicate that A. laticeps is widespread in the main black- and clear-water tributaries of the Amazon River but does not occur - or is rare - in the white water rivers. G��ry (1961, 1977) and Libert (1996/7) considered Anostomoides to be a sister group of Laemolyta, based on the large adult size (up to 350 mm), compressed body and slightly upturned mouth. Nevertheless, in contrast to species of Laemolyta, which possess delicate and multicuspidate premaxillary teeth and dentary teeth with a straight border, species of Anostomoides have strong incisiform teeth in both jaws with incipient cusps on only a few teeth. In some specimens these cusps are more evident, while in others they are almost imperceptible. In contrast to the other two species of Anostomoides, A. passionis possesses teeth with straight, smooth borders, without cusps; only occasionally do the intermediate premaxillary teeth show a small salience at the margin but without forming a true cusp. The absence of cusps in the upper jaw teeth seems to reveal similarities of A. passionis with species of the genus Leporinus. However, the slanted and slightly upturned mouth, the fringed lips and the high and compressed body constitute a set of characteristics placing the new species in the genus Anostomoides. Further phylogenetic studies may shed some light on the intrafamilial relationships of the anostomid genera and help to ascertain the proper positioning of the species of the genus Anostomoides., Published as part of Geraldo Mendes dos Santos & Jansen Zuanon, 2006, Anostomoides passionis, a new fish species from rio Xingu, Brasil (Characiformes: Anostomidae)., pp. 59-68 in Zootaxa 1168 on pages 61-67

[[Anostomoides passionis, new species (continued)]] Diagnosis Anostomoides passionis n. sp. is distinguished from the other two congeneric species by the lower lateral line scale count (38-39 versus 39-41 in A. atrianalis and 42-44 in A. laticeps); premaxillary teeth with straight and smooth borders, without cusps (vs. bicuspidate to somewhat tricuspid in the other two species); and by the color pattern (brownish-grey with two round to heart-shaped dark blotches on the side and deep red fins, vs. three transverse dark bands on the side in A. laticeps and absence of dark blotches or bands on the side in A. atrianalis). Description Refer to Figs. 1 and 2 for a general view of the holotype and one of the paratypes, and to Table 1 for measurements and body proportions. Body deep and laterally compressed. Dorsal profile gently sloped from snout to dorsal fin base; slightly slanted posteroventrally at dorsal fin base, slightly convex between end of dorsal fin base and origin of adipose fin, then gently concave to caudal fin base. Ventral body profile gently curved from tip of lower jaw to pectoral fin insertion, slightly convex to almost straight to anal opening, slanted posterodorsally at anal fin base and somewhat concave at caudal peduncle. Caudal peduncle almost rectangular, slightly longer than high. Post pelvic region compressed but without forming keel. Dorsal fin with upper margin slightly convex when fully spread; median dorsal fin rays approximately two times longer than first and last rays. Dorsal and adipose fins well separated, anterior portion of adipose fin base partially covered with scales. Pectoral fin wide, with convex margin, its tip reaching midway to base of pelvic fin. Pelvic fins wide with round edges, located slightly in advance of mid-body, and well separated from each other when spread. Anal fin with border slanted posterodorsally, its tip surpassing level of hypural joint when adpressed. Caudal fin deeply forked with long and wide lobes with rounded tips. Dorsal fin ii, 10; pectoral fin i, 15-16; pelvic fin i, 8 and anal fin ii, 8-9. Head stout and approximately conical, laterally compressed and covered with thick skin. Snout conical and relatively long with nasal openings set close together and separated by thin fold of skin. Anterior nare a short tube with posterior flap; posterior nare round with lamellae clearly visible inside. Interorbital distance large (ca. 2.4 times in head length). Eye with free orbital rim, relatively small (contained ca. 5.2 times in head length) and placed low on side of head (orbit’s lower edge located below main longitudinal body axis). Mouth terminal to slightly upturned, with lips fleshy and thick, covered internally with numerous papillae. Lower jaw shorter and set behind anterior margin of upper jaw with mouth closed. Gill rakers short and fleshy, numbering 17-20 on first branchial arch, of which 7-8 are located on epibranchial and 10-12 on hypobranchial. Teeth incisiform, with borders almost straight, excavated on the inner (lingual) side. Symphyseal teeth larger, wider and showing a slightly convex border, the following ones becoming smaller posteriorly, with truncate border and sometimes with small lateral saliencies forming incipient cusps (Fig. 3). Four teeth in each premaxillary and four in each dentary. Scales large and cycloid. Lateral line straight with 38-39 perforated scales, the pores ramified and composed of 2-4 divergent, usually independent rami. Six to 6.5 series of scales between the dorsal fin origin and the lateral line and 5.5-6.0 series to the pelvic fin origin. Sixteen series of scales around caudal peduncle; 11-13 irregularly set scales along the space between the dorsal and adipose fins. Color pattern in alcohol. Background color brownish grey, slightly darker at dorsum. Scales with dark edges and central portion yellowish, forming an incipient reticulate pattern on the body. Two dark blotches on the side, round to heart-shaped, over the lateral line series of scales (one, more conspicuously located at the level of posterior half of dorsal fin, and another at anal fin level); these blotches occupy 2-3 scales horizontally as well as vertically. Caudal fin uniformly yellowish to light grey; anal fin grayish with darker interradial membrane; adipose fin with central portion dark grey, base and free edge yellowish; pelvic fin grey with yellowish edges; dorsal and pectoral fins uniformly light grey. Live color pattern. Dorsal area olive grey, ventral portion lighter and yellowish. Two black, round to heart-shaped blotches over the lateral line scales, one placed at the level of the anterior portion of dorsal fin, and another at anal fin level. Scales with base and free edge darker than the central area, producing a conspicuous reticulated pattern. Fins red to dark orange, suffused with dark melanophores at the base of dorsal and caudal fins, tip of anal fin and central portion of adipose fin (Fig. 2). Distribution Presently known only from rio Xingu, State of Pará. Ecological notes All specimens of A. passionis collected in rio Xingu were found in areas with moderate to strong current (up to 0.80 m*sec-1) and bottom substrate composed of sand, pebbles and scattered rocks of various sizes. Partially submerged boulders composed the main landscape at all collecting sites (Fig. 3). On one occasion two specimens were collected side-by-side in a gill net, which suggests that this species may form small groups, at least during the dry season. Local fishermen say that A. passionis may form groups of up to a hundred individuals during the early rainy season, when ripe females are commonly caught. During snorkeling sessions conducted in the dry season, one of us (JZ) observed a single large specimen of A. passionis swimming among dark recesses among submerged boulders, at a depth up to 2 m. The fish moved slowly among the rocks, foraging in feeding bouts of three to four bites directed to the ceilings of small caves under the boulders or at crevices among rocks. The biting produced a loud rasping sound, clearly audible underwater. Stomach contents of two specimens of A. passionis caught during the low water season were composed mainly of fragments of sponges. On another occasion, one fish was observed in a mixed group of several anostomid species (Leporinus tigrinus Borodin, L. julii Santos, Jégu & Lima, L. brunneus Myers, L. friderici (Bloch) and Leporellus vittatus (Valenciennes)). Other anostomid fishes observed occupying the large spaces under and among boulders were Leporinus megalepis Günther, Sartor respectus Myers & Carvalho, Pseudanos sp., Anostomus ternetzi Fernández-Yépez and Synaptolaemus cingulatus Myers & Fernández-Yépez. Smaller fishes, mainly individuals of the tetragonopterin Astyanax dnophos Lima & Zuanon, pike cichlids (Crenicichla spp.) and armored suckermouth catfishes (Loricariidae) also shared the rocky shelters in the rapids. Anostomoides passionis is locally known as “piau do sarão.” Piau is a common popular name for anostomids, and “ sarão ” is the vernacular name of a plant species of the family Mirtaceae, common in the seasonally flooded margins of small rocky islands in rio Xingu. According to the local fishermen, A. passionis feeds on the fruit of these plants during the early flooding season. Etymology From the Latin passio, meaning a feeling, in allusion to the round to heart-shaped dark blotches on the side of the fish, as well as the deep red color of its fins. Discussion The genus Anostomoides was proposed by Pellegrin (1908) based on the type species A. atrianalis, described from three specimens collected in 1887 by Chaffanjon in the río Orinoco, Venezuela. Later, Eigenmann (1912) described Schizodontopsis laticeps, based on four specimens collected in British Guiana (Crab Falls and Gluck Island), included subsequently in Anostomoides as A. laticeps. According to Pellegrin’s (1908), Anostomoides is an intermediate genus between Leporinus and Anostomus with a distinct dentition: the upper jaw bears compressed teeth, the median ones bicuspidate and the lateral ones somewhat tricuspid; lower jaw teeth also compressed with straight cutting edges, truncate, not denticulate, as in Leporinus. The teeth in Anostomus are aligned sideto-side, whereas in Leporinus the teeth are arranged in a “stair-like” pattern, with the second tooth placed slightly under the anterior one and so on. Anostomoides presents a “reversed” pattern of teeth arrangement, where each tooth partially covers the anterior one (Géry, 1961). Myers (1950) proposed a diagnostic key for the genera of Anostomidae but did not include the genus Anostomoides, arguing that the data supplied by Pellegrin did not present relevant information, despite concluding that the genus proposed by that author was distinct enough to be considered valid. Géry (1961) considered Myers’s (1950) work to be a useful contribution to the knowledge of the anostomids, rendering it one of the best-known fish taxa among South American characins at the time, although the omission of the genus Anostomoides in the identification key was pointed out as a problem. From this standpoint, and based on the three specimens analyzed by Pellegrin, Géry (1961) redescribed Anostomoides atrianalis Pellegrin, 1908, considering Anostomoides a valid genus after comparing it to Leporinus, Anostomus, Synaptolaemus, and Laemolyta. According to Mago Leccia (1970), A. atrianalis is one of the 27 anostomid species occurring in Venezuela and in the Orinoco basin. The species is considered rare both in collections and in nature. Anostomoides atrianalis is known only from río Orinoco, in Venezuela, while A. laticeps has been reported in British Guiana (Eigenmann, 1912) and various rivers of the Amazon basin such as the Tocantins (Santos et. al, 1984; Santos & Jégu, 1989), Uatumã (Santos & Jégu, 1996), Jamari (Santos, 1991), Xingu (Zuanon, 1999), Araguaia, Negro, Purus, and Tapajós (pers. obs.). These records indicate that A. laticeps is widespread in the main black- and clear-water tributaries of the Amazon River but does not occur - or is rare - in the white water rivers. Géry (1961, 1977) and Libert (1996/7) considered Anostomoides to be a sister group of Laemolyta, based on the large adult size (up to 350 mm), compressed body and slightly upturned mouth. Nevertheless, in contrast to species of Laemolyta, which possess delicate and multicuspidate premaxillary teeth and dentary teeth with a straight border, species of Anostomoides have strong incisiform teeth in both jaws with incipient cusps on only a few teeth. In some specimens these cusps are more evident, while in others they are almost imperceptible. In contrast to the other two species of Anostomoides, A. passionis possesses teeth with straight, smooth borders, without cusps; only occasionally do the intermediate premaxillary teeth show a small salience at the margin but without forming a true cusp. The absence of cusps in the upper jaw teeth seems to reveal similarities of A. passionis with species of the genus Leporinus. However, the slanted and slightly upturned mouth, the fringed lips and the high and compressed body constitute a set of characteristics placing the new species in the genus Anostomoides. Further phylogenetic studies may shed some light on the intrafamilial relationships of the anostomid genera and help to ascertain the proper positioning of the species of the genus Anostomoides.

A. atrianalis: MNHN 87798, 1 ex. and MNHN 87799, 1 ex., r��o Orinoco, Venezuela, 1887., Published as part of Geraldo Mendes dos Santos & Jansen Zuanon, 2006, Anostomoides passionis, a new fish species from rio Xingu, Brasil (Characiformes: Anostomidae)., pp. 59-68 in Zootaxa 1168 on page 60

We describe Anostomoides passionis, a new species of anostomid fish from rio Xingu. The species attains 306 mm SL and is distinguished from the other two congeneric species by the lateral line scale count (38–39, instead of 39–41 in A. atrianalis and 42–44 in A. laticeps) and by the color pattern: brownish-grey with two round to heart-shaped, dark blotches on the side (a larger one under the dorsal fin and another above the origin of the anal fin). Anostomoides passionis inhabits rocky stretches of the rio Xingu with moderate to high current. Stomach contents of two specimens of A. passionis caught during the low water season were composed mainly of fragments of sponges.

We studied a specialised assemblage of sand-dwelling fish species from a streamlet in central Amazonia. The five sanddwelling species comprised 15.2 % of the total number in the streamlet (33 species). Two of the sand-dwellers are daytime foragers, Characidium cf. pteroides (Crenuchidae) and Stauroglanis gouldingi (Trichomycteridae), whereas three ones are night-time foragers, Gymnorhamphichthys rondoni (Rhamphichthyidae), "Imparfinis" pristos and Mastiglanis asopos (Heptapteridae). With the exception of C. cf. pteroides, the remainder species bury in the sand during their resting period. All five species bear a cryptic, sand-colour pattern, and some are translucent, traits which we regard as advantageous both for evasion from predators and for approaching prey (for the daytime foragers). All five species are microphagous carnivores and their foraging tactics range from generalised sit-and-wait (C. cf. pteroides) to active searching for interstitial prey (G. rondoni). A unique "drift-trap" system made up by the extended barbels and filamentous first pectoral-fin rays is employed by M. asopos. We regard the small size and low number of vertebrae (which is functionally expressed by fast displacements in the sand) as additional features advantageous to explore the sand habitat, allowing diving quickly in the substrate to evade predators and to forage for small prey in sand interstices or plant debris. The relationship between morphological and behavioural characters suited to life in sandy substrates is examined under the perspective of the current phylogenies for each group of psammophilous fishes here studied. The mapping of these characters demonstrates that not all of them evolved specifically for strict psammophily. Instead, some of them may represent the final step of a transformation series or synapomorphies of higher hierarchical levels. Several characters linked to psammophily, such as small body, large eyes, and scarce pigmentation are probably paedomorphic traits. We consider that the little variable specific composition of fish sand-dwelling assemblages and the wide (although patchy) geographical distribution of their species in the Amazon are due to the widespread occurrence and low complexity of this specialised habitat. The pre-existence of benthic habits, small size, and the broad distribution of rivers with sandy beds, mainly in the Amazon and Orinoco basins, possibly played a determinant role in the origin and diversification of psammophilous assemblages among freshwater fishes in South America. Estudamos uma comunidade especializada de espécies de peixes psamófilos de um igarapé na Amazônia central. As cinco espécies psamófilas correspondem a 15.2 % do número total estimado de espécies do igarapé (33 espécies). Duas das espécies psamófilas são forrageadores diurnos, Characidium cf. pteroides (Crenuchidae) e Stauroglanis gouldingi (Trichomycteridae), ao passo que três são forrageadores noturnos, Gymnorhamphichthys rondoni (Rhamphichthyidae), "Imparfinis" pristos e Mastiglanis asopos (Heptapteridae). Com exceção de C. cf. pteroides, as demais espécies ficam enterradas na areia durante seus períodos de repouso. Todas as cinco espécies apresentam padrão de colorido críptico na areia e algumas são translúcidas, características consideradas vantajosas tanto para evasão de predadores como para aproximação às presas (no caso dos forrageadores diurnos). Todas as espécies são carnívoras micrófagas e suas táticas de forrageamento variam de tocaia e espreita (C. cf. pteroides) a procura ativa de presas intersticiais (G. rondoni). Uma tática peculiar de caça ("armadilha-de-deriva"), com uso de barbilhões estendidos e primeiros raios da nadadeira peitoral filamentosos, é empregada por M. asopos. Consideramos que o tamanho pequeno e o baixo número de vértebras (funcionalmente expresso por deslocamentos rápidos) são caracteres adicionais vantajosos para explorar o hábitat arenoso, permitindo o enterramento rápido na areia para evadir dos predadores ou capturar as pequenas presas nos interstícios arenosos ou restos vegetais. As relações entre os caracteres morfológicos e comportamentais adequados à vida em substrato arenoso são analisadas sob a perspectiva das filogenias de cada grupo de peixes psamófilos aqui estudados. O mapeamento destes caracteres demonstra que nem todos evoluíram especificamente para a psamofilia estrita. Ao contrário, alguns podem representar o estágio final de uma série de transformação ou sinapomorfias de níveis hierárquicos mais elevados. Vários caracteres relacionados à psamofilia, como corpo pequeno, olhos grandes, pigmentação escassa, são provavelmente atributos pedomórficos. Consideramos que a composição específica pouco variável das comunidades psamófilas e a distribuição geográfica ampla de suas espécies (embora pontual) são devidas à estabilidade e à baixa complexidade deste hábitat especializado. A pré-existência de hábitos bentônicos, pequeno tamanho e a ampla distribuição de rios com leitos arenosos, principalmente nas bacias dos rios Amazonas e Orenoco, possivelmente tiveram um papel preponderante na origem e diversificação das assembléias de peixes psamófilos na ictiofauna de água doce da América do Sul.

Parancistrus nudiventris, new species, is described and compared with the congener P. aurantiacus. The new species has only been recorded from rio Xingu and can be distinguished from P. aurantiacus by having a naked abdomen (plated in P. aurantiacus), the presence of bluish dots in living specimens or spotted in preserved specimens (uniformly dark or clear brown or mottled, never spotted in P. aurantiacus), larger interbranchial distance (39-56% in HL vs. 24.9-39.5% in P. aurantiacus), narrower interorbital distance (26.8-38% in HL vs. 38.5-43.1% in P. aurantiacus). Parancistrus nudiventris also has buccal teeth more conspicuous than in P. aurantiacus. Main skeletal differences include the presence of a strong condyle on the lateral ethmoid for articulation with the metapterygoid in P. nudiventris (not seen in P. aurantiacus); anguloarticular processes short in P. nudiventris (long in P. aurantiacus); opercle with odontodes, partly exposed in P. nudiventris (completely embedded in skin in P. aurantiacus). Parancistrus nudiventris, espécie nova, é descrita e comparada com P. aurantiacus. Esta nova espécie só foi registrada no rio Xingu e pode ser diferenciada de P. aurantiacus pela ausência de placas no abdome (abdome totalmente coberto em P. aurantiacus), pela presença de pontos azulados nos exemplares recém-coletados ou pontilhado claro nos exemplares preservados (em P. aurantiacus a coloração é uniformemente marrom escura ou clara, ou manchada, nunca pontilhada), distância interbranquial mais larga (39-56% no comprimento padrão vs. 24.9-39.5% em P. aurantiacus), distância interorbital mais estreita (26.8-38% no comprimento padrão vs. 38.5-43.1% em P. aurantiacus). Parancistrus nudiventris também apresenta dentes bucais mais conspícuos do que P. aurantiacus. As principais diferenças osteológicas incluem a presença de um forte côndilo no etmóide lateral para articulação com o metapterigóide em P. nudiventris (côndilo este não observado em P. aurantiacus); processos no ângulo-articular curtos em P. nudiventris (mais longos em P. aurantiacus); opérculo parcialmente exposto e com odontódios em P. nudiventris, mas completamente incluso na pele em P. aurantiacus.

Objective. - To assess the prevalence of stings by small spiny driftwood catfish (carataí) of the genus Centromochlus (Auchenipteridae) accidentally caught in buckets during bucket bathing by riverside people along the Brazilian Amazon and to determine the probability of catching specimens of these fish during random throws of a bucket into the river. Methods. - We interviewed 27 adult residents living at the confluence of the Negro and Solimões rivers in Brazil regarding whether or not they had ever been stung by driftwood catfish while bucket bathing. To assess the likelihood of catching catfish in bathing buckets, we randomly threw a typical plastic bucket used for bathing in 4 series of 10 throws into the river at dusk or night around a floating house. Results. - Seventeen of the 27 subjects (63%) reported being injured by driftwood catfish during bucket bathing. Three individuals (17.6%) had been injured 2 to 3 times, totaling 23 puncture accidents. All stings occurred at dusk or early night. In the 4 series of 10 bucket throws, we caught 3 driftwood catfish (in 1 series we did not catch any fish). Thus, the chance of catching a driftwood catfish in a single bucket throw at dusk was slightly less than 10%. Conclusions. - The prevalence of stings by driftwood catfish to people bucket bathing in this section of the Brazilian Amazon is high, partly because of the relatively high chances of catching these small catfish during random throws of a bathing bucket into the river.

Astyanax dnophos, new species, is described from the lower rio Xingu, Pará, Brazil. The new species is distinguished from its purported congeners by the presence of a broad longitudinal, midlateral dark stripe that extends from the snout to the caudal peduncle. Astyanax dnophos dwells on shadowed, rocky shelters on rapids, and it is apparently one of the few species of Characidae outside Serrasalminae reported to be rheophilic. Astyanax dnophos, nova espécie, é descrita do baixo rio Xingu, Pará, Brasil. A nova espécie pode ser distinguida de suas presumíveis congêneres pela presença de uma larga faixa longitudinal escura no meio do corpo que se estende do focinho ao pedúnculo caudal. Astyanax dnophos habita abrigos sombreados sob rochas nas corredeiras e aparentemente é uma das poucas espécies de Characidae, excetuando Serrasalminae, citada como sendo reofílica.

As enchentes anuais dos rios na Amazônia alagam extensas áreas de floresta conhecidas como várzeas ou igapós. Estas áreas têm papel importante na vida dos peixes da região, pois são fontes de alimento e de abrigo. Acreditamos que o desmatamento destas áreas ocasiona prejuízos à ictiofauna principalmente pela diminuição da quantidade e diversidade de alimento disponível. O estudo da relação entre a quantidade de floresta e a dieta de Parauchenipterus galeatus (Auchenipteridae, Siluriformes), Mylossoma duriventre (Characidae, Characiformes)e Triportheus elongatus (Characidae, Characiformes)permitiu registrar pela primeira vez a influência direta da floresta alagada na ecologia alimentar de peixes na Amazônia Central. The annual flooding of the rivers in the Amazonia extends over large forest areas known as várzeas or igapós. These areas play an important role in the life of the fishes, as a source of food and shelter. We believe that the deforestation of these areas may affect negatively the fish fauna mainly by decreasing the amount of food resources and consequently the diversity of food types available. The study of the relationship between the riparian forest cover and the diet of Parauchenipterus galeatus (Auchenipteridae, Siluriformes), Mylossoma duriventre (Characidae, Characiformes) and Triportheus elongatus (Characidae, Characiformes) allowed to refer for the first time on the direct influence of the flooded forest in the feeding ecology of fishes in Central Amazonia.

Records of cleaning symbiosis between freshwater fish are scarce. Here we report on juvenile catfish, Platydoras costatus, cleaning the piscivorous characin Hoplias cf. malabaricus in a stream of the rio Araguaia drainage in the Brazilian Amazon. The scarcity of records on cleaning behavior in freshwater systems seems to be in part a consequence of the few observational studies under natural conditions in the Neotropics. Otherwise, the rareness of this behavior in freshwaters is possibly related to the short evolutionary time available to the fish fauna to develop these complex interactions, when compared to the ocean environment. Registros de simbiose de limpeza entre peixes dulcícolas são raros. No presente trabalho registramos um juvenil de Platydoras costatus, limpando uma traíra, Hoplias cf. malabaricus em um riacho do rio Araguaia, Bacia Amazônica. A escassez de registros de comportamento de limpeza em peixes de água doce parece ser uma conseqüência dos poucos estudos subaquáticos nos Neotrópicos. Por outro lado, a raridade deste comportamento em ambientes dulcícolas está possivelmente relacionada ao curto tempo evolutivo disponível para o desenvolvimento de interações complexas, quando comparada ao ambiente marinho.

The effect of host plant inundation on survivorship of Symmeria paniculata's galling herbivores was investigated in Central Amazonian floodplain forest. The majority of submerged galls were alive (62% of morphospecies 1 and 70% of morphospecies 2). Survivorship was similar between submerged leaves and new leaves that were never submerged. Some submerged galls were eaten by fish. To the best of our knowledge, this is the first report of galling insect survivorship under severe flooding.

Monogamy is rare in fishes and is usually associated with elaborate parental care. When parental care is present in fishes, it is usually the male that is responsible, and it is believed that there is a relationship between the high energetic investment and the certainty of paternity (except in the case of sneaker males). Osteoglossum bicirrhosum is considered a monogamous fish, and has particular behavioral traits that permit the study of mating systems and parental care, such as male mouthbrooding. We investigated the genetic relationships of males with the broods found in their oral cavities in Osteoglossum samples collected in a natural environment in the lower Purus river basin, Amazonas, Brazil. Fourteen broods were analyzed for parentage (268 young and 14 adult males) using eight microsatellite loci. The results indicate that eleven broods show a monogamous system. In one brood, however, approximately 50% of the young were genetically compatible with being offspring of another male, and in another two broods, none of the subsampled young were compatible with the genotypes of the brooding male. The result of this first brood may be explained by the extra-parental contribution of a sneaker male, whereas cooperative parental care may explain the result in the other two broods. Monogamia é rara em peixes e está geralmente associada a cuidado parental elaborado. Quando cuidado parental está presente em peixes, usualmente o macho é responsável, e acredita-se que exista uma relação entre investimento energético elevado e a certeza da paternidade (exceto no caso de machos oportunistas). Osteoglossum bicirrhosum é considerado monogâmico e possui determinadas características comportamentais que permitem o estudo de sistemas de acasalamento e cuidado parental, como incubação bucal dos ovos e filhotes pelos machos. Quatorze ninhadas (268 filhotes e 14 machos adultos) foram coletadas em ambiente natural na bacia do baixo rio Purus, Amazonas, Brasil e analisadas para parentesco utilizando oito loci de microssatélites. Os resultados sugeriram, para onze ninhadas, um sistema de acasalamento monogâmico. Em uma ninhada, no entanto, cerca de 50% dos jovens eram geneticamente compatíveis como sendo descendentes de outro macho, e em outras duas ninhadas nenhum dos filhotes amostrados eram filhos dos machos que estavam realizando o cuidado. O resultado da primeira ninhada pode ser explicado pela contribuição extra-par de um macho oportunista, enquanto que o cuidado parental cooperativo pode explicar os resultados nas outras duas ninhadas.

We present karyotypic characteristics and report on the occurrence of ZZ/ZW sex chromosomes in Ancistrus ranunculus (rio Xingu) and Ancistrus sp. "Piagaçu" (rio Purus), of the Brazilian Amazon. Ancistrus ranunculus has a modal number of 2n=48 chromosomes, a fundamental number (FN) of 82 for both sexes, and the karyotypic formula was 20m+8sm+6st+14a for males and 19m+9sm+6st+14a for females. Ancistrus sp. "Piagaçu" presented 2n=52 chromosomes, FN= 78 for males and FN= 79 for females. The karyotypic formula was 16m+8sm+2st+26a for males and 16m+9sm+2st+25a for females. The high number of acrocentric chromosomes in karyotype of Ancistrus sp. "Piagaçu" differs from the majority of Ancistrini genera studied so far, and may have resulted from pericentric inversions and translocations. The lower number of chromosomes in A. ranunculus indicates that centric fusions also occurred in the evolution of Ancistrus karyotypes. We conclude that karyotypic characteristics and the presence of sex chromosomes can constitute important cytotaxonomic markers to identify cryptic species of Ancistrus. However, sex chromosomes apparently arose independently within the genus and thus do not constitute a reliable character to analyze phylogenetic relations among Ancistrus species. Nós apresentamos características cariotípicas e registramos a ocorrência de cromossomos sexuais ZZ/ZW em Ancistrus ranunculus (rio Xingu) e Ancistrus sp. "Piagaçu" (rio Purus), da Amazônia Brasileira. Ancistrus ranunculus teve um número modal de 2n=48 cromossomos, um número fundamental (NF) de 82 para ambos os sexos, e a fórmula cariotípica 20m+8sm+6st+14a para machos e 19m+9sm+6st+14a para fêmeas. Ancistrus sp. "Piagaçu" apresentou 2n=52 cromossomos, NF=78 para machos e NF= 79 para fêmeas. A fórmula cariotípica foi de 16m+8sm+2st+26a para machos e 16m+9sm+2st+25a para fêmeas. O alto número de cromossomos acrocêntricos no cariótipo de Ancistrus sp. "Piagaçu" difere da maioria dos gêneros de Ancistrini estudada até o momento, e pode ter resultado de inversões pericêntricas e translocações. O número mais baixo de cromossomos em A. ranunculus indica que fusões cêntricas também ocorreram na evolução dos cariótipos de Ancistrus. Nós concluímos que as características cariotípicas e a presença de cromossomos sexuais podem constituir marcadores citotaxonômicos importantes para identificar espécies crípticas de Ancistrus. Entretanto, cromossomos sexuais aparentemente surgiram de forma independente dentro do gênero e, deste modo, não constituem um caráter confiável para ser usado em análises de relações filogenéticas entre espécies de Ancistrus.

We present a synthesis of the first 10 years of Long Term Ecological Research project in Amazonian Forest. We elucidate the natural dynamics of forest ecosystem processes and associated biota, and its changes caused by distinct pressures of selective timber extraction and forest fragmentation. We found that, for both plants and animals, densities of individuals and distribution of species assemblages are spatially heterogeneous at the mesoscale, even in relatively undisturbed forests, and that associations with topo-edaphic variables allow prediction of a considerable part of this variation. For biological groups whose dynamics were studied in the short-term, levels of change in species composition and densities were relatively high, and these changes were generally in tune with spatial environmental variation. The impact of selective logging on assemblages and ecosystem processes was normally moderate, and around 19 years were needed for recovering forest biomass and tree size distribution. Continued studies are needed to determine the time required for recuperation of timber stocks and pre-logging floristic composition. Selective logging appears to be compatible with the biodiversity conservation, but reduction and better planning of road access may be more important than planned logging intensities. Habitat-loss' impact on organisms and ecosystem processes is large and long-lasting, since it induces the loss of many taxonomic groups and species, higher tree mortality and accelerated forest dynamics. There was a negative synergy between the impacts of habitat loss and climatic changes, and a better understanding of these processes can only be obtained through long-term research. © 2015 Associação Brasileira de Ciência Ecológica e Conservação.

Following behavior is a widespread feeding tactic among marine fishes, but remains poorly documented for freshwater fishes. The present study describes such association between two freshwater species: the minute armored catfish Parotocinclus maculicauda and the South American darter Characidium sp. During underwater observations in an Atlantic Forest stream, we recorded Characidium sp. closely following P. maculicauda (

Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network ( Rede Amazônia Sustentável , RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far.

Leporinus amazonicus, a new species of anostomid fish, is described from the central portion of the Amazon lowlands. It is a medium-sized fish (up to 250 mm SL) with streamlined body (maximum body height approximately 25% of SL) and high lateral line scale counts (45–47). Leporinus amazonicus is morphologically similar to the slender bodied species L. cylindriformis Borodin, 1929 and L. brunneus Myers, 1950, but differs from them by the higher lateral line scale count (41–43 in L. cylindriformis and 36–42 in L. brunneus) and by a different color pattern. Moreover, L. amazonicus is apparently restricted to the white waters of the Amazon lowlands whereas L. cylindriformis and L. brunneus are known only from clear and black waters of several of the Rio Amazonas tributaries. Despite intensive collecting efforts historically developed in Brazilian Central Amazon, just a few specimens of L. amazonicus were caught, indicating that the new species is relatively rare in that area and apparently do not join in large schools. However, this supposed rarity may be biased by the concentration of our collecting efforts around Manaus, which may represent a marginal distribution of this species. Nevertheless, the presence of a new species of a taxonomically well-known fish family in an area intensively exploited by commercial and subsistence fisheries evidences the need for fish species surveys in the Amazon, even in supposedly well sampled sites and around the most populous areas.

Macrophyte rafts can enhance fish dispersal in the Amazon River basin, and determining whether raft properties (e.g., size and plant species richness) can predict fish species richness and composition is important in order to understand the underlying factors of fish dispersal. We tested for a relationship between the plant species richness and fish species richness in the rafts and determined whether there exists a significant pattern of concordance between rafts composition and fish assemblages in a River–Lake system close to Manaus, Amazonas, Brazil. We estimated the cover of each species of macrophyte and collected fish in 20 macrophyte rafts of different sizes. Macrophyte species richness was not a good predictor of fish species richness. We found a significant correlation between the compositional similarities of macrophytes and fishes when the data for presence/absence were analyzed, but not when abundance data were used. However, the congruence patterns were clearly related to raft size, and we found a correlation between plants and fishes, using both presence/absence and abundance data, when only large rafts were used in the analysis. For small rafts, there were no significant correlations using any type of data. These findings show that the composition of fish assemblage dispersal in the rafts depends on the composition of macrophytes of which the rafts are composed and on stochastic processes of raft splitting.

Floating litter banks are an ephemeral habitat consisting of branches, twigs, flowers, seeds, and fruits that are trapped on the stream water surface by a variety of retention mechanisms. These heterogeneous materials form a deep layer of dead plant matter that is colonized by a variety of organisms, including fish that forage on the aquatic macroinvertebrates found in this unique habitat. In this study, we aimed to characterize which fish species occupy the floating litter banks and their trophic characteristics, as well as determine if fish assemblage composition and species richness can be predicted by the size of the floating litter banks. Fish sampling was conducted in five rivers located in the Amazon basin. Of the 31 floating litter banks sampled that contained fish, 455 individuals were recorded and were distributed within 40 species, 15 families and five orders. Siluriformes were the most representative order among the samples and contained the largest number of families and species. The fish fauna sampled was mainly composed of carnivorous species that are typically found in submerged litter banks of Amazonian streams. The fish assemblage composition in the kinon can be predicted by the volume of the floating litter banks using both presence/absence and abundance data, but not its species richness. In conclusion, kinon banks harbor a rich fish assemblage that utilizes this habitat for shelter and feeding, and may function as a refuge for the fishes during the peak of the flooding season. Bancos de folhiço flutuantes são habitats efêmeros constituídos de troncos e galhos de árvores, flores, sementes e frutos retidos por uma variedade de mecanismos. Estes materiais formam uma camada espessa de matéria vegetal morta, que é colonizada por diferentes organismos, incluindo peixes que se alimentam de macroinvertebrados aquáticos presentes neste habitat. Nosso objetivo foi caracterizar as espécies e características tróficas dos peixes que ocupam esses bancos de folhiço flutuantes, bem como determinar se a composição da assembleia de peixes e a riqueza de espécies podem ser previstas pelo tamanho dos bancos. A amostragem dos peixes foi realizada em cinco rios da bacia amazônica. Dos 31 bancos de folhiço flutuantes amostrados que continham peixes, foram registrados 455 indivíduos distribuídos em 40 espécies, 15 famílias e cinco ordens. Siluriformes foi a ordem mais representativa, com o maior número de espécies e famílias. A fauna de peixes coletados foi composta principalmente por espécies carnívoras, que geralmente são encontrados em bancos de folhiço submersos de igarapés amazônicos. A composição das assembleias de peixes do 'kinon' pode ser prevista pelo volume desses bancos de liteira flutuante, tanto utilizando dados de presença/ausência quanto de abundância, mas não de riqueza de espécies. Em conclusão, os bancos de folhiço flutuante abrigam uma rica assembleia de peixes, que utilizam esse habitat como local de abrigo e de alimentação, e podem funcionar como refúgio para a ictiofauna dos bancos de folhiço submerso durante a estação chuvosa.

Camouflage is one of the most widespread defence modes used by substrate-dwelling animals, whereas transparency is generally found in open-water organisms. Both these defence types are regarded as effective against visually guided predators. We present here three assemblages of similarly-sized freshwater fish and shrimp species which apparently rely on camouflage and transparency to evade some of their potential predators. In one of the associations, there is a transition from cryptic colours and translucency to transparency of the component species according to the position each of them occupies in the habitat. The likeness between the fishes and the shrimps is here regarded as a type of protective association similar to numerical or social mimicry. Additionally, we suggest that the assemblage may contain Batesian-like mimicry components. Camuflagem é um dos tipos de defesa mais bem distribuídos entre os animais que vivem no substrato, sendo a transparência geralmente encontrada em organismos pelágicos. Ambos os tipos de defesa são considerados como eficientes contra predadores visualmente orientados. Apresentamos três conjuntos de espécies de peixes e camarões de tamanhos similares, que aparentemente dependem da camuflagem e transparência para escapar de potenciais predadores. Em uma das associações, há uma transição de coloração críptica ou translúcida para transparente, de acordo com a posição que cada espécie ocupa no habitat. A semelhança entre peixes e camarões é aqui considerada como um tipo de associação protetiva, similar a mimetismo numérico ou social. Além disso, sugerimos que o conjunto pode conter elementos similares ao mimetismo Batesiano.