Rio Madeira Basin Research Articles

Satanoperca curupira, a new cichlid species from the rio Madeira basin in Brazil (Teleostei: Cichlidae).

Satanoperca curupira, new species, is described from the rio Madeira basin in the State of Rondônia, Brazil. It is distinguished from all congeners by the following combination of characters: 3-7 dark-brown oblique stripes on the lachrymal (vs. 2 well-defined dark-brown stripes, or dark-brown stripes absent) and an irregular pattern of dark-brown stripes on cheek and opercular series (vs. cheek without dark-brown markings or with light-beige rounded spots). According to meristic and color pattern characters, the new species is considered a member of the S. jurupari species group, and is syntopic with S. jurupari, which is widespread in the Amazon basin. The restricted geographical range of the new species is congruent to that observed for some other Satanoperca species.

Taxonomic Revision of the GenusAphyodite, with Description of Two New Species (Teleostei: Characidae)

The genus Aphyodite has a complex taxonomic history. It was described as monotypic, and the only diagnosis provided was “an Aphyocharax with a scaled caudal fin”. After the description, the genus was revised twice, but some morphological inconsistences remained, pending a proper morphological analysis. Currently, Aphyodite is a member of Aphyoditeinae and can be distinguished from all the other representatives of this subfamily by having the first infraorbital with a conspicuous sensory canal not reaching the anterior edge of the bone. During the revision of the genus, two new species were found: Aphyodite apiaka, new species, from the Rio Madeira basin, that can be diagnosed from its congeners by the length of the first infraorbital sensorial canal, which is longer than half length of bone; and Aphyodite tupebas, new species, from the Rio Solimões basin, that can be diagnosed from its congeners by the possession of only conical teeth in the premaxilla.

Hyphessobrycon petricolus, a new species of tetra (Characiformes: Characidae) from the rio Madeira basin, Mato Grosso, Brazil.

A new species of Hyphessobrycon is described from the rio Roosevelt, rio Madeira basin, Mato Grosso State, Brazil. Hyphessobrycon petricolus sp. n. can be distinguished from its congeners by the unique combination of the following features: a well-defined, relatively narrow dark midlateral stripe on body extending from immediately behind posterior margin of opercle to the middle caudal-fin rays, relatively conspicuous humeral blotch, and 16-20 branched anal-fin rays. Comments on the remaining Hyphessobrycon species presenting a conspicuous dark midlateral stripe are presented.

Taxonomic revision of Galeocharax (Characiformes: Characidae: Characinae)

ABSTRACT The taxonomy of Galeocharax, a genus of freshwater fishes distributed in most South American cis-Andean river systems, except the rio Negro, rio São Francisco and rio Xingu basins and the eastern drainages of Brazil, is herein revised. A total of 1229 specimens were examined from which 680 had meristic and morphometric data taken. Osteological and morphological features were also examined through radiographs, scanning electron microscopy and in cleared and stained specimens. Three of the four species previously considered as valid are herein recognized: Galeocharax humeralis from rio Paraguay and lower rio Paraná basins; Galeocharax goeldii, from rio Madeira basin, with records of geographical distribution expanded to the río Madre de Dios, río Beni, rio Mamoré and rio Guaporé basins and Galeocharax gulo, which is widespread throughout rio Amazonas, río Orinoco, rio Tocantins, and upper rio Paraná basins. Galeocharax knerii is herein considered a junior synonym of Galeocharax gulo. A key to species of Galeocharax is presented.

A new genus of Neotropical rheophilic catfishes, with four new species (Teleostei: Siluriformes: Pseudopimelodidae)

ABSTRACT Rhyacoglanis, a new genus of the South American freshwater catfish family Pseudopimelodidae is described from cis-Andean portions of the continent. Rhyacoglanis is distinguished from other genera of the family by three synapomorphies: presence of a light blotch on the cheek; a connection between the middle of the dark caudal-fin stripe and the dark caudal-peduncle pigmentation; and 30-35 total vertebrae. Species of Rhyacoglanis are rheophilic and strongly associated with rapids and other swift-flowing waters. A phylogenetic analysis based on 41 morphological characters yields a hypothesis of monophyly of the Pseudopimelodidae and Rhyacoglanis. Pimelodus pulcher Boulenger, 1887, from the western Amazon basin is designated as type-species of the new genus and redescribed. Four new species are described: Rhyacoglanis annulatus, from the río Orinoco basin, with a nearly ringed dark band on the caudal peduncle, and a larger distance between anus and anal-fin origin; R. epiblepsis, from the rio Madeira basin, with numerous dark spots scattered on the body, and rounded caudal-fin lobes; R. paranensis, from the upper rio Paraná basin, with three distinct dark bands on the body, and 31-33 total vertebrae; and R. seminiger, from the rio Juruena basin, with subdorsal and subadipose dark bands fused anteroposteriorly, and a separate dark band on the caudal peduncle.

Wrapped in flames: Corydoras hephaestus, a new remarkably colored species from the Rio Madeira basin (Teleostei: Callichthyidae).

A new species of Corydoras is described from the upper Rio Machado, Rio Madeira basin, Rondônia State, Brazil. The new species can be distinguished from its congeners by the absence of contact between the posterior process of the parieto-supraoccipital and the nuchal plate; a ventral laminar expansion of the infraorbital 1 conspicuously developed; and the posterior margin of the pectoral-fin spine with serrations along almost of its entire length, only lacking in the distal portion. Additionally, Corydoras hephaestus possesses dorsal and pectoral spines short, and exhibits an unusual color pattern in life. The conservation status of the new species and other endemic species are briefly commented.

A new species of Hyphessobrycon Durbin (Characiformes: Characidae) from rio Aripuanã, rio Madeira basin, Brazil.

A new species of Hyphessobrycon is described from the rio Aripuanã, rio Madeira basin, Amazonas State, Brazil. Hyphessobrycon procyon can be distinguished from its congeners by the unique combination of the following features: elongation of the dorsal fin in mature males, absence of dark blotches on the dorsal fin, and presence of two humeral blotches. The possibility of a relationship of the new species within H. elachys, H. heliacus, H. loweae, H. moniliger, and H. peugeoti is discussed based on the sharing of characteristics related to the sexual dimorphism and tooth morphology.

A new long-snouted species of Corydoras Lacépède, 1803 (Siluriformes: Callichthyidae) from the rio Madeira basin.

A new species of Corydoras is described from the rio Aripuanã, rio Madeira basin, Mato Grosso State, Brazil. The new species can be distinguished from its congeners by the presence of the following features: long mesethmoid, with anterior tip well developed, conspicuously larger than 50% of bone length; posterior margin of dorsal-fin spine with serrations directed towards tip of spine; one to two longitudinal black stripes on flanks; absence of a black blotch across the eyes (mask); absence of a large black blotch on dorsal fin; and transversal black bars on caudal fin. Comments on endemism in interfluvial region between Madeira and Tapajós rivers are briefly discussed.

A new large species of Myloplus (Characiformes, Serrasalmidae) from the Rio Madeira basin, Brazil.

Myloplus zorroi sp. n. is described from the Rio Madeira Basin in Amazonia. The new species had been treated as an undescribed Tometes species because of the absence of a marked abdominal keel and few small spines forming its prepelvic serrae, features commonly found in the species of the Myleus clade of the Serrasalmidae (species of genera Myleus, Mylesinus, Ossubtus and Tometes) and also in species of Utiaritichthys. Myloplus zorroi sp. n. shares the following characters with its congeners and Utiaritichthys: molariform teeth (versus incisiform teeth in Myleus clade members); a labial row of premaxillary teeth separated from lingual row by an internal gap (versus absence of internal gap between premaxillary teeth rows); and an ascending process of premaxilla wide from its base to the tip (versus ascending process tapering from its base to the tip). Like other Myloplus species, Myloplus zorroi sp. n. differs from Utiariticthys by having a deeper body, approximately 60% of standard length (versus usually less than 50% of standard length). Considering all the morphological evidence, including the presence of 13–19 low spines forming the prepelvic serrae in Myloplus zorroi sp. n. versus more than 20 high spines forming a marked prepelvic keel in other species of Mylopus, the new species is here assigned to Myloplus. Comparisons of the new species with nominal species of Myloplus, representatives of the Myleus clade, and other related taxa are provided.

Two new species of Corydoras Lacépède, 1803 (Siluriformes: Callichthyidae) from the rio Madeira basin, Brazil

Abstract Two new species of Corydoras are described from the rio Madeira basin, Brazil. The intermediate long-snouted new species can be distinguished from its congeners by presenting the following combination of features: posterior margin of dorsal-fin spine with laminar serrations directed towards the origin of the spine; presence of two longitudinal black stripes on flanks; anterior portion of dorsal fin with sparse black chromatophores, not forming any conspicuous pattern; absence of a conspicuous black marbled coloration pattern on head; black spots on caudal fin, some spots arranged, forming transversal bars; and brownish dorsal-fin spine. The short-snouted new speciescan be distinguished from its congeners by the following combination of features: short mesethmoid; posterior laminar expansion of infraorbital 2 very reduced, not in contact with compound pterotic; two or three longitudinal black stripes on flanks; absence of an oblique or vertical black blotch across the eye; anterior portion of dorsal fin with sparse black chromatophores, not forming any conspicuous pattern; and ventral surface of trunk naked or covered by sparse platelets.

A new species of Moenkhausia Eigenmann (Characiformes: Characidae) from the upper rio Machado at Chapada dos Parecis, rio Madeira basin, Brazil

ABSTRACT A new species of Moenkhausia is described from the upper rio Machado at Chapada dos Parecis, rio Madeira basin, Rondônia State, Brazil. Among congeners, the new species is similar to Moenkhausia chlorophthalma, M. cotinho , M. lineomaculata , M. plumbea, and M. petymbuaba by having dark blotches on the anterior portion of the body scales, which are absent in the remaining species of the genus. The new speciesdiffers from aforementioned species by possessing blue eyes in life, 15-18 branched anal-fin rays, and a well-defined, round caudal-peduncle spot that does not reach the upper and lower margins of the caudal peduncle and does not extend to the tip of the middle caudal-fin rays.

A new Silver Dollar species of Metynnis Cope, 1878 (Characiformes: Serrasalmidae) from Northwestern Brazil and Southern Venezuela

ABSTRACT A new Metynnis is described from the rio Negro in Brazil and Venezuela, and from black- or clearwater tributaries in Brazil including the rios Parauari, Uatumã, Trombetas, and Sucunduri (the latter belonging to the rio Madeira basin). The new species can be distinguished readily from all congeners by having a high concentration of dark chromatophores on the lateral line scales. It can be further distinguished by the combination of head length 24.3-27.5% of SL, 13-18 gill-rakers on upper limb and 16-24 gill-rakers on lower limb. The new species is most similar to and likely most closely related to Metynnis hypsauchen . These two species share a similar color pattern, body shape and sexual dimorphism of the anal fin. However, they differ in that M. hypsauchen has a lightly pigmented lateral line. The new species is also distinguished from M. hypsauchen by having 56-65 predorsal scales and 90-104 lateral line scales (vs . 36-54, and 65-82, respectively). A detailed osteological description of the new species is provided.

A new species of Characidium Reinhardt (Ostariophysi: Characiformes: Crenuchidae) from headwaters of Rio Pacaás Novos, Rio Madeira basin, Rondônia, Brazil.

Characidium summus, new species, is described from rio Pacaás Novos, rio Madeira basin, Rondônia, Brazil. The new species is the unique among congeners for completely lacking an adipose fin and having a complete lateral line. Characidium summus can be further distinguished from congeners, including C. vestigipinne that also has a complete lateral line and adipose fin absent, vestigial or reduced by the absence of dark bars or spots on head, body or fins, except for a dark blotch on the rear of the opercle, a narrow midlateral dark stripe, and a dark basicaudal spot. In addition, C. summus possess a vestigial supraorbital and a remarkably small pseutotympanum. The possible mimetic relationship between the new species with Erythrinus erythrinus is discussed.

Description of three new species of Moenkhausia (Teleostei, Characiformes, Characidae) with the definition of the Moenkhausia jamesi species complex.

From the examination of extensive comparative material currently identified as M. jamesi we verified that there are, at least, three new species under this name. These, along with M. jamesi and M. justae, form what we herein called the M. jamesi species complex, by sharing the following group of characters: a short maxilla, with its distal margin not exceeding anterior third of the second infraorbital; first through third teeth of the inner row of premaxilla and first and second dentary teeth with cusps arranged in a pronounced arch, humeral spot positioned between the fourth and seventh scales of the lateral line and extending up to four scale rows above the lateral line and one scale row below the lateral line, and a vertically oval to round spot at the base of the caudal fin rays. Moenkhausia ischyognatha sp. n., from Rio Xingu basin, differs from the other species of the complex by its lower head depth. Moenkhausia alesis sp. n., from the river system Tocantins-Araguaia, differs from M. jamesi, M. ischyognatha, and M. sthenosthoma by the number of scale rows above the lateral line. Moenkhausia sthenosthoma sp. n., from the Rio Madeira basin, differs from M. jamesi by the number of scale rows between the lateral line and the midventral scale series. Moenkhausia justae can be diagnosed from the other species of the complex by having a tri to pentacuspidate tooth on the maxilla.

Hyphessobrycon lucenorum (Characiformes: Characidae), a new species from the rio Madeira basin, Rondônia State, Brazil.

A new species of characid is described from the upper rio Machado, a tributary of the rio Madeira basin, Rondônia, Brazil. Hyphessobrycon lucenorum can be distinguished from all congeners by the unique combination of the presence of a conspicuous rounded humeral blotch and a broad and diffuse longitudinal stripe. The new species is included within the Hyphessobrycon agulha group. The high number of endemic species of fishes occurring in the headwater tributaries of three river systems (rio Madeira, rio Tapajós, and rio Paraguai) draining the watershed defined by the Chapada dos Parecis is discussed.

Mercury Transfer During Pregnancy and Breastfeeding: Hair Mercury Concentrations as Biomarker

Hair mercury (HHg) concentration is a biomarker of exposure that is widely used to assess environmental contamination by fish methylmercury and neurodevelopment in children. In the Rio Madeira basin (Brazilian Amazon), total HHg concentrations in 649 mother-infant pairs were measured at birth (prenatal exposure) and after 6 months of exclusive breastfeeding; these mother-infant pairs were from high fish-eating communities (urban, n = 232; rural, n = 35; and Riverine, n = 262) and low fish-eating tin-miner settlers (n = 120). Differences in kinetics were seen between Hg exposure from fish consumption and environmental exposure to a tin-ore mining environment. Overall maternal HHg concentrations (at childbirth and after 6 months of lactation) were higher than those of infant HHg. However, the relative change in HHg after 6 months of lactation showed that mothers decreased HHg while infants increased HHg. The relative change showed a consistently higher increase for girls than boys with a statistical significance only in high fish-eating mothers. The correlation coefficients between maternal and newborn hair were high and statistically significant for mothers living in urban (r = 0.66, p < 0.001), rural (r = 0.89, p < 0.001), and Riverine (r = 0.89, p < 0.001) communities not for tin miner settlers (r = 0.07, p = 0.427). After 6 months of exclusive breastfeeding, correlation coefficients showed high correlation coefficients and statistical significance for all groups (urban, r = 0.73, p < 0.001; rural, r = 0.88, p < 0.001; Riverine, r = 0.91, p < 0.001) except for Tin miners (r = -0.07, p = 0.428). A linear model analysis was used to assess the longitudinal associations of maternal total HHg and total HHg at birth (0 days) and 6 months of age in exclusively breastfed infants. Regression analysis significantly predicted HHg in newborn from maternal HHg for high fish-eating maternal-infant pairs. The concentration of mercury accumulated in newborn tissues (in utero and during breastfeeding) relevant to both, maternal sources and infant exposure, can be reliably assessed from maternal hair.

Redescription of Astyanax guaporensis Eigenmann, 1911 (Characiformes: Characidae), a small characid from the rio Madeira basin.

During recent expeditions to several localities in the rio Madeira basin, a poorly known species of Characidae described more than a century ago, Astyanax guaporensis Eigenmann, was collected. The species is herein redescribed based on the type material and many recently collected specimens. The species seems to occur only in the rio Madeira basin, rio Amazonas drainage. The species is mainly recognized among its congeners by having five to nine maxillary teeth, a series of V-shaped marks on the midlateral line of body, and the absence of a black mark on the caudal peduncle.

Engraulisoma taeniatum Castro, 1981 (Characiformes: Characidae): range extension with new records in the rio Madeira basin, Rondônia and Amazonas states, Brazil

Engraulisoma taeniatum is a rare fish recorded in few collections around the world. In Brazil E. taeniatum was only known from the rio Paraguay drainage according to the available scientific literature. Herein the geographic range of the species in the Brazilian territory is extended to tributaries of the rio Madeira basin in the States of Rondônia and Amazonas.

Crenicichla chicha, a new species of pike cichlid (Teleostei: Cichlidae) from the rio Papagaio, upper rio Tapajós basin, Mato Grosso, Brazil

Crenicichla chicha, new species, occurs in clear, fast-running waters with rocky substrates in the rio Papagaio and tributaries. It is distinguished from all other Crenicichla species by the combination of two character states: infraorbitals 3 and 4 co-ossified (vs. separated) and 66-75 scales in the row immediately above to that containing the lower lateral line (E1 row scales). Crenicichla chicha shares a smooth preopercular margin, co-ossification of infraorbitals 3 and 4, and some color features with C. hemera from the adjacent rio Aripuanã drainage, rio Madeira basin. It differs from Crenicichla hemera in more E1 scales (66-75 vs. 58-65) and presence of a conspicuous black narrow stripe running from infraorbital 3 obliquely caudoventrad toward the preopercular margin vs. a rounded and faint suborbital marking present on infraorbitals 3-4. Examination of the type series and additional material from the rio Aripuanã confirms that Crenicichla guentheri Ploeg, 1991 is a junior subjective synonym of C. hemera Kullander, 1990.

Southern extension of the geographical range of the pygmy marmoset &lt;i&gt;Cebuella pygmaea niveiventris&lt;/i&gt; (Lönnberg, 1940) in the southwestern Amazon basin, state of Rondônia, Brazil

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