Fernando C. P. Dagosta

A new species of Hyphessobrycon Durbin (Characiformes: Characidae) from the middle rio São Francisco and upper and middle rio Tocantins basins, Brazil, with comments on its biogeographic history

A new species of Hyphessobrycon Durbin is described from tributaries of the rio Grande (rio Sao Francisco basin) draining east to the Serra Geral de Goias, of the rio Sao Domingos (upper rio Tocantins basin) and rio do Sono basins (middle rio Tocantins basin). Hyphessobrycondiastatos can be diagnosed from its congeners by the absence of humeral spot, 15-18 branched anal-fin rays, 1-3 maxillary conical to tricuspid teeth, a relatively well-defined dark caudal-peduncle spot, and elongation of dorsal- and anal-fin rays in mature males. The biogeographical significance of the distribution of the new species is evaluated and discussed.

A New Species of Hyphessobrycon (Characiformes: Characidae) from the Upper Rio Juruena Basin, Central Brazil, with a Redescription of H. cyanotaenia

A new species of Hyphessobrycon is described from the Rio Papagaio, a tributary of the Rio Juruena, Rio Tapajós basin, Brazil. The new taxon can be distinguished from its congeners by having a well-defined and relatively narrow dark midlateral stripe on body extending from the upper half of the posterior margin of the eye to the middle caudal-fin rays, absence of a humeral blotch, 16–19 branched anal-fin rays, 2–4 maxillary teeth, six branched pelvic-fin rays, and the absence of dark pigmentation crossing the eye. Hyphessobrycon cyanotaenia, a species described from few specimens from the aquarium trade without precise locality, is redescribed herein based on extensive material, and its known distribution is discussed and rectified from the original description.

Biogeography of Amazonian fishes: deconstructing river basins as biogeographic units

Biogeography of Amazonian fishes (2,500 species in vastly disjunct lineages) is complex and has so far been approached only partially. Here, we tackle the problem on the basis of the largest database yet on geographical distribution and phylogenetic relationships of Amazonian fishes, including all information available. Distributions of 4,095 species (both Amazonian and outgroups) and 84 phylogenetic hypotheses (comprising 549 phylogenetically-informative nodes) were compiled, qualified and plotted onto 46 areas (29 Amazonian and 17 non-Amazonian). The database was analyzed with PAE, CADE, BPA and BPA0, yielding largely congruent results and indicating that biogeographic signal is detectable on multiple dimensions of fish distribution, from single species ranges to cladistic congruence. Agreement is especially pronounced in deeper components, such as Trans-Andean, Cis-Andean, Western Amazon and Orinoco basins. Results show that all major Amazonian tributaries, as well as the Amazon basin itself, are non-monophyletic and constitute hybrid sets of heterogeneous biotic partitions. Amazonian drainages should not be assumed a priori as historically cohesive areas, contrary to widespread practice. Our hypothesis allows reevaluation of broader issues in historical biogeography, such as the predictive power of biogeographic hypotheses, the vicariant/ dispersal duality, the significance of widely distributed taxa, and the need for temporal dimension in biogeographic patterns.

Hemigrammus ataktos: a new species from the rio Tocantins basin, central Brazil (Characiformes: Characidae)

A new species of Hemigrammus is described from the middle rio Tocantins basin, central Brazil. The new species can be distinguished from all congeners by having a black midlateral stripe on the body extending from the posterior margin of the eye to the median caudal-fin rays. Mature males possess dorsal-, pelvic-, and anal-fin rays elongate, features that also help to recognize the new species. Although the new species is described in Hemigrammus, some specimens present a complete series of pored scales in the lateral line. A discussion about the generic allocation of the new species is presented.

A new species of Moenkhausia Eigenmann (Characiformes: Characidae) from the rio Arinos basin, Brazil

A new species of Moenkhausia from the upper rio Xingu basin is described. Moenkhausia eurystaenia is distinguished from all congeners, except M. heikoi and M. phaeonota, by the presence of a dark, broad longitudinal stripe from the opercle to the end of caudal peduncle. The new species is distinguished from M. heikoi mainly by having 18-21 branched anal-fin rays (vs. 24-26) and the absence of a round blotch at the end of the caudal peduncle (vs. present). Moenkhausia eurystaenia can be distinguished from M. phaeonota mainly by the anterior portion of longitudinal band darker at horizontal septum (vs. darker below horizontal septum), the deep dark pigmentation along horizontal septum extending anteriorly up to humeral region (vs. extending up to vertical through pelvic-fin origin), number of vertebrae 34 (vs. 36-37), and others additional measurements.

A name for the ‘blueberry tetra’, an aquarium trade popular species of Hyphessobrycon Durbin (Characiformes, Characidae), with comments on fish species descriptions lacking accurate type locality

A new species of Hyphessobrycon is described from a tributary of the upper Rio Tapajós, Amazon basin, Mato Grosso, Brazil. Its exuberant colour in life, with blue to purple body and red fins, is appreciated in the aquarium trade. Characters to diagnose the new species from all congeners are the presence of a single humeral blotch, absence of a distinct caudal-peduncle blotch, absence of a well-defined dark mid-lateral stripe on body, the presence of 16-18 branched anal-fin rays, nine branched dorsal-fin rays and six branched pelvic-fin rays. A brief comment on fish species descriptions solely based on aquarium material and its consequence for conservation policies is provided.

Moenkhausia rubra, a new species from rio Juruena, upper rio Tapajós basin, Brazil (Characiformes: Characidae)

Moenkhausia rubra, new species, is described from the upper rio Juruena, rio Tapajos basin, Mato Grosso, Brazil. The new species is distinguished from its congeners, except M. hemigrammoidesand M. nigromarginata, by the dark pigmentation on the anteriormost rays of both dorsal and anal fins. Moenkhausia rubrais distinguished from the aforementioned species by the number of branched anal-fin rays 17-20 (vs. 20-25), presence of a dark blotch on the caudal peduncle extending to middle caudal-fin rays, absence of longitudinal black zigzag stripes between longitudinal rows of scales on body, and other details of coloration.

A new species of Moenkhausia Eigenmann (Characiformes: Characidae) from the upper rio Juruena basin, Central Brazil

Moenkhausia lineomaculata, new species, is described herein from the upper rio Juruena, upper rio Tapajós basin. The new species seems to be part of a monophyletic group formed by M. cosmops, M. cotinho, M. diktyota, M. forestii, M. oligolepis, M. sanctaefilomenae, and M. pyrophthalma, the Moenkhausia oligolepis/M. sanctaefilomenae complex, by sharing a reticulated color pattern on body and the presence of a light area preceding a wide, dark caudal-peduncle blotch. The new species is distinguished from these species, except M. cotinho, by the presence of longitudinal series of dark dots on body, and from M. cotinho by the humeral blotch evenly pigmented along its length and by having the dark line along horizontal septum starting approximately at the vertical through dorsal-fin origin. The new species presents intraspecific variation in lateral-line scales perforation, a feature often present in species of the aforementioned group.

New species of Creagrutus Günther (Characiformes: Characidae) from rio Tapajós basin, Brazil, with comments on its phylogenetic position

Creagrutus nigrotaeniatus n. sp. is described from the rio Juruena basin, upper rio Tapajós system, Mato Grosso State, Brazil. Creagrutus nigrotaeniatus differs from its congeners by having the dentigerous surface of the premaxilla longitudinally elongate from ventral view, 4-5 post-anal scales and 2-4 maxillary teeth. The new species also has the anterior margin of hyomandibula straight or slightly concave which is a unique condition within the genus, and possesses a series of non-exclusive osteological modifications (e.g. medial opening of the dentary foramen located distinctly anteroventral to the tip of Meckels cartilage; anterior portion of the laterosensory canal segment in first infraorbital terminating distinctly posterior to the anterior margin of this bone; presence of the third posttemporal fossa within the epioccipital; one epural present). A comparison with Caiapobrycon tucurui is provided and the placement of the new species within Creagrutus and its close relationship with C. cracentis, C. gephyrus, and C. maxillaris are discussed.

A new sexually dichromatic miniature Hyphessobrycon (Teleostei: Characiformes: Characidae) from the Rio Formiga, upper Rio Juruena basin, Mato Grosso, Brazil, with a review of sexual dichromatism in Characiformes

Hyphessobrycon myrmex sp. nov., is described from the Rio Formiga, upper Rio Juruena, upper Rio Tapajós basin, Mato Grosso, Brazil. The new species can be distinguished from congeners by having the lower half of the body deeply pigmented with dark chromatophores, chromatophores concentrated above the anal fin and forming a broad, diffuse, dark midlateral stripe and by having a dense concentration of dark chromatophores along unbranched dorsal-fin rays and distal portions of the two or three subsequent branched rays. In life, H. myrmex exhibits a conspicuous sexual dichromatism, with adult males red to orange and females and immatures pale yellow. A list containing 108 sexually dichromatic taxa in six families of Characiformes is provided and the distribution of this poorly known type of dimorphism across the Characiformes is discussed.