Navegando por Assunto "Rio Trombetas (Bacia do Amazonas)"

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Acesso aberto (Open Access)
Revisão taxonômica de Gymnorhamphichthys (Gymnotiformes, Rhamphichthyidae) com descrição de duas novas espécies
(Universidade Federal do Pará, 2010) RAMOS, Cristiane do Socorro; WOSIACKI, Wolmar Benjamin; http://lattes.cnpq.br/0040413891328104
A taxonomic revision of the genus Gymnorhamphichthys is presented, a diagnosis for the genus is modified and expanded, five nominal species are recognized, and two new species are described: Gymnorhamphichthys sp. n. 1, from rivers of Paraguay basin, is diagnosed by thin bars on the dorsal region of its body, bars long slender reaching or exceeding below the lateral line, number of bars 6-19, and by the low number of anal rays (141-177), among other characters; Gymnorhamphichthys sp. n. 2, from Amazon basin, is diagnosed by the presence of a dark mask on the head, wide rectangular-shaped bars, and by the high number of anal rays (185-260), among other characters. A dichotomous key to species is provided.
Acesso aberto (Open Access)
Revisão taxonômica de Tometes Valenciennes, 1850 (Characiformes: Serrasalmidae) das drenagens do Escudo das Guianas
(Universidade Federal do Pará, 2013-02-21) ANDRADE, Marcelo Costa; JÉGU, Michel Louis Arthur Marie Ange François; http://lattes.cnpq.br/1270768412397418; GIARRIZZO, Tommaso; http://lattes.cnpq.br/5889416127858884
The genus Tometes Valenciennes, 1850 was originally described for the typespecies T. trilobatus, by presenting incisiform and bi- tricuspid teeth. However, the genus was synonymized with Myleus Müller and Troschell, 1844 for approximately a century and a half until being revalidated with an addition of two new species descriptions, T. lebaili and T. makue. This study presents a taxonomic review of Tometes from Guyana Shield where the three nominal species are recognized as valid and here were re-described, also a new species from Trombetas basin was described, increasing the diversity and distribution of genus. Among the main characteristics of diagnosis were observed: T. trilobatus is distinguishes from its congeners by having dentary and premaxillary teeth with the central cusp with rounded edge (vs. teeth with the central cusp or principal cusp with sharp edge). T. lebaili differs from others Tometes by having mouth oblique dorsally directed (vs. terminal mouth). T. makue is different by having a few spines on the serrae prepelvic, always between 0 and 9 spines (vs. over 9 spines). Already the new species is distinguished by the neurocranium with a slight concavity at the level of the epiphyseal bar, and also by having scales of irregular size (vs. dorsal profile of the neurocranium without a slight concavity, and scales of regular size). All species of Tometes are strictly rheophilic, and occur exclusively in the rapids of shield rivers, complex and fragile biotopes that are threatened by anthropogenic activities. The conclusions reached by this study highlight the urgent challenge to understand more fully existing species/habitat relationships.
Acesso aberto (Open Access)
Tometes camunani (Characiformes: Serrasalmidae), a new species of phytophagous fish from the Guiana Shield, rio Trombetas basin, Brazil
(2013-06) ANDRADE, Marcelo Costa; GIARRIZZO, Tommaso; JÉGU, Michel Louis Arthur Marie Ange François
A new species of Serrasalmidae, Tometes camunani, is described from the upper drainages of the rio Trombetas basin, Pará State, Brazil. The new species is distinguished from its congeners by having neurocranium with a slight concavity at the level of the frontal bone (vs. concavity absent, dorsal profile of neurocranium straight). It can be further distinguished from its congeners by having teeth with central cusp taller and acute (vs. central cusp shorter and with rounded edge in T. trilobatus), a terminal mouth (vs. upturned mouth in T. lebaili), and 12-26 prepelvic spines (vs. 0-9 in T. makue). The new species is strictly rheophilic like other species of Tometes, and occurs exclusively in the rapids of shield rivers, complex and fragile biotopes that are threatened by anthropogenic activities. An identification key to the species of the Myleus group is provided.