Tometes camunani (Characiformes: Serrasalmidae), a new species of phytophagous fish from the Guiana Shield, rio Trombetas basin, Brazil

Abstract

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. Uma espécie nova de Serrasalmidae, Tometes camunani, é descrita para as drenagens superiores da bacia do rio Trombetas, estado do Pará, Brasil. A espécie nova distingue-se dos congêneres pela presença de uma ligeira concavidade no neurocrânio na altura do frontal (vs. concavidade ausente, perfil dorsal do neurocrânio reto). Também pode ser adicionalmente distinguido dos seus congêneres por possuir dentes com a cúspide central mais alta e cume agudo (vs. cúspide central mais baixa e com cume arredondado em T. trilobatus), a boca terminal (vs. boca orientada para cima em T. lebaili), e 12-26 espinhos pré-pélvicos (vs. 0-9 em T. makue). A espécie nova é estritamente reofílica, como as demais espécies de Tometes, e ocorre exclusivamente nas zonas encachoeiradas dos rios de escudo, biótopos complexos, frágeis e ameaçados por ações antropogênicas. Uma chave de identificação para as espécies do grupo Myleus é apresentada.

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

“…Tometes spp.) may even develop irregularly-shaped red spots over flanks and anal fin (Andrade et al, 2013). Serrasalmus Lacépède 1803 is the most species-rich genus of Serrasalmidae , but no references to sexual dichromatism in Serrasalmus spp.…”

Length-weight relationships and condition factor of the eaglebeak pacu Ossubtus xinguense Jégu, 1992 (Characiformes, Serrasalmidae), an endangered species from Rio Xingu rapids, northern Brazil

“…The data were grouped into size class according to Jégu (1992), classified as 'juveniles' when less than 10 cm SL, and as 'adults' when greater than 10 cm SL. The adults were further grouped according to sexual dimorphism evidenced by family (Andrade et al, 2013), where the specimens were classified as 'female' when having the anal-fin falcate and as 'male' when having a 2nd lobe on the anal fin.…”

Tometes kranponhah and Tometes ancylorhynchus (Characiformes: Serrasalmidae), two new phytophagous serrasalmids, and the first Tometes species described from the Brazilian Shield

“…Neotropical Serrasalmidae are generally easily recognized by their compressed, disc‐shaped bodies, dorsal fin preceded by a strong predorsal spine and midventral keel formed by a series of abdominal spines (Géry, , ). Individuals in the Myleus clade, an unusual group of serrasalmids, do not, however, possess a marked midventral keel in the prepelvic area, because these spines are poorly developed or even absent (Andrade et al ., ). Other diagnostic morphological features of this group are the presence of incisiform teeth and no internal gap separating the two rows of premaxillary teeth (Jégu, ).…”