Search

To date, the taxonomic status and phylogenetic affinities within Hyphessobrycon , even among other genera in Characidae, remain unclear. Here, we determined five new mitochondrial genomes (mitogenomes) of Hyphessobrycon species ( H. elachys , H. flammeus , H. pulchripinnis , H. roseus , and H. sweglesi ). The mitogenomes were all classical circular structures, with lengths ranging from 16,008 to 17,224 bp. The type of constitutive genes and direction of the coding strand that appeared in the mitogenomes were identical to those of other species in Characidae. The highest value of the Ka/Ks ratio within 13 protein-coding genes (PCGs) was found in ND2 with 0.83, suggesting that they were subject to purifying selection in the Hyphessobrycon genus. Comparison of the control region sequences among seven Hyphessobrycon fish revealed that repeat units differ in length and copy number across different species, which led to sharp differences in mitogenome sizes. Phylogenetic trees based on the 13 PCGs did not support taxonomic relationships, as the Hyphessobrycon fish mixed with those from other genera. These data were combined to explore higher level relationships within Characidae and could aid in the understanding of the evolution of this group., Competing Interests: All the authors declared no potential interest., (© 2021 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)

A new species of Hyphessobrycon is described from a marshland area in the headwaters of Rio Jequitinhonha basin, Minas Gerais, Brazil. The new species differs from congeners by presenting a single well-delimited conspicuous humeral blotch, rounded to vertically oval, restricted to the area dorsal to the lateral-line row of scales, without a narrower downward extension, greatest body depth anterior to dorsal-fin origin, bony processes in anal and pectoral-fin rays of males and four teeth in the inner row of the premaxillary bone. The new species presents a set of morphological features shared by some species currently assigned to Hasemania, Myxiops and to the Astyanax scabripinnis complex. Some of these features are discussed., (© 2019 The Fisheries Society of the British Isles.)

This study assessed the width of the trophic niche of four characid species (Bryconops giacopinii, Bryconops inpai, Hyphessobrycon aff. melazonatus and Iguanodectes geisleri) found under different co-occurrence circumstances in Amazonian upland streams. The study was conducted during the rainy season of 2011 at eight sites of two micro-basins of the Ducke Reserve, Manaus, Amazonas, Brazil. The four species were studied in the following circumstances: only one of the species occurring in the stream; two species co-occurring; three species co-occurring. The relative volume of the food items in the fish stomachs was used to calculate Hurlbert's trophic-niche breadth for the individuals of each species in the different co-occurrence circumstances. Hyphessobrycon aff. melazonatus changed their diet when occurring in syntopy with other characid species of similar feeding habits, as shown by a significant narrowing of its trophic niche. The opportunistic habits and great feeding flexibility of these characid species make the partitioning of food resources possible and act as an important ecological mechanism that facilitates the coexistence of different species, possibly by attenuating the effects of direct competition for food. In addition, the low carrying capacity of these upland forest streams may be an important environmental factor influencing the results of this study., (© 2016 The Fisheries Society of the British Isles.)