Hyphessobrycon bifasciatus, Ellis, 1911

‘ HYPHESSOBRYCON’ BIFASCIATUS View in CoL CLADE

Composition: Thiscladeiscomposedof‘ Hyphessobrycon ’ bifasciatus Ellis, 1911 , ‘ Hyphessobrycon ’ isiri Almirón et al., 2006 and ‘ Hyphessobrycon ’ igneus Miquelarena et al., 1980 , among the analysed species. However, the taxon sampling is not oriented to investigate the relationships of these species and this clade could include other taxa that were not analysed here. The diagnosis herein provided is based only on these three species and may have to be adjusted with the inclusion of more related taxa. Even though this clade is stable and well-supported, we prefer not to erect a new genus for it given the low taxon sampling in Hyphessobrycon and that, under certain conditions, the morphologically divergent species Gymnocharacinus bergii was obtained as sister-group of H. isiri (see Discussion).

The species included herein share the presence of a rhinosphenoid lacking a dorsal projection, a relatively long supraoccipital process projected dorsal to middle length of Weberian apparatus neural complex, presence of an anterior branch in the maxillary tubules for blood vessels and an incomplete lateral line. This clade is supported by two molecular and ten morphological synapomorphies: anterior extension of nasal extending only slightly anterior to mesethmoid wing (11:0), fourth infraorbital longer dorsoventrally than longitudinally (92:1), sixth infraorbital leaving a conspicuous naked area in anterior region of dilatator fossa (94:1), laterosensory pore anterior to dilatator fossa oriented dorsomedially (115:0), interrupted lateral line (123:1), canal of lateral line on caudal-fin membrane absent (125:0), coronomeckelian bone mainly lateral to Meckelian cartilage (159:0), eight or fewer dentary teeth (198:0), posterior tip of quadrate not reaching posterior margin of symplectic (234:1) and presence of 17 or fewer gill filaments attached to leading edge of first ceratobranchial (303:0).