Oligosarcus, Gunther

Genus Oligosarcus View in CoL .

The genus Oligosarcus was traditionally considered to be related with Acestrorhynchus ( e. g. Menezes, 1969). Géry (1977), classified both genera in the tribe Acestrorhynchini of the subfamily Characinae . The phylogeny of Buckup (1998), however, did not yield a close relationship between these two genera, and Acestrorhynchus was excluded from the Characidae . The monophyly of Oligosarcus was not tested in the literature, although the species of this genus share some unique or unusual characters within Characidae , mostly involving their dentition ( Menezes, 1969). The morphologically most generalized described species of this genus, Oligosarcus pintoi Campos is not herein analyzed, and probably some of the listed synapomorphies would apply to a subclade within Oligosarcus . According to the present analysis, the undescribed new species included in this clade (treated as an undescribed new genus and species by Mirande, 2009) should be described as a species of Oligosarcus .

Synapomorphies:

1. Temporal fossa (13): (1> 0) well developed. Paralleled in Brycon meeki , Bryconexodon juruenae , and Salminus brasiliensis .

2. Dorsal expansion of rhinosphenoid (48): (1> 0) absent. Paralleled in nodes 201 and 212 and in Agoniates anchovia .

3. Articulation between second and third infraorbitals (62): (0> 2) posteroventrally angled. Paralleled in the Characinae , in node 176, and in Bryconops melanurus and Hollandichthys multifasciatus .

4. Ectopterygoid teeth row (159): (0> 1) present. Paralleled in node 168 and in Acestrorhynchus pantaneiro , Distichodus maculatus , Hoplias cf. malabaricus , Serrasalmus maculatus , and Xenagoniates bondi .

5. Position of longitudinal cartilage dorsal to ectopterygoid (161): (0> 1) displaced laterally and separated from medial margin of mesopterygoid. Paralleled in node 211 and in Exodon paradoxus .

6. Bony lamellae bordering laterosensory canal of suprapreopercle (176): (0> 1) present. Paralleled in Markiana nigripinnis .

7. Number of branched anal-fin rays (288): (1> 0) 24 or less. Reversal of synapomorphy 5 of the Characidae . Paralleled in nodes 200 and 277 and in Acestrorhynchus pantaneiro and Iguanodectes geisleri .

8. Uroneurals (306): (0> 1) two pairs. Reversal of synapomorphy 15 of node 205. Paralleled in the Tetragonopterinae , in node 276, and in Bryconamericus scleroparius , Galeocharax humeralis , and Markiana nigripinnis .