Stpgichthpinae Gérp, 1972

Melo, Bruno F, Ota, Rafaela P, Benine, Ricardo C, Carvalho, Fernando R, Lima, Flavio C T, Mattox, George M T, Souza, Camila S, Faria, Tiago C, Reia, Lais, Roxo, Fabio F, Valdez-Moreno, Martha, Near, Thomas J & Oliveira, Claudio, 2024, Phylogenomics of Characidae, a hyper-diverse Neotropical freshwater fish lineage, with a phylogenetic classification including four families (Teleostei: Characiformes), Zoological Journal of the Linnean Society (Zool. J. Linn. Soc.) 202 (1), pp. 1-37 : 17-21

Stpgichthpinae Gérp, 1972 , new usage

Type genus: Stygichthys Brittan and Böhlke, 1965 .

Included genera: Astyanax (in part), Coptobrycon , Deuterodon , Myxiops Zanata and Akama, 2004, and Stygichthys.

Definition: The least inclusive crown clade that contains Stygichthys typhlops , Astyanax mutator Eigenmann, 1909 , and Deuterodon iguape Eigenmann, 1907 . This is a minimum-crown-clade definition. See Figure 5 for a reference phylogeny of Stygichthyinae.

Etymology: The River Styx is the main river in the Underworld of ancient Greek mythology.

Remarks: Phylogenetic analysis of the UCE dataset resolves Stygichthyinae as monophyletic and the sister-lineage of all other species of Acestrorhamphidae , except for Trochilocharax ornatus and Oxybrycon paroulus ( Fig. 5). Monophyly of Stygichthyinae was supported in previous phylogenomic studies, but with more limited taxon sampling (Betancur-R et al. 2019, Melo et al. 2022a).

Within Stygichthyinae, the UCE inferred phylogeny includes a clade with three species provisionally classified as Astyanax that comprise a new and unnamed genus: Astyanax sp. Kuribrong that is probably an undescribed species with a very similar pattern as exhibited in A. wappi Valenciennes in Cuvier and Valenciennes, 1850, and Astyanax mutator Eigenmann 1909 that, contrary to a previous hypothesis, is not resolved in Deuterodon ( Terán et al. 2020) . Hyphessobrycon eos Durbin, 1909 is probably an unnamed genus. The Brazilian blind characid Stygichthys typhlops and Coptobrycon bilineatus (Ellis, 1911) are both deeply branching monotypic lineages in Stygichthyinae. Based on morphological characters, Coptobrycon was suggested to be related to Grundulus Valenciennes in Cuvier and Valenciennes, 1846 (Langeani and Serra 2010), but the lineages are distantly related in the UCE phylogeny ( Figs 5, 7).

The two species of Myxiops [ Myxiops aphos Zanata and Akama, 2004 and Myxiops pelecus (Bertaco and Lucena, 2006), new combination (former Astyanax pelecus ); Table 1 ] are resolved as a monophyletic group and the sister-lineage of Deuterodon . The genus Myxiops was described based on an exclusive combination of morphological characteristics (Zanata and Akama 2004). Analysis of morphological characters resulted in phylogenies where species of Myxiops were nested in Deuterodon ( Terán et al. 2020) . Given the relationships inferred from the UCE loci, we revalidate Myxiops ( Fig. 5; Table 1 ). Similarly, Terán et al. (2020) found M. aphos and M. pelecus as belonging to a monophyletic clade reinforcing the new combination Myxiops pelecus . Eigenmann (1907) described Deuterodon distinguishing it from other characids by the number and position of premaxillary teeth. Our results corroborate the expansion of Deuterodon to include several species traditionally classified in Astyanax ( Terán et al. 2020) . All species of Deuterodon are found in the Atlantic rainforest zone, mainly in coastal rivers flowing directly into the Atlantic Ocean ( Fig. 5).