Pristellinae Gérp and Boutière, 1964

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 : 23-24

Pristellinae Gérp and Boutière, 1964 , new usage

Type genus: Pristella Eigenmann, 1908 .

Included genera: Gymnocorymbus , Moenkhausia (in part), Hemigrammus (in part), and Pristella .

Definition: The least inclusive crown clade that contains Pristella maxillaris and Gymnocorymbus thayeri Eigenmann, 1908 . This is a minimum-crown-clade definition. See Figure 6 for a reference phylogeny of Pristellinae.

Etymology: From the ancient Greek πΡίστις (pɹˈɪstiz) a name used by ancient Mediterranean authors for the largetooth sawfish, Pristis pristis (Thompson 1947: 219).

Remarks: The delimitation of Pristellinae presented here includes Hemigrammus unilineatus , the type species of the genus, and was partially resolved in phylogenetic analyses as the ‘ Hemigrammus clade’ (Mirande 2009, 2010, 2019). The clade was characterized by homoplastic morphological characters: a dorsal bony process in the rhinosphenoid (Mirande 2009) and incomplete lateral line (Mirande 2010).

Within Pristellinae Gymnocorymbus is the sister-lineage of all other species in the clade ( Fig. 6). In previous phylogenetic studies, Gymnocorymbus was resolved as closely related to other genera with a very deep body such as Brachychalcinus , Orthospinus , Poptella , Stethaprion , and Stichonodon (Javonillo et al. 2010, Mirande 2010, 2019, Oliveira et al. 2011, Benine et al. 2015). The phylogeny inferred from UCE loci strongly resolves Gymnocorymbus with other lineages of Pristellinae.

Lima et al. (2021) obtained a clade containing Pristella and Bryconella pallidiþons (Fowler 1946) as the sister-lineage of a clade comprising many of the species included in Pristellinae. In the phylogeny inferred from the UCE loci, Pristella and H. erythrozonus Durbin, 1909 are sister-lineages and they form the sister-group of species currently classified as Moenkhausia and Hemigrammus ( Fig. 6).

In the UCE phylogeny, Aphyodite grammica Eigenmann, 1912 is sister to Hemigrammus microstomus Durbin, 1918 and nested in a clade of species currently classified as Hemigrammus ( Fig. 6). Morphological phylogenetic analyses resolve Aphyodite as closely related to Atopomesus , Aphyocharacidium , Axelrodia , Leptobrycon , Microschemobrycon , Oxybrycon , Parecbasis , and Tytobrycon Géry, 1973 (Mirande 2010, Esguícero and Castro 2016). However, molecular ( Oliveira et al. 2011, Mariguela et al. 2013, Britzke et al. 2018, Melo et al. 2022a) or combined molecular and morphological hypotheses ( Mirande 2019) resolve Aphyodite more closely related to species classified in Pristellinae, including the type species Hemigrammus unilineatus . As the resolution of Aphyodite being well supported in the phylogeny inferred from UCE loci and corroborated in other studies, we classify Aphyodite grammica as a species of Hemigrammus ( Table 1 ). A recent taxonomic revision of Aphyodite resulted in the description of two species: Aphyodite apiaka Esguícero and Castro, 2017 and A. tupebas Esguícero and Castro, 2017 . In addition to Aphyodite grammica , we classify A. apiaka and A. tupebas as species of Hemigrammus , resulting in the new combinations Hemigrammus grammicus , Hemigrammus apiaka , and Hemigrammus tupebas ( Table 1 ). Considering this new composition of Hemigrammus , the three species previously classified in Aphyodite are the only species of Hemigrammus possessing a single row of premaxillary teeth.

Although there are no known morphological synapomorphies for Pristellinae, all species in the clade lack a caudal spot and many species have a broad stripe across the eye and a dark stripe along the anal-fin base. These features were used to define the Hemigrammus lunatus Durbin, 1918 species-group ( Ota et al. 2014, 2019). It was suggested these shared colour patterns provided evidence for a clade containing H. barrigonae Eigenmann and Henn, 1914 , H. changae Ota et al., 2019 , H. lunatus , H. machadoi Ota et al., 2014 , and H. ulreyi (Boulenger, 1895) , possibly related to Moenkhausia colletii (Steindachner, 1882) .

The UCE phylogeny corroborates phylogenies inferred from mitochondrial and nuclear loci in resolving a close relationship

between Hemigrammus ulreyi and Moenkhausia colletii (Britzke et al. 2018). In addition, the UCE phylogeny resolves the Hemigrammus lunatus species-group as monophyletic ( Fig. 6), but more inclusive than previously ( Ota et al. 2014, 2019) ( Fig. 6). Following the phylogenetic relationships resulting from analysis of the UCE loci ( Fig. 6), we are proposing the generic reassignment of Moenkhausia colletii , M.eigenmanni Géry, 1964 , M. melogramma Eigenmann, 1908 (present study), and M. copei and M. flaoa (based on Britzke et al., 2018) to Hemigrammus , under the new combinations Hemigrammus colletii , Hemigrammus copei , Hemigrammus eigenmanni , Hemigrammus flaous , and Hemigrammus melogrammus ( Fig. 6; Table 1 ). Moenkhausia conspicua Soares and Bührnheim, 2016 and M. oenerei Petrolli et al., 2016 have not been sampled in any molecular phylogenetic analysis, but exhibit a broad stripe across the eye and a dark stripe along the anal-fin base and are probably closely related to species in the Hemigrammus lunatus species-group; however, pending their inclusion in a phylogenetic analysis we avoid the transfer of these species to Hemigrammus at this time. Within the Hemigrammus lunatus species-group, H. eigenmanni lacks the dark stripe across the eye but has a dark stripe of variable intensity along the anal-fin base. This feature is also shared by H. unilineatus (with less intensity), H. grammicus , and H. microstomus , possibly supporting the close relationship of these species to the H. lunatus species-group.

As pointed out by previous authors (Mirande 2010, Britzke et al. 2018, Soares et al. 2020, Marinho et al. 2021), the relationships resolved in the UCE phylogeny highlight the weakness of the degree of lateral line perforation as a diagnostic character to distinguish Hemigrammus and Moenkhausia , which can be attributed to the paedomorphic condition retained during a truncated development (Marinho et al. 2021). The phylogenetic relationships within Pristellinae ( Fig. 6) suggest that pigmentation patterns are more consistent with clades resolved in the phylogeny than is the degree of development of the laterosensory system or caudal-fin squamation. Biogeographically, species of Pristellinae are mostly distributed in Amazon–Orinoco–Guianas; some species of Pristella and Hemigrammus are distributed in the São Francisco basin; Gymnocorymbus ternetzi and H. ulreyi are distributed in the La Plata, and H. lunatus is distributed in both Amazon and La Plata basins ( Fig. 6).