Leporellus Lütken, 1875

Sidlauskas, Brian L., Melo, Bruno F., Birindelli, José L. O., Burns, Michael D., Frable, Benjamin W., Hoekzema, Kendra, Dillman, Casey B., Sabaj, Mark H. & Oliveira, Claudio, 2025, Molecular phylogenetics, a new classification, and a new genus of the Neotropical fish family Anostomidae (Teleostei: Characiformes), Neotropical Ichthyology (e 240076) 23 (1) : -

Leporellus Lütken, 1875

Phylogenetic definition. Leporellus is herein defined as the clade within Anostomidae for which scales covering the caudal-fin rays and three or more dark stripes on the caudal fin, as inherited by Leporellus vittatus , are apomorphies.

Diversity. Though Toledo-Piza et al. (2024) considered the genus to encompass just two valid species ( Leporellus pictus and L. vittatus ) data herein suggest higher intrageneric diversity ( Fig. 4).

Leporininae Eigenmann, 1912

Type-genus. Leporinus Agassiz, 1829 .

Phylogenetic definition. The crown clade originating in the most recent common ancestor of Leporinus fasciatus , Hypomasticus mormyrops (Steindachner, 1875) , and Insperanos nattereri (Steindachner, 1876) . This definition is based on the combined molecular and morphological phylogenetic hypothesis of Sidlauskas et al. (2021)

Diversity. Leporininae includes 128 species allocated among the genera Abramites , Brevidens , Anostomoides , Hypomasticus , Insperanos , Laemolyta , Leporinus , Megaleporinus , Rhytiodus , and Schizodon .

Taxonomic changes to alleviate non-monophyly. With two thirds of the known species in Anostomidae now placed in a phylogenetic context, we can reassign several species to correct some obvious cases of genus-level paraphyly or polyphyly ( Tab. 4).

For example, because three analyzed specimens of Anostomus brevior Géry, 1961 are placed with high statistical support (96% bootstrap; 1.0 posterior probability) as sister to a clade containing both sequenced species of Petulanos and not with the remainder of Anostomus ( Figs. 4, S 1, S 2) we formally transfer Anostomus brevior to an expanded concept of Petulanos . Similar logic justifies the transfer of Leporinus striatus to the new genus Brevidens .

The remaining taxonomic changes involve the composition of Hypomasticus , originally conceived as a subgenus of Leporinus possessing subterminal or inferior mouths (Borodin, 1929; Géry, 1960). Results here and elsewhere have reconstructed many species of Hypomasticus [including the type-species, H. mormyrops ] as belonging to a distinct lineage originating early in the history of the family (Sidlauskas, Vari, 2008; Ramirez et al., 2017b; Birindelli et al., 2020b; Sidlauskas et al., 2021). However, the composition of that clade is broader than originally envisioned, and molecular results here ( Fig. 5) and elsewhere (Birindelli et al., 2020b; Sidlauskas et al., 2021) universally agree that it contains several species with terminal mouths that have been traditionally assigned to Leporinus . Based on their inclusion in this clade in molecular analysis, we transfer Leporinus granti Eigenmann, 1912 , L. lebaili Géry & Planquette, 1983 , L. melanostictus Norman, 1926 , and L. torrenticola Birindelli, Teixeira & Britski, 2016 to Hypomasticus . Though not included in our molecular sampling, we also transfer Leporinus arcus , L. gomesi Garavello & Santos, 1981 , L. nijsseni Garavello, 1990 and L. santosi Britski & Birindelli, 2013 to Hypomasticus based on their morphological similarity to Leporinus granti (now H. granti ) in aspects of coloration, body shape, dentition and squamation (Britski, Birindelli, 2013; Birindelli et al., 2019).

On the other hand, results herein ( Fig. 6) agree with several other studies (Ramirez et al., 2017b; Mirande, 2019; Birindelli et al., 2020b; Sidlauskas et al., 2021) in concluding that Hypomasticus julii (Santos, Jégu & Lima, 1996) and H. pachycheilus (Britski, 1976) are distantly related to the remainder of Hypomasticus . Though Sidlauskas, Vari (2008) transferred those species to Hypomasticus on account of their strongly inferior mouth position, results here and elsewhere have clarified this as a morphological convergence. As such, we transfer those two species back to their original placement in Leporinus .

In total, these changes begin to alleviate the non-monophyly of Leporinus . While it would be possible to elevate other clades to generic status, we refrain from doing so because of the large number of species in Leporinus that still await inclusion in molecular phylogenies, and our generally low confidence in predicting their phylogenetic placement. Some of the subclades recognized herein include species that differ substantially in patterns and body shapes [e.g., the Leporinus ecuadorensis Eigenmann & Henn, 1916 , L. melanopleura Günther, 1864 and L. friderici (Bloch, 1794) clades] and many of the missing species have not been included in any modern studies of morphology or genetics. Further changes to the genus-level taxonomy of Leporinus surely await, but reassignments beyond those reported here are premature.

Genus-level relationships. Leporellus is the sister clade to Anostominae . Within

Anostominae , we reconstruct a basal split between a clade containing Gnathodolus and Sartor on one hand, and the members of Anostomus , Petulanos , Pseudanos and

Synaptolaemus on the other. Synaptolaemus appears as sister to the remaining three genera, and Anostomus (as amended above) is sister to Pseudanos plus Petulanos ( Fig. 3). Even with the taxonomic changes summarized above, the large genus Leporinus is non-monophyletic in its current composition. As such we divide it into several clades for the purposes of discussion ( Fig. 3). The basal split within subfamily Leporininae separates Hypomasticus from the remaining taxa, noting that Hypomasticus as conceived herein includes some former species of Leporinus ( Tab. 4). The next split within the family divides the Leporinus ecuadorensis clade from all other members of Leporininae . A clade containing Anostomoides , Laemolyta , Rhytiodus , and Schizodon appears as sister to a clade containing Abramites , Brevidens , Megaleporinus , and all remaining members of Leporinus . Rhytiodus and Schizodon are sister taxa, with Laemolyta appearing as the closest genus to that pair and Anostomoides sister to the clade containing all three. Abramites and Megaleporinus are sister taxa, with Brevidens as the most closely related lineage to that pair. The Leporinus jamesi clade appears as sister to the clade containing Brevidens , Abramites and Megaleporinus . The Leporinus fasciatus clade contains the type-species for the genus and shares a sister relationship with the Leporinus friderici clade. The Leporinus pachycheilus clade is sister to that pair. The Leporinus melanopleura clade is sister to the clade containing Abramites , Megaleporinus , Brevidens , and the Leporinus fasciatus , L. friderici , L. jamesi Garman, 1929 and L. pachycheilus clades.

Due to the large number of species in Anostomidae , we prefer to initially report species-level relationships within each of its subclades visually rather than textually, as in Fig. 4, which details Anostominae and Leporellinae. Such figures are based on the maximum likelihood results and include bootstrap values reported categorically. Asterisks mark the few instances in which a clade appears in the maximum likelihood reconstruction, but not the Bayesian. The full trees with exact support values resulting from likelihood and Bayesian analyses appear in Figs. S1 and S 2. A detailed comparison of these relationships to previous hypotheses appears below.