[Ichthyology • 2026] Characidium lilloi • A New Species of Characidium (Characiformes: Crenuchidae) from the Northwestern La Plata Basin in Argentina

Characidium lilloi

Terán, Méttola, Alonso, Montes, Méndez-López, Miranda, Aguilera & Mirande, 2026

DOI: doi.org/10.1643/i2025064  

 x.com/IchsAndHerps

Abstract

Using an integrative approach that combines molecular and morphological analyses, we describe Characidium lilloi, a new species from the Andean portion of the northwestern La Plata basin, specifically from the upper Bermejo and Juramento River basins in Argentina. Specimens were examined for morphometric, meristic, and osteological traits. Genetic analyses based on COI and CYTB sequences were conducted to infer its phylogenetic relationships. The new species is distinguished by a unique combination of morphological characters including an unscaled isthmus, absence of dark stripes or spots on fins, 7–13 regular transversal bars, 14 scales around the caudal peduncle, 35–37 scales in longitudinal series, and highly developed nasal flaps; and molecular evidence. Characidium lilloi, new species, was found to be closely related to C. fasciatum and C. gomesi and represents the first known member of the C2 Clade in the northwestern La Plata basin. Ecologically, C. lilloi, new species, inhabits fast-flowing mountain rivers within the Yungas and Chacoan. This discovery underscores the northwestern La Plata basin as a biogeographic hotspot of endemism and reinforces its importance as a high-priority area for freshwater conservation.

Lateral views of live paratypes of Characidium lilloi.
 CI-FML 8196, 36.8–49.1 mm SL,
Argentina, El Rey National Park, Río Popayán.

Scale bar = 1 cm. 

Characidium lilloi, new species

Etymology.—This species is named in honor of the Argentine naturalist Miguel Lillo (1862–1931), a pioneer who recognized the importance of public investment in science and education. In his commitment to advancing these fields, Lillo donated his personal assets before his death, ensuring the continuity of his legacy through several key institutions. These include the Facultad de Ciencias Naturales e Instituto Miguel Lillo, the Fundación Miguel Lillo, and the Unidad Ejecutora Lillo–CONICET, all of which have played significant roles in the development of science and education in Argentina. The specific name lilloi, thus, not only pays tribute to Lillo’s contributions but also honors the dedication of public workers in Argentina who promote and contribute to the progress of science, education, and technology.   

Guillermo E. Terán, V. Ezequiel Méttola, Felipe Alonso, Martín M. Montes, Alejandro Méndez-López, Guido Miranda, Gastón Aguilera and J. Marcos Mirande. 2026. A New Species of Characidium (Characiformes: Crenuchidae) from the Northwestern La Plata Basin in Argentina. Ichthyology & Herpetology. 114(2):283-298 DOI: doi.org/10.1643/i2025064 [23 June 2026]

  x.com/IchsAndHerps/status/2069532500280381641

Utilizando un enfoque integrador que combina análisis moleculares y morfológicos, se describe Characidium lilloi, una nueva especie proveniente del sector andino del noroeste de la cuenca del Plata, específicamente de las cuencas altas de los ríos Bermejo y Juramento en Argentina. Los ejemplares fueron examinados en cuanto a caracteres morfométricos, merísticos y osteológicos. Se realizaron análisis genéticos basados en las secuencias de los genes mitocondriales COI y CYTB con el fin de inferir sus relaciones filogenéticas. La nueva especie se distingue por una combinación única de caracteres morfológicos incluyendo el istmo sin escamas, ausencia de bandas oscuras o manchas en las aletas, presencia de 7 a 13 barras transversales regulares, 14 escamas alrededor del pedúnculo caudal, 35 a 37 escamas en la serie longitudinal, y lóbulos nasales altamente desarrollados; y evidencia molecular. Characidium lilloi, nueva especie, se encuentra estrechamente relacionada con C. fasciatum y C. gomesi, y representa el primer miembro conocido del Clado C2 en el noroeste de la cuenca del Plata. Desde el punto de vista ecológico, C. lilloi, nueva especie, habita ríos de montaña de corriente rápida, dentro de las ecorregiones de las Yungas y el Chaco. Este hallazgo resalta al noroeste de la cuenca del Plata como un hotspot biogeográfico de endemismos, y refuerza su importancia como una región de alta prioridad para la conservación de ambientes dulceacuícolas.

[Ichthyology • 2026] Hemigrammus serrazul • A New Hemigrammus (Characiformes: Acestrorhamphidae) from the rio Cuiabazinho Drainages, upper rio Paraguai Basin, Mato Grosso, Brazil

   

Hemigrammus serrazul  

Ferreira, Ribeiro & Carvalho, 2026

DOI: doi.org/10.1590/1982-0224-2025-0157

 

Abstract

A new species of Hemigrammus is described from tributaries of the rio Cuiabazinho, upper rio Paraguai basin, Mato Grosso State, Brazil. It can be readily distinguished from all its congeners by a unique combination of characters, including a distinctive body coloration pattern without spots, the number of perforated lateral-line scales (12–15), the number of branched rays on anal fin (21–25), and the presence of small bony hooks at the tips of the lepidotrichia of the second to fourth branched rays of the pelvic fins, which are absent in the anal fin. We also provide a brief discussion on the recent taxonomic reconfiguration of Hemigrammus.

Keywords: Freshwater fish; Rio Cuiabá drainage; Serra Azul; Serrana Province of Mato Grosso; Taxonomy

 Color pattern variations in live specimens of Hemigrammus serrazul: A. Male; B. Female.

Photo by Alexandre C. Ribeiro.  

Hemigrammus serrazul, new species

Diagnosis. Hemigrammus serrazul can be distinguished from most congeners (except of H. apiaka (Esguícero& Castro, 2017), H. erythrozonus Durbin, 1909, H. gracilis (Lütken, 1875), H. mimus Böhlke, 1955, and H. tupebas (Esguícero& Castro, 2017) by flank uniformly colored, without spots, i.e., no humeral and caudal spots, just a tiny and narrow longitudinal stripe (vs. species with spots in humeral and/or caudal peduncle). From H. apiaka, H. erythrozonus, H. gracilis, H. mimus, and H. tupebas, H. serrazul differs by premaxillary teeth in two rows: outer with three to five tricuspid teeth, inner with five ...

Etymology. The specific epithet serrazul refers to the type locality where the new species was collected, the Serra Azul, the local portion of the so-called Serrana Province of Mato Grosso, a range of escarped relief that serves as a watershed divide between the rio Cuiabá, Paraguai, and Arinos basins. A noun in apposition.

Hemigrammus serrazul, live specimen in aquarium, photographed just after capture in córrego Cocal (CPUFMT 8218), upper rio Paraguai basin, municipality of Rosário Oeste, Mato Grosso State, Brazil. Inserir:

Photo by Alexandre C. Ribeiro.

Katiane Mara Ferreira, Alexandre Cunha Ribeiro and Fernando Rogério Carvalho. 2026. A New Hemigrammus (Characiformes: Acestrorhamphidae) from the rio Cuiabazinho Drainages, upper rio Paraguai Basin.  Neotrop. ichthyol. 24 (01); DOI: doi.org/10.1590/1982-0224-2025-0157

[Ichthyology • 2025] Hyphessobrycon ribeiroi • A New Hyphessobrycon (Characiformes: Acestrorhamphidae) from the Central Amazon Basin, Brazil

Hyphessobrycon ribeiroi

Lima, Silva-Oliveira, Oliveira & Faria, 2025

 

Papéis Avulsos De Zoologia. 65;  

scielo.br/j/paz 

Researchgate.net/publication/388856173

Abstract

A new species of Hyphessobrycon is described from the region of the lower rioTapajós basin, state of Pará, and tributaries of the northern bank of the Amazon River from the rio Itapiranga basin westward to the lower rio Negro basin, states of Amazonas and Roraima, Brazil. The new species exhibits a color pattern consisting in a conspicuous single humeral blotch and a conspicuous caudal peduncle blotch, a pattern shared with several congeners. It can be diagnosed from those congeners by some other pigmentary features, and from some of them by maxillary teeth, and/or branched anal-fin rays counts, anal-fin morphology, and fin hooks arrangement in matures males.The new species is most similar morphologically to a non-congener, Hemigrammus schmardae, with which it was found syntopically at the lower rio Negro but can be distinguished from it by some color pattern features. An analysis based on the cytochrome c oxidase I gene indicates that the new species is closely related to Hyphessobrycon ericae.

Keywords: Barcoding; Hemigrammus schmardae ; Hyphessobrycon ericae ; rio Tapajós; rio Negro

Hyphessobrycon ribeiroi, new species, living aquarium specimens, no locality data.

Hyphessobrycon ribeiroi, new species  

 Diagnosis: Hyphessobrycon ribeiroi can be distinguished from most species currently assigned to the genera Hyphessobrycon and Hemigrammus, except He. hyanuary, He. levis, He. melanochrous, He. schmardae, He. vorderwinkleri, Hy. duragenys, Hy. eos, Hy. ericae, Hy. frankei, Hy. langeanii, Hy. santae, Hy. reticulatus, Hy. rutiliflavidus, Hy. tenuis, Hy. tropis, Hy. uaiso, Hy. wosiackii, and Hy. zoe by the presence of single humeral blotch and a caudal peduncle blotch extending into the basis of the middle caudal fin rays (vs. two humeral blotches or absence of a blotch in the humeral region or caudal peduncle). It can be distinguished from aforementioned species, except Hy. ericae and Hy. wosiackii, by possessing a vertically elongated humeral blotch with a posterior backward extension (vs. humeral blotch never presenting a posterior backward extension). The new species can be diagnosed from ...

Etymology: The specific epithet is a homage to Frank Raynner Ribeiro, professor of the Universidade Federal do Oeste do Pará, as a recognition of its contribution to the knowledge of South American Siluriformes and also the fishes from the rio Tapajós basin.

Flávio C.T. Lima, Cárlison Silva-Oliveira, Claudio Oliveira and Tiago C. Faria. 2025. A New Hyphessobrycon (Characiformes: Acestrorhamphidae) from the Central Amazon Basin, Brazil. Papéis Avulsos De Zoologia. 65; e202565011. DOI: 10.11606/1807-0205/2025.65.011

  https://www.scielo.br/j/paz/a/nfFVZnYpfgBPdnt9KBQTJ6H

 Researchgate.net/publication/388856173_A_new_Hyphessobrycon_from_the_Central_Amazon_basin_Brazil

  x.com/PAZ_journal/status/2026326260490678454

[Ichthyology • 2026] Hyphessobrycon pastanai • A New Hyphessobrycon (Characiformes: Acestrorhamphidae: Hyphessobryconinae) of the Hyphessobrycon agulha lineage from the lower Aripuanã Basin, Brazil, with comments about the lineage

Hyphessobrycon pastanai

 Faria, Ohara, Monteiro & Oliveira, 2026

 DOI: doi.org/10.1111/jfb.70379 

  Researchgate.net/publication/401289168

 

Abstract

A new species of Hyphessobrycon is described from a tributary of Rio Jatuarana, lower Rio Aripuanã basin, Rio Madeira basin, Apuí, Amazonas. The new species is part of the Hyphessobrycon agulha lineage, with the typical midlateral narrow black stripe immediately followed dorsally by an iridescent stripe. Its phylogenetic position is corroborated by the DNA barcoding methodology, which also indicates the new species as closely related to Hyphessobrycon ericae and Hyphessobrycon ribeiroi, with both possessing very distinct colour patterns. The new species can be distinguished from all species of Hyphessobrycon by the association of a well-defined and horizontally elongated humeral blotch with a ventral diffuse expansion, a conspicuous caudal peduncle blotch restricted to the ventral half of the caudal peduncle and proximal half of mid rays of caudal fin, the presence of a red midlateral stripe dorsal to the iridescent stripe and lateral-line scale counts.

Keywords: biodiversity, Hyphessobrycon ericae, Hyphessobrycon ribeiroi, Ichthyology, Rio Amazonas

Hyphessobrycon pastanai n. sp. Living specimens.
Brazil, Amazonas, Apuí, stream tributary of Rio Jatuarana, Rio Aripuanã basin, Rio Madeira basin.
(a) MZUSP 117609, unsexed; (b) LBP 32949, female. 

Hyphessobrycon pastanai n. sp. 

Etymology: The specific epithet is a homage to Dr. Murilo Nogueira de Lima Pastana, dear friend, ichthyologist and curator in the Museu de Zoologia da Universidade Estadual de São Paulo, as a recognition of its important contributions to the knowledge of fishes from the Apuí region. A genitive noun.

Hyphessobrycon heterorhabdus and Hyphessobrycon agulha species groups representatives.
(a) Hy. heterorhabdus, ZUEC 17135, female, Brazil, Belém region, picture of Douglas A. Bastos.
(b) Hy. agulha, LBP 33136, female, Brazil, Rio Mamuru basin.

Tiago C. Faria, Willian M. Ohara, Iann Leonardo Pinheiro Monteiro and Claudio Oliveira. 2026. A New Hyphessobrycon (Characiformes: Acestrorhamphidae) of the Hyphessobrycon agulha lineage of Hyphessobryconinae from the lower Aripuanã Basin, Brazil, with comments about the lineage. Journal of Fish Biology.  DOI: doi.org/10.1111/jfb.70379 (26 February 2026)  

  Researchgate.net/publication/401289168_A_new_Hyphessobrycon_from_the_lower_Aripuana_basin_Brazil

[Ichthyology • 2025] Psalidodon terezinhae, P. velhochico & P. paiva • Unraveling a 150-Year-Old Enigma: Psalidodon rivularis (Characiformes: Acestrorhamphidae: Acestrorhampinae), a Species Complex or a Polymorphic Species

 (a, b) Psalidodon terezinhae 
 (c, d) h  P. velhochico 
 (e, f) P. paiva  

Rodrigues-Oliveira, Assis, Pimente, Soares, Silva, Rocha, Menegidio, Pasa & Kavalco, 2025

DOI: doi.org/10.3390/biology14121793

Abstract

Psalidodon rivularis, a fish endemic to the São Francisco River Basin and known as “piaba do córrego,” has long been regarded as a widely distributed species complex, exhibiting remarkable morphological and cytogenetic variation, even in sympatry. This study aims to determine whether P. rivularis represents a single polymorphic species or a group of cryptic species. We analyzed meristic, morphometric, and karyotypic data from 419 specimens identified as P. rivularis, as well as from the related species Astyanax turmalinensis and Hyphessobrycon santae. Additionally, we inferred the phylogeny of the group using NGS data from 25 individuals, incorporating both mitochondrial and nuclear genomic sequences. Our integrative results support the recognition of at least five distinct species within the P. rivularis complex. The true P. rivularis (called morphotype 1) has 46 chromosomes, while the others have 50 and differ in both morphology and distribution. One of these corresponds to Psalidodon santae comb. nov.—which includes A. turmalinensis as a junior synonym—and three others are newly described species. These findings clarify the diversity of fishes in the São Francisco River Basin and highlight the importance of conserving its unique freshwater ecosystems.

Keywords: cytotypes; cryptic species; phylogenomics; morphometrics

Psalidodon terezinhae (a) holotype, LaGEEvo 27-4521, 53.0 mm SL, Lage stream, Abaeté River drainage and (b) LaGEEvo 35-529, 45.0 mm SL, Funchal River, Indaiá River drainage.
  P. velhochico (c) holotype, LaGEEvo 28-5079, 77.0 mm SL, Rasga Canga Waterfall, São Francisco River drainage and (d) LaGEEvo 51-4999, 75.0 mm SL, Casca d’Anta Waterfall, São Francisco River drainage.
P. paiva (e) holotype, LaGEEvo 29-2072, 62.0 mm SL, Bonito stream, Borrachudo River drainage and (f) LaGEEvo 55, 34.5 mm SL, Usina do Abaeté dam Lagoon, Abaeté River drainage.

Psalidodon terezinhae sp. nov.

Psalidodon velhochico sp. nov.

Etymology. The specific epithet velhochico is used as a noun in apposition and refers to the popular nickname of the São Francisco River in Brazil, affectionately called “Velho Chico” (“Old Chico”) by Brazilians.

Psalidodon paiva sp. nov.

Etymology. The specific epithet is used as a noun in apposition and honors the Paiva family, whose life, portrayed in the Brazilian Oscar-winning film “Ainda Estou Aqui” (2024), was profoundly affected by the imprisonment, disappearance, and execution of the family patriarch, Rubens Paiva, during the Brazilian military dictatorship.

Igor Henrique Rodrigues-Oliveira, Priscila Martins de Assis, Luiz Guilherme Pereira Pimente, Rafael Augusto Silva Soares, Iuri Batista da Silva, Renan Rodrigues Rocha, Fabiano Bezerra Menegidio, Rubens Pasa and Karine Frehner Kavalco. 2025. Unraveling a 150-Year-Old Enigma: Psalidodon rivularis (Acestrorhamphidae: Acestrorhampinae), a Species Complex or a Polymorphic Species. Biology. 14(12), 1793. DOI: doi.org/10.3390/biology14121793 [16 December 2025]

 

Simple Summary: This study investigates a group of closely related fish species from southeastern Brazil known as the Psalidodon rivularis complex. These fishes are very similar in appearance, which has made it difficult to know exactly how many species exist. By combining information from their body shape, body measurements, chromosome counts, and DNA, we found that what was once thought to be a single species includes at least five distinct ones. The true P. rivularis has 46 chromosomes, while the others have 50. One of them corresponds to Psalidodon santae, which was previously classified in another genus, and three are new species described here. Our results also suggest that their diversity arose through processes such as changes in chromosome numbers, hybridization between populations, and morphological divergence, potentially within broader scenarios that may involve vicariant or adaptive processes. These fishes live in small rivers and streams of the Upper São Francisco River basin, environments that are rich in unique species but threatened by human activities. Recognizing and protecting these new species is essential for conserving the biodiversity of Brazilian freshwater ecosystems.

[Ichthyology • 2025] Inpaichthys luizae • An Ode to Beauty: the Discovery of one of the most spectacular Tetras (Characiformes: Acestrorhamphidae) - A New Species of Inpaichthys from the rio Juruena, Brazil

 Inpaichthys luizae

 Dagosta, 2025

 

DOI: doi.org/10.1590/1982-0224-2025-0052

 

Abstract

Inpaichthys luizae is described from tributaries of the rio dos Peixes basin, a tributary of the rio Juruena basin in central Brazil. The species is distinguished from all its congeners by the presence of well-defined, relatively broad oblique dark ventrolateral stripe on body, extending approximately from end of pectoral fin rays to base of middle caudal-fin rays, and continuing straight onto the tip of the middle caudal-fin rays. It shares seven of the eight synapomorphies attributed to the genus and exhibits all the defining characteristics of the clade I. kerri + I. parauapiranga, suggesting a close relationship with these species. Several morphological characters found in I. luizae, other species of Inpaichthys, and closely related groups are discussed. The biogeography of Inpaichthys is briefly addressed.

Keywords: Amazon; Biogeography; Rio Tapajós basin; Taxonomy

 Inpaichthys luizae 
Life coloration of the holotype, MZUSP 130243 (male, 30.2 mm SL). 
 Sexual dimorphism of I. luizae: A. MUBIO 691 (male, 31.5 mm SL); B. MUBIO 691 (female, 38.2 mm SL);
C. Unvouchered specimen (male); D. Unvouchered specimen (female).

Photos C–D by André Bulgarelli.

Inpaichthys luizae, new species

 

Diagnosis. Inpaichthys luizae can be easily distinguished from all congeners by the autapomorphic presence of a well-defined, relatively broad oblique dark ventrolateral stripe on body, extending approximately from end of pectoral fin rays to base of middle caudal-fin rays, and continuing straight onto the tip of the middle caudal-fin rays (vs. well-defined longitudinal stripe absent, or dark lateral stripe never oblique). Additionally, I. luizae can also be distinguished from I. nambiquara and I. parauapiranga by the absence of humeral blotch (vs. two in I. parauapiranga and one in I. nambiquara). It is further distinguished from I. kerri by 19–21 branched anal-fin rays (vs. 22–26 branched anal-fin rays).

  Fernando Cesar Paiva Dagosta. 2025. An Ode to Beauty: the Discovery of one of the most spectacular Tetras (Characiformes: Acestrorhamphidae) - A New Species of Inpaichthys from the rio Juruena, Brazil. Neotrop Ichthyol. 23(3):e250052. DOI: doi.org/10.1590/1982-0224-2025-0052

[Ichthyology • 2025] Moenkhausia solaris • A New Species of Moenkhausia (Characiformes: Acestrorhamphidae) from the Amazon basin at Serra do Cachimbo, Pará, Brazil

Moenkhausia solaris

da Silva, de Santana & Marinho, 2025

 DOI: doi.org/10.1590/1982-0224-2025-0089 

 

Abstract

A new species of Moenkhausia is described from the headwaters of the Curuá and Teles Pires River basin, localities restricted to the Serra do Cachimbo, Pará, Brazil. The new species is diagnosed by the presence of dark blotches concentrated on the anterior portion of scales from the second to seventh longitudinal series, presence of red pigmentation on the adipose and caudal fins in life, green coloration in the ventral portion of the eye and absence of a longitudinal black stripe on body. The new species is morphologically similar and probably closely related to other Moenkhausia species endemic to the Brazilian Shield tributaries, particularly those restricted to the Serra do Cachimbo, sharing with them unique pigmentation traits. The ichthyofauna of the Serra do Cachimbo is notably distinct and characterized by high levels of endemism, likely influenced by geological barriers such as rapids and waterfalls that act as biogeographic barriers. The restricted and disjunct distribution of the new species in tributaries of Xingu and Tapajós basins suggests a historic headwater capture event in the Serra do Cachimbo plateau.

Keywords: Biogeography; Headwater capture; Moenkhausia clorophthalma; Tapajós; Xingu

   Live specimens of Moenkhausia solaris, aquarium specimens, not preserved. Photo by Oliver Lucanus. 

Moenkhausia solaris, new species

Diagnosis. Moenkhausia solaris is distinguished from all congeners, except M. cambacica Marinho, Ohara & Dagosta, 2021, M. clorophthalma Sousa, Netto-Ferreira & Birindelli, 2010, M. lineomaculata Dagosta, Marinho & Benine, 2015, M. parecis Ohara & Marinho, 2016, M. petymbuaba Lima & Birindelli, 2006, and M. plumbea Sousa, Netto-Ferreira & Birindelli, 2010, by the presence of a dark blotch on the anterior portion of each scale of the second to seventh longitudinal series (vs. pigmentation absent or, when present, concentrated at the posterior margin of scales, forming a reticulate pattern). Moenkhausia solaris can be distinguished from all the aforementioned species, except M. petymbuaba, by having the adipose fin and the base of caudal-fin lobes red (vs. hyaline in M. lineomaculata and yellowish in ...

Etymology. The specific epithet solaris comes from Latin, meaning sunny or pertaining to the sun. In allusion to the bright gold color of body and red color of the adipose and caudal fin present in live specimens. An adjective.

 

One of the localities where Moenkhausia solaris was collected, MZUSP 128883, a small stream tributary of 13 de Maio River at the area of PCH Salto Três de Maio, upstream of the dam.

 

 José Igor da Silva, Yasmim de Santana and Manoela Maria Ferreira Marinho. 2025. A New Species of Moenkhausia (Characiformes: Acestrorhamphidae) from the Amazon basin at Serra do Cachimbo, Pará, Brazil. Neotrop. ichthyol. 23(03) DOI: doi.org/10.1590/1982-0224-2025-0089 

[Ichthyology • 2025] Psalidodon pessalii • A New Species of Psalidodon (Characiformes: Acestrorhamphidae) from the Upper Rio São Francisco Basin, Brazil, with Comments on Hasemania

 

Psalidodon pessalii

 Teixeira, Salvador, Mirande & Lima, 2025 

 

DOI: doi.org/10.1643/i2024065

Abstract  

A new species of Psalidodon without an adipose fin and with an interrupted lateral line and scaleless caudal fin is described from a marshland area in headwater tributaries of Rio Paraopeba, Rio São Francisco basin, Minas Gerais, Brazil. The new species can be promptly distinguished from all members of the Acestrorhamphidae by the presence of an ossified canal segment on the dorsal portion of the preopercular laterosensory canal running across the posterodorsal tip of the fourth infraorbital and posterior portion of the fifth infraorbital (vs. preopercular laterosensory canal lacking an ossified canal segment in the fourth and fifth infraorbitals). The new species fits the classical definition of the genus Hasemania; however, a comprehensive phylogenetic analysis carried out herein to assess its phylogenetic relationships revealed it as the sister group of Psalidodon crenuchoides, new combination. Further, both species are deeply nested within the genus Psalidodon, as recently redefined, which led to the generic reallocation of the latter. Comments on the phylogenetic position of the new species, as well as its conservation status, are presented.

Psalidodon pessalii.
(A) Preserved holotype, ZUEC 18283, male, 41.5 mm SL;
(B) freshly collected paratype, ZUEC 6387, SL uncertain.

Psalidodon pessalii, new species 

Etymology.—The specific epithet honors our fellow ichthyologist Tiago Casarim Pessali. With the constant support of his family, he has contributed in many ways to the knowledge of the Brazilian freshwater fishes, especially those occurring in the coastal drainages of eastern Brazil in the State of Minas Gerais. A noun in the genitive case.

 

Tulio F. Teixeira, Gilberto N. Salvador, Juan Marcos Mirande and Flávio C. T. Lima. 2025. A New Species of Psalidodon (Characiformes: Acestrorhamphidae) from the Upper Rio São Francisco Basin, Brazil, with Comments on Hasemania. Ichthyology & Herpetology. 113(1); 131-142. DOI: doi.org/10.1643/i2024065 (3 April 2025)

Uma nova espécie de Psalidodon sem nadadeira adiposa, com linha lateral interrompida e nadadeira caudal sem escamas é descrita de áreas pantanosas de afluentes de cabeceira do rio Paraopeba, bacia do rio São Francisco, Minas Gerais, Brasil. A nova espécie pode ser prontamente distinguida de todos os membros de Acestrorhamphidae por apresentar um segmento de canal ossificado da porção dorsal do canal laterossensorial pré-opercular passando pela extremidade póstero-dorsal do quarto infraorbital e porção posterior do quinto infraorbital (vs. canal laterossensorial pré-opercular sem um segmento de canal ossificado no quarto e quinto infraorbitais). A nova espécie se enquadra na definição clássica do gênero Hasemania, no entanto, uma análise filogenética abrangente realizada para avaliar suas relações filogenéticas revelou tratar-se do grupo irmão de Psalidodon crenuchoides, nova combinação, e que ambas espécies estão profundamente aninhadas dentro do gênero Psalidodon, como recentemente redefinido, o que levou à realocação genérica da última. Comentários sobre a posição filogenética da nova espécie, bem como seu status de conservação, são apresentados.

[Ichthyology • 2025] Characidium dumonti • A New Species of Characidium (Characiformes: Crenuchidae) from the Iguaçu National Park, Rio Iguaçu Basin, Paraná, Brazil

 

 Characidium dumonti 

Stabile, Reis, Oliveira & Graça, 2025

DOI: doi.org/10.1111/jfb.70035

Abstract

A new species of Characidium is described from the Iguaçu National Park, Brazil. The new species can be diagnosed from the congeners by the absence of conspicuous vertical bars, blotches and spots along the sides of the body, the presence of a scaled isthmus and adipose fin, a series of scales below lateral line and the presence of a thin dark midlateral stripe. The reticulated colour pattern of melanophores along the posterior edge of scales found in the new species is similar to that found in C. xanthopterum, with which it presents 4.2% of genetic distance. Morphological and molecular analyses showed that it is a new species, supported by multiple species delimitation methods (Assemble Species by Automatic Partitioning, the General Mixed Yule Coalescent method, and the Poisson Tree Process and its Bayesian implementation). The new species is a sister group of C. itarare, a species that occurs in the Paranapanema river basin (upper Paraná river). Despite being located within a conservation unit, the new species is known from only two creeks, raising concerns about its long-term conservation.

Keywords: COI, conservation unit, freshwater fish, integrative taxonomy, south American darters

Live specimens of Characidium dumonti before fixation, sampled in Córrego Carlos Giovanni, tributary of Rio São João, Rio Iguaçu basin, Lower Rio Paraná.

 Photograph by Natália de Paula Lopes.

  Characidium dumonti, sp. nov.

Diagnosis: Characidium dumonti can be distinguished from its congeners, except Characidium bolivianum Pearson 1924, C. chicoi da Graça, Ota & Domingues 2019, C. iaquira Zanata, Ohara, Oyakawa & Dagosta 2020, C. kamakan Zanata & Camelier 2015, C. lanei Travassos 1967, C. nana Mendonça & Netto-Ferreira 2015, C. samurai Zanata & Camelier 2014, C. summus Zanata & Ohara 2015, C. tapuia Zanata, Ramos & Oliveira-Silva 2018, and C. xanthopterum Silveira, Langeani, da Graça, Pavanelli & Buckup 2008 by the absence of conspicuous dark-brown vertical bars, blotches and spots along the sides of body (vs. presence of conspicuous dark-brown vertical bars, blotches and spots along the sides of body in the remaining congeners). Characidium dumonti can be distinguished from C. bolivianum, C. iaquira, C. kamakan, C. lanei and C. summus by the scaled isthmus (vs. scaleless isthmus). From C. chicoi and C. nana by the presence of adipose fin (vs. absence of adipose fin). From C. xanthopterum by the presence of five scales series below lateral line (vs. four). From C. samurai and C. tapuia by the presence of a thin dark midlateral stripe occupying half scale height in vertical through dorsal-fin origin and one scale height on caudal peduncle (vs. broad lateral stripe occupying at least one scale height). The new species can be further distinguished from all congeners except C. xanthopterum by the presence of a reticulated colour pattern, with melanophores along the posterior edge of the scales (vs. absence of a reticulated colour pattern, without melanophores along the posterior edge of the scales) and from C. xanthopterum by the shorter dorsal and pelvic-fin height, 19.1%–23.7% and 12.1%–18.1% of Ls (vs. 24.9%–32.2% and 21.6%–27.4% of Ls), and shorter predorsal distance 44.5%–48.0% of Ls (vs. 49.2%–56.7% of Ls).

Etymology: The specific name dumonti was chosen in honour of Alberto Santos-Dumont (1873–1932), who is regarded as the father of aviation. In 1916, Dumont visited the area around the Iguaçu Falls and worked to convince the government to create a natural park there. His efforts were essential for the establishment of the Iguaçu National Park, a place that protects the type locality of Characidium dumonti and home of many other species. A genitive.

  

Map of the distribution of Characidium dumonti, inside Iguaçu National Park (INP-orange), Rio Iguaçu, lower Rio Paraná basin, Paraná, Brazil. The yellow circles represent localities of paratypes and the red star represents the type locality.

 

Bruno H. M. Stabile, Renan B. dos Reis, Alessandra V. de Oliveira and Weferson J. da Graça. 2025. A New Species of Characidium (Characiformes: Crenuchidae) from the Iguaçu National Park, Rio Iguaçu Basin, Paraná, Brazil. Journal of Fish Biology. DOI: doi.org/10.1111/jfb.70035 [09 April 2025]

[Ichthyology • 2024] Leporinus lignator • New banded Leporinus (Characiformes: Anostomidae) from the Madeira River basin, Brazil, and Redescription of L. bleheri, based on integrative taxonomy

Leporinus lignator

Boaretto, Ohara, Souza-Shibatta & Olivan Birindelli, 2024

 Neotrop. ichthyol. 22(4); 

www.scielo.br/j/ni/a/tRpkwnSVH3PndG7cmztzv8C 

Abstract

Leporinus bleheri was described for the Guaporé-Iténez basin, in the border between Bolivia and Brazil. More recently, specimens of a similar-looking banded Leporinus were sampled in distinct rivers in the Madeira basin. Herein, we use an integrative approach combining molecular and morphological data to investigate the taxonomic status of the new samples. Morphometric data were used to perform a Principal Components Analysis (PCA). Both species specimens were cleared and double-stained for osteological description. DNA barcodes were used to investigate the genetic distance between samples and for species delimitation analyses. Molecular markers COI, CytB, 16S, Myh6, RAG1, and RAG2 were applied to estimate the phylogenetic relationships of the two species. Our results show morphological and genetic differences between samples of L. bleheri and the new species. Both species are herein (re)described and illustrated. The new species is distinguished from L. bleheri by having 12 scale rows around the caudal peduncle (vs. 16). The genetic distance between the new species and L. bleheri was of 3.93%, and species delimitation analysis recovered the samples as separated molecular units. The multi-loci analysis corroborated the sister-group relationships between both species, including them within the Leporinus fasciatus group, which was recovered as non monophyletic.

Keywords: Anostomoidea; Amazon; Ostariophysi; Species delimitation analysis; Taxonomy

Leporinus lignator, MZUEL 21727, holotype, 152.96 mm SL
(A), MZUEL 21726, paratype, 117.01 mm SL (B), and holotype in life (C), type-locality
(D), Machado River, Madeira River basin, Brazil.

Leporinus lignator, new species

Diagnosis. Leporinus lignatoris distinguished from all other anostomids except L. affinis, L. altipinnis, L. bleheri, L. desmotes, L. enyae, L. fasciatus, L. jatuncochi, L. pearsoni, L. tigrinus, L. villasboasorum, and L. y-ophorus, by having dark vertical bars encircling the body in adults and nine branched pelvic-fin rays (vs. horizontal bars, dark blotches or dark transversal bars not encircling the body, and eight branched pelvic-fin rays). Leporinus lignator is distinguished from the formers except for L. bleheri and L. tigrinus by having three unicuspid teeth on the premaxillary and four on the dentary (vs. 3/3 or 4/4). Leporinus lignator is distinguished from L. bleheri and L. tigrinus by having 12 scales around the caudal peduncle (vs. 16).

Etymology. The specific epithet, lignator, is allusive to its type-locality, the Machado River, part of the Madeira River basin. In Portuguese, Machado means axe, and Madeira means wood. Lignator is Latin (m.) for a lumberjack who cuts trees into logs, often using axes. A noun in apposition.

Boaretto, Mariana; Pascoal Ohara, Willian; Massaharu Souza-Shibatta, Lenice; Olivan Birindelli, José Luís. 2024. New banded Leporinus (Characiformes: Anostomidae) from the Madeira River basin, Brazil, and Redescription of L. bleheri, based on integrative taxonomy. Neotrop. ichthyol. 22(4); https://www.scielo.br/j/ni/a/tRpkwnSVH3PndG7cmztzv8C/ 

[Ichthyology • 2024] Schizodon unimaculatus • A New Species from the lower Rio São Francisco with a reappraisal of the Schizodon species presenting a caudal-peduncle blotch (Characiformes: Anostomidae)

Schizodon unimaculatus 

Garavello, Britski, Oliveira & Melo, 2024

DOI: 10.11646/zootaxa.5537.2.5 

x.com/BrunFMelo

 

Abstract

Schizodon unimaculatus new species, is described from the lower sections of the Rio São Francisco in northeastern Brazil. The new species differs from all known Schizodon species by the combination of presenting a subinferior mouth, a prominent dark brown blotch on the caudal peduncle, a dark brown longitudinal stripe along the lateral line, and three series of small dark dots horizontally aligned forming interrupted lines on the dorsal and middle regions of the trunk. It differs from congeners with a horizontal stripe and a dark blotch on the caudal peduncle, viz., S. knerii, S. rostratus, S. jacuiensis, S. nasutus, S. isognathus, S. altoparanae, S. vittatus, and S. trivittatus, by the combination of scale counts in lateral line and around caudal peduncle, color pattern, mouth position, and body proportions. The subinferior mouth additionally distinguishes the new species from S. knerii, S. jacuiensis, S. nasutus, S. altoparanae, S. platae, S. isognathus, and S. rostratus. Principal component and canonical variation analyses additionally distinguish the new species from S. knerii, S. altoparanae, and S. nasutus. We discuss the taxonomic history, relationships, and significance of mouth morphology, coloration, and meristic characters in taxonomic studies of Schizodon.

 Pisces, Anostomoidea, Characiformes, morphometrics, Ostariophysi, taxonomy

Schizodon unimaculatus

Julio C. Garavello, Heraldo A. Britski, Alexandre K. Oliveira and Bruno F. Melo. 2024. Schizodon unimaculatus, A New Species from the lower Rio São Francisco with a reappraisal of the Schizodon species presenting a caudal-peduncle blotch (Teleostei: Anostomidae).  Zootaxa. 5537(2);  288-294245-258. DOI: doi.org/10.11646/zootaxa.5537.2.5

 x.com/BrunFMelo/status/1854904351237583223

[Ichthyology • 2024] Phylogeographic Patterns of Cyphocharax (Characiformes: Curimatidae) from trans-Andean Rivers and northward expansion to lower Central America

  

Cyphocharax spp.

in Melo, Conde-Saldaña, Villa-Navarro, McMahan et Oliveira, 2024.

DOI: 10.1111/jfb.15777 

x.com/TheFSBI

Abstract

Phylogenetic analyses of mitochondrial and nuclear data of 31 specimens of Cyphocharax from trans-Andean rivers support the presence of one lineage of Cyphocharax aspilos in Lago Maracaibo and three cryptic lineages of Cyphocharax magdalenae: (1) Cauca-Magdalena and Ranchería, (2) León and Atrato, and (3) Chucunaque-Tuira, Santa María, and Chiriquí basins of Central America. Results suggest that the Serranía del Perijá facilitated Late Miocene cladogenetic events, whereas post-Isthmian C. magdalenae expansion was enabled by gene flow across the lower Magdalena valley and Central American lowlands. Time-calibrated phylogenetics indicate that the C. magdalenae colonized lower Central America in the Pliocene (3.7 MYA; Ma), the divergence Atrato-Magdalena occurred in Late Pliocene (3.0 Ma) and the split Ranchería-Magdalena during the Middle Pleistocene (1.3 Ma). Updated geographic distribution data support the hypothesis that the Cordillera de Talamanca functions as a barrier to northward expansion of C. magdalenae in Central America.

Keywords: Characiformes, Magdalena, Maracaibo, Ostariophysi, Serranía del Perijá, Talamanca

Bruno F. Melo, Cristhian C. Conde-Saldaña, Francisco A. Villa-Navarro, Caleb D. McMahan and Claudio Oliveira. 2024. Phylogeographic Patterns of Cyphocharax from trans-Andean Rivers and northward expansion to lower Central America (Teleostei, Curimatidae). Journal of Fish Biology. 105(1); 314-325. DOI: doi.org/10.1111/jfb.15777

 x.com/TheFSBI/status/1813834913109422246

[Ichthyology • 2024] Myloplus aylan & M. sauron • Integrative Taxonomy of the Black-barred Disk Pacus (Characiformes: Serrasalmidae), including the Redescription of Myloplus schomburgkii and the Description of Two New Species

Myloplus sauron Pereira, Ota, Machado, Collins, Ândrade, Garcia-Ayala, Jégu, Farias & Hrbek, 
Myloplus aylan Pereira, Ota, Machado, Collins, Ândrade, Garcia-Ayala, Jégu, Farias & Hrbek, 
Myloplus schomburgkii (Jardine, 1841) 

in Machado, Pereira, Ota, Collins, Ândrade, Garcia-Ayala, Jégu, Farias et Hrbek, 2024

DOI: 10.1590/1982-0224-2023-0095 

Abstract

Presently, Myloplus schomburgkii is the most easily recognized species among the serrasalmids by having a vertical black bar in the middle of the body. However, through a broad taxonomic review, including DNA barcoding and morphological analyses, we were able to identify and describe two new species that also share a dark vertical bar on the flank. In addition, we redescribe M. schomburgkii, designating a neotype and restricting the type-locality to rio Negro in Barcelos, Amazonas State, Brazil. The three lineages of black-barred pacus present high molecular divergences (7.9–11%) and can be distinguished by differences in the shape of the vertical bar, shape of females’ anal fin, number of total vertebrae, number of total branched dorsal-fin rays, among other characters. Although the existence of these two new species has been hidden due to many morphological similarities, mainly the presence of the black bar, the three lineages do not compose a monophyletic group, with one of the new species being recovered as sister to Ossubtus xinguense. This result reinforces the necessity of the redefinition of the Myleini genera.

Keywords: Amazon basin; COI; DNA barcoding; Myleini; Neotype

 

Myloplus sauron, color pattern in life. Young specimen from Xingu River basin, specimen not preserved.

Myloplus schomburgkii, color pattern immediately after capture. 

A. INPA 60149, neotype, 203.9 mm SL, male, with second lobe well developed and remarkable breeding coloration. 

B. INPA 52507, 197.1 mm SL, female. Both from Amazonas, Barcelos municipality, rio Negro.

Myloplus aylan, coloration immediately after capture. Mature female, lago Uauaçu, Purus River basin. Photographed by Lucia Rapp Py-Daniel.

Myloplus aylan Pereira, Ota, Machado, Collins, Ândrade, Garcia-Ayala, Jégu, Farias & Hrbek, new species

Diagnosis. Myloplus aylan can be distinguished from all congeners, except M. schomburgkii and M. sauron n. sp. (described below), by the presence of a vertical black bar on the flank commonly extending from the dorsal-fin base to the pelvic-fin distal end (vs. absence of any conspicuous mark on the flank in the rest of the congeners). The new species can be diagnosed from M. schomburgkii and M. sauron by the following characters: parietal bone with dorsal surface markedly concave in lateral view (vs. straight to slightly concave), 82–95 (mode 84) total perforated scales on lateral line [vs. 68–87 (mode 79) in ...

Etymology. The specific name honors the late Aylan Moraes Andrade, Carine Moraes and Marcelo Andrade’s son, born on December 23, 2022, who passed away prematurely on July 6, 2023. Marcelo is one of the authors of this manuscript and this is a tribute to record all the love and dedication of his parents who will never forget him. A noun in apposition.

Myloplus sauron Pereira, Ota, Machado, Collins, Ândrade, Garcia-Ayala, Jégu, Farias & Hrbek, new species

Etymology. The specific name sauron alludes to the Eye of Sauron, from J. R. R. Tolkien’s “The Lord of the Rings”. The elliptical body of Myloplus sauron, marked with a vertical, black bar tapering toward both ends, resembles the famous vertical-pupilled eye from the novel. A noun in apposition.

Sympatric occurrence of Myloplus schomburgkii (left) and M. aylan (right) in rio Água Boa do Univini, tributary of rio Branco. Both specimens are mature males, the specimens has not being preserved.

Myloplus schomburgkii (Jardine, 1841) 

Etymology. Myloplus schomburgkii was described in honor of Robert H. Schomburgk, who, during an expedition to English Guyana, collected individuals of the species, took notes, and illustrated (Fig. 14) the specimen used by Jardine (1841) to describe the new species. A genitive noun.

 

  Valéria N. Machado, Victória D. Pereira, Rafaela P. Ota, Rupert A. Collins, Marcelo Ândrade, James R. Garcia-Ayala, Michel Jégu, Izeni P. Farias and Tomas Hrbek. 2024. Integrative Taxonomy of the Black-barred Disk Pacus (Characiformes: Serrasalmidae), including the Redescription of Myloplus schomburgkii and the Description of Two New Species.   Neotrop. ichthyol. 22 (2); DOI: 10.1590/1982-0224-2023-0095