[Ichthyology • 2026] Laimosemion laranja • A New killifish of the Genus Laimosemion (Cyprinodontiformes: Rivulidae) from Rio Cajari in the Brazilian Amazon

Laimosemion laranja 

Abrantes, Lima, Nielsen, de Lira, da Silva & Berbel-Filho, 2026

 

DOI: doi.org/10.3897/zse.102.187659

Abstract

Based on morphological and molecular evidence, this study describes a new species of rivulid of the genus Laimosemion from the lower Rio Amazonas Basin in the south of the state of Amapá in northern Brazil. The new species, Laimosemion laranja sp. nov., exhibits a color pattern characteristic of the L. geayi species group, consisting of longitudinal rows of spots on the anterior portion of flank and oblique chevron-shaped bars on the posterior portion of flank. It can be distinguished from its congeners by unique combination of characters, including position of dorsal-fin origin relative to anal-fin rays, frontal squamation pattern of head, counts of transverse and longitudinal scale series, fin-ray counts, vertebral count, osteology of caudal fin, and number of neuromasts in infraorbital series. Partial sequences of the mitochondrial cytochrome c oxidase subunit I (cox1) gene indicates that the new species diverges genetically by 5.3% from its closest relatives, L. agilae and L. strigatus, by 9.2% from L. dibaphus, and 12.3% from L. geayi. We further discuss the systematic relationships within the L. geayi species group and the conservation status of the new species based on IUCN criteria, including recommendations for its conservation.

Key Words: Amapá State, Amazonas Estuary and Coastal Drainages Ecoregion, Amazonian ichthyofauna, conservation

Laimosemion laranja new species
 Holotype [INPA–ICT 062600], male, 26.8 mm SL; 
 Paratype [INPA–ICT 062601], female, 20.1 mm SL 
Brazil, Amapá, Laranjal do Jari, Rio Cajari, Amazonas Basin.

photos: Y. Abrantes. 

 

Laimosemion laranja sp. nov.

Diagnosis. Laimosemion laranja differs from the six congeners of the L. geayi group by having eight scales in transverse series (vs.7 in L. dibaphus and L. strigatus, 9 in L. geayi, 9–10 in L. agilae and L. cladophorus, and 9–11 in L. mabura). It can be distinguished from all other congeners of the L. geayi group, except L. agilae and L. cladophorus, by dorsal-fin origin positioned on transversal plane through bases of 4th–6th anal-fin rays in both sexes (vs. of 7th–8th anal-fin rays). It differs from L. agilae by frontal squamation pattern of head (E squamation vs. F squamation) and from ...

Etymology. The specific epithet ‘laranja’ is a name with a dual allusion. It refers to the bright orange color pattern on males of the new species (‘laranja’ means the color, as it also means the fruit in Portuguese), and is also an homage to the municipality of Laranjal do Jari, founded on December 17, 1987, in the south of Amapá State, Brazil, from where the species is currently only found. A noun in apposition.

Sampling localities of Laimosemion laranja new species.
 Localities one and two (A, B), and the type locality (C). Brazil, Amapá, Laranjal do Jari, Rio Cajari, Amazonas Basin.

 Photos: W.M. Berbel-Filho.

Yuri Gomes Abrantes, Sergio Maia Queiroz Lima, Dalton Tavares Bressane Nielsen, Fabio Origuela de Lira, Márcio Joaquim da Silva, Waldir Miron Berbel-Filho. 2026. A New killifish of the Genus Laimosemion (Cyprinodontiformes, Rivulidae) from Rio Cajari in the Brazilian Amazon. Zoosystematics and Evolution. 102(4): 1079-1088. DOI: doi.org/10.3897/zse.102.187659 [20 Aug 2026]

[Ichthyology • 2025] Xenurolebias tupinikin • Habitat and Conservation Assessment of Annual Killifishes of the Genus Xenurolebias (Cyprinodontiformes: Rivulidae: Cynolebiinae) from Coastal Floodplains, Including the First Record South of the Rio Doce, Southeastern Brazil

  

Xenurolebias tupinikin

 Gomes, Sarmento-Soares, Martins-Pinheiro & Leite, 2025

 Xenurolebias izecksohni,  X. cricarensis 

DOI: doi.org/10.3390/d17090644 

Abstract

The Atlantic Forest coastal tablelands is home to a wide diversity of small-sized freshwater fish sharing a biogeographically congruent distributional pattern. The annual killifish Xenurolebias are among these remarkable inhabitants in the riparian wetlands with four species in the area. Xenurolebias pataxo are located between the Jucuruçu and Mucuri rivers, geographically replaced by Xenurolebias myersi at the Riacho Doce and the Rio Itaúnas, and, further south, Xenurolebias cricarensis are in the floodplains of the Rio São Mateus and Xenurolebias izecksohni, living in temporary environments of the Rio Barra Seca, north of the Rio Doce. Due to their restricted habitat in the lowlands, these annual killifish could all be designated as a target species, providing benefits in the conservation of riparian wetlands. However, less is known about their habits and real distribution. Otherwise, the accelerated habitat loss is worrisome. Two of these species are threatened with extinction on Red Lists; one is Near-Threatened; and one is Data-Deficient. After ten years since the last species description, our investigations revealed a fifth species, the first recorded south of Rio Doce. The present contribution aims to characterize the occupied habitat by each species within the temporary environments and present an updated distributional data on these fish. Additionally, a new Xenurolebias is described, the first one recorded south of Rio Doce.

Keywords: Atlantic Forest; Rio Riacho; swamp; cloud fish; endemism

 Diagnostic features for Xenurolebias tupinikin. 

Dark blotch overlapping the median portion of the last stripe on the caudal peduncle (arrows).

 Xenurolebias tupinikin: 

MNRJ 56004, male, holotype, 23.4 mm SL; 

MNRJ 56005, female, paratype, 35.4 mm SL. 

Pool at flooded area on Sertão do Riacho stream, Aracruz, Espírito Santo, Brazil.

Xenurolebias tupinikin sp. nov. 

 Diagnosis. Xenurolebias tupinikin is distinguished from remaining congeners by adult males presenting in life a dark blotch overlapping the median portion of the last stripe on the caudal peduncle (Figure 2). It further differs from congeners, except X. myersi, by presenting the dorsal and anal fin borders with a black outline. Additionally, it is distinct from X. myersi by a body depth of 25.9–27.9 in SL (vs. 29.0–31.4 in SL).

It differs from X. izecksohni and X. cricarensis by the caudal fin in males with 5–6 bars (vs. 7–14 bars) and by male head depth 64.5–76.9% of HL (vs. 81.2–85.6% of head length in males). It further differs from X. pataxo and X. myersi due to no yellow spots on the distal half of the dorsal fin in males (vs. yellow spots present).

Etymology. The specific name is a reference to the Tupiniquim Indigenous people, inhabitants of lowlands in the central north of Espírito Santo. On the left margin of the Rio Comboios is the Indigenous land Comboios (Figure 4, green stripes near coast), which corresponds to the nearest human occupation relative to the environments inhabited by these fish.

 Xenurolebias izecksohni: (A) MBML 14205, male, 54.2 mm SL; (B) MBML 14208, female, 29.6 mm SL. Isolated pool in flooded area in Barra Seca, Linhares, Espírito Santo, Brazil.

Images: Bruno Pinheiro.

Couple of Xenurolebias cricarensis in field aquarium. Female in front, male behind.

 Image: Bruno Pinheiro.

 Bruno Pinheiro Gomes, Luisa Maria Sarmento-Soares, Ronaldo Fernando Martins-Pinheiro  and Gustavo Rocha Leite. 2025. Habitat and Conservation Assessment of Annual Killifishes of the Genus Xenurolebias (Rivulidae: Cynolebiinae) from Coastal Floodplains, Including the First Record South of the Rio Doce, Southeastern Brazil. Diversity. 17(9), 644. DOI: doi.org/10.3390/d17090644 [12 September 2025]

(This article belongs to the Special Issue Evolution, Systematic and Conservation of Freshwater Fishes)

[Ichthyology • 2025] Campellolebias insularis • A New and threatened Species of internally inseminating Seasonal Killifish of Campellolebias (Cyprinodontiformes: Rivulidae) endemic to a continental island in the Atlantic Forest, Southern Brazil

 

  Campellolebias insularis 

 Volcan, Garcez, Robe, Feltrin, Costa & Lanés, 2025.  

DOI: doi.org/10.1016/j.jcz.2025.03.004 

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Abstract

Campellolebias comprises small internally inseminating seasonal fishes that inhabit temporary pools in tropical and subtropical areas of the Atlantic Forest. It currently encompasses four species. Integrative taxonomy was used here to investigate a possible new species found in the island of Florianópolis, southern Brazil. The examined material confirm that it pertains to a new species. Furthermore, minimum genetic distances found between this and other species of Campellolebias regarding mitochondrial markers were higher than 3 %. This new species is distinguished from all other species of Campellolebias by the combination of a series of character states, including the color pattern in both sexes, pelvic-fin bases separated by an interspace, pelvic-fin tips reaching base of the 1st anal-fin ray in males and the urogenital papilla in females, by possessing 1–2+24-29 infraorbital neuromasts, 2–4 otic neuromasts, and by the anal-fin origin being positioned at a vertical between the base of the 4th and 6th dorsal-fin ray in females. Campellolebias insularis, new species, occurs exclusively in small temporary wetlands in areas under strong threat due to real estate development, in the island of Florianópolis. Due to the advanced stage of habitat loss and degradation, its restricted distribution area, and the reduced populations sizes, the species is considered Critically Endangered. Additionally, comments are provided on the putative relationships of the new species, its conservation status, and an identification key for the species of Campellolebias.

 

Keywords: Annual fish, Conservation, Endangered species, Identification key, Neotropical region, Taxonomy

  Campellolebias insularis, new species, UFRJ 14432, live male holotype, Florianópolis, Santa Catarina, Brazil. 

Photo by Wilson Costa.

  Campellolebias insularis, new species, UFRGS 29965, male paratype, Florianópolis, Santa Catarina, Brazil.

Photo by Matheus Volcan.

Matheus Vieira Volcan, Daiana Kaster Garcez, Lizandra Jaqueline Robe, Caio Roberto Magagnin Feltrin, Wilson José Eduardo Moreira Costa and Luis Esteban Krause Lanés. 2025. A New and threatened Species of internally inseminating Seasonal Killifish of Campellolebias (Cyprinodontiformes: Rivulidae) endemic to a continental island in the Atlantic Forest, Southern Brazil. Zoologischer Anzeiger.  316; 75-84. DOI: doi.org/10.1016/j.jcz.2025.03.004

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[Ichthyology • 2025] Titanolebias calvinoi • The Rise of a Titan: A New Species of the giant Titanolebias Killifishes (Cyprinodontiformes: Rivulidae), and its phylogeny

 

Titanolebias calvinoi 

Alonso, Terán, Alanís, Waldbillig, Montes, Bugeau, Barneche, Shimabukuro, Táboas, Maroli & Almeida, 2025

DOI: doi.org/10.1016/j.jcz.2025.04.009 

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ABSTRACT

The genus Titanolebias comprises the largest-bodied seasonal killifishes, inhabiting temporary wetlands of the La Plata Basin and adjacent areas in South America. Here, we describe a new species from the Eastern Chacoan region, representing the first record of the genus in this area, providing important biogeographic and evolutionary insights. Phylogenetic analyses confirm the monophyly of Titanolebias, placing T. monstrosus as the sister species to the remaining species of the genus and recovering the new species as sister to a clade composed of T. prognathus, T. elongatus, and T. cheradophilus. Titanolebias species, exhibits reduced sexual dimorphism, potentially associated with a trophic shift toward larger prey in the origin of this genus and presents several potential cases of aggressive mimicry. Megalebias genus represents a case of convergent evolution towards ichthyophagy with Titanolebias. Morphological analyses reveal that the new species present the diagnostic characters of the genus Titanolebias and can be distinguished by its unique coloration and other morphological traits. Behavioral and ecological data are also provided. Despite its restricted distribution and the vulnerability of ephemeral wetlands to habitat loss, the species is found within a National Park. This discovery provides valuable insights into convergent evolution linked to trophic shifts and contributes to the understanding of the evolution, phylogeny, ecology, and biogeography of Neotropical fishes, offering new avenues for future research and conservation policies for this threatened group of fishes.

Key words: sexual dimorphism, aggressive mimicry, biogeography, endemisms, temporary wetlands, annual fishes, conservation, Aplocheiloidei

 Live color pattern variability and ontogenetic changes in Titanolebias calvinoi n. sp. males.

 Titanolebias calvinoi, new species

Etymology: The specific epithet is dedicated to Pablo Andrés Calviño, in recognition of his notable contributions to Neotropical ichthyology and his pioneering efforts in the study and promotion of knowledge about killifish. Calviño has not only actively participated in scientific research on this group of fish but has also distinguished himself as one of the most notable aquarists and breeders in the region. Additionally, he has significantly contributed to the training of human resources in this field, enhancing public awareness and understanding through the organization of activities, creation of dissemination materials, and his dedicated teaching efforts, being one of the founders of the Killi Club Argentino (KCA). The term calvinoi is a patronymic in the genitive case.

 

Felipe Alonso, Guillermo Enrique Terán, Wilson Sebastián Serra Alanís, Marcos Martin Waldbillig, Martin Miguel Montes, Baltazar Bugeau, Jorge Adrian Barneche, Marina Ibañez Shimabukuro, Francisco González Táboas, Malena Maroli and Matías Jesús Almeida. 2025. The Rise of a Titan: A New Species of the giant Titanolebias Killifishes, and its phylogeny (Cyprinodontiformes: Rivulidae). Zoologischer Anzeiger. In Press DOI: doi.org/10.1016/j.jcz.2025.04.009 [3 May 2025]

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[Ichthyology • 2022] Moema juanderibaensis • A New Species of the Seasonal Killifish Genus Moema (Cyprinodontiformes: Rivulidae) from the Piraí watershed in the Southwest Amazon Basin

 

Moema juanderibaensis

 Drawert, 2022 

DOI: 10.1590/1982-0224-2022-0067  

   Researchgate.net/publication/366335860

 

Abstract

Moema, a genus of the Rivulidae family, currently comprises 20 valid species. Most of these species inhabit temporary pools in the Amazon basin and only one species is found in the upper Paraguay basin. A new member of this genus from the upper Río Madeira drainage is here described. Males of the new species differ from all congeners by the combination of a color pattern consisting of oblique, sometimes chevron-like, irregular rows of red and light blue double-dots on body; dark yellowish to golden pectoral fins with no visible markings; and a stripe pattern on the ventral section of caudal fin with a very narrow black marginal line, intermittent or even absent. The existence of infrageneric species groups within Moema, the geographic distribution and taxonomic aspects of the species present in the Ríos Mamoré and Iténez/Guaporé rivers drainages, and the observation of intraspecific aggression between males and amphibious lifestyle in the new species are discussed.

Keywords: Bolivian Amazon basin; New species; Rivulids; Taxonomy; Temporary water bodies

 

Moema juanderibaensis, MNKP 16539, holotype, male, 41.9 mm SL
(24 days after collection, left side),
Bolivia, Santa Cruz, Santa Rosa del Sara.

Moema juanderibaensis, MNKP 16539, holotype, male, 41.9 mm SL
(2 days after collection, right side),
Bolivia, Santa Cruz, Santa Rosa del Sara.

Moema juanderibaensis, new species

Diagnosis. Moema juanderibaensis differs from congeners by a unique combination of the following characters on males: pattern of oblique, sometimes chevron-like, irregular rows of red and light blue double-dots on flanks; dark yellowish to golden pectoral fin with no visible markings (dots or spots); and ventral part of caudal-fin stripe pattern with very narrow black marginal line, intermittent or even absent (vs. never in this combination). The new species is distinguished from Moema apurinan, M. beucheyi, M. funkneri, M. hellneri, M. heterostigma, M. nudifrontata, M. pepotei, M. piriana, M. portugali, M. quiii, M. schleseri, and M. staecki by the oblique arrangement of red and light blue double-dots on flanks (vs. flank color pattern arranged in horizontal lines or rows of dots). It differs from M. manuensis, M. obliqua, M. peruensis, M. rubrocaudata, M. schleseri, and M. wischmanni by the presence of red dots on flanks mostly arranged in oblique, sometimes chevron-like, rows (vs. absence of dots, or arranged in vertical rows or randomly distributed). It is distinguishable from M. boticarioi, M. kenwoodi, and M. obliqua by the absence of dots, spots or any other markings on pectoral fins of males (vs. presence of dark reddish-brown dots, few dark green dots or longitudinally elongated dark brown spots); from M. claudiae by the absence of black humeral blotch in males (vs. presence); and from M. schleseri by the ground color of pectoral fins (brown-yellowish to golden vs. hyaline) and color pattern of ventral section of caudal fin (thin black marginal line, sometimes intermittent and inconspicuous or even absent, and broad deep orange to red stripe vs. ventralmost black stripe broad, and orange stripe with dark red dots). Additionally, it is also distinguished from M. boticarioi by the absence of brown dots or other marks on dorsum (vs. dorsum with brown dots).

Etymology. Named juanderibaensis in reference to the name of the ranch “Juan Deriba” where the type locality is situated. An adjective.

Heinz Arno Drawert. 2022. A New Species of the Seasonal Killifish Genus Moema (Cyprinodontiformes: Rivulidae) from the Piraí watershed in the Southwest Amazon basin.   Neotrop. ichthyol. 20(4). DOI: 10.1590/1982-0224-2022-0067   

  Researchgate.net/publication/366335860_A_new_species_of_Moema_from_the_Pirai_watershed_in_the_SW_Amazon_basin

Resumen: Moema, un género de la familia Rivulidae, actualmente comprende 20 especies válidas. La mayoría de estas especies habitan en charcos temporales de la cuenca amazónica y solo una especie se encuentra en la cuenca alta del Río Paraguay. Un nuevo miembro de este género de la cuenca alta del Río Madeira es descrito aquí. Los machos de la especie nueva se diferencian de todos los congéneres por la combinación de un patrón de color de filas irregulares oblicuas, a veces en forma de chevrón, de puntos dobles rojos y azul claro en el cuerpo; aletas pectorales de color amarillento oscuro a dorado sin marcas visibles; y un patrón de rayas en la sección ventral de la aleta caudal con una línea marginal negra muy estrecha, intermitente o incluso ausente. Se discute la existencia de grupos infragenéricos de especies dentro de Moema, la distribución geográfica y aspectos taxonómicos de las especies presentes en el drenaje de los Ríos Mamoré e Iténez/Guaporé, y la observación de agresión intraespecífica entre machos y estilo de vida anfibio en la nueva especie.

Palabras clave: Cuenca amazónica de Bolivia; Cuerpos de agua temporales; Nueva especie; Rivúlidos; Taxonomía

[Ichthyology • 2024] Austrolebias ayoreode • Redescription of Austrolebias accorsii (Cyprinodontiformes: Rivulidae) and Description of A New Species of the Genus from the upper Paraguay River Basin

Austrolebias ayoreode

 Drawert & Ergueta, 2024

DOI: 10.1590/1982-0224-2024-0001  

Abstract

Austrolebias accorsii is redescribed based on specimens from type-locality, nearby temporary pools, and other locations within the same hydrologic unit. Additionally, a novel Austrolebias species is described, exclusively found in two temporary waterbodies in “Abayoy”, a unique vegetation type situated in the transitional zone between the Dry Chaco, Chiquitano Dry Forest, and Pantanal Flooded Savannas ecoregions in southeastern Bolivia, bordering Paraguay, where the last voluntarily isolated indigenous people outside the Amazon in America reside. Diagnostic characters for both species are presented. Within Austrolebias two species groups are recognized with different morphological characters, geographical distribution, and ecological traits of their habitats. Furthermore, we suggest the usage of median and interquartile range rather than mean and standard deviation to analyze morphometric and meristic data of rivulids, given the typically non-Gaussian distribution of this data.

Keywords: Chaco; Killifish; Seasonal fish; Taxonomy; Temporary water bodies

Austrolebias ayoreode. Males (immediately after collection).
Two uppermost: MNKP 16590, paratypes, 34.7–34.8 mm SL, Bolivia, Santa Cruz, Cordillera, Charagua Iyambae Guarani Autonomous Territory, Ñembi Guasu Conservation and Ecological Importance Area.
Lower six: MNKP 16587, paratypes, 21.2–34.7 mm SL, collected with uppermost.

Austrolebias ayoreode. Male and female (1 day after collection).
Above: MNKP 16612, holotype, male, 50.7 mm SL, Bolivia, Santa Cruz, Cordillera, Charagua Iyambae Guarani Autonomous Territory, Ñembi Guasu Conservation and Ecological Importance Area.
Below: MNKP 16587, paratype, female, 38.1 mm SL, collected with holotype.

Austrolebias ayoreode. Females (immediately after collection).
Above: MNKP 16590, paratype, 26.1 mm SL; Bolivia, Santa Cruz, Cordillera, Charagua Iyambae Guarani Autonomous Territory, Ñembi Guasu Conservation and Ecological Importance Area.
Below: MNKP 16587 (vertically flipped), paratype, female, 38.1 mm SL, collected with MNKP 16590.

Austrolebias ayoreode, new species 

Diagnosis. Austrolebias ayoreode males differs from all congeners, except A. accorsii, A. ephemerus,and A. vandenbergi, by presence of 1–3 transverse rows of scales on basal anterior and median portion of anal fin. Males of A. ayoreode can be distinguished from A. accorsii, A. ephemerus, A. melanoorus, A. queguay, and A. vandenbergi by presence of whitish to pale yellowish dots on flanks usually vertically aligned in unarranged rows (vs. absent in A. accorsii; mostly coalesced in vertical bars in A. ephemerus, A. melanoorus, and A. queguay; absent or, when rarely present, sparse and scattered in A. vandenbergi); from A. accorsii and A. vandenbergi by urogenital papilla mostly ...

Etymology. The name ayoreode is an eponym conferred in reference to the indigenous Ayoréode people, who historically occupied vast expanses of the northern Dry Chaco, and of whom a few groups still persist in the area of the type-locality of this species, standing as the last indigenous people in voluntary isolation outside of the Amazon in the Americas. Through this nomenclature, we intent to perpetuate the memory of the existence of the Ayoréode and emphasize the imperative of preserving their ancestral territory, which also is the habitat of the species described herein.

Heinz Arno Drawert and Carlos Ergueta. 2024. Redescription of Austrolebias accorsii (Cyprinodontiformes: Rivulidae) and Description of A New Species of the Genus from the upper Paraguay River basin.   Neotrop. ichthyol. 22 (2); DOI: 10.1590/1982-0224-2024-0001  

[Ichthyology • 2020] Melanorivulus larissae • A New Species of the Melanorivulus pictus Species-group (Cyprinodontiformes: Rivulidae) from the Rio Paraná Basin in Brazil

Melanorivulus larissae 

Ywamoto, Nielsen & Oliveira, 2020

 DOI: 10.11646/zootaxa.4852.1.6

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Abstract

A new species of the genus Melanorivulus belonging to the Melanorivulus pictus species group is herein described, from a tributary of the Rio Grande, Rio Paraná basin, São Paulo State, Brazil. The new species can be distinguished from all other species of the Melanorivulus pictus species group by the unique presence of sides of body of males light bluish gray with 10–12 oblique red bars, 8 of which chevron-like, bifurcated and complete, i.e., running from dorsum to ventral area, and 2–4 incomplete, with vertices of the chevron-like bars along midbody, pointing forward. Comments on the putative relationships of the new species, as well as concerning its conservation status, are presented.

Keywords: Cyprinodontiformes, Rio Grande basin, Rivulus, Melanorivulus apiamici, Melanorivulus leali, Cerrado, Killifishes

 

Melanorivulus larissae, new species, living holotype, male, ZUEC 17154, male, 23.4 mm SL. 

Photo by Eric V. Ywamoto.

Melanorivulus larissae, new species 

Etymology. Named in honor of Larissa da Silva Sobral, daughter of the discoverer of the species.  

 Eric Venturini Ywamoto, Dalton Tavares Bressane Nielsen and Claudio Oliveira. 2020. Description of A New Species of the Melanorivulus pictus Species-group (Cyprinodontiformes: Rivulidae) from the Rio Paraná Basin in Brazil.  Zootaxa. 4852(1); 125–132. DOI: 10.11646/zootaxa.4852.1.6

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[Ichthyology • 2014] Papiliolebias ashleyae • A New Annual Fish (Cyprinodontiformes: Rivulidae) from the upper Rio Mamoré basin, Bolivia

Papiliolebias ashleyae 

 Nielsen & Brousseau, 2014 

Abstract 

Papiliolebias ashleyae n. sp. is described from Bolivia, departamento de Santa Cruz, Rio San Pablo, upper Mamoré basin. Papiliolebias ashleyae n. sp. is distinguished from other Papiliolebias species by a combination of characters: male overall color pattern of body, caudal- and pelvic-fins brownish red (vs. dark blue); transverse brownish red bars in dorsal and anal fins located between black and white bar at base of dorsal and anal fins and blue area in distal part of dorsal and anal fins (vs. absence of redbrown stripe on the remaining species of the genus, where the color of dorsal and anal fins is blue with a black stripe and white spots at the base of the fins); dorsal-fin origin at vertical through base of anal fin rays 9th-10th (vs. dorsal fin origin at vertical through base of anal fin rays 7th-8th in P. bitteri and 6th-9th in P. hatinne) and pelvic fins separated by small interspace of 4 mm (vs. not separated).

Fig. 1. Papiliolebias ashleyae, male, holotype, 34.7 mm SL: Bolivia, San José dos Chiquitos (in life).

Photo by D. Nielsen.

Papiliolebias ashleyae, n. sp.

Diagnosis: Papiliolebias ashleyae differs from the remaining species of Papiliolebias by a lower prepelvic length in males (43.6-44.7% SL vs. 44.9- 51.5% SL), a lower pre-pelvic length in females (43.3-46.8% SL vs. 48.2-51.7% SL), and by the color pattern of males which shows an overall redbrownish coloration, including the dorsal, caudal and pelvic fins basis (vs. overall color pattern dark blue, but never red-brown). It also presents a reddish-brown stripe on the basis of the dorsal and anal fins, with whitish blotches, and distal portion of anal- and caudal-fins bluish (vs. absence of reddish-brown stripe in the remaining species of the genus, where the caudal and anal-fin basis possess white and black spots); dorsal-fin origin at vertical through base of anal-fin rays 9th-10th (vs. 7th-8th in P. bitteri and 6th-9th in P. hatinne); body with brownish-red background and iridescent greenishblue scales, forming slender, oblique, ladder-like stripes (vs. oblique thick lines arranged parallel to each other); pelvic-fin red, with three spots (from basal to distal portion of fin): white, dark red and white (vs. dark blue without spots); third pelvic fin-rays transformed into a filament (vs. third pelvic-fin ray not transformed into a filament), and pelvic-fin separated by a small 4 mm interspace (vs. not separated).

Etymology: In honor of the daughter of Dr. Roger Brousseau, Ashley Kimberly Brousseau, who collected the first specimen of the species.

Dalton Tavares Bressane Nielsen and Roger Brousseau. 2014. Description of A New Annual Fish, Papiliolebias ashleyae (Cyprinodontiformes: Rivulidae) from the upper Rio Mamoré basin, Bolivia. aqua, International Journal of Ichthyology. 20(1); 53-59. 

http://www.aqua-aquapress.com/pdf/20(1)-Papiliolebias-ashleyae.pdf

theguardian.com/environment/gallery/2017/sep/06/upto-381-new-species-discovered-in-the-amazon-in-pictures

[Ichthyology • 2019] Austrolebias ephemerus • A New Annual Fish (Cyprinodontiformes: Rivulidae) from the upper Rio Paraguai basin, Brazilian Chaco

Austrolebias ephemerus

Volcan & Severo-Neto, 2019

  DOI: 10.11646/zootaxa.4560.3.6

Abstract

A new species of Austrolebias belonging to the A. bellottii species group is herein described from the Brazilian Chaco, Mato Grosso do Sul state, constituting the northernmost record of the genus in Brazil, as well as the first record of this genus on the left bank of the Rio Paraguai. The new species is distinguished from all other species of the A. bellottii group by the following combination of characters: pectoral fin posterior margin reaching vertical between base of 4th and 7th anal fin rays in females, a high number of gill rakers in the first branchial arch, a lower head width in both sexes, and a small number of neuromasts in the preopercular series. Additionally, we provide information on ecology and the conservation status of the new species.

Keywords: Pisces, Austrolebias bellottii species group, seasonal pool, conservation, killifish

Matheus Vieira Volcan and Francisco Severo-Neto. 2019. Austrolebias ephemerus (Cyprinodontiformes: Rivulidae), A New Annual Fish from the upper Rio Paraguai basin, Brazilian Chaco.  Zootaxa. 4560(3); 541–553.  DOI: 10.11646/zootaxa.4560.3.6

[Ichthyology • 2018] Austrolebias queguay • A New Species of Annual Killifish (Cyprinodontiformes, Rivulidae) Endemic to the lower Uruguay River Basin

Austrolebias queguay

Serra & Loureiro, 2018  

  DOI: 10.3897/zse.94.29115  

Abstract
In this article we describe a new species of the annual fish genus Austrolebias from the lower Uruguay river basin. The fusion of the urogenital papilla to the first anal fin ray in males and the pigmentation pattern, indicates a close relationship with the clade formed by A. bellottii, A. melanoorus, and A. univentripinnis. The new species can be differentiated from those by the following combination of characters: presence of well-defined light bands contrasting with the sides of the body, the distal portion of the anal fin dark gray, pelvic fins dark bluish green and bases united at about 50–80% on their medial margins, pectoral fins with iridescent blue sub-marginal band, and general coloration of body bluish green. The new species can only be found in wetlands of the Queguay river, an area included in the Uruguayan protected areas system and represents so far the only annual fish species endemic to the lower Uruguay river basin.

Key Words: Austrolebias bellottii species group, Systematics, La Plata basin

Austrolebias queguay sp. n. 
Figure 2. A. paratype male (ZVCP 11620); B. non type male, not preserved (right side, photo flipped)

Figure 2. A. Austrolebias queguay sp. n. paratype male (ZVCP 11620); B. A. queguay non type male, not preserved (right side, photo flipped); C. i non preserved male; D. A. univentripinnis male (UFRGS 18064, right side photo flipped); E. A. melanoorus topotype male (ZVCP13651); F. Detail of pectoral and pelvic fins of A. melanoorus; G. Detail of pectoral and pelvic fins of  A. queguay.

Figure 3. A. Austrolebias queguay sp. n. female: paratype ZVCP 11620; B. A. bellottii female (ZVCP 11560); C. A. univentripinnis female (UFRGS 18066); D. A. melanoorus topotype female (ZVCP 13651).

Austrolebias queguay sp. n.

Austrolebias sp. in Loureiro et al. (2018)

Diagnosis: The new species differs from all the other species of the genus except Austrolebias bellottii, A. univentripinnis and A. melanoorus, by the presence of the urogenital papilla attached to the anal fin in males (vs. free from the anal fin). It differs from A. bellottii and A. univentripinnis by the presence of well-defined light blue bands contrasting with the sides of the body in adult males (vs. vertical rows of light blue dots) (Fig. 2); from A. melanoorus, by the presence of dark gray coloration of the distal portion of the anal fin in males (vs. distal portion of anal-fin black), pelvic-fins dark bluish green (observed in ventral view) and bases united at about 50–80% on their medial margins (vs. dark gray and united about 50% or less), pectoral-fins with iridescent blue sub-marginal band (vs. sub-marginal band absent), and general coloration of the body bluish green (vs. grayish sky blue).

 Figure 6. Geographic distribution of Austrolebias queguay sp. n. (orange dots, Uruguay river basin), A. bellottii (yellow dots, Paraná and Uruguay river basins), A. melanoorus (red dots, Negro and Yaguarón river basins), and A. univentripinnis (green dots, Yaguaron river basin). Orange star indicates type locality.

Figure 7. Type locality of Austrolebias queguay sp. n., wetlands of middle Queguay river basin.

Etymology: The specific name, queguay, is in reference to Queguay river basin, the type locality of the new species, treated as a noun in apposition to the generic name.

Distribution: Austrolebias queguay is endemic to the wetlands of middle Queguay river basin (30 meters above sea level), Paysandú Department, Uruguay, which flows to the lower Uruguay river (Fig. 6).

Ecology: As many species of the family Rivulidae, A. queguay presents an annual life cycle which includes drought resistant eggs and diapausing embryos. All species of Austrolebias are obligate annuals (Berois et al. 2016). In the Pampa biome there is not a defined dry season, so dried environments can be found between mid spring to early fall (depending on the year), when evaporation is higher than precipitations (Williams 2006; García et al. 2017). Austrolebias species can be found in small grassland ponds and seasonal floodplain wetlands; however the new species has been found so far only in the latter environments (Fig. 7).


 Wilson S. Serra and Marcelo Loureiro. 2018. Austrolebias queguay (Cyprinodontiformes, Rivulidae), A New Species of Annual Killifish Endemic to the lower Uruguay River Basin. Zoosystematics and Evolution. 94(2): 547-556.  DOI: 10.3897/zse.94.29115

[Ichthyology • 2017] Austrolebias camaquensis • A New Annual Fish of the Genus Austrolebias (Cyprinodontiformes: Rivulidae) from Rio Camaquã basin, Laguna dos Patos system, Brazilian Pampa

Austrolebias camaquensis 

 Volcan, Gonçalves & Lanés, 2017

 DOI:  10.11646/zootaxa.4338.1.7 

Abstract

A new species of Austrolebias is described from the middle course of the Rio Camaquã, Laguna dos Patos system, Rio Grande do Sul, Brazil. The new species belongs to the Austrolebias alexandri species group, which is distinguished from the remaining congeners by the presence of a dark gray pectoral fin with bright blue iridescence in males. The new species is distinguished from all remaining species of the A. alexandri species group by the following combination of characters: presence of well-defined bright blue bars on the flank in males, shorter caudal fin length in males and females, contact organs in the first three rays of the pectoral fin in males, one to two post-optic neuromasts (rarely three), basihyal width of 50% of the length, and basihyal cartilage about 50–60% of the basihyal length. The recognition of this new species belonging to the A. alexandri group endemic of the middle course of Rio Camaquã and the recent discovery of Austrolebias bagual in the same general region reinforces the claim of the middle Rio Camaquã basin as an area of endemism for annual fishes and as such, a priority area for conservation in southern Brazil.

Keywords: Pisces, Austrolebias, killifish, Rio Camaquã basin, temporary wetland, threatened fish, conservation

 Matheus Vieira Volcan, Ândrio Cardozo Gonçalves and Luis Esteban Krause Lanés. 2017. A New Annual Fish of the Genus Austrolebias (Cyprinodontiformes: Rivulidae) from Rio Camaquã basin, Laguna dos Patos system, Brazilian Pampa. Zootaxa. 4338(1); 141–152. DOI:  10.11646/zootaxa.4338.1.7

[Ichthyology • 2016] Melanorivulus polychromus • A New Species of Killifish (Cyprinodontiformes: Rivulidae) from the rio São José dos Dourados Drainage, middle rio Paraná Basin, southwestern Brazil, with A Redescription of Melanorivulus apiamici

Melanorivulus polychromus

Nielsen, Neves, Ywamoto & de Aguiar Passos,  2016

Abstract

A new species of Melanorivulus is described from the middle rio Paraná basin, São Paulo state, Brazil. Melanorivulus polychromus, new species, is found in a tributary of the left bank of the rio Paraná basin, the rio São José dos Dourados. It differs from all congeners by the combination of a metallic green to light green ground colour in males, with 6-8 oblique red bars forming chevronlike rows, the chevron tips along the midline of the body pointing toward the head, and irregular narrow red lines and incomplete red bars along the lower half of the body. Melanorivulus apiamici, also endemic from the middle rio Paraná basin, is redescribed.

Nielsen, D.T.B., Neves, P.A.B.A., Ywamoto, E.V. and de Aguiar Passos, M. 2016. Melanorivulus polychromus, A New Species of Killifish from the rio São José dos Dourados Drainage, middle rio Paraná Basin, southwestern Brazil, with A Redescription of Melanorivulus apiamici (Cyprinodontiformes: Rivulidae). aqua, International Journal of Ichthyology. 22(2); 79-88.