[Ichthyology • 2026] Mesoaphyosemion izyarae • A New killifish Species (Cyprinodontiformes: Nothobranchiidae) from southern Equatorial Guinea

Mesoaphyosemion izyarae Ott, Sonnenberg & Van der Zee,

in Sonnenberg, Ott, Rodriguez, Olias, Martinez et Van der Zee, 2026. 

DOI: doi.org/10.11646/zootaxa.5759.4.5

Abstract

Mesoaphyosemion izyarae sp. nov., is described from a small left-bank tributary of the Mitemele River in southern Equatorial Guinea. The new species is distinguished from all other described Mesoaphyosemion species by a unique combination of male colouration characters: dorsal fin yellow with red streaks between fin rays; anal and pelvic fins yellow with black or dark red margin, basally light blue, caudal fin in centre black with red streaks between fin rays, broad yellow area on dorsal and ventral margin, body metallic light blue with more or regular rows of red dots on side, posteriorly denser and forming a reticulated pattern. The species status is supported by mtDNA analyses, including nine of the eleven described valid Mesoaphyosemion species.

Pisces, phylogeny, colour pattern, taxonomy, mtDNA, Rio Mitemele, Pleistocene rainforest refuge  

Mesoaphyosemion izyarae.
Male (1) and female (2) from the type locality, Rio Mveň basin, near the village of Efulan, Equatorial Guinea (not preserved). 

Mesoaphyosemion izyarae sp. nov., Ott, Sonnenberg & Van der Zee

Diagnosis. Mesoaphyosemion izyarae shares with other species of the genus a combination of the following characteristics in the male: a mostly metallic pale blue, blue or blue-green colouration on the sides; an often variable pattern of red dots on sides, in most species irregularly distributed, in others forming more or less regular stripes or blotches; a latero-ventral red line on the caudal peduncle; unpaired fins without, or with only short, fin extensions, caudal fin nearly straight, slightly rounded or weakly trilobate; no conspicuous markings on ventral side of the head; adults have a yellow snout. Unfortunately, none of these characteristics is diagnostic on its own as they are also known from other nothobranchiid genera or species groups but, in combination, they are significant.

Mesoaphyosemion izyarae is distinguished from all other known Mesoaphyosemion species by a unique combination of colour pattern features in the male: dorsal fin yellow with red streaks between fin rays; anal and pelvic fins yellow with black or dark red margin, basally light blue, caudal fin black in...

RAINER SONNENBERG, HEINZ OTT, ADOLFO GONZALEZ RODRIGUEZ, CARLOS VIZCAINO OLIAS, FRANCISCO PORTAL MARTINEZ and JOUKE R. VAN DER ZEE. 2026.  Description of Mesoaphyosemion izyarae (Cyprinodontiformes: Nothobranchiidae), A New killifish Species from southern Equatorial Guinea. Zootaxa. 5759(4); 453-463. DOI: doi.org/10.11646/zootaxa.5759.4.5 [2026-02-18]

[Ichthyology • 2025] Gambusia nobilis, G. pyrros & G. echelleorum • A Total Evidence Approach justifies Taxonomic Splitting of the Endangered Pecos gambusia (Cyprinodontiformes: Poeciliidae: Gambusia) into Three Species

 Gambusia nobilis (Baird & Girard 1853)

Gambusia pyrros 
Gambusia echelleorum 

 Portnoy, Bretzing-Tungate, Fields, Bean, Smith, Dolan, Blanchard & Conway, 2025 

DOI: doi.org/10.1098/rsos.251025

Abstract

Gambusia nobilis is a federally endangered species found across a fragmented distribution within the Pecos River Drainage of Texas and New Mexico, USA. Drought, human water usage, and potential hybridization and competition with introduced congeners threaten species persistence. Therefore, a population genomics study was conducted to provide critical information for conservation planning. Unsupervised clustering suggested hierarchical structure, with a primary K = 3, and deep divergences were detected among samples grouped into the Leon Creek watershed, the Toyah Creek watershed, and water bodies within the Bitter Lake National Wildlife Refuge (F’ST = 0.55–0.76 for putatively neutral data). Phylogenetic analyses showed three distinct clades corresponding to these groups, with divergence times estimated to be in the last 50 000 years. Complimentary morphological analyses detected differences among the three groups, including features of male colour pattern, and the number of caudal-fin rays in both sexes. Taken as a whole, the results indicate that the endangered G. nobilis comprises three species (two of which are named herein as G. pyrros n. sp. and G. echelleorum n. sp.), rather than one, and the study highlights the daunting yet critical task of documenting species diversity during a period of unprecedented diversity loss.

Keywords: Chihuahua desert, genetic drift, taxonomy, Poeciliidae, species delimitation

Subjects:biology, evolution, genomics, taxonomy and systematics

Distribution and relationships of the Gambusia nobilis species complex.
  (a) Map showing distribution of G. nobilis, G. pyrros n. sp. and G. echelleorum n.sp. within Chihuahuan desert ecoregion of western Texas and southeastern New Mexico. (b) Closer view of area surrounded by dashed rectangle (b) in (a), showing location of G. echelleorum samples from Bitter Lake watershed in New Mexio, type locality indicated by black asterisk (*). (c) Closer view of area surrounded by dashed rectangle (c) in (a), showing location of G. nobilis samples from Leon Creek watershed and G. pyrros samples from Toyah Creek watershed in Texas, type localities indicated by black asterisk (*).
(d) Clade equivalent to the Gambusia nobilis species complex from the Maximum Likelihood phylogram based on 5989 loci showing relationships of G. nobilis, G. pyrros and G. echelleorum, numbers above branches represent bootstrap values (full topology available in electronic supplementary material, figure S7). (e) Discriminant analysis of principal components using the unsupervised clustering algorithm, K-means (= 3), using 3502 single nucleotide polymorphism-containing loci and 212 individuals (G. nobilis, n = 63; G. pyrros, n = 79; G. echelleorum, n = 70). Basemap in (a) created with SimpleMappr. Satellite images in (b) and (c) obtained from Google Earth.

Male individuals of the three members of the Gambusia nobilis species complex photographed in life against different background and in different views (lateral and dorsal) to document variation in colour pattern.
(a) Left side, lateral view, against light grey background: (i) G. nobilis (TCWC 21102.01); (ii, iii) G. pyrros (TCWC 21103.02, paratypes); (iv) G. echelleorum (TCWC 21104.01, holotype); (v-vii) G. echelleorum (TCWC 21105.01, paratypes). (b) Left side, lateral view, against dark grey background: (i, ii) G. nobilis (TCWC 21102.01); (iii) G. pyrros (TCWC 21103.02, paratype); (iv) G. echelleorum (TCWC 21104.01, holotype); (v) G. echelleorum (TCWC 21105.01, paratype). (c) Dorsal view (background variable): (i, ii) G. nobilis (TCWC 21102.01); (iii, iv) G. pyrros (TCWC 21103.02, paratypes); (v) G. echelleorum (TCWC 21104.01, holotype); (vi) G. echelleorum (TCWC 21105.01, paratype

 Gambusia nobilis (Baird & Girard 1853)

  Gambusia pyrros new species

Diagnosis: A member of the Gambusia nobilis species group (sensu Rauchenberger [1989]) most similar to G. nobilis and G. echelleorum. The characters distinguishing G. pyrros from G. nobilis are listed in the diagnosis of the latter. Gambusia pyrros is distinguished from G. echelleorum by the same characters that distinguish G. nobilis from G. echelleorum, plus: body colour of males orange-red or yellow-orange (figures 1d and 2b(ii); electronic supplementary material, figure S8) (versus yellow-grey to light cream; figures 1d and 2b(iii); electronic supplementary material, figure S8), anal fin of male orange-red at base in life (figure 2d(ii)) (versus orange; figure 2d(iii)), a higher modal number of total caudal-fin rays (29–32, mode 31 versus 25–29, mode 27; figure 2e), a higher modal number of branched caudal-fin rays (12–15, mode 14 versus 9–14, mode 12).

Etymology: From the Greek pyrros, meaning flame-coloured, a reference to the bright yellow, orange and red colours of the median fins of males in life. A noun in apposition. Proposed common name: flame gambusia.

  Gambusia echelleorum new species

Diagnosis: A member of the Gambusia nobilis species group (sensu Rauchenberger [1989]) most similar to G. nobilis and G. pyrros. The characters distinguishing G. echelleorum from G. nobilis and G. pyrros are listed in the diagnoses provided for the latter two.

Etymology: Named for Alice and Anthony Echelle in honour of their work on Gambusia nobilis. A noun in the genitive. Proposed common name: New Mexico Gambusia.

David S. Portnoy; Robert J. Bretzing-Tungate; Andrew T. Fields; Megan G. Bean; Ryan K. Smith; Elizabeth P. Dolan; Rose Blanchard and Kevin W. Conway. 2025. A Total Evidence Approach justifies Taxonomic Splitting of the Endangered Pecos gambusia into Three Species. R Soc Open Sci. (2025) 12 (11): 251025. DOI: doi.org/10.1098/rsos.251025 [26 Nov 2025]

 

[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] Nothobranchius iridescens, N. marmoreus, ‘Lacustricola’ gemma, ... • Review of Cyprinodontiform Fishes in the Upper Congo Drainage with Descriptions of New Species of Seasonal Nothobranchius (Nothobranchiidae) and ‘Lacustricola’ Lampeye (Procatopodidae) in South-Eastern DR Congo

 

Nothobranchius iridescens, N. katemomandai, N. marmoreus, 
N. dubieensis, ‘Lacustricola’ gemma 

Nagy, 2025 

  

DOI: doi.org/10.70322/ecoldivers.2025.10006 

ABSTRACT

 The cyprinodontiform fish fauna of the Bangweulu–Mweru and Upper Lualaba freshwater ecoregions, situated in the uppermost Congo River drainage, has been reviewed. This study introduces four newly described species of seasonal Nothobranchius killifish and a novel species of lampeye belonging to the genus ‘Lacustricola’. Nothobranchius iridescens, new species, from the Kafila system in the Lufira drainage, is characterized in male colouration by anal fin with irregular red-brown spots and stripes, creating two irregular submedial and medial bands and with broad yellow subdistal band; and a caudal fin with a slender light blue subdistal band, densely marked with irregular red spots, and narrow dark brown distinct distal margin. Nothobranchius katemomandai, new species, from the Kay system in the upper Lualaba drainage, is characterized in male colouration by an anal fin with narrow brown submedial band, followed by a slender yellow band, a slender red-brown band and a slender dark brown distal band; and a caudal fin with brown spots proximally and medially, and with slender white to light blue subdistal band and a narrow dark grey distal band. Nothobranchius marmoreus, new species, from the Lufukwe system in the Lake Mweru basin, is characterized in male colouration by a body with irregular red-brown patches and stripes, forming a marble-like mottled pattern; and anal and caudal fins with slender yellow to amber subdistal band and broad dark brown distal band. Nothobranchius dubieensis, new species, from the Lubule system in the Luvua drainage, is characterized in male colouration by an anal fin with narrow dark brown submedial band, narrow yellow and orange medial bands, narrow white subdistal band, and slender dark brown distal band; and a caudal fin with irregular red-brown spots and stripes proximally and medially, followed by an irregular narrow red-brown subdistal band and slender white distal band, and with interrupted red-brown fin tips. ‘Lacustricola’ gemma, new species, from the Kay system in the upper Lualaba drainage, is characterized by a pattern of iridescent, diamond-shaped, light blue spots in scale centres below mid-longitudinal series on posteroventral portion of flank; median fins yellow to hyaline, with dark grey stripes perpendicular to fin rays; dorsal fin with light blue distinct margin; anal fin with dark grey margin. Analysis of mitochondrial COI gene sequences revealed that the five new species represent phylogenetically distinct lineages. These findings not only underscore their genetic uniqueness but also confirm their placement within the Nothobranchius brieni species group and the genus ‘Lacustricola’. Species of the genus Nothobranchius complete their seasonal life cycle in ephemeral natural habitats within freshwater wetlands, while ‘Lacustricola’ species migrate to breed in flooded areas of shallow, typically seasonal wetland habitats at the onset of the rainy season. These wetlands are highly vulnerable to a variety of human-induced stressors and threats, including agricultural cultivation, water extraction, urban expansion resulting in land-use pressure, and increased pollution, particularly from industrial activities such as mining. Therefore, it is essential to protect the integrity of these unique aquatic habitats throughout all the seasons of the year to maintain healthy wetland ecosystems and safeguard the distinctive seasonal freshwater biodiversity they support.

Keywords: Bangweulu–Mweru freshwater ecoregion; Barcoding; Conservation; Killifish; Upper Lualaba freshwater ecoregion

 Nothobranchius iridescens, New Species

Etymology. The specific epithet iridescens is a Latin participial adjective deriving from the ancient Greek word iris (ἶρις), rainbow, referring to the colourful appearance of the males, containing different colours of the rainbow, such as yellow and red in the fins, reflective blue on the body slightly shifting hue depending on the angle of light.

 Nothobranchius katemomandai, New Species

Etymology. The specific epithet is given in honour of friend Bauchet Katemo Manda, professor at the University of Lubumbashi, the discoverer of this species, for his dedication to the research of the ichthyofauna of the Democratic Republic of Congo. The exciting adventures and numerous challenges faced during joint research expeditions will always remain vivid memories.

 Nothobranchius marmoreus, New Species

Etymology. The specific epithet marmoreus is a Latin adjective deriving from the ancient Greek word marmaros (μάρμαρος) in the meaning of resembling marble, marblelike, and in reference to the irregularly mottled marbled colour pattern on the body of the males.

Nothobranchius dubieensis, New Species

Etymology. The specific name is given in reference to Dubie township in south-eastern DR Congo, near which place this species is found, and the type locality is situated. An adjective derived from the geographical name.

‘Lacustricola’ gemma, New Species

Etymology. The specific epithet gemma is derived from the ancient Greek word γέμω, originally meaning “precious stone” or “gem”. It refers to the pattern of the body scales, which are adorned with numerous iridescent, diamond-shaped markings, evoking the appearance of tiny gems. The name also alludes to the relatively small adult size of the species. It is treated as a noun in the nominative singular, standing in apposition to the generic name.

 

Béla Nagy. 2025. Review of Cyprinodontiform Fishes in the Upper Congo Drainage with Descriptions of Four New Species of Seasonal Nothobranchius (Nothobranchiidae) and a New Species of ‘Lacustricola’ Lampeye (Procatopodidae) in South-Eastern DR Congo. Ecol. Divers. 2(2), 10006. DOI: doi.org/10.70322/ecoldivers.2025.10006 

https://x.com/BaukaManda/status/1940645555790925893

[Ichthyology • 2025] Profundulus hectori • A New Species of Profundulus (Cyprinodontiformes: Profundulidae) from southeastern Mexico

[A-B] Profundulus hectori
  [C-D] P. punctatus 

Domínguez-Cisneros, Velázquez-Velázquez, Domínguez-Domínguez & Beltrán-López, 2025

 DOI: doi.org/10.1590/1982-0224-2024-0096  

Abstract

A new species of Profundulus is described from several localities in the Grijalva river basin and rivers of the Isthmus of Tehuantepec, in southern Mexico, using a combination of morphological and molecular data. Genetically, it is separated from other Profundulus species analyzed by a minimum of 3.86% uncorrected p-distance for the nd2 mitochondrial gene. The new species can be distinguished from its congeners by the following combination of characters: presence of a set of large black spots on the scales on the sides of the body, a set of black spots whose size is equal to or greater than 50% of the diameter of the pupil in the new species, a larger number of scales on the lateral line and a larger number of predorsal scales. Based on the phylogenetic analysis of molecular sequence data, the new species is recovered close related to P. chimalapensis, supported by posterior probability of 0.96, and this clade was recovered close related to P. oaxacae, with a posterior probability of 1.0 and bootstrap support of 100. This is the twelfth member of the genus Profundulus.

Keywords: Biodiversity; Freshwater fish; Phylogeny; Profundulids; Taxonomy

 

General morphology and live coloration patterns in
Profundulus hectori, A. Male, B. Female, Sabinal River, tributary of Grijalva River, Tuxtla Gutierrez, Chiapas. Collected in December 16, 2022 by E. Velázquez-Velázquez and M. Anzueto-Calvo.
 Profudulus punctatus, C. Male, D. Female, Arroyo tributario del Río Zanatenco, Tonalá Chiapas. Collected on March 21, 2023 by Ernesto Velázquez and Manuel Anzueto.

Profundulus hectori, new species

Etymology. In recognition of his many contributions to the study and conservation of freshwater fishes in Mexico, this species is named after our friend and colleague, the Mexican ichthyologist Hector Espinosa Perez, recently deceased. A noun in a genitive case.

Sara Elizabeth Domínguez-Cisneros, Ernesto Velázquez-Velázquez, Omar Domínguez-Domínguez and Rosa Gabriela Beltrán-López. 2025. A New Species of Profundulus (Cyprinodontiformes: Profundulidae) from southeastern Mexico. Neotrop Ichthyol. 23(2):e240096. DOI: doi.org/10.1590/1982-0224-2024-0096  

[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 

 facebook.com/LuisEstebanKrauseLanes

 

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

 facebook.com/LuisEstebanKrauseLanes/posts/24056141400642849

 

[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 

facebook.com/FelipeAlonsoIctio

 

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 • 2025] Phalloceros mimbi • A New Species of the Phalloceros harpagos species complex (Cyprinodontiformes: Poeciliidae) from the middle and lower Uruguay River Floodplains

 

Phalloceros mimbi

 Serra, Scarabino, Gobel & Laufer, 2025

DOI: doi.org/10.30550/j.azl/2096 

 Researchgate.net/publication/390504997

Abstract

Phalloceros mimbi sp. nov. is described from specimens collected in the floodplains of the middle and lower Uruguay River in Uruguay (Río Negro and Salto Departments) and Argentina (Entre Ríos Province). This species belongs to the P. harpagos species complex and is diagnosed by the following unique combination of characters: 1) presence of a symmetric hood-like structure located immediately anterior to the urogenital papilla in females, 2) absence of large papillae at the mandibular symphysis of large adult females, 3) possession of well-developed hooks positioned in distal portion of gonopodial appendices of males and 4) lateral spot usually present in both sexes. To date, P. mimbi has not been found coexisting in sympatry with other Phalloceros species. The geographically closest species is P. caudimaculatus, who differs from P. mimbi by the absence of hooks in gonopodial appendix in males. Two of the three known populations of P. mimbi are relatively protected from the main threats to the species. However, conservation initiatives should consider its presence and ensure that it receives the necessary attention; considering that its global distribution occupies less than 200.000 km2 and its occurrence area represents less than 10% of the national territory it must be considered a priority for conservation and an Threatened Species for the species list of Sistema Nacional de Áreas Protegidas (SNAP) of Uruguay.

Keywords: Poeciliinae, freshwater fishes, conservation, Argentina, Uruguay

Phalloceros mimbi sp. nov. 

 

Wilson Serra, Fabrizio Scarabino, Noelia Gobel and Gabriel Laufer. 2025. A New Species of the Phalloceros harpagos species complex (Cyprinodontiformes: Poeciliidae) from the middle and lower Uruguay River floodplains. Acta Zoológica Lilloana. 309–326. DOI: doi.org/10.30550/j.azl/2096 

 Researchgate.net/publication/390504997_A_new_species_of_Phalloceros_from_the_middle_and_lower_Uruguay_River_floodplains

[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