[PaleoIchthyology • 2026] Nazaria limnica • A New deep bodied ray-finned fish (Osteichthyes: Actinopterygii) from the Permian Pedra do Fogo Formation (Northeastern Brazil) and its phylogenetic and paleogeographic affinities

Nazaria limnica

Richter, Cisneros, Kammerer, Pardo, Marsicano, Fröbisch, Smith & Angielczyk, 2026

 DOI: doi.org/10.1080/02724634.2026.2697805  

Artwork by Juan C. Cisneros & Martha Richter

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ABSTRACT

A deep bodied ray-finned fish is reported from Cisuralian lacustrine deposits of the Parnaíba Basin. Its ecological niche and systematic affinities are discussed, considering the paleogeographic distribution of selected Permo-Carboniferous deep bodied fishes from several separate sedimentary successions of western Gondwana. The occurrence of deep bodied fishes in the Parnaíba Basin mirrors the presence of a similarly shaped but less derived and distantly related taxon, Paranaichthys longianalis from the late Permian of the Paraná Basin of southern Brazil. The new taxon’s unique combination of characters includes an elongated pectoral fin; posteriorly inclined suspensorium; deep flank scales ornamented with fine vertical striae, tiny mandibular teeth and palatal crushing dental plates. It shares with Guildayichthys and Discoserra two preopercular bones, a supraorbital, and marginal teeth on the lower jaw. Phylogenetic analyses were performed based on two datasets. Dataset 1 included 53 characters coded for 26 deep bodied and fusiform fish fossils from Brazil, North America, China, South Africa, and Australia, with results indicating that is most closely related to the North American order Guildayichthyformes, known from marine rocks of Pennsylvanian age. Dataset 2 included 119 taxa coded for 293 characters. The two analyses place the new taxon as the sister group of a clade comprised of Blourugia and Paranaichthys. However, the results of the study of both datasets show a high degree of uncertainty about the interrelationships between the new taxon and other deep bodied Paleozoic fish species.

SYSTEMATIC PALEONTOLOGY

OSTEICHTHYES Huxley, 1880

ACTINOPTERYGII Cope, 1887

NAZARIA, gen. nov.

 

Etymology—Named after the municipality of Nazária in the State of Piauí, where the fossils were collected.

NAZARIA LIMNICA, gen. et sp. nov.

Etymology—Derives from the Greek epithet limne (‘lake’) a reference to the lacustrine paleoenvironment where the fishes lived.

Nazaria limnica, MAP PV1029 (holotype).
A, part; B, counterpart (reversed). The caudal and anal fins are not preserved in the holotype.

Abbreviations: vrs, ventral ridge scales.

Nazaria limnica, MAP PV1029 (holotype).
A, skull and anterior part of the trunk (dorsal crest not figured here); B, identification of skull bones as preserved in A and, augmented drawing of one of the anteriormost trunk scales, showing its vertical ornamental ridges and dorsal of the peg-and-socket articulation system. The hatched lines indicate uncertain bone boundaries.

Abbreviations: An, angular; a.In, anterior infraorbital; br, branchiostegal rays; Cl, cleithrum; Cla, clavicle; De, dentary; Dro, dorsal rostral; Dsp, dermosphenotic; Ent?, impression of an entopterygoid?; Ex, extrascapulars; Fr, frontal; Ju, jugal; mt, mandibular teeth; Mx, maxilla; Na, nasal; Op, operculum; Pa, parietal; Pmx-ant, premaxilla-antorbital; Pop1, preoperculum 1; Pop2, preoperculum 2; Psp, post-spiracular; Sco, scapulocoracoid; So, suborbitals; Sop, suboperculum; St, supratemporal; Su, supraorbital; Vo, vomer; VRo, ventral rostral.

 Nazaria limnica, MAP PV1029 (holotype).
A, detail of the mouth and surrounding region; B, details of the dentition.

 Abbreviations: maxt?, possible maxillary crushing teeth; mt, mandibular marginal teeth; Mx, maxilla; Vo, vomer (vomerine tooth plate).

Tentative reconstruction of the skull pattern and anteriormost flank scales of Nazaria limnica, based on MAP PV1029 (holotype), after rearrangement of some taphonomically dislocated bones (jugal, lachrymal and ventral preopercular). Short, dotted lines represent inferred bone limits (preoperculum, suboperculum, and ventral limit of the suprachleithrum). The inset features the skull sensorial line pattern.

Abbreviations: An, angular; a.In, anterior infraorbital; app, anterior process of parasphenoid; asp, posterior ascending process of parasphenoid; br, branchiostegal rays; Cl, cleithrum; Cla, clavicle; Dro, dorsal rostral; Dsp, dermosphenotic; Ent?, impression of an entopterygoid?; Ex, extrascapulars; Fr, frontal; Ju, jugal; Mx, maxilla; Na, nasal; Op, operculum; P1, pectoral fin; Pa, parietal; Par, parasphenoid; Pmx-ant, premaxilla-antorbital; Pop1, preoperculum 1; Pop2, preoperculum 2; Psp, post-spiracular; Sco, scapulocoracoid; So, suborbitals; Sop, suboperculum; sr, sclerotic ring; St, supratemporal; Su, supraorbital; Vo, vomer; Vro, ventral rostral.

Life reconstruction of Nazaria limnica, based on a composite rendering of characters observed on either the holotype, the paratype or both.

Art by Juan C. Cisneros based on Martha Richter reconstruction.

 

Martha Richter, Juan C. Cisneros, Christian F. Kammerer, Jason D. Pardo, Claudia A. Marsicano, Jörg Fröbisch, Roger M. H. Smith and Kenneth D. Angielczyk. 2026. A New deep bodied ray-finned fish (Osteichthyes/Actinopterygii) from the Permian Pedra do Fogo Formation (Northeastern Brazil) and its phylogenetic and paleogeographic affinities. Journal of Vertebrate Paleontology. e2697805. DOI: doi.org/10.1080/02724634.2026.2697805 [26 Aug 2026]

 bsky.app/profile/cisneros.bsky.social/post/3mtzp3mskp225

 bsky.app/profile/jdpardo.bsky.social/post/3mtyrzy7tw225

[Ichthyology • 2026] Molecular Phylogenetics and A New Taxonomy of the Neotropical Electric Fishes (Actinopterygii: Otophysi: Gymnotiformes)

 

Representatives of the six gymnotiform families Apteronotidae (A), Sternopygidae (S), Gymnotidae (G), Electrophoridae (E), Hypopomidae (H), and Rhamphichthyidae (R). 

Top to bottom, and left to right, are: Rhamphichthys rostratus (R), Archolaemus janeae (S), Sternarchorhamphus muelleri (A), Eigenmannia magoi (S), Gymnotus carapo (G), Sternarchorhynchus sp. (A), Apteronotus galvisi (A), Orthosternarchus tamandua (A), “Apteronotus” (Genus B) cuchillejo (A), Apteronotus eschmeyeri (A), Apteronotus cf. albifrons (A), Gymnorhamphichthys sp. (R), Sternarchorhynchus marreroi (A), Sternopygus aequilabiatus (S), Adontosternarchus devenanzii (A), Steatogenys duidae (R), Brachyhypopomus occidentalis (H), Hypopomus artedi (H), and Electrophorus multivalvulus (E). 

in Janzen, Sabaj, Crampton et Lovejoy, 2026.

DOI: doi.org/10.1016/j.ympev.2026.108678 

Photos by M. Sabaj.

  

Highlights: 

• New 9 gene molecular tree for 202 species of Neotropical electric knifefishes (order Gymnotiformes)

• A new taxonomy is proposed, based on the most extensive phylogenetic analysis to date.

• Strong phylogenetic support for 6 families, including the Electrophoridae (electric eels)

• Two main groups of species defined by either pulse or wave-type electric signals.

• Two new suborders: Pulseoidei for pulse-type species and Sinusoidei for wave-type species.

Abstract

The order Gymnotiformes—Neotropical electric eels and knifefishes—comprise a distinctive lineage of freshwater fishes characterized by electrogenesis and electroreception. Despite their ecological, evolutionary, and neurobiological significance, phylogenetic relationships within the order remain incompletely resolved. We present the most taxonomically inclusive molecular phylogeny of Gymnotiformes to date, based on two mitochondrial and seven nuclear genes from 202 species representing 31 of 36 extant genera. Maximum likelihood and Bayesian inference analyses provide strong support for a concordant species-level phylogenetic arrangement that we use to propose a revised classification of Gymnotiformes, including new suprageneric names and reassignments of some taxa and species. We found support for six monophyletic families, including Electrophoridae (electric eels). We propose two new suborders corresponding to electric signal type: Pulseoidei (pulse-type) and Sinusoidei (wave-type), an arrangement that does not allow determination of whether a pulse or wave-type signal was ancestral. In Apteronotidae, the subfamilies Sternarchorhamphinae and Apteronotinae are supported; within Apteronotinae, we establish the tribe Steatogenini to include Porotergus, Sternarchella, and close relatives. We resolve the non-monophyly of Apteronotus with generic reassignments. For Sternopygidae, we support the monophyletic subfamilies Sternopyginae and Eigenmanniinae and resolve polyphyly in Rhabdolichops and Eigenmannia via generic reassignments. Within Gymnotus, we support six species groups. We confirm the sister-group relationship between Hypopomidae and Rhamphichthyidae and clarify their internal structure, including support for six species groups within the diverse genus Brachyhypopomus. Our study provides a robust phylogenetic framework for Gymnotiformes and establishes a foundation for future work on systematics, biogeography, trait evolution, and comparative neurobiology.

 

Keywords: Neotropical, Systematics, Electric eel, Knifefish, Electric organ discharges

Sinusoidei subord. nov. changed from “Sinusoidea” of Albert 2001

Pulseoidei subord. nov. changed from “Pulseoidea” of Alda et al. 2018

Representatives of the six gymnotiform families Apteronotidae (A), Sternopygidae (S), Gymnotidae (G), Electrophoridae (E), Hypopomidae (H), and Rhamphichthyidae (R). 

Top to bottom, and left to right, are: Rhamphichthys rostratus (R), Archolaemus janeae (S), Sternarchorhamphus muelleri (A), Eigenmannia magoi (S), Gymnotus carapo (G), Sternarchorhynchus sp. (A), Apteronotus galvisi (A), Orthosternarchus tamandua (A), “Apteronotus” (Genus B) cuchillejo (A), Apteronotus eschmeyeri (A), Apteronotus cf. albifrons (A), Gymnorhamphichthys sp. (R), Sternarchorhynchus marreroi (A), Sternopygus aequilabiatus (S), Adontosternarchus devenanzii (A), Steatogenys duidae (R), Brachyhypopomus occidentalis (H), Hypopomus artedi (H), and Electrophorus multivalvulus (E). 

Photos by M. Sabaj.

  

 

 Francesco H. Janzen, Mark H. Sabaj, William G.R. Crampton, Nathan R. Lovejoy, 2026. Molecular Phylogenetics and A New Taxonomy of the Neotropical Electric Fishes (Actinopterygii: Otophysi: Gymnotiformes). Molecular Phylogenetics and Evolution. In Press, 108678. DOI: doi.org/10.1016/j.ympev.2026.108678 [10 July 2026]

[Ichthyology • 2026] Brachygobius jennie • A New bumblebee goby (Gobiiformes: Oxudercidae) from Hengqin Island, Guangdong Province, China

Brachygobius jennie  

 Tian, Wu, Lan, Lavoué & Huang, 2026. 

 DOI: doi.org/10.3897/zse.102.184142

Abstract

A new species of bumblebee goby, Brachygobius jennie sp. nov. (Teleostei, Oxudercidae), is described based on 31 specimens collected from the Hengqin Island, Guangdong Province, China. This new species is distinguished from all other valid species of Brachygobius by its extreme small size (SL < 9 mm) and distinctive number, position, size and shape of its black bars. It possesses four complete (forming ring) or nearly complete post-cephalic, relatively narrow bars, two of which are located posterior to the base of the anal fin. The first bar behind the head extends pigmentation to the first dorsal fin but does not reach the midventral line. The second bar, chevron-shaped and located below the second dorsal fin, extends pigmentation onto that fin and ventrally reaches the midventral line and the anal fin. Cytochrome oxidase subunit I-based analyses, including six out of the eight valid species of Brachygobius, show Brachygobius jennie sp. nov. to be more than 10% genetically divergent from other species, supporting the morphological diagnosis and confirming its distinct taxonomic status. With a maximum size of less than 9 mm SL (based on observations of 106 specimens), the new species is not only the smallest species of Brachygobius, but also one of the smallest known gobioid fishes.

Key Words: Fish, Gobioidei, integrative taxonomy, new species, miniature vertebrates

Diagnostic marking pattern comparison among all species of Brachygobius having four post-cephalic black bands, the last two located posterior to the base of the anal fin. Left column: schematic drawings highlighting diagnostic marking patterns based on information from type material and original descriptions; from top to bottom: 
Brachygobius jennie sp. nov. based on its description (this study); B. aggregatus, based on a drawing of a type specimen (plate 4 in Herre 1940); B. kabiliensis, based on the drawing of the holotype (fig. 19 in Inger 1958); and B. nunus, based on the drawing of a specimen of Gobius alcockii Annandale, 1906 (fig. 1 in Annandale 1906), a junior synonym of B. nunus, and the description of B. nunus by Hamilton (1822). Red arrowheads indicate diagnostic differences. Right column: photographs of live non-type specimens illustrating the corresponding left schematic patterns (all photos from the authors).

Live photographs of four paratypes of Brachygobius jennie sp. nov., illustrating intra-specific marking pattern.

Photographed by Mr. Haocong Yang and Mr. Danyang Zhou.

Brachygobius jennie sp. nov. 

 Jiangyan Tian, Jianyong Wu, Chunliu Lan, Sébastien Lavoué and Jianrong Huang. 2026. Brachygobius jennie, A New bumblebee goby (Teleostei, Oxudercidae) from Hengqin Island, Guangdong Province, China. Zoosystematics and Evolution. 102(3): 853-863.  DOI: doi.org/10.3897/zse.102.184142 [17 Jun 2026]

[Ichthyology • 2026] Redefinition of Stemonosudis intermedia (Ege, 1933) (Aulopiformes: Paralepididae) and Description of Stemonosudis dianea, A New Species from the western Atlantic Ocean

[A-B] Stemonosudis dianea  Ho & Bemis, 2026 
Stemonosudis intermedia  (Ege, 1933)

 

DOI: doi.org/10.1111/jfb.70342

 

Abstract

We examined specimens of slender barracudina in the genus Stemonosudis collected from the western Atlantic Ocean. Investigation revealed that seven specimens represent the first adult records of Stemonosudis intermedia (Ege, 1933), previously known only from juveniles. We redescribed S. intermedia based on the holotype and newly recognized adult and juvenile specimens, and using this ontogenetic series, we document changes in coloration from light-brown juveniles to black adults. We also determined that some specimens from the western Atlantic Ocean previously identified as S. intermedia represent a new species, which we describe herein based on three adults and five juvenile specimens. The new species differs from congeners by having 43–44 anal-fin rays, 117–121 total vertebrae and a pale mouth, gill chamber and gill arches, among a combination of other characters. We also provide information on the lectotype of S. similis (Ege, 1957), which remains known only from the type series.

Keywords: biodiversity, biogeography, Ichthyology, nomenclature, taxonomy

Stemonosudis dianea sp. nov., fresh coloration.
(a) Holotype USNM 407498, 332 mm SL, photograph by Cristina Castillo.
(b) Paratype USNM 407509, 348 mm SL, photograph by Sandra Raredon.

 Stemonosudis dianea sp. nov.

English name: Diane's Slender Barracudina

Stemonosudis intermedia (Ege, 1933), fresh coloration of adults. Right side photographed, reflected to face left. USNM 407096, 277 mm SL. (a) Lateral view of body. (b) Close up of head.

Photographs by Ross Robertson.

Hsuan-Ching Ho and Katherine E. Bemis. 2026. Redefinition of Stemonosudis intermedia (Ege, 1933) and Description of A New Species from the western Atlantic Ocean (Aulopiformes: Paralepididae). Journal of Fish Biology. DOI: doi.org/10.1111/jfb.70342 [30 March 2026]

https://www.fisheries.noaa.gov/feature-story/ferocious-predator-and-important-prey-new-barracudina-species-named-smithsonian

[Ichthyology • 2021] Lethrinus mitchelli • A New Species of Emperor Fish (Acanthuriformes: Lethrinidae) from Milne Bay Province, Papua New Guinea

Lethrinus mitchelli

Allen, Victor & Erdmann, 2021

DOI: doi.org/10.5281/zenodo.5172763 

Abstract 

A new species of emperor fish, Lethrinus mitchelli, is described on the basis of three specimens, 109.4–111.3 mm SL, collected from 20 m at the East Cape region of Milne Bay Province, Papua New Guinea. It is similar to the sympatric relatives L. semicinctus and L. rubrioperculatus, but differs in color pattern and has a narrower cheek (cheek height 3.2–3.6 in head length vs. 2.4–2.9). Other diagnostic features include head length (2.7 in SL) greater than body depth (3.0–3.1 in SL); the snout excluding the lip 1.3–1.4 in cheek height; the snout profile nearly straight, without a prominent hump, and about 55° to the upper jaw; conical lateral jaw teeth; the interorbital area nearly flat or convex; the fourth dorsal-fin spine longest; lateral-line scales 47; transverse scale rows below and above the lateral line 15 and 4.5 rows; and a fully-scaled area adjacent to the prominent bony spine at the posteriormost margin of the opercle (excluding fleshy flap). The new species has a distinctive color pattern: brown dorsally, whitish ventrally, with a broad, brown, posteriorly tapering band on the midlateral body, partially split anteriorly by a relatively broad, ascending diagonal white band. Lethrinus mitchelli is 6.11% sequence divergent (pairwise) in the mtDNA COI marker from its nearest relative, L. semicinctus, also from the East Indies. A table of COI divergences among mtDNA lineages assigned to 27 of the 28 known species of Lethrinus shows a set of distinctly different lineages, from 3.32% to 20.85% divergent from each other (minimum interspecific distances). 

Key words: taxonomy, ichthyology, phylogenetics, coral reef fishes, Indo-Pacific, DNA barcodes, mtDNA COI 

Lethrinus mitchelli n. sp.
blotchy pattern on rubble bottom, about 200 mm SL, East Cape Region, Milne Bay Province, Papua New Guinea
 preserved holotype, 110.1 mm SL, East Cape Region, Milne Bay Province, Papua New Guinea.

photos: G.R. Allen.

Lethrinus mitchelli n. sp.
[upper] about 200 mm SL, East Cape Region, Milne Bay Prov., Papua New Guinea; 
[lower] blotchy pattern on rubble bottom, about 200 mm SL, East Cape Region, Milne Bay Province, Papua New Guinea.

photos: G.R. Allen

 Allen, G.R., Victor, B.C. and Erdmann, M.V. 2021. Lethrinus mitchelli, A New Species of Emperor Fish (Teleostei: Lethrinidae) from Milne Bay Province, Papua New Guinea. Journal of the Ocean Science Foundation. 38, 66–77. DOI: doi.org/10.5281/zenodo.5172763 

[Ichthyology • 2026] Crossorhombus pescadores • A New lefteye Flounder of the Genus Crossorhombus (Teleostei: Bothidae) from Penghu Islands, western Taiwan

Crossorhombus pescadores 

 Amaoka, Su & Ho, 2026

DOI: doi.org/10.3897/zookeys.1273.167628

Abstract

A new lefteye flounder, Crossorhombus pescadores sp. nov., is described based on five specimens collected from Penghu Islands. This new species differs from the other four congeners by having a pair of small black spots on the caudal fin, a horizontal triangular bluish-black marking on the blind side of body in male, the front wings of the marking reaching the base of dorsal and anal fins, and a combination of morphometric characters, including a larger head, deeper body, smaller eyes, fewer dorsal- and anal-fin rays and lateral-line scales, and other characters. A key to all five nominal species of Crossorhombus is provided.

Key words: Biodiversity, ichthyology, identification key, sexual dimorphism, taxonomy, western Pacific

Crossorhombus pescadores sp. nov., NMMB-P 42260, holotype, male, 99.8 mm SL, preserved.
A. Ocular side; B. Blind side.

Paratypes of Crossorhombus pescadores sp. nov., showing ocular sides (odd numbers) and blind sides (even numbers).
A. HUMZ 237066, immature male, 74.8 mm SL; B. NMMB-P 42263, female, 92.4 mm SL; C. NMMB-P 42262, immature female, 58.0 mm SL.

 Crossorhombus pescadores sp. nov

Diagnosis. A species of Crossorhombus differing from its congeners in having: caudal fin with light-gray band along posterior sub-margin; a pair of small black spots on band at upper and lower fourth rays, respectively; a bluish-black, horizontal triangular marking on blind side of body in male; a series of dark blotches along dorsal and ventral margins of body; combination of some meristic and proportional characters: large head; small upper and lower eyes; slightly longer pectoral-fin on ocular side; fewer dorsal- and anal- fin rays and fewer scales in lateral line and others.

Etymology. The specific name “pescadores” is the old name of the type locality, meaning “fishermen” in Portuguese. It is treated as a noun in apposition.

 Kunio Amaoka, Yo Su and Hsuan-Ching Ho. 2026. A New lefteye Flounder of the Genus Crossorhombus (Teleostei, Bothidae) from Penghu Islands, western Taiwan. ZooKeys. 1273: 15-25. DOI: doi.org/10.3897/zookeys.1273.167628 [13 Mar. 2026]

[Ichthyology • 2026] Butis bargabhimae • A New Species of butid fish (Gobiiformes: Butidae) from the Rupnarayan River, Purba Medinipur, West Bengal, India

  

Butis bargabhimae

Maiti, Mandal, Das, Pahari & Bhattacharya, 2026  

DOI: doi.org/10.11646/zootaxa.5763.4.9 

  academia.edu/164972645

 

Abstract

Butis bargabhimae sp. nov. is morphologically similar to B. koilomatodon and B. delagoensis but can be distinguished from both of these morphologically by the presence of interorbital scales (IOS 2–3/7–8/2–3), auxiliary scales, bands on the pectoral fin, and the absence of a row of alternating blackish and yellowish spots at the base of the caudal fin. The NCBI BLAST result of COI gene shows 86% similarity with both B. koilomatodon and B. delagoensis. The COI sequence MN171371.1 submitted as B. koilomatodon from Bangladesh shows 99% similarity with B. bargabhimae sp. nov. and belongs to the same clade rather than the clade of B. koilomatodon from the state of Kerala in India and those from other countries. It seems B. koilomatodon from Bangladesh is a misidentification and should be included under B. bargabhimae sp. nov. Likewise COI sequence of B. koilomatodon, as reported earlier by Pahari et al. (2024), suggests this was a misidentification and should be redesignated as B. delagoensis.

Pisces, Estuarine fish, gudgeon goby, mitochondrial COI, short snout Butis

Butis bargabhimae sp. nov. Holotype Female (Reg. No. ZSI FF 10992).
I: Longer 3 rd and 4 th spine. II: Oblique dark bands on body. III: Dark median spot at pectoral fin base. IV: Light and dark alternate bands on pectoral fin.

Butis bargabhimae sp. nov.

Subhadeep MAITI, Sudipta MANDAL, Mitali DAS, Priti Ranjan PAHARI and Tanmay BHATTACHARYA. 2026. Butis bargabhimae sp. nov., A New Species of butid fish (Teleostei: Gobiiformes: Butidae) from the Rupnarayan River, Purba Medinipur, West Bengal, India. Zootaxa. 5763(4); 588-596. DOI: doi.org/10.11646/zootaxa.5763.4.9 [2026-03-05]

  academia.edu/164972645/Butis_bargabhimae_A_new_species_of_butid_fish_from_the_Rupnarayan_River_Purba_Medinipur_West_Bengal_India

[Ichthyology • 2025] Allohistium anas • Genomic and Phenotypic Delimitation of Species in a Temperate Aquatic Biodiversity Hotspot

 

Allohistium anas Near & MacGuigan,

in MacGuigan, Taylor, Ghezelayagh, Wood, Simmons, Mollish et Near, 2025. 

Cinder Darter  ||  DOI: doi.org/10.1093/sysbio/syaf083 

Abstract

Biologists have relied on morphological characteristics to identify, define, and formally describe species for the past 250 years. The advent of phylogenetic species concepts and the introduction of molecular data have spawned new species delimitation methods applicable to a wide range of eukaryotic lineages. However, these approaches heavily emphasize genomic data, often overlooking phenotypic traits. We present and implement a species delimitation approach that utilizes genome-wide markers from ddRAD-seq and meristic morphological traits, which have long been used to identify and delineate fish species. Our methodology employs unsupervised machine learning to analyze morphological data without a priori species assignments, allowing phenotypic patterns to emerge independently from genomic-based species delimitation. We apply our combined genomic and phenotypic methodology to the freshwater systems of Southeastern North America, a biodiversity hotspot where conservation efforts are hampered by an incomplete knowledge of species diversity. Our investigation focuses on the darter clade Allohistium, a threatened lineage comprising two described species. Through phylogenomic, population genetic, and phenotypic model comparisons, we provide evidence supporting the delimitation of a third species of Allohistium, which we formally describe. Our approach shows how unsupervised machine learning can reveal cryptic morphological diversity that might otherwise be obscured by taxonomic preconceptions. This study demonstrates that model testing using diverse lines of evidence yields a more comprehensive, data-driven hypothesis of species diversity.

Darters, ddRAD-seq, methodology, North America, phenotype, species delimitation

Live photographs of Allohistium specimens.

Photo credit to Jon M. Mollish. YPM = Yale Peabody Museum, YFTC = Yale Fish Tissue Collection.

Allohistium anas Near and MacGuigan new species

Cinder Darter

Diagnosis. Allohistium anas differs from Allohistium cinereum and Allohistium maydeni by a higher number of lateral line scales (Supplementary Table S4), modally 43 versus 42 vertebrae (Shepard and Burr 1984), a larger proportion of individuals with greater than 80% of the cheek covered with scales, and more than 50% of the individuals with 10–40% of the nape covered with scales. In addition, Allohistium anas is never resolved as the sister lineage of Allohistium cinereum sensu stricto in mtDNA gene trees (Powers et al. 2004, 2012) or phylogenomic analyses of ddRAD-seq loci (see below). Allohistium maydeni differs from Allohistium anas and Allohistium cinereum in having modally 11 versus 12 dorsal fin spines (Supplementary Table S5; Powers et al. 2012), 12 versus 13 dorsal fin rays (Supplementary Table S6; Powers et al. 2012), and the presence of conspicuous red coloration on the skin covering the upper and lower oral jaws (Fig. 2).

Etymology. The species name anas is from the Latin word for duck, in reference to the distribution of the species in the Duck River system. The common name Cinder Darter is in reference to the common name of A. cinerum, the Ashy Darter.

Daniel J MacGuigan , Adam Taylor , Ava Ghezelayagh , Julia E Wood , Jeffrey W Simmons , Jon M Mollish and Thomas J Near. 2025. Genomic and Phenotypic Delimitation of Species in a Temperate Aquatic Biodiversity Hotspot. Systematic Biology. syaf083. DOI: doi.org/10.1093/sysbio/syaf083 [27 November 2025]

[Ichthyology • 2025] Aepysomanthias & Poroanthias gen. nov., Pelontrus, Zalanthias, ... • A 40-year Taxonomic Enigma: Multigene Phylogeny Resolves the Polyphyly of Plectranthias (Perciformes: Anthiadidae) and supports A Revised Taxonomy

Plectranthias, Pelontrus, Sayonara, Xenanthias, Zalanthias, 
 Aepysomanthias and Poroanthias Tang & Chen gen. nov. 

in Tang et Chen, 2025.  

DOI: doi.org/10.1093/zoolinnean/zlaf148 

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Abstract

Anthiadidae, a family of shallow and deep-water reef-associated fishes, include about 250 species distributed widely from tropical to temperate regions, with the majority found in the tropical Indo-West Pacific (IWP). Despite their broad distribution, the phylogeny and taxonomy of this family remain unresolved, particularly at the generic level, due to challenges in sampling from deep-water zones. Plectranthias, the most species-rich genus, has been suspected of non-monophyly since its last revision over 40 years ago. In this study, we explore the phylogenetic relationships of anthiadids using a multigene dataset (one mitochondrial and four nuclear genes) from 103 specimens across 19 genera, with a focus on IWP Plectranthias. Our results confirm the polyphyly of Plectranthias, revealing seven distinct clades. Based on this new phylogenetic framework and morphological re-examinations, we propose a taxonomic revision, including the resurrection of the genera Pelontrus, Sayonara, Xenanthias, and Zalanthias, and the establishment of Aepysomanthias and Poroanthias Tang and Chen gen. nov. The revised taxonomy restricts Plectranthias to 20 currently recognized species.

 

systematics, taxonomic revision, anthias, Indo-West Pacific, Tropical Deep-Sea Benthos, osteology, diagnostic characters, Serranidae, new genus

 

Chi-Ngai Tang and Wei-Jen Chen. 2025. A 40-year Taxonomic Enigma: Multigene Phylogeny Resolves the Polyphyly of Plectranthias (Perciformes: Anthiadidae) and supports A Revised Taxonomy. Zoological Journal of the Linnean Society. 205(3); zlaf148. DOI: doi.org/10.1093/zoolinnean/zlaf148 [11 November 2025]  

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[Ichthyology • 2026] ‘Geophagus’ pirangaensis • A New endemic pearl cichlid of the ‘Geophagus’ brasiliensis (Cichliformes: Cichlidae) species group from the Piranga River, upper Doce River Basin, southeastern Brazil

 

‘Geophagus’ pirangaensis  Assis, Dergam & Henschel, 

in Assis, Dergam, Cunha, Machado, Hrbek, Vicente, Queiroz et Henschel, 2026

DOI: doi.org/10.1111/jfb.70324

Abstract

A new species of pearl cichlid of the ‘Geophagus’ brasiliensis species group, endemic to the Piranga River, a major tributary of the upper Doce River basin in the state of Minas Gerais, southeastern Brazil, is herein described. The new species is delimited using an integrative approach, with molecular-based species delimitation methods coupled with morphological diagnosis. For this, we developed a matrix containing 27 sequences of the mitochondrial gene cytochrome c oxidase subunit I (COI) of species of the ‘G.’ brasiliensis species group obtained from GenBank and three new sequences generated in this work. The species delimitation method applied to the morphological characters was Population Aggregation Analysis (PAA), and the species delimitation methods applied to the nucleotide sequences were the branch coalescence methods: Bayesian Poisson Tree Processes (bPTP), General Mixed Yule Coalescent (GMYC) single-threshold and GMYC multi-threshold. The three molecular-based species delimitation methods corroborate that the haplotypes of ‘Geophagus’ from the Piranga River represent a new species distinguished from all other in the ‘G.’ brasiliensis species group by exclusive presence of clear, rounded spots in the posteriormost dorsal-fin rays in fixed adult specimens, and the combination of the following morphological characters: long snout (46.22%–52.74% of head length), tall head (94.08%–101.15% of head length), terminal mouth, 25 or 26 longitudinal scales on the E0 series, 14 or 15 spines on the dorsal fin, absence of bluish dots on the most anterior soft rays of the anal fin in live specimens and absence of bluish and longitudinal lines in the basal region of the caudal fin of live specimens. This work is the first description of a new species of the ‘G.’ brasiliensis species group from the Doce River basin.

Keywords: Atlantic forest, fish taxonomy, freshwater fish, Geophagini, integrative taxonomy, mitochondrial DNA

‘Geophagus’ pirangaensis, new species from Piranga River, upper Doce basin, Ponte Nova municipality, Minas Gerais, Brazil:
top, MZUFV13723, live subadult specimen, 63.61 mm SL, collected by E. Henschel and photographed by C.E. de Assis;
bottom, MZUFV14666, live adult specimen, 96.21 mm SL, collected by C.E. de Assis and photographed by E. Henschel.

Scale bar: 10 mm.

‘Geophagus’ pirangaensis sp. n. Assis, Dergam & Henschel

 Diagnosis: ‘G.’ pirangaensis possess a unique diagnostic feature within the ‘G.’ brasiliensis group characterized by the presence of clear, rounded spots in the posteriormost dorsal-fin rays of fixed adult specimens (vs. absence, or, when present, spots are elliptical). It also differs from ‘G.’ brasiliensis by having a considerably longer snout (46.22%–52.74% HL vs. 38.36% HL) and terminal mouth (vs. subdorsal); from ‘G.’ diamantinensis by having a taller head (94.08%–101.15% HL vs. 77–86% HL) and terminal mouth (vs. subterminal); from ‘G.’ iporangensis by having a caudal fin with a rounded distal margin (vs. straight distal caudal-fin margin) and 25 or 26 longitudinal scales in the E0 series (vs. 27 or 28); from ‘G.’ itapicuruensis by having a dark and rounded mid-lateral spot of live specimens (vs. dark and vertically elliptical mid-lateral spot) and 14 or 15 spines on the dorsal fin (vs. 13); from ‘G.’ multiocellus by the absence of small bright spots in the central region of the bluish spots on the caudal fin of living specimens (vs. presence) and terminal mouth (vs. subterminal); from ‘G.’ obscurus by having small bluish spots in the opercular region of living specimens (vs. large bluish spots in the opercular region); from ‘G.’ rufomarginatus by the absence of bluish dots on the most anterior soft rays of the anal fin of living specimens (vs. presence), presence of denticles on gill rakers of the first branchial arch (vs. absence) and terminal mouth (vs. subterminal); and from ‘G.’ santosi by the absence of bluish and longitudinal lines in the basal region of the caudal fin of living specimens (vs. presence) and terminal mouth (vs. subterminal).

Cidimar E. de Assis, Jorge A. Dergam, Amanda F. Cunha, Valéria N. Machado, Tomas Hrbek, Natállia M. de F. Vicente, Victor de Queiroz and Elisabeth Henschel. 2026. A New endemic pearl cichlid of the ‘Geophagus’ brasiliensis (Cichliformes: Cichlidae) species group from the Piranga River, upper Doce River Basin, southeastern Brazil. Journal of Fish Biology. DOI: doi.org/10.1111/jfb.70324 [05 January 2026]  

[Ichthyology • 2025] Sayonara flavolineata • A New Deep-water anthiadid perchlet (Perciformes: Anthiadidae) from Vietnam

 Sayonara flavolineata

Tang, Vo & Gill, 2025

  RAFFLES BULLETIN OF ZOOLOGY. 73; 

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Abstract

 A new species of deep-water anthiadid perchlet, Sayonara flavolineata, is described from seven specimens collected off Nha Trang, southeastern Vietnam. Based on morphological features, it is assigned to a recently resurrected genus Sayonara Jordan & Seale, 1906, a former junior synonym of Plectranthias. Sayonara flavolineata, new species is distinctive in having yellow and reddish orange stripes when fresh, a horizontal dusky stripe in the middle of spinous dorsal fin, and a slightly concave dorsal profile of the head. It is further distinguished from other anthiadids by the following combination of characters: dorsal-fin rays X, 15; pectoral-fin rays 15–16; branched caudal-fin rays 8+7; lateral-line scales 31–35; circumpeduncular scales 12; predorsal scales extending anteriorly to posterior nostrils; body scales bearing basal cteni; scales present on maxilla, infraorbital, and mandibles; presence of trisegmental pterygiophores in both dorsal and anal fins; and two supraneurals. We updated and revised the record of species previously classified under Plectranthias in Vietnam. Including the new species, five species are now known from Vietnam and are reclassified to recently resurrected genera including Sayonara, Xenanthias, and Zalanthias.

Key words. taxonomy, species diversity, Plectranthias

Fresh colouration of Sayonara flavolineata, new species.
 A, holotype, OIM-E.55852 (field code: Q.01204-2), 101.1 mm SL; B, paratype, NMMB-P 41621 (field code: Q.01204-1), 107.9 mm SL.

Photos by Q. V. Vo.

CHI-NGAI TANG, QUANG VAN VO & ANTHONY C. GILL. 2025. Sayonara flavolineata (Perciformes: Anthiadidae), A New Deep-water anthiadid perchlet from Vietnam.  RAFFLES BULLETIN OF ZOOLOGY. 73; 698–708.

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[Ichthyology • 2025] Eugnathogobius ganuensis • A New Species of Eugnathogobius (Gobiidae) from Peninsular Malaysia

Eugnathogobius ganuensis

Koreeda, Seah & Motomura, 2025

DOI: doi.org/10.3390/taxonomy5040071

Abstract

The new estuarine goby Eugnathogobius ganuensis n. sp. is described from 5 specimens (4 males: 27.0–31.5 mm standard length; 1 female: 27.5 mm standard length) collected from a small ditch in the lower reach of the Terengganu River basin, east coast of Peninsular Malaysia. The new species is easily distinguished from other congeners, except E. kabilia, by the following a combination of characteristics: 16 segmented caudal-fin rays; 30 or 31 longitudinal scale lows; high first dorsal fin (especially in males); no head pores; shoulder with oblique black band; transverse black markings on each scale; paired black blotches on caudal-fin base; and distinct black dots on upper caudal fin. Although E. kabilia is very similar to the new species, the latter has a shorter jaw in males (well-extended in the former), high first dorsal fin (low), first dorsal-fin second spine length > 16.8% of standard length (<13.6%), throat yellowish in the fresh condition (whitish), and a yellowish second dorsal fin (reddish in males of E. kabilia). Because the type locality of the new species is clearly not a natural environmental feature and no salinity during the low tide, despite being included in the tidal area, the true habitat is suggested as being the upper reaches of estuarine areas. 

Keywords: taxonomy; morphology; Calamiana; South China Sea

 Fresh holotype (male) of Eugnathogobius ganuensis n. sp. (UMTF 13296, 30.0 mm SL).

Fresh paratypes of Eugnathogobius ganuensis n. sp.
((A): KAUM–I. 219716, male; (B): KAUM–I. 219718, male;
(C): UMTF 13297, male; (D): KAUM–I. 219721, female).

Eugnathogobius ganuensis n. sp.

Type locality (A) and live individuals (B–D) of Eugnathogobius ganuensis n. sp., Terengganu, Peninsular Malaysia.

White and black arrows indicate E. ganuensis n. sp. and Oxyeleotris urophthalmus, respectively.

 Reo Koreeda, Ying Giat Seah and Hiroyuki Motomura. 2025. A New Species of Eugnathogobius (Gobiidae) from Peninsular Malaysia. Taxonomy. 5(4), 71. DOI: doi.org/10.3390/taxonomy5040071 [17 December 2025]