Fishes of the world

🧬 Can Quantitative Traits Improve Phylogenetic Inference? 🧩

Quantitative traits have long been challenging in cladistics, but a new study shows they provide strong evolutionary signals without the need for subjective discretization. 📊🔬

💡 We simulated 9,000 matrices under different evolutionary processes (Brownian motion, Ornstein-Uhlenbeck, and early burst) and a**lyzed their accuracy in phylogenetic reconstructions using parsimony in TNT. The results reveal that:

✅ Properly coded continuous characters can accurately infer species relationships, regardless of the evolutionary model.
✅ Equal weighting or implied weighting does not significantly affect tree reconstruction.
✅ Continuous traits are more effective at resolving shallow nodes in phylogenetic trees.

🌿 These findings highlight the potential of quantitative traits in phylogenetics and open new perspectives for their application in evolutionary studies.

📖 More details in the full study (📎 https://onlinelibrary.wiley.com/doi/full/10.1111/cla.12606).

🔍 What are your thoughts on using continuous traits in phylogenetics? Drop a comment below! ⬇️

A week of learning about Neotropical ichthyology

River Geomorphology and Fish Diversity Around the Manseriche Gorge, the Last Andean Crossing Is in Peril

J. D. Abad, H. Chicchon, J. Chuctaya, A. Mendoza, H. Valverde, C. Oshiro, M. Montoya (2024)

The transition from the Andes to the Amazon lowland hosts a high biodiversity and currently is facing several anthropogenic activities, including hydropower infrastructure projects. Little is known about the geomorphology of the Andean gorges, rivers and the interaction with the fish diversity upstream and downstream of gorges. The Marañón River is a major river that connects the Andes to the Amazon lowland and it carries 40% of the sediment load arriving to Brazil. The Santiago River is the last tributary into the Marañón River before the last gorge (Manseriche). Current plans for hydropower reservoirs include the construction of several dams along the Marañón River, being the largest with a 4,500 MW capacity at the Manseriche Gorge (MG). This study seeks to characterize the baseline processes of the hydrogeomorphology and fish diversity. Results show that the Santiago River is under transitional morphodynamic regime while the Marañón River is a fully developed anabranching river. This study reveals a clear difference in fish species richness and abundance between the upstream and downstream regions of the MG, with some species only found in specific regions. The MG acts as a natural boundary condition for the hydrogeomorphology and fish diversity. If the hydropower dam at MG was built, the reservoir in the upstream reach will produce the Santiago River to disappear and sedimentation to occur, consequently modifying sediment transport boundary conditions for the lower Marañón River.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2024WR037322

A new sponge-dwelling goby (Gobiidae: Bathygobius) from Indonesia, Philippines, and Australia.

Allen, G.R., Erdmann, M.V. & Ichida, N.K. (2024)

Bathygobius mero Allen et al., 2024

A new species of goby, Bathygobius mero, is described from eastern Bali, Indonesia on the basis of 8 adult specimens, 26.3–36.0 mm SL. There are also photographic records from Sumba, Indonesia, Cebu, Philippines, and Queensland, Australia. Diagnostic features include 19–21 (usually 20) pectoral-fin rays with the upper three rays free from the membranous portion of the fin and each with two filamentous tips, a mostly scaleless predorsal midline except for two or three scales in front of first dorsal-fin origin, and 33 or 34 lateral scales. The live coloration is overall pale greyish with a dense covering of reddish-brown freckles, a brown spot (about one third of pupil size) at the uppermost part of the gill opening, and reddish-brown spotting on the fins. The new species has a commensal association with the large barrel sponge (Xestospongia testudinaria), unlike other members of the genus, which are typically free-living bottom dwellers. It also inhabits deeper water (9–30 m, but usually below about 15 m) than most Bathygobius, which are mainly confined to shallow water less than 10 m deep.

https://zenodo.org/records/14003729

Evolutionary history of Chinese karst loaches (Nemacheilidae, Karstsinnectes): new insights from mitochondrial-based genomes and description of a new species from Guangxi, China.

Luo, T., Luo, F.-W., Lan, C.-T., Xiao, M.-Y., Zhou, J.-J., Liao, M., Xiao, N. & Zhou, J. (2024)

Karstsinnectes daxinensis Luo et al., 2024

The genus Karstsinnectes of blind fishes known as karst loaches from China was established in 2023 during a revision of the genus Oreonectes (Nemacheilidae). Six species are recorded in this study and some taxonomic progress has been made; however, the lack of genetic data for some species (e.g., K. anophthalmus) may have weakened our current understanding of Karstsinnectes. This study reassessed the phylogeny and evolutionary history of Karstsinnectes by integrating a combination of previously published and newly sequenced mitochondrial genomic data. A phylogenetic tree was developed that was able to divide Karstsinnectes into two clades corresponding to drainages and clarify the phylogenetic position of K. anophthalmus. Divergence times show that Karstsinnectes originated at the Oligocene/Miocene boundary (~22.37 Mya), with the most recent common ancestor occurring in the early Miocene (~18.87 Mya) and interspecific divergence occurring in the late Miocene. Ancestral area reconstruction suggests that the most recent common ancestor of Karstsinnectes most likely inhabited the Hongshui River basin and dispersed into the Zuojiang-Yujiang, Beipanjiang, and Youjiang river basins during the early Miocene (~18.87 Mya), middle Miocene (~12.78 Mya), and late Miocene (~6.71 Mya), respectively.

https://zse.pensoft.net/article/133964/

Discovery of two new species of cobia (Pisces; Rachycentridae) inhabiting the makran coast of the northern Arabian Sea with notes on their biology and ecology.

Panhwar, S.K. & Kashani, I. (2024)

Rachycentron blochii Panhwar & Kashani, 2024
Rachycentron makranensis Panhwar & Kashani, 2024

Cobia, Rachycentron canadum has long been regarded as the sole species in the family Rachycentridae, and has a wide distribution in tropical and sub-tropical regions of the Atlantic, Indian Ocean and western Pacific. This study describes two newly identified species, Rachycentron blochii sp. nov. and Rachycentron makranesis sp. nov. from Gwadar in the northern Arabian Sea. The newly discovered species differ significantly from their relatives in multiple morphological traits, such as head profile, mouth, pectoral fin, caudal fin, caudal peduncle, dorsal and a**l fin bases, gill rakers, and body coloration. Additionally, species delimitation was further supported by examining body scales and otoliths (sagitta, lapillus, and asteriscus), with shapes also delimiting species. The recent finding increases the number of cobia species in the northern Arabian Sea, Pakistan. Moreover, details on the biological and ecological aspects such as feeding habits, age assessment, habitat preferences and fishery-related details are presented.

Fig.. The holotypes (AFBL-11) (a) Rachycentron blochii sp.nov, (AFBL-12), Rachycentron makranesis sp.nov. and Rachycenron canadum sampled from newly established Gwadar fish harbour on 18.11.2023.

https://www.sciencedirect.com/science/article/pii/S0044523124001086?via%3Dihub

Phylogenomic and anatomical evidence for the Late Cretaceous diversification of African characiform fishes, including a new family, under the influence of the Trans-Saharan Seaway.

Melo, B.F. & Stiassny, M.L.J. (2024)

Lepidarchidae fam. n. Melo & Stiassny, 2024

Geological evidence supports the occurrence of an epicontinental Trans-Saharan Seaway bisecting the African continent during the Late Cretaceous to early Paleogene. The seaway formed a wide saltwater channel connecting the Neotethys with the South Atlantic, yet no previous study has investigated its impact on freshwater fish diversification. Phylogenomic data and time-calibrated trees indicate a Late Cretaceous signature for the appearance of three modern lineages of characiform fishes. Phylogenetic a**lyses using ultraconserved elements of 83 characiforms reveals that Alestidae, Hepsetus, and Lepidarchidae fam. nov. originated during the Santonian-Campanian of the Late Cretaceous (84–77.5 million years ago; Ma). Lepidarchidae consists of two monotypic taxa not previously recognized as sister species: the Niger tetra Arnoldichthys endemic to the lower Niger and Ogun rivers of Nigeria, and the dwarf jellybean tetra Lepidarchus from coastal rivers of Ghana, Côte d'Ivoire, Liberia, Sierra Leone, and Guinea. Microcomputed tomography scans (µCT) of 117 characiforms provide three novel morphological characters supporting Hepsetus and Lepidarchidae, four characters for monophyly of Lepidarchidae and five for a restricted Alestidae.

https://academic.oup.com/evolinnean/advance-article/doi/10.1093/evolinnean/kzae030/7848922?login=true

A new genus for the Blackfin Sucker, Thoburnia atripinnis (Cypriniformes: Catostomidae).

Armbruster, J.W. (2024)

Vexillichthys n. gen. Armbruster, 2024
Type species: Moxostoma (Thoburnia) atripinne Bailey, 1959

Thoburnia atripinnis is more closely related to Hypentelium (hogsuckers) than it is to other Thoburnia, and its presence in the Barren River of Kentucky is disjunct from that of true Thoburnia. Its unique morphology is unlike that of the easily recognized hogsuckers, making placement of the species within Hypentelium untenable; thus, a new genus is described. The new genus can be separated from all other catostomids by the presence of thin, black, prominent stripes on the body, a large black mark on the anterodist al portion of the dorsal fin, presence of pads ventrally on the leading portion of the pectoral fin, lateral laminae of the dermethmoid angled anteriorly, and the base of the lateral ethmoid narrow.

https://mapress.com/zt/article/view/zootaxa.5536.2.8

Dzihunia pseudoamudarjensis, a new nemacheilid loach from the Syr Darya drainage (Teleostei: Nemacheilidae).

Sheraliev, B. & Kayumova, Y. (2024)

Dzihunia pseudoamudarjensis Sheraliev & Kayumova, 2024

Dzihunia pseudoamudarjensis, new species, is described from the middle portion of the Great Fergana Ca**l in the Fergana Valley. The new species is distinguished from its congeners by having a complete lateral line with 84–86 pores, a slenderer caudal peduncle, a smaller dorsal and a**l fin depth, and a wider interorbital distance. A key to Dzihunia species is provided.

FIGURE 4. Dzihunia pseudoamudarjensis, Uzbekistan: Great Fergana Ca**l: from top: SWU 08122023002, 86 mm SL (paratype); BSFC 0073, 102 mm SL (paratype); not preserved, about 95 mm SL; SWU 08122023002, 93 mm SL (paratype).

https://mapress.com/zt/article/view/zootaxa.5536.1.8

A new freshwater pipefish species (Syngnathidae: Microphis) from the Sunda shelf islands, Indonesia.

Haÿ, V., Mennesson, M.I., Dahruddin, H., Sauri, S., Limmon, G., Wowor, D., Hubert, N., Keith, P. & Lord, C. (2024)

Microphis arrakisae Haÿ et al., 2024

A new species of freshwater pipefish, Microphis arrakisae sp. nov., is described from the West Indonesian Islands (Java, Bali and Lombok). This species is morphologically very close to Microphis retzii (Bleeker, 1856), which is found in the eastern Indonesian Islands (Sulawesi, Ceram, Ambon and Papua). However, it can be distinguished by its in vivo coloration. Furthermore, genetic a**lysis of the partial COI gene (barcoding) indicates that it represents a distinct genetic lineage in the Indonesian region.

https://mapress.com/zt/article/view/zootaxa.5536.1.5

Historical biogeography of North American killifishes (Cyprinodontiformes) recapitulates geographical history in the Gulf of México watershed

Hernández-Ávila, S. G., Hoagstrom, C. W., & Matamoros, W. A. (2024)

This study explores the phylogenetic relationships and biogeography of North American killifishes, focusing on five families within Cyprinodontiformes. Using DNA sequences and fossil calibrations, researchers constructed a time-calibrated phylogeny showing that this clade originated along the Gulf of Mexico coast in the Eocene. While speciation was mostly uniform, a marked increase occurred in Cyprinodontidae around 10.9 million years ago. Coastal fluctuations likely promoted cycles of dispersal and vicariance, while inland migration and resilience in harsh environments contributed to the clade's adaptability and current diversity.

https://academic.oup.com/zoolinnean/article/202/2/zlae105/7845214?login=true

Diving deeper into the taxonomy of the Neoscopelus species complex (Myctophiformes: Neoscopelidae) with the description of Neoscopelus serranoi sp. nov.

Neoscopelus serranoi Bañón et al., 2024

Bañón, R., Barros-García, D., Arronte, J.C., Rábade, S., Del Rio, J.L., Baldó, F. & De Carlos, A. (2024)

https://mapress.com/zt/article/view/zootaxa.5529.3.4

Previous studies have highlighted possible cryptic biodiversity in the genus Neoscopelus. This hypothesis was tested using new morphological, molecular and biogeographical data on species of this genus caught in the north Atlantic between 2010 and 2022. The information obtained has been combined with available data in an integrative approach, including a review of morphological characters reported in the ichthyological literature and DNA-based species delimitation a**lyses. The main outcome of the present study is the description of Neoscopelus serranoi sp. nov. from the Atlantic and southwestern Indian Oceans. The new species is morphologically very similar to Neoscopelus microchir from which differs in having a shorter a**l-fin base, a shorter pelvic fin, more dorsal and pectoral-fin rays, less a**l-fin rays, fewer gillrakers and fewer isthmus and lateral photophores.