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Mejia & Buckup 2026 (2)

Abstract: During the Pleistocene, repeated fluctuations in sea level changed the coastal landscape of southeastern Brazil. When sea levels fell, large areas of the continental shelf became exposed. Neighbouring rivers could merge or develop connections, allowing freshwater fish populations to spread between drainage systems. When sea levels rose again, these connections disappeared, isolating populations in separate river basins. Researchers investigated whether these historical changes contributed to the evolution and geographical distribution of whiptail catfish populations previously identified as Rineloricaria steindachneri. The study combined mitochondrial DNA markers (COI and CytB), a nuclear DNA marker (RAG1), and detailed morphological measurements (Mejia & Buckup 2026). Our analysis revealed clear genetic and morphological distinction between the two Rineloricaria morphotypes: R. steindachneri and the newly described R. capixaba. These results confirming our earlier delimitation of the former species (Mejia, Buckup, 2024), which restricted R. steindachneri to the lower Paraíba do Sul basin, while the geographic distribution of R. capixaba is assigned to the coastal Itabapoana, Itapemirim, Iconha, and Benevente river basins of southern Espírito Santo. Mitochondrial COI data demonstrate strong differentiation (Fst = 0.861; Nm = 0.08) and an average K2P divergence of ~2.0%, supporting their recognition as distinct evolutionary lineages and matching the 2–3% threshold commonly used to delimit freshwater fish species (Ward et al., 2009; Pereira et al., 2013; Ribolli et al., 2017). Reproduction: The Rineloricaria species are usually cave spawners, where the female will place their eggs after the male has cleaned inside. The male will then guard and fan the eggs until hatching. The eggs will hatch in 4-5 days whereas the male can now be removed. More breeding information can be found here in the articles breeding section. Lays up to 200 green eggs. The male may be nervous if disturbed but rearing the fry separately poses no problems. Aquarium Care: As with all Rineloricaria provide long leaved plants or bamboo stalks for them to hang on to. Also include rocks and bogwood into the aquarium with a sand substrate. Provide some pvc piping for breeding purposes. A good community tank fish if kept with non aggressive species. Diet: Omnivore. Vegetable food such as cucumber and other various foods such as tablet, flake and frozen. Etymology: The specific name steindachneri: Honours the Austrian ichthyologist Franz Steindachner (1834-1919), who was the first to report this fish, albeit under the name R. lima.

None

Loricaria steindachneri

Loricariidae

South America: Lower Paraíba do Sul River basin, Minas Gerais and Rio de Janeiro states (southeastern Brazil). Type locality: Eastern Brazil, from the Rio Preto to the Rio Parahyba.

19.0cm. (7½ins) TL.

22-25°c (71-77°f)

6.0-7.0.

Ferraris, C.J. Jr., 2003. Loricariidae - Loricariinae (Armored catfishes). p. 330-350. In R.E. Reis, S.O. Kullander and C.J. Ferraris, Jr. (eds.) Checklist of the Freshwater Fishes of South and Central America. Porto Alegre EDIPUCRS, Brasil.
Ferraris, C.J. Jr., 2007. Checklist of catfishes, recent and fossil (Osteichthyes: Siluriformes), and catalogue of siluriform primary types. Zootaxa 1418:1-628.
Fish in the News 2026.
Froese, R. and D. Pauly. Editors. 2026. FishBase. World Wide Web electronic publication. www.fishbase.org, ( 06/2026 ).
Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio). 2022. Rineloricaria steindachneri. The IUCN Red List of Threatened Species 2022.
Mejia, E., & Buckup, P. A. (2026). Past connection and isolation of Rineloricaria (Siluriformes: Loricariidae) across southeastern Brazilian coastal drainages: evidence for palaeodrainage connectivity and description of a new species. Neotropical Ichthyology, 24(3), e260024.