The most remarkable anatomical specialization of threadfins (Percomorphacea: Polynemidae) is the division of their pectoral fin into an upper, unmodified fin and a lower portion with rays highly modified into specialized filaments. Such filaments are usually elongate, free from interradial membrane, and move independently from the unmodified fin to explore the environment. The evolution of the pectoral filaments involved several morphological modifications herein detailed for the first time. The posterior articular facet of the coracoid greatly expands anteroventrally during development. Similar expansions occur in pectoral radials 3 and 4, with the former usually acquiring indentations with the surrounding bones and losing association with both rays and filaments. Whereas most percomorphs typically have four or five muscles serving the pectoral fin, adult polynemids have up to 11 independent divisions in the intrinsic pectoral musculature. The main adductor and abductor muscles masses of the pectoral system are completely divided into two muscle segments, each independently serving the pectoral-fin rays (dorsally) and the pectoral filaments (ventrally). Based on the innervation pattern and the discovery of terminal buds in the external surface of the filaments, we demonstrate for the first time that the pectoral filaments of threadfins have both tactile and gustatory functions.
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http://dx.doi.org/10.1038/s41598-020-74896-y | DOI Listing |
A cusk-eel, known from the Galápagos Archipelago since 1905, which has remained undescribed, is herein formally named, Ophidion galapagensis Lea & Robins. The species is known from 10 collections, including material from Isla del Coco. The species is endemic to the Galápagos Archipelago-Isla del Cocos biogeographic complex and is compared to the seven known eastern Pacific ophidiine cusk-eels; its relationship to these species is unclear.
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Key Laboratory for Animal Genetics & Molecular Breeding of Jiangsu Province, College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, PR China. Electronic address:
J Fish Biol
September 2024
Museu de Zoologia da Universidade de São Paulo, São Paulo, Brazil.
A new species of Eigenmannia is described from the Rio Branco basin, Roraima, Brazil, based on morphological and molecular datasets. It is distinguished from all congeners by the following combination of characters: lateral line stripe extending from first perforated lateral line scale to distal portion of caudal filament, presence of superior midlateral stripe with origin posterior to end of body cavity anal-fin hyaline, caudal filament corresponding to 15.2%-43.
View Article and Find Full Text PDFZootaxa
October 2022
Departamento de Ecologia e Biologia Evolutiva, Universidade Federal de São Paulo, Campus Diadema, Avenida Conceição, 545, Centro, 09920-000 Diadema, SP, Brazil. .
The genus Rineloricaria comprises 69 valid species and has been considered monophyletic by some authors. The taxonomic history of Rineloricaria is quite complex, especially concerning its wide distribution and morphological plasticity that make it difficult to diagnose and describe new species. Even with the great species-richness of the genus and the huge diversity of the system, the Tocantins-Araguaia River basin hosts only three formally described species of Rineloricaria: R.
View Article and Find Full Text PDFJ Fish Biol
December 2022
Laboratory of ecology o aquatic communities and invasions, A. N. Severtsov Institute of Ecology and Evolution, Russian Academy of Sciences, Moscow, Russia.
A new species, Bathysphyraenops radhae, is described from the equatorial western Indian Ocean. It resembles Bathysphyraenops declivifrons in the shape of snout and number of pseudobranchial filaments in adults but can be readily distinguished from all known members of Howellidae by its characteristically armed preopercle and in strong reduction or absence of spinules on scales around the pectoral fin. The genus Bathysphyraenops is rediagnosed, and the characteristics useful in diagnosing the howellid genera are briefly discussed.
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