A new rheophilic South American darter (Crenuchidae: Characidium) from the rio Juruena basin, Brazil, with comments on morphological adaptations to life in fast-flowing waters

Local trade, spatial occurrence and conservation of hypostomus soniae (siluriformes, loricariidae), an ornamental fish endemic to the tapajos river, Brazil

Hypostomus soniae is a small sized armored catfish endemic to the Tapajos River basin and ranked as one of the most exploited ornamental fish in the Santarem export marketplace. This study aims to evaluate distributional patterns of Hypostomus soniae and contribute to the species conservation in the face of development of the ornamental fish trade in the Amazon region. We compiled data associated with geographic coordinates in public repositories, supplemented with original field records. We compared our data to published records in the literature and museum collections to check for accuracy. To investigate the fishery and commercialization of H. soniae, we conducted interviews with ornamental fish stakeholders from the local trade. We also made direct observations in the fishing sites and export facilities in Santarem. A cluster analysis of the geolocation data was carried out to explore the spatial distribution patterns. The volume of captures and exportation of H. soniae decreased during the period 2020-2023. The occurrence of H. soniae was associated with annual rainfall ranging from 2,000 mm to 2,500 mm and concentrated in two municipalities of the State of Mato Grosso and two of the Para State. The species distribution area has been threatened, unfortunately, by fishermen who do not respect the laws that support artisanal fishing in the Amazon.

A new species of Characidium (Characiformes: Crenuchidae) from the rio Doce basin, Brazil

Abstract A new species of Characidium is described from the tributaries of the upper and middle rio Doce basin, Minas Gerais, Brazil. The new species is distinguished from most congeners, except C. cricarense, C. hasemani, C. helmeri, C. kalunga, C. pterostictum, C. schubarti, C. summus, and C. travassosi by lacking scales in the area between the anterior limit of the isthmus and the anterior margin of cleithrum. The new species differs from the aforementioned species by a series of characters, including the presence of the adipose fin, 2–4 scales between the anus and anal fin, two rows of dentary teeth, presence of the parietal branch of the supraorbital canal, 4 scale rows above the lateral line, and absence of two conspicuous inclined dark bands on each caudal-fin lobe. The new species further differs from most congeners with an unscaled ventral surface of the isthmus by the presence of 33–34 pored scales on the lateral line and by the dark dashes on the caudal fin-rays not forming well-defined bands.

A new, narrowly distributed, and critically endangered species of Characidium (Characiformes: Crenuchidae) from the Distrito Federal, Central Brazil

ABSTRACT A new species of Characidium is described from the Cerrado biome, in Brasília, Distrito Federal, Central Brazil. The new species can be readily diagnosed by the presence of two or three longitudinal rows of dots along the body sides, absence of bars, by the short pectoral fin, which does not reach the vertical through the dorsal fin origin. Additional useful diagnostic characters are the scaled isthmus, absence of the adipose fin, and the terminal mouth. The new species is only known from the córrego Taquara and its tributaries, a tributary of ribeirão do Gama, upstream from lago Paranoá, in the upper rio Paraná basin. In accordance to the IUCN Red List Categories and Criteria, the new species is categorized as Critically Endangered.