SCOTCAT.COM  

Alejandro López-Méndez (3)

Abstract: Phenacorhamdia comprises 15 species distributed across the major river basins of South America,with P. tenebrosa beingthe only species recorded in Argentina. After the examination of specimens of Phenacorhamdia from the upper Bermejo River basin, Paraná River basin, in northwestern Argentina, we conclude that they belong to a new species which is described herein. The new species is distinguished from the remaining members of the genus by a combination of non-unique characters including: maxillary barbel surpassing the distal tip of the adpressed pectoral fin; light-brown background colouration of the body; the conical teeth; 41–42 vertebrae; iii–iv,7–9 anal-fin rays, among other features. The morphological analysis performed shows a clear distinction of the new species from congeners, and the greater genetic distance based on the gen COI between P. bermejo with P. tenebrosa, provides additional support for the recognition of the new species herein described (Aguilera G, et al. 2026). Habitat: Phenacorhamdia bermejo inhabits the upper Bermejo River basin, where it was found at four localities, three on the San Francisco River basin in Jujuy Province and one at the Bermejo River in Salta. Colouration: The overall pigmentation consists of uniform, minute mottling, producing a homogeneous reddish-brown hue across the body. The head is slightly darker than the rest of the body, while pigmentation on the caudal peduncle is concentrated midlaterally, gradually fading towards the dorsal and ventral regions. The pectoral, pelvic, and anal fins are hyaline, with the dorsal fin similarly transparent but displaying chromatophores concentrated along the rays, which becoming less conspicuous towards the distal tips. The adipose fin exhibits chromatophores concentrated at the base, extending to about middle depth of the fin, with a gradual fading towards the distal margin. The caudal fin shows denser pigmentation near the base, which progressively fades towards the distal margin. Head, in ventral view, with chromatophores restricted to the preoperculomandibular laterosensory canal. Clear absence of pigmentation from the origin of the pectoral fin to the anal-fin origin, giving it a silvery appearance (Aguilera G, et al. 2026). Etymology: The specific epithet “bermejo” is a Spanish word meaning reddish in English and refers to both the colouration of live specimens which present a reddish-brown hue across the body, and to the name of the river basin where the specimens of Phenacorhamdia bermejo were collected. A noun in apposition.

None

None

Heptapteridae

South America: Upper Bermejo River basin.

5.0cm. (2ins)

24-26°C (75-79°F)

6.0-7.0.

Aguilera G, Terán GE, Cortéz Hernández MA, Katz AM, Azevedo-Santos VM, Benitez M, Mirande M. Hidden diversity in the Paraná River basin: a new species of Phenacorhamdia (Siluriformes: Heptapteridae) from the Bermejo River, Argentina. Neotrop Ichthyol. 2026; 24(1):e250189.
Fish in the News 2026.