Tuesday, February 13, 2018

[Ichthyology • 2016] Panaqolus claustellifer • A New Species of Panaqolus (Siluriformes: Loricariidae) from the rio Branco


 Panaqolus claustellifer 
 Tan, Souza & Armbruster, 2016


A new species of Panaqolus is described from material from the Takutu River and the mainstem rio Branco. The new species is diagnosed from congeners by its color pattern consisting of dark and light bars on the body, bands on the fins, and with dots and vermiculations absent (vs. no bars in P. albomaculatus, P. nix, P. nocturnus, and P. koko, vs. fins unbanded in P. albomaculatus, P. dentex, P. koko, and P. nix, and vs. dots and vermiculations present in P. albivermis and P. maccus). The new species is diagnosed from barred species of Panaqolus by its specific bar number and orientation and color pattern on its head, with bars oriented in a anteroventral-posterodorsal direction (vs. anterodorsal-posteroventral bars in P. gnomus), having consistently 5 bars (n = 4) on the trunk that do not increase with size (vs. number increasing with size in P. purusiensis and vs. 6-12 in P. changae), and the color pattern on the head of straight lines extending from posterior to the eye to the snout margin, splitting in the middle portion of the line in larger specimens (vs. small, dense reticulate lines in P. changae). Biogeographically, we infer that the new species ancestrally originated in the Amazon river, dispersing to the Takutu River after the Amazon captured part of the Proto-Berbice.

 Keywords: Brazil, Guyana, Hypostominae, Takutu River.


Fig. 1. Panaqolus claustellifer, new species, CSBD F1702/AUM 44721, Takutu River, holotype, adult male, 61.6 mm SL, lateral view is of right side and flipped horizontally. Photo by Milton Tan. 

Panaqolus claustellifer, new species

Diagnosis. Panaqolus claustellifer is diagnosed from most other described species of Panaqolus by its color pattern of dark and light bars on the body, bands on the fins, and with dots and vermiculations absent (vs. no bars in P. albomaculatus, P. nix, P. nocturnus, and P. koko, vs. fins unbanded in P. albomaculatus, P. dentex, P. koko, and P. nix, and vs. dots and vermiculations present in P. albivermis and P. maccus ). Additionally, Panaqolus claustellifer is diagnosed from P. albivermis, P. albomaculatus, and P. nix by dentaries forming an acute angle ~70º vs. dentaries forming a very acute angle to dentaries parallel), and from P. koko by spoon-shaped teeth with small lateral cusps vs. quadrate teeth with strong lateral cusps. Panaqolus claustellifer is diagnosed from other barred species of Panaqolus by the specific bar number and orientation and color pattern on the head, with bars oriented in a anteroventral-posterodorsal direction (vs. anterodorsal-posteroventral bars in P. gnomus), having consistently 5 bars (n = 4) on the trunk that do not increase with size (vs. number increasing with size in P. purusiensis and fading at body sizes >85 mm SL, and vs. 6-12 in P. changae), and the color pattern on the head of straight lines extending from posterior to the eye to the snout margin, splitting in the middle portion of the line in larger specimens (vs. small, dense reticulate lines in P. changae).

Etymology. From the Latin claustellum , meaning keyhole, and the Latin fero , meaning to bear. Refers to the dark brown lines on the snout surrounding a keyhole-like shape of light-brown base coloration. Treated as a masculine adjective.

Ecological notes. Individuals of Panaqolus claustellifer were found in shallow cataracts along the Takutu river, a whitewater system. The substrate was sandy with lateritic rocks interspersed. Surrounding habitat consisted of a narrow strip of gallery forest, but mostly savanna. Small specimens <20 mm SL (AUM 47717, AUM 65708) likely represent young-of-year that have hatched less than a couple weeks prior to collection.

Distribution. Panaqolus claustellifer occurs in the Takutu river and the mainstem rio Branco of Brazil and Guyana.


Milton Tan, Lesley S. de Souza and Jonathan W. Armbruster. 2016. A New Species of Panaqolus (Siluriformes: Loricariidae) from the rio Branco. Neotropical Ichthyology. 14(2); e150033. DOI:  10.1590/1982-0224-20150033

 Uma espécie nova de Panaqolus é descrita do rio Branco e seu afluente, rio Tacutu. A nova espécie é diagnosticada de suas congêneres pelo padrão de colorido composto por barras escuras e claras alternadas no corpo e nadadeiras, não formando máculas ou vermiculações nas nadadeiras (vs. sem barras no corpo em P. albomaculatus, P. nix, P. nocturnus, e P. koko, e vs. sem barras nas nadadeiras em P. albomaculatus, P. dentex, P. koko, e P. nix, e vs. máculas e vermiculações presentes em P. albivermis e P. maccus). A nova espécie é diagnosticada das espécies de Panaqolus com barras pelo número e orientação das barras e pelo padrão de colorido cefálico, com as barras orientadas posterodorsalmente (vs. posteroventralmente em P. gnomus), pela presença de cinco barras (n = 4) no tronco que não aumentam com o tamanho (vs. número aumentando com o tamanho em P. purusiensis e vs. 6-12 barras em P. changae), e o padrão de colorido cefálico composto por linhas retas da margem posterior do olho à margem do focinho, dividida medianamente em indivíduos maiores (vs. linhas pequenas e vermiculadas em P. changae). Nos inferimos que a nova espécie originou-se ancestralmente no rio Amazonas, dispersando para o rio Tacutu após o Amazonas capturar parte do Proto-Berbice. 


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