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| Hyphessobrycon citrus |
Abstract
The Serra do Cachimbo is a highland area at the southeastern portion of the Amazon Forest drained by the headwaters of tributaries of rios Xingu and Tapajós. It is known as an area of high level of endemism of fish, low species diversity, and very few taxa with broad distribution in the other parts of the Amazon. Despite its biogeographical importance, there are still many poorly sampled areas. Four expeditions to the region yielded in the rediscovery of a poorly known, endemic species, Hyphessobrycon cachimbensis, and the discovery of a similar, allopatric undescribed congener, frequently misidentified as H. cachimbensis. We provided the redescription of H. cachimbensis and the description of the new species. Both can be differentiated from most congeners by having a conspicuous longitudinal dark stripe on body and anal-fin base convex in males, due to thicker musculature insertion in the region. Other diagnostic features are mostly related to counts of scales and fin rays.
Keywords: Endemism; Ostariophysi; Rio Tapajós; Rio Xingu; Tetra
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| Hyphessobrycon citrus, Brazil, Pará State, rio Tapajós basin, rio Teles Pires drainage, tributary of rio Braço Norte. A. MZUSP 128236, holotype, 38.0 mm SL, male; B. MZUSP 101429, paratype, 39.4 mm SL, female. |
Hyphessobrycon citrus, new species
Diagnosis. Hyphessobrycon citrus can be distinguished from its congeners, except H. cachimbensis, H. chiribiquete, H. comodoro, H. cyanotaenia, H. fernandezi, H. melanostichos, H. nigricinctus, H. paucilepis, H. petricolus, H. piranga, H. psittacus, H. scholzei, H. sovichthys, H. stegemanni, H. taphorni, H. tuyensis, and H. vilmae,by the presence of a well-defined, relatively narrow dark midlateral stripe on body, from immediately behind the opercular opening to the tip of middle caudal-fin rays (vs. longitudinal stripe absent, stripe starting approximately at vertical through the dorsal-fin origin, or midlateral dark stripe becoming blurred towards the caudal peduncle). It can be distinguished from the aforementioned species, except H. cachimbensis, H. chiribiquete, H. comodoro, H. cyanotaenia, H. melanostichos, H. nigricinctus, and H. petricolus, by the presence of a humeral spot (vs. absence). Hyphessobrycon citrus can be distinguished from H. cachimbensis, H. comodoro, H. cyanotaenia, and H. melanostichos by having the longitudinal black stripe starting immediately behind the opercle (vs. starting at the posterior margin of orbit), from H. chiribiquete, H. nigricinctus and from H. cachimbensis by having 14–17 anal-fin rays (vs. 18 or more), and from H. petricolus by having 14 horizontal scale rows around caudal peduncle (vs. 12) and non-symphyseal teeth of the premaxillary inner row with 7 to 9 cusps (vs. 3 to 5). The yellow citrus coloration and a vivid colored red eye in life also help distinguishing H. citrus from congeners.
Etymology. The specific epithet comes from the Latin “citrus”, referring to its bright yellow coloration similar to several citrus fruits. A noun in apposition.
Manoela Maria Ferreira Marinho and Fernando Cesar Paiva Dagosta. 2024. Redescription of Hyphessobrycon cachimbensis (Characiformes: Characidae) with the Description of A New congener from the Serra do Cachimbo, Brazil. Neotrop. ichthyol. 22 (2); DOI: 10.1590/1982-0224-2023-0127
