Abstract

Hyphessobrycon chiribiquete n. sp. is described from the Río Caquetá drainage in Colombia and the Río Ucayali drainage in Peru, western Amazon. The new species is diagnosed from its congeners by having the following combination of characters: a conspicuous narrow midlateral stripe, starting on the sides of the body behind the opercle near the lateral line; lateral stripe overlapped anteriorly with a vertically elongated humeral blotch; inner premaxillary teeth pentacuspid; margin of anal fin falcate in mature males.
KEYWORDS: Hyphessobrycon agulha, neotropical diversity, Río Caquetá drainage, Río Ucayali drainage,
Serrania de Chiribiquete

INTRODUCTION

Hyphessobrycon is one of the most species-rich genera of Characidae, with 159 species currently considered as valid (Faria et al., 2018; Ohara et al., 2019; Teixeira et al., 2020) distributed from southern Mexico (Miller et al., 2006) to the Río de La Plata in Argentina (Menni, 2004). The genus was described by Durbin (in Eigenmann, 1908) as “a Hemigrammus with naked caudal” fin. Further diagnostic characters
were presented by Eigenmann (1917: 50–51) in the most comprehensive revision on the genus so far. It is nowadays consensual that Hyphessobrycon, as are several other species-rich genera within Characidae (e.g., Astyanax, Hasemania, Hemigrammus, Moenkhausia) is polyphyletic, as corroborated by phylogenetic analyses based on both molecular and morphological data (Javonillo et al., 2010; Mirande, 2010, 2019; Ohara, Mirande & Lima, 2017; Oliveira et al., 2011). Despite that, the traditional definition of the genus of Eigenmann (1917) is still used in taxonomic studies, mainly for practical reasons. Nevertheless, some species groups have been proposed within this genus, based primarily on similarities of colour pattern, shape of body and fins, and secondary sexual characters (Ingenito et al., 2013; Lima et al., 2014; Moreira & Lima, 2017; Ohara & Lima, 2015; Pastana & Ohara, 2016; Weitzman & Palmer, 1997).

In 2004, one of the authors (FCTL) joined a survey of the fishes from terra firme streams from the Jenaro Herrera area in the Río Ucayali, Peru, when several specimens of a distinctive Hyphessobrycon species were collected. Subsequent surveys of fish collections (namely MZUSP, MUSM, ANSP, MHNG and NRM) revealed a few additional specimens of the species. Recently (2016–2019), two of the other authors (JIM and AUB) collected several specimens of a Hyphessobrycon species from tributaries of the middle Río Caquetá basin in the Serranía de Chiribiquete, Colombia, that on subsequent examination proved to be conspecific with the specimens from Peru. The aim of the present contribution is to describe this species.

MATERIALS AND METHODS

The sampled fishes were anaesthetized by immersion in a eugenol
solution before being fixed and preserved. They were collected during
the expeditions for the nomination of the Serranía de Chiribiquete
National Park as a world heritage site of UNESCO, under authorization

20172000005311 issued by the subdirector’s office of management

of protected areas of the National Natural Parks of Colombia and permission to collect biological diversity for scientific research resolution # 0778 7 July 2017. Morphometric and meristic data were taken following Fink and Weitzman (1974) and Menezes and Weitzman (1990), except for counts of the horizontal scale rows below the lateral line, which were counted to the pelvic-fin origin. In the description, the frequency of each count is given in parenthesis after the respective count. An asterisk indicates counts of the holotype. Morphometric data were expressed as percentages of standard length (LS), except subunits of the head, which were expressed in percentages of head length. Counts of supraneurals, vertebrae, procurrent caudal-fin rays, unbranched anal-fin rays, branchiostegal rays, gill-rakers, dentary teeth and teeth cusps were taken from cleared and stained specimens (CS), prepared according to Taylor and van Dyke (1985). Vertebrae of the Weberian apparatus were counted as four elements, and the fused PU1 + U1 counted as a single element. Institutional acronyms follow Sabaj (2019).

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