Hyphessobrycon rutiliflavidus described from Mato Grosso

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Brazilian scientists have described a new species of tetra from the upper Paraguai River drainage.

The new characid, named Hyphessobrycon rutiliflavidus in a recent issue of Zootaxa by Fernando Carvalho, Francisco Langeani, Carlos Miyazawa and Waldo Troy, can be distinguished from other members of the genus in having a combination of:

a black humeral spot that is slightly diffuse at tips; a dark blotch on the caudal peduncle blotch; a midlateral longitudinal stripe on the body that is more conspicuous posteriorly and extending from vertical through the anterior third of pectoral fin to the caudal-peduncle blotch and extending through the median caudal-fin rays; anal fin with iii,15 to iv,19 rays; upper jaw length 42.3"49.5% HL; maxilla with 2"5 teeth; all fins of males reddish-orange and of females yellowish.

Hyphessobrycon rutiliflavidus, named after the sexually dimorphic colour of the fins in this species (from the Latin rutilus, meaning red and flavidus, meaning yellowish), in known only from its type locality in the upper Paraguai River drainage.

According to the authors, the type locality ...is situated approximately 479 m above sea level. Its riparian vegetation is relatively well conserved, surrounded by cerrado formation.

Riffles, runs, and pools are present, and Hyphessobrycon rutiliflavidus occurs preferentially in lentic portions. The water is cold and transparent; bottom is mostly of silt and rocks.

Syntopic species, collected with cast nets and fish-hooks, were Parodon aff. nasus, Astyanax asuncionensis...Knodus chapadae...Hypostomus sp., and Ancistrus sp. Stomach contents of five specimens of Hyphessobrycon rutiliflavidus examined contained debris of vascular plants, algae, and arthopods...

For more information, see the paper: Carvalho, FR, F Langeani, CS Miyazawa and WP Troy (2008) Hyphessobrycon rutiliflavidus n. sp., a new characid fish from the upper rio Paraguai, State of Mato Grosso, Brazil (Characiformes: Characidae). Zootaxa 1674, pp. 39"49.