A new genus and species of inseminating tetra has been described as Phallobrycon adenacanthus in a recent issue of the journal Zootaxa.
According to authors Narcio Menezes, Katiane Ferreira and Andr Netto-Ferreira, the new tetra is distinguished from other members of the Characidae in having two developed spines on the unbranched portions of the fifth to seventh anal-fin rays associated with swollen glandular tissue (that is not organized into an organ) on the anterior portion of the anal fin in sexually mature males.
The new tetra also has a urogenital papilla modified into a copulatory organ and lacks pelvic-fin hooks.
Phallobrycon adenacanthus is known from the Xingu River drainage, where it inhabits the main channels of rivers with fast flowing and shallow clear waters, having an abundance of rocks and thick sand.
For more information, see the paper: Menezes, NA, KM Ferreira and AL Netto-Ferreira (2009) A new genus and species of inseminating characid fish from the rio Xingu basin (Characiformes: Characidae). Zootaxa 2167, pp. 47"58.