The "candy cane tetra" is most likely now described as the species
Hyphessobrycon bentosi. This name has a rather confusing history, as it was used for more than one of the very similarly-coloured and patterned fishes commonly known as the Rosy Tetra, Roberti Tetra, Ornate Tetra, and more recently HY511 (candy cane, peppermint). Weitzman & Palmer (1997) proposed the "Rosy clade" of several species in
Hyphessobrycon that share some features such as a black blotch in the dorsal, a dark humeral (shoulder) patch, and white in some fins. The Black Phantom and Red Phantom, Serpae, Bleeding Heart, and others were also in this "clade." In proposing this, Weitzman & Palmer (1997) suggested that
Hyphessobrycon bentosi was the species known as the "Roberti" by Gery (1977). This was acknowledged by the authors to not be a complete phylogenetic study, so it was inevitable that subsequent studies might sort things out. And this happened in Zarske (2014) whose paper can be viewed for free here:
http
/researcharchive.calacademy.org/research/ichthyology/catalog/getref.asp?id=33403
The Abstract is in English but the main text is in German, with some nice photos. Zarske described the "Roberti" tetra as a distinct species for the first time, and named it
Hypohessobrycon jackrobertsi. He also re-described
H. sweglesi (Red Phantom), and another two new species,
H. dorsalis and
H. paepkei. And
H. bentosi was clarified.
The species in the "Rosy clade" proposed by Weitzman & Palmer (1997) may turn out to be some of or perhaps the only true
Hyphessobrycon species when this large genus is finally sorted out phylogenetically. Several ichthyologists now suggest that these species are
Hyphessobrycon senso stricto [= in the strict sense]. This genus was originally raised as a sub-genus of
Hemigrammus by Durbin in Eigenmann (1908). In those days, external characteristics along with internal physiology like dentition were used to establish genera and species. The species in both genera were identical in all characteristics except that the caudal fin is scaled in
Hemigrammus but not
Hyphessobrycon, but more recent study has revealed that even this is not a defining characteristic as it can occur in intermediate conditions (de Lucina, 2003).
It is now a certainty that the genus
Hyphessobrycon which is comprised of more than 160 valid or nominate species is a polyphyletic assemblage that contains several distinct monophyletic genera. Polyphyletic means that the genus contains fish descended from very different ancestors so they are not that closely related, whereas monophyletic means that the species within the genus are the descendants of one common ancestor and are thus very closely related.
Hemigrammus (holding more than 80 valid or nominate species) is in the same boat.
Byron.
