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08-30-2013, 01:45 PM #31
But Steeler's idea that they might be the bentosi species is worth considering. That was one that came up a lot when I was trying to figure out what I had. But usually when I clicked on info about the bentosi, a photo would come up where the fins were red and white, with no black. And they were sometimes called "candy cane" tetras. None of that really seemed to fit my fish either, but it seemed like a closer match than the Rosy tetras.
It is true that the term "white tipped rosy tetra" was one of the first terms I tried Googling.
So Steeler, are you saying that you see black shoulder patches on the fish in my photos? When their lights come on a little later this morning, I will have to go and examine them some more.
Thank you both for your continued help.
My plan for today involves going to Petco to get a few more fish so I can slowly increase the numbers of most of my schools.
08-30-2013, 04:48 PM #32Banned Discus fish
- Join Date
- Nov 2008
- Vancouver, BC, Canada
The species known as the "Roberti" or "Robert's" Tetra was originally thought to be a hybrid of other bentosi-group species, but Gery [in his monmumental book Characoids of the World, 1977] opinioned that it is a distinct species that subsequently was sometimes seen as "H. robertsi." Weitzman & Palmer (1997) identified this fish as the true H. bentosi, and Lima & Malabara in Reis et al. (2003) established H. robertsi as a synonym of H. bentosi Durban 1908. H. rosaceus was established by Weitzman & Palmer (1997) as a distinct species from H. bentosi and confirmed by Lima & Malabara in Reis et al. (2003).
The difference between these two species is easy to observe. First, to back up a bit; I always like to know the whole story, so bear with me. The genus Hyphessobrycon--the name from the Greek hyphesson [believed to mean "slightly smaller"] and brycon [=to bite]--was erected by C.H. Durbin in 1908 and presently contains more than 100 valid distinct species. The classification is incertae sedis, a Latin term meaning "of uncertain placement," that is applied by ichthyologists to any classification that has some doubt. Hyphessobrycon was formerly considered within the subfamily Tetragonopterinae, but Javonillo et.al. (2010) suggest that this subfamily should be restricted to species within the genus Tetragonopterus since they do not share physiological characteristics with species in other genera such as Hyphessobrycon, and others have followed this reasoning.
Authors that have recently studied the systematics of the genus Hyphessobrycon have unanimously pointed out that the group is not well defined and its monophyly is yet uncertain, hence the incertae sedis. A monophyletic genus is one wherein the species share a common ancestor, thus linking them together physiologically; all species will have descended from one ancestor. This is clearly not the case with the varied species in Hyphessobrycon. Mirande (2009) for example has proposed several revisions to the family Characidae based upon phylogenetic diagnosis. Some genera have been moved to a new subfamily, while others are now (temporarily) assigned to a specific clade within the family pending further study. The recognition of groups of species [clades] within Hyphessobrycon is based primarily on similarities of color patterns; an hypothesis of its intra-relationships is currently unavailable, except for the rosy tetra clade proposed as monophyletic by Weitzman & Palmer (1997).
The rosy tetra clade of some 30 species within the genus Hyphessobrycon share several traits in colour and pattern. All species are somewhat disk-shaped and share the "flag" signal, being a very conspicuous black spot on the dorsal fin, usually underlined by a white or sometimes yellow zone and tipped with white depending upon species. They also share a darkened humeral or shoulder patch immediately posterior of the gill covers. The underlining white or yellow zone on the dorsal fin is absent in some species, including H. bentosi. The humeral spot is sometimes pale, usually due to the fish being maintained over a light-coloured substrate or otherwise stressed. But it is present in all species in this clade.
So, the fish in the photos is clearly H. rosaceus. I have had this species, and I currently have H. bentosi (my favourite of the two, as it is a bit darker in the mauve and the extended black dorsal and anal fins are majestic indeed) and when I acquired the latter I put them in with the rosys. They shoaled together as if the same species, but then all species in this clade do this; In my 5-foot tank I have had Black Phantoms, Rosys, Roberti (H. bentosi), and Bleeding Hearts together, and they remain in one large group. This certainly supports Weitzman's hypothesis that these "rosy" species are closely related phylogenetically. Ichthyologists also surmise that the species will likely cross-breed, so if one intends breeding one must be careful.
Last edited by Byron; 08-30-2013 at 04:54 PM.
08-30-2013, 06:46 PM #33
So than are we to just disregard this source: http://www.google.com/url?sa=t&rct=j...1495398,d.cGE? That states; "A beautiful species that is very similar to a host of others in the genus, some of which are undescribed. The most common of these in the hobby is H. bentosi. The two are so similar in appearance that H. rosaceus was once considered to be a subspecies of H. bentosi. The easiest way to distinguish them is by the presence of a dark marking just behind the operculum in H. bentosi, which is lacking in H. rosaceus".
One way our another Finnie, you purchased a very desirable fish, much superior than the Pristilla, IMO.
Last edited by steeler58; 08-30-2013 at 06:54 PM.Perfection is not attainable, but if we chase perfection we can catch excellence.
Once you learn to quit, it becomes a habit. -Vince Lombardi
“Be more concerned with your character than your reputation, because your character is what you really are, while your reputation is merely what others think you are.” ― John Wooden
Sandy Hook Elementary......Lest We Forget
08-30-2013, 08:34 PM #34Banned Discus fish
- Join Date
- Nov 2008
- Vancouver, BC, Canada
Hyphessobrycon rosaceus is one of the rosy tetras that has a pale humeral marking and was originally described by Durbin as having no humeral spot. That this species actually has one can be seen from Figs. 1-3 & 5. The spot has faded away in the preserved specimens in Figs. 4 & 6. [Weitzman & Palmer, "The Rosy Tetra, Hyphessobrycon rosaceus, Its Identification and Brief History as an Aquarium Fish," Tropical Fish Hobbyist, July 1997, p. 160]
When Matt returns from his collecting trip to SE Asia, I'll mention this and we can have a pow-wow. It may well be that he is only pointing out the lack of as dark a patch as the other species. I honestly can't remember if I saw the humeral patch on my rosy tetras or not; I haven't had this species for a while.
Last edited by Byron; 08-30-2013 at 08:37 PM.