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Anyone got Poll 1967?
September 22, 2015
1:06 pm
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coelacanth
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Poll, M. (1967) Révision des Characidae nains africains. Annales Musée Royal de l’ Afrique Centrale, Sciences Zoologique,
162, 1–158.
Trying to get to the bottom of what the Yellow-tailed Congo tetra actually is.

September 24, 2015
1:09 pm
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Matt
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My books have been in storage for over a year but think I have a hard copy. Will check. Is there a possibility it isn't A. caudalis then?

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September 25, 2015
2:22 pm
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coelacanth
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The figure in Boulenger (drawing of the type as Petersius caudalis) here http://www.biodiversitylibrary.....6/mode/1up shows a fish with a shape nothing like the "caudalis" of the aquarium hobby. Additionally, the colour is described as "reddish, with a silvery lateral band, which becomes blackish on the caudal peduncle and extends as a black band on the caudal fin", again, nothing like the fish in the hobby and no mention of the distinctive caudal fin patterning (which you would have thought would be noted, given that other colours are mentioned). It has to be assumed that as Boulenger originally described the fish and this is also his work, he was happy with the figure and discussion of the species in the catalogue.
Some of the syntypes for caudalis can be seen here http://research.amnh.org/vz/ic.....index.html, again, to me these do not look like the hobby "caudalis". Note there is no sign of any pale stripes either side of the dark central rays to the caudal fins in any of these specimens, but note the deep body form (which agrees with the figure in Boulenger).
If you look at the holotype for Duboisialestes (now Alestopetersius) bifasciatus on the same page, that shows a fish with a caudal displaying a dark central stripe, pale stripes to either side, then darker lobes, which is superficially like the hobby "caudalis" (but not looked any more closely, not had the time).
To confuse the situation. there are two fish preserved here http://research.amnh.org/vz/ic.....index.html listed as caudalis. Not sure what to make of those TBH.
The latest edition of Amazonas magazine has an article featuring the "real" A. caudalis (a fish which does agree superficially in form and colour with the description by Boulenger).
The hobby "caudalis" is obviously very numerous and easy to collect given the frequency with which it appears in imports, so it has to be assumed that it's described.
Not sure when the name "caudalis" was attached to this form, wouldn't surprise me if it was another Baenschism as with the various Moon Tetras.
So, I'd like to read the original description of D. bifasciatus by Poll to see what is said about the caudal fin.

September 26, 2015
10:48 am
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Matt
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Very interesting stuff, I will look at the references here and look for the book this arvo.

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September 26, 2015
11:56 am
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coelacanth
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This has been rattling round my tiny mind since we had a go at unravelling the various "Moon Tetras", and then re-emerged while chatting with Oliver Lucanus about where some new sexeh tetras may be located. There's always a risk of "Emperor's New Clothes" in challenging nomenclature that has been accepted in the hobby for a long time, but I think it's very possible that the "caudalis" of the hobby is not the fish that Boulenger described.

Hans Evers has sent me another paper on the Lefini but it's at work and I've haven't had a chance to look at it properly, need to drop it onto my Galaxy so I can pick at bits when and as I have the chance.

September 26, 2015
4:56 pm
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Matt
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Don't suppose you could scan that Amazonas article?

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September 27, 2015
12:19 pm
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coelacanth
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I've only seen the digital edition, but I've tagged you in on FB to a thread relating to this.

September 27, 2015
3:05 pm
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oaken
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I sent you a PM, Matt.

September 27, 2015
3:29 pm
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Matt
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Here we go...

1967-D.-bifasciatus-Poll-1.jpgImage Enlarger

 1967-D.-bifasciatus-Poll-2.jpgImage Enlarger

 1967-D.-bifasciatus-Poll-3.jpgImage Enlarger

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September 27, 2015
3:31 pm
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Matt
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oaken said
I sent you a PM, Matt.

Got it, thanks Gustav!

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September 27, 2015
11:50 pm
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Matt
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So, colour pattern of D. bifasciatus according to Poll is "a thin, dark medio-lateral stripe, sometimes inconspicuous; on the contrary black marks well-defined on the fins, median and lateral caudal rays black at the base and posterior border".

Does seem to fit the fish in the hobby quite well. Type locality? 

https://www.google.co.uk/maps/place/Bokuma,+Democratic+Republic+of+the+Congo/@-0.2765158,18.2458255,8.46z/data=!4m2!3m1!1s0x1a09d170855d3c43:0xd56e767af99623fb

For comparison, A. caudalis type locality:

https://www.google.co.uk/maps/place/Boma,+Democratic+Republic+of+the+Congo/@-5.8348082,13.0579806,14z/data=!3m1!4b1!4m2!3m1!1s0x1a5cec3fa147569b:0x851fdc508b0faa3a

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September 28, 2015
2:26 pm
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coelacanth
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OK, type locality of D. (now A.) bifasciatus is a long way upstream (and up a trib.) from what, as far as I know, were the main collecting areas for most of the past couple of decades, but for a river like this that may not mean much when you consider the distributions of some of possible analogues from the Neotropics like Moenkhausia collettii, dichroura, lepidura etc.
Similarly, the type locality for A. caudalis is a long way downstream from these same areas, same comments on distribution apply.

However, if you look at the descriptions and figures of both A. caudalis and D. bifasciatus, and the preserved specimens of same, I know which I think is closest (although with some differences) to the "caudalis" of the aquatic trade.
It's a stretch to believe that all the specimens Boulenger had to work with had unusually deep bodies (maybe through age or a particular regional variation), and that due to preservation all indicators of the distinctive tail pattern had been removed (but then why the specific mention of "reddish, with a silvery lateral band"?).

In the paper by Mbimbi and Stiassny: A new Alestopetersius (Characiformes: Alestidae) from the Kwilu River (Kasai basin) of central Africa; with a phylogeny for the genus and synonymy of Duboisialestes, there's an image of a preserved fish labelled A. caudalis which again, doesn't look like the hobby "caudalis". There's also an image of a fish labelled D. bifasciatus, but annoyingly the caudal is damaged (although in general form it looks "right").

All very confusing!

September 28, 2015
8:23 pm
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Matt
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Had a look at Mbimbi and Stiassny and I think it looks pretty close as well, and agree that although the type locality is quite far upstream it doesn't preclude the fish in the hobby being A. bifasciatus, or at least a very close relative.

Considering to annotate the profile now...

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October 20, 2015
5:31 pm
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ad4m
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I too have become aware that "caudalis" may not really be that. I have seen photos of a deeper bodied, red tailed fish that has been claimed to be the true caudalis.
I also saw this at a shop yesterday. It was in with a tank of A. brichardi, below a tank of the yellow tailed "caudalis". This I believe may be bifasciatus.

http://i445.photobucket.com/albums/qq173/e36loon/IMAG5318_1.jpgImage Enlarger

October 21, 2015
11:31 am
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Matt
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Nice fish, it certainly does look close! If that is bifasciatus, what do you think the hobby 'caudalis' might be?

Also, welcome to the forum. :)

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