July 11, 2012
I'm currently looking into the Betta foerschi-complex, partly because I'm interested in keeping one of the species at home and for the other part because I see there's a lot of confusion about the nature of the species included (the picture of the male fish in the description of Betta foerschi on Seriously fish, for instance, is not B. foerschi according to the article in which B. strohi was described.)
Unfortunately, I still lack the article in which, amongst others, Betta mandor was first described. Does anyone happen to have a digital copy of:
Tan, H. H. and P. K. L. Ng, 2006 - Ichthyological Exploration of Freshwaters 17(2): 97-114 Six new species of fighting fish (Teleostei: Osphronemidae: Betta) from Borneo.
Your help would be greatly appreciated.
June 13, 2011
July 11, 2012
August 31, 2011
It's so difficult to find publications of IEF because they are not free.
For any help, there is an illustrated key of the genus Betta available in french and in english!
All actually described species are included.
It cost around 10 € plus the shipping costs, send a mail to Michel dantec ([email protected])
July 11, 2012
August 31, 2011
I'ven't find these pics of foerschi. Anyone can give me the links?
I send a small extract of the key for the difference between foerschi and strohi.
I think too that this group must be re-examined in the future becaus the description of these two species not clear and not really scientific! There is a lot of confusions!!!!!!!!
The images in question are here.
August 31, 2011
July 11, 2012
I've saved two pictures from both species accounts and added a line or two...
One of the pictures in the mandor profile is clearly not a male of Betta mandor. It is too stocky and the line drawn according to the pictures from the key macrostoma posted corresponds with what we'd expect to see in Betta foerschi.
The picture in the Betta foerschi profile is somewhat less clear. The line passes just below the eye, but the body of the fish seems to be too slender for foerschi. I suspect that the fish pictured is not completely swimming in a vertical plane, but somewhat tilted. I took some measurements. The relative length of the dorsal fin base is 12.7% of the Standard length (according to the description of B. mandor, this measure is between 10,0 and 12,2% in B. rubra and B. foerschi. Accroding to Schaller & Kottelat 1989) the measurement for B. strohi would be a bit more than it is for B. mandor: 12,6-15,8 vs. 12,3-16.7 % SL). Based on that measurement alone, the fish at least is not Betta foerschi, but it could still be either B. mandor or B. strohi.
Tan & Ng 2006 do not give measurements for the relative length of the caudal fin for Betta strohi, but they do differentiate B. mandor from B. foerschi based on this measurement. According to them, TL is 136.7-149.1 % SL for B. mandor vs. 127.2-133.5 % for B. foerschi. Schaller and Kottelat did give this measurement for their B. strohi and it is a bit wider than for B. foerschi; 127.0-141.4. This particular fish has a measure of 126.2%, which is only very slightly below the range given for B. foerschi and B. strohi. We did, however, just conclude that this fish is not B. foerschi. Based on the relatively short caudal, it is not B. mandor either, which can only lead to the conclusion that it is B. strohi.
For the last few years I have imported all members of the current Betta foerschi complex, from different Asian exporters and different localities.
While there are differences in tail shape and tail length between the "species" of strohi, mandor and foerschi - I am not 100% sure that they are individual species and merely just variations in locality. I can fairly easily look at an individual and name it according to the trade name it was imported under but I think that they are commonly mixed up at collection points, exporters and such like along the way. So what has been imported as "mandor" for the last few years could easily actually be "strohi".
What I can say for sure is that I have kept and bred individuals of all of these fish and to describe a fish on how stout it is - in my opinion - nonsense. Especially with a genus which is so prone to obesity. Also, these fish are very long lived and Betta individuals can reach double figures in age... in which case they often look very different from when they were younger.
None of the photos here show mature fish more than a year or so old!
Frustrating if you want to know for sure, but that's Betta keeping.... Just don't get into the pugnax group!!!!!
August 31, 2011
I'm totally agree with Colin, it's really frustrating
It sure that there are some variations in body shape or fins with age, there also great variation between wild stocks an tank stocks (obesity, diffrence in fins development in dimidiata group.....).
It's important and more complicated to use meristics counts to attempt to discriminate the species.
It's difficult but it's important to try to progress in our modest knowledge of these amazing fishes.
Probably, as I've already said, some species in foerschi or pugnax groups must be re-examinated, the limits between them are not very clear.... To be continued....
July 11, 2012
I was wondering when Colin would pop up
After reading the descriptions of B. mandor and B. strohi critically, I was left with a feeling of something missing. I read your post last night and figured it'd be wise to sleep over things. Now I know what I was missing, together with something that struck me as rather awkward: No explicit reason is mentioned to describe both species. I.e., both articles fail to mention what's so special about the populations studied that validates the description of a new species, instead of just reporting on new finds of the already described one. The thing that seemed awkward is the source of the holotype of B. mandor: The holotype is mentioned to be from the “aquarium trade”.
Of course, a trader could be very honest and accurate when giving data on collection localities, but I would always be very careful in case someone were economically dependant on this kind of knowledge.
Based on the descriptions a simple key can be made which would separate B. foerschi from the other two based on the line from caudal base over pectoral, which would not touch the eye. The others would be separated based on the relative length of the tailfin. Meristic characters all show some degree of overlap.
We could start playing the Devil’s advocate and state that there’s a single species, with a fairly large distribution and a lot of intraspecific variance. If I interpret Colin’s post well, that’s not far off… Would you concur and question the viability of the three species? It would be nice to have some definitive proof in the form of a few fish from a known locality, showing character states of more than one of the species according to their respective descriptions. I’m not a ‘lumper’ per sé, but cleaning op a taxonomical mess seems pretty appealing at the moment. Wish I had the funds to go over there myself...
I think that my main point - and one that emphasises the potential problem with using aquarium trade stock - is that all three of the similar species are on the same trade list at the same time and that it is all too easy for mix ups to be made along the way... e.g. at the catch location, at the collector's premises in Borneo, at the packing facility, at the unpacking facility in Singapore, at the exporter's facility in Singapore, at the packing process in Singapore and then eventually here at the trader in europe.... There are a lot of links in the chain to get species confused...
Sometimes I look at the fish I get and think... hmmm, that strohi looks like the mandor I got last time????? Best I can do is sell them on with the name they were imported under and remind people not to mix them
In fact, I am ordering fish this week so might be worth ordering a couple pairs of each for a comparison?
July 11, 2012
That'd be a good one. Too bad there's a big, cold and salty puddle between you and me, or I'd come over and relieve you of some of them...
Matt, you are of course absolutely right. Measuring from photographs, unless they are taken in a standardized way, is pretty much a no go, although I think that these particular photographs may actually be good enough to do so. I have almost finished translating the strohi article. (remind me next time: translating from one language you're only partly fluid in to another is fairly time consuming 😉 )
The table with morphometrical and meristic characters is interesting. My earlier remark about there being an overlap between the meristics of both species is actually a bit of an understatement... There's absolutely nothing you could actually count that would discriminate B. strohi from B. foerschi. Some relative lengths would, but as Colin pointed out, fish may change according to their age. Schaller and Kottelat also mention this and state that fish species should not be described based on material that has been kept in aquarium conditions. The types of B. foerschi spent 9 months in a tank prior to their description and only the three types were used as a reference when describing B. strohi.
Pro describing strohi as a species of its own is the fact that they are found in a riversystem separated from the one foerschi is found in by hills and two other drainages (although they fail to mention if anyone had ever tried to find either species within these drainages). They at least live separated from one another. Betta mandor comes from a different freshwater ecoregion entirely, so vicariance between strohi/foerschi and mandor is plausible. Still, I'd not be wishing to make a bet. They could also be looking the way they look because of, for example, phenotypic plasticity.
Colin, do you know what de habitats of the three look like? Are they somehow different?
July 17, 2012
An interesting discussion.
Just to verify whether I am right or not. Arjan, you got the description of mandor two days ago and now you challenging all the stuff published about these species by Kottelat and Tan (the leading experts in the field of south-east Asian fish taxonomy)? Amazing.
I think the 'Illustrated key to the genus Betta' by Jerome Cardot (see post by macrostoma above) is a helpful tool to determine species of the genus Betta. All differences between the species are depicted and described.
I agree with you Arjan that there is no explicit reason included in the description of mandor (very unusual there is no discussion at all) why the differences mentioned in the diagnosis constitute the new species. However, that does not mean that the diagnostic characters (or character states) are invalid.
Photographs of fish specimens are in common use for fish descriptions and species descriminations (even to obtain morphometric data). However, the photograph depicted here (see post above) is not suitable. The fish is slightly bent and not plane to the focal surface.
If I understand Colin correct then he is just saying that it is possible that all sorts (mandor, foerschi, strohi) are mixed up during transport. He is not (Colin, please correct me, if I am wrong) suggesting that the taxa are synonyms.
Anyway, I agree with Arjan and macrostoma that the differences between the species mentioned are not very convincing.
July 11, 2012
Actually, Kottelat challenged his own description, at least partly, when stating that species should not be described using types that were kept in aquariums for a longer period. The types of B. foerschi were kept in a tank for 9 months before being described and in fact Schaller and Kottelat ought to have at least redescribed it based on fresher material, before describing a new species which could just as well be the same as the first.
I was not really impressed by the 2006 article this topic was started about. Of course, any discriminating character could be a valid character, that's the general idea of using characters (be they morphological, ecological, molecular or what not) in systematics, but a discussion of some kind is considered good practice in any scientific communication. There is, like you say, non whatsoever in this article, which makes it hard to understand the motivation of the authors.
You could say I'm challenging "all the stuff written by Kottelat and Tan", but that would not be correct. I don not challenge the conclusions they reached, I would just like to know why they described two species without telling us all why they should be species of their own, instead of local forms. The amount of material examined is small, samples were taken from a few locations only and there's no reason not to assume that there would be a lot more info to be gathered in the region between the collection localities. They could be right just as well as wrong, and there's no way to tell which option fits the biological truth best.
I guess my opinion differs from those of many fish taxonomists because of the fact that we use entirely different definitions and criteria for what we'd call a species. I put more emphasis on the evolutionary explanation and I like to see that incorporated in the argumentation is some way or the other. Fish taxonomy and particularly the alpha-taxonomy of the fish species of SE Asia is heavily influenced by Maurice Kottelat, who uses a definition of species which is very pragmatic indeed, but which discards many elements I feel are as important as the mere presence of characters that would distinguish one class of organisms from another, like the earlier mentioned phenotypic plasticity or other reasons not to split two populations since they share a common ancestor.
For a discussion, see http://www.alice-dsl.net/meson.....ept_en.pdf
This is all very arbitrary of course. Any definition of what one calls a species and the boundaries he feels are usable is equally valid. In both articles however, the authors fail to inform their reader on which definition and which standards are used, which is a pity indeed.
July 17, 2012
Arjan, I re-read the paper and have to agree. It is indeed all but not very informative. Tan & Ng just add few new names. Nothing about species concept, biogeography, and why it should be treated as an independent lineage. Kullander has heavily criticized such papers (see http://www.taprobanica.com/dow.....rticle=401 ).
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