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Description of Betta mandor

Home Forums Ichthyology Description of Betta mandor

Viewing 4 posts - 16 through 19 (of 19 total)
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  • #348506

    Arjan
    Participant

    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 ūüėČ )

    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?

    #348503

    Amazonas
    Participant

    Hi all.
    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.
    Greetings, Amazonas

    #348504

    Arjan
    Participant

    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. ūüėȬ†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/mesonauta/Betta_Artkonzept_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.

    #348727

    Amazonas
    Participant

    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/download.php?article=401 ).

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