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Re: [diatom_forum] Gomphonema truncatum

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  • Richard Carter
    Charles, My intent was certainly not to confuse -- I was just trying to suggest that there is a group of species that look much alike, as is becoming
    Message 1 of 38 , Apr 26, 2012
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      My intent was certainly not to confuse -- I was just trying to suggest that there is a group of species that look much alike, as is becoming increasingly the case throughout the "diatom world".  Increased understanding of morphology, ultrastructure, ranges of variation, ecological preferences, etc., etc., has led to the inescapable conclusion that there are far more diatom taxa than have been previously described.  Every new study seems to contain descriptions of new taxa, not only when the study region is a distant one, but even in central Europe, which has been intensively studied for two centuries now.

      I have reached the conclusion that the amateur is simply not equipped to keep up with this explosion of taxa; comparatively poor optical equipment, and more importantly the relative inaccessability of the necessary literature (unless one lives in San Francisco or Philadelphia!), makes it pretty clear that an amateur with limited finances cannot "correctly" name most of the species he/she encounters.  I have personally decided to abandon the effort to learn diatom taxonomy -- to "throw in the towel", as it were.  I'll continue with my interests in micropaleontology, but the world of living diatoms is clearly out of my reach.  Each diatom is much too long a journey........!

      Warmest regards,


      From: charles suslavage <suslavage@...>
      To: diatom_forum@yahoogroups.com
      Sent: Wednesday, April 25, 2012 10:55 PM
      Subject: Re: [diatom_forum] Gomphonema truncatum

      Hi Dick,
      Thank you, now I am thoroughly confused. Interestingly I first had the freshwater California diatoms as G. constrictum and then changed to G. truncatum. I based my revision on the images from River Diatoms. Their description of G. truncatum is as follows “Valves asymmetrical to transapical axis (heteropolar), symmetrical to apical axis. Cells wedge-shaped in girdle view with pseudosepta visible. Apices broadly rounded to broadly sub-capitate at the head pole and more narrowly rounded at the tail pole. Raphe often slightly sinuous. A single stigma is present on one side of the central area. Striae coarse, radiate and often visibly punctate.
      I also have a description of G. constrictum from “Diatoms of the Streams of Eastern Connecticut”. “Valve cuneate, with the middle portion inflated; constricted below the upper apex. Lower portion of the valve tapering slightly to rounded apices; upper apex broadly rounded. Axial area distinct; central area one sided. Median stria terminated by one isolated puncta, opposite median striae shortened. Striae radiate, except in the upper constricted portion, where they become almost parallel.”
      Each diatom seems a long journey.

    • Richard Carter
      Rob, A very stimulating post!  I think your list of questions is excellent -- I m sure each of us would offer different answers, but I also think that we
      Message 38 of 38 , May 2, 2012
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        A very stimulating post!  I think your list of "questions" is excellent -- I'm sure each of us would offer different answers, but I also think that we each need to consider such questions.

        Thanks much,


        From: Rob Kimmich <kimmich46@...>
        To: diatom_forum@yahoogroups.com
        Sent: Wednesday, May 2, 2012 12:10 PM
        Subject: [diatom_forum] Diatom Directions


        Your note adds a lot to this great discussion of amateur study of diatoms. I have had your experience of using the SEM images to explain what I see with the LM. Dick has been one of my main sources for learning, too.

        I see this discussion as what to do about distinguishing species, if that is possible for anyone, even with an SEM and a molecular lab. Even Dick, with the university library in Phoenix, is challenged, as he says. From my seat, the naming discussions have been cordial so far, e.g., Charles asking Dick to clarify a name as far as possible and Dick replying with a careful answer.

        I certainly share the frustration I think I hear from Dick about pinning down an identification. I am finding that taking on any of this demands an acceptance of just not being able to know. Your point about not caring about naming accuracy may be the way to go here.

        Hearing from you, Dick, and Dave helps me try to figure out what direction I want to take with all the images that I am accumulating and what it is I want to learn. Do I want to make species (or genus) lists of collections made? Am I happy with naming to genus? Do I want to learn more ecology? How important is sharing what I learn? (This forum has been a good place for that so far.) Do I want to continue developing LM technique?

        By the way, would you be willing to ID some extant Mastogloia from the California desert?

        Best regards,

        On Wed, May 2, 2012 at 9:08 AM, klaus.kemp <klaus.kemp@...> wrote:
        Due to a catastrophic meltdown of my hard drive on my laptop I have been kept out of the loop for some time, only to find that where evryone behaved and everyone gained something from the group I now find there are ripples of dissent] and over what NAMES!
         May I remind you all that when I first joined the group I quoted my dear friend Bernard Hartley who on our first meeting said " We must/ should never fall out over a name". Now I find that there is dissent over naming of Diatoms, those of you old enough and studied Diatoms before the advent of TEM, SEM will remember the advocates of doom and gloom saying these would be the death of amateurs. As it turned out it was far from the truth with the instruments often showing details which had been seen by amateurs and in fact the reverse was also true we often went back to our slides after seeing an SEM photo and lo and behold we now see what has been missed before.
         This brings me to my main point, do not throw your dummies out of the pram over such an issue as names of Diatoms, I was very intimidated by the naming of Diatoms until I joined this group and Charles has been instrumental in my starting to enjoy this, true my main reason for avoiding that was lack of literature and with each of Charles's posting I learned a little more.
          Charles if you are serious about throwing in the towel would you consider exchanging emails with me and continue your excellent teachings? I would be honoured and do not give a damn about if you are up to date within the last hour.

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