Re: [diatom_forum] Gomphonema truncatum
- Charles,Goodness, you are not boring anyone, I'm sure! Your images are quite nice, and certainly instructive.As far as I know, the most recent publication on this group of Gomphonema taxa is this one:
In this paper Reichardt disambiguates G. constrictum and G. truncatum, the former having uniseriate striae throughout, while the latter exhibits biseriate striae near the valve margins. He describes four new species: G. clava from Botswana, G. laticollum from La Réunion, G. latipes from Québec, and G. pala from Austria. And he transfers the variety macilentum from G. truncatum to G. capitatum.
Reichardt, E. 2001 Revision der Arten um Gomphonema truncatum und G. capitatum In: Jahn, R., Kociolek, J.P., Witkowski, A. & Compère, P. (eds), Lange-Bertalot-Festschrift: Studies on Diatoms. Dedicated to Prof. Dr. Dr. h.c. Horst Lange-Bertalot on the occassion of his 65th Birthday. A.R.G. Gantner Verlag. K.G., pp. 187-224
I have not seen this paper, unfortunately, so I can't offer any insights as far as species discrimination is concerned. Apparently there is another species in this group, too -- G. italicum Kützing, also discussed in the paper. There may be others, as far as I can tell without having seen the publication.
The ANSP image database offers 1 image of G. truncatum, 2 of G. capitatum, 2 of G. italicum, and 2 of G. pala. Unfortunately, none of G. latipes, nor does that name occur in their list. Perhaps if we look through the reports of the taxonomy workshops we'll find out why? The one image of G. pala with locality data is from the Neversink River, NY. Both images of G. italicum are from a pond in PA.
I note that G. latipes was described from specimens in the collection of our late friend, Robert McLaughlin.
From: charles <suslavage@...>
Sent: Tuesday, April 24, 2012 9:24 PM
Subject: [diatom_forum] Gomphonema truncatum
Hopefully not to bore everyone I have posted two images of Gomphonema truncatum Ehrenberg 1832, synonyms; Gomphonema constrictum var. truncatum (Ehrenberg) Gutwinski 1887, Gomphonema constrictum var. truncatum (Ehrenberg; Ehrenberg) Gutwinski 1888, or so I hope my ID is correct. The first image G_truncatum1 (eight diatoms) are from a lake here in California all from the same strew slide. I was looking for variation and was surprised in not finding anything of note with the exception of one aberrant that lacks the isolated central pore. The second G_truncatum2 (three diatoms) are from half a world away from Toome Bridge and I believe there are two varieties pictured.
I would be interested in seeing a picture from anyone of a living Gomphonema and or a frustule in girdle view. I have no idea as to identifying this genus if it is not in valve view.
I apologize to all especially Dick the T in truncatum on the images should be lower case.
- 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 each need to consider such questions.Thanks much,Dick
From: Rob Kimmich <kimmich46@...>
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?
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.
FOR THOSE WHO THINK WE ARE OUT OF DATE "WHAT ARE YOU DOING HERE"?