Help on Licmophora ID

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75RR
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Help on Licmophora ID

#1 Post by 75RR » Sat Aug 10, 2019 2:05 pm

Help on Licmophora ID

Have been unable so far to ID this Licmophora: viewtopic.php?f=6&p=69170#p69089

It does not seem to fit any of the Licmophora mentioned in DIATOMEAS PLANCTÓNICAS DEL LITORAL DE ANDALUCÍA https://www.researchgate.net/publicatio ... CIA_ESPANA which is my go to reference for marine diatom IDs in my area.

These are: Licmophora flabellata (Carmichael) Agardh, Licmophora abbreviata Agardh, Licmophora reichardtii Grunow and Licmophora mediterranea Mereschkowsky.


Have come across a another study just a little further up the coast: https://www.researchgate.net/publicatio ... tal_waters which references a Licmophora colosalis

I think it looks like a match but would like some corroboration

Would appreciate it if someone can have a look and comment
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Re: Help on Licmophora ID

#2 Post by Hobbyst46 » Sat Aug 10, 2019 3:02 pm

How about:
Licmophora gracilis (appears more appropriate)
L. Grandis (?)
This time again, I look at the diatoms from Greece, Croatia, Sardinia etc, the center of our small pond...
Last edited by Hobbyst46 on Sat Aug 10, 2019 3:14 pm, edited 1 time in total.
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Re: Help on Licmophora ID

#3 Post by 75RR » Sat Aug 10, 2019 3:09 pm

Hobbyst46 wrote:How about:
Licmophora gracilis (appears more appropriate)
L. Grandis (?)
Thanks for looking Hobbyst46.

Do you have a link that shows the similarities?
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Re: Help on Licmophora ID

#4 Post by Hobbyst46 » Sat Aug 10, 2019 3:15 pm

http://www.diatomloir.eu/Site%20Diatom/ ... 20Sea.html
not very detailed drawings, but still illustrative
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Re: Help on Licmophora ID

#5 Post by Hobbyst46 » Sat Aug 10, 2019 3:23 pm

Sorry, my response was really hasty amd superficial. I now looked at the article by the four Spanish researchers, they put much effort to elucidate the differences among these speci. So, SEM and DNA analysis are required...
Yet, your posted DIC image of the live diatom is far more attractive than the optical microscopy photos in the article...

I have seen Lycmophora diatoms (tentative identification) in local benthic samples, but they were much smaller and less elongated.
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Re: Help on Licmophora ID

#6 Post by 75RR » Sat Aug 10, 2019 3:40 pm

I now looked at the article by the four Spanish researchers, and they are really elucidating the differences among these speci. So, perhaps SEM is the key.
Have to agree that SEM provides much more detail but as Kimi Räikkönen says: it is what it is!

Here are some images from the links above:
Attachments
1 copy.jpg
1 copy.jpg (91.86 KiB) Viewed 750 times
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2 copy.jpg (230.55 KiB) Viewed 750 times
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Re: Help on Licmophora ID

#7 Post by Hobbyst46 » Sat Aug 10, 2019 4:05 pm

75RR wrote:...
Having looked again at the article, IMHO "your" diatom is L. Grandis and not Colosalis, or Remulus, because:
1) the Remulus appears to be of a clearly distinct shape.
2) the article claims that the stria density of Colosalis is high, 21-27/10 um.
I counted the stria per um in your posted image, assuming that the diatom is 280um, and found it to be 15 stria/10 um.

Citation from the articles: "and small cells of L. colosalis could be easily mistaken for L. grandis using light microscopy."
I withdraw the L. Gracillis possibility, the size and stria density do not fit.
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Re: Help on Licmophora ID

#8 Post by 75RR » Sat Aug 10, 2019 5:28 pm

Don't know if the punctae on the edges of my valve view photograph correspond to the stria, either way Licmophora grandis would seem to have a similar number to what Licmophora colosalis has (Striae 23–27 in 10 µm) according to this link: see bold text

https://naturalhistory2.si.edu/smsfp/IR ... grandi.htm

Licmophora grandis Species Description

In girdle view, cells are wedge-shaped and heteropolar, with a varying number of girdle bands (Fig. 1, upper; line drawing modified from Hustedt 1930-66) and rather narrow in valve view, with a spathulate apex tapering gradually in width to a slightly capitate antapex (Fig. 1, lower; and Fig. 2, SEM external view). The first girdle band has an internal septum that is visible in both girdle and valvar views (Fig. 1, arrows). The valve sternum is narrow but distinct (Fig. 3, detail of Fig. 2). The areolae are somewhat elongate in the transapical axis (Fig. 3), which is an uncommon feature in Licmophora. The apex of the valve shown in Fig. 2 has a rimoportula (Fig. 3); the antapex does not (Fig. 4, detail of Fig. 2). The presence/absence of rimoportulae at either end of Licmophora valves seems to be a variable feature.

Honeywill (1998) gives a size range of 40-62µm long and 9-10µm wide, while Hustedt (1930-66) gives 90-180µm long and 10-14µm wide. The valve in Fig. 2 is 256µm long and 16µm wide, beyond recorded range, but the similarity of valve shape, areolar shape, and areolar number (22-23 in 10µm) places it in L. grandis. It was seen only in Haulover Canal, between Mosquito Lagoon and the northern IRL; it has been reported from Florida Bay. Globally, it has a wide distribution in temperate and subtropical coastal areas, becoming rare in boreal climates.

However I feel that the girdle band of Licmophora grandis is wider (more fan shaped) See Fig. 1, while that of Licmophora colosalis is much narrower .

I must say that I am beginning to feel that trying to ID Licmophora sp without a solid background in diatom identification is optimistic at best!
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Re: Help on Licmophora ID

#9 Post by Hobbyst46 » Sat Aug 10, 2019 6:08 pm

Maybe some more high quality DIC images of the live diatoms of the genera and species will, on the long term, provide more clues than optical or SEM images of neatly cleaned frustules ?...
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Re: Help on Licmophora ID

#10 Post by 75RR » Sat Aug 10, 2019 6:24 pm

Hobbyst46 wrote:Maybe some more high quality DIC images of the live diatoms of the genera and species will, on the long term, provide more clues than optical or SEM images of neatly cleaned frustules ?...
Researchers seem to rely on SEM, perhaps a cleaned and mounted specimen will allow a LM (light microscope) to discern sufficient detail to ID these diatoms, though I doubt it.

This is a bit disappointing because algaebase, where I have been contributing images, will only accept photos of samples identified to species level.

So, pretty pictures and no home to go to.

Many thanks for your efforts Hobbyst46
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Re: Help on Licmophora ID

#11 Post by Hobbyst46 » Sat Aug 10, 2019 6:36 pm

75RR wrote:
Hobbyst46 wrote:Maybe some more high quality DIC images of the live diatoms of the genera and species will, on the long term, provide more clues than optical or SEM images of neatly cleaned frustules ?...
Researchers seem to rely on SEM, perhaps a cleaned and mounted specimen will allow a LM (light microscope) to discern sufficient detail to ID these diatoms, though I doubt it.

This is a bit disappointing because algaebase, where I have been contributing images, will only accept photos of samples identified to species level.

So, pretty pictures and no home to go to.

Many thanks for your efforts Hobbyst46
My pleasure. Such riddles sometimes become personal!

I tried but failed to find a specific pattern of stria/dots that distinguish between colosalis and grandis.

BTW, Belando and two authors of the Spanish research article about L. colosalis had published another article, in 2012, about L. species they found in the salty lagoon. I have no access to that article.
http://apps.webofknowledge.com/full_rec ... ge=1&doc=8

Licmophora species from a Mediterranean hypersaline coastal lagoon (Mar Menor, Murcia, SE Spain)

By:Belando, MD (Belando, M. D.)[ 1 ] ; Marin, A (Marin, A.)[ 1 ] ; Aboal, M (Aboal, M.)[ 2 ]

If it mattered, I would contact the principal author and specifically ask about the stria density: is it really a reliable feature of a genus/species. In view of these inconsistencies between the Spanish article and the Smithsonian data base (the latter has no info about L. colosalis), in regards to the stria per 10um.
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Re: Help on Licmophora ID

#12 Post by 75RR » Sat Aug 10, 2019 7:13 pm

The article by Maria Dolores Belando Torrentes, Juan F. Jimenez, Marina Aboal and Arnaldo Marín: Licmophora colosalis sp. nov. (Licmophoraceae, Bacillariophyta), a large epiphytic diatom from coastal waters mentions a lagoon.

https://www.researchgate.net/publicatio ... tal_waters See Abstract below:

The characteristic wedge-shape and large size of some diatom species in the genus Licmophora can make them seem relatively easy to identify. However, this is not always the case, as many species diagnoses are based solely on light microscopy and type material is not available and species may be difficult to distinguish from each other. This study provides the description and phylogenetic position of Licmophora colosalis sp. nov, which has large cells and extremely long dichotomously-branched stalks that form macroscopic arborescent colonies. Material for this study was collected from a hypersaline Mediterranean lagoon, but this species has also been reported from Florida and the Red Sea. It was studied using scanning electron microscopy and sequencing of the nuclear small subunit rDNA (SSU) and the chloroplast marker rbcL. Its colonies and cell morphometry are compared with three morphologically similar taxa: L. remulus, L. gigantea and L. grandis.

It may well be the article you referenced.

I am thinking, if no one comes up with a different ID and given the similarity between the diatoms Licmophora remulus, Licmophora gigantea and Licmophora grandis and the need to use scanning electron microscopy and sequencing of the nuclear small subunit rDNA (SSU) and the chloroplast marker rbcL to distinguish between them that I could in all fairness present my photos to Algaebase as Licmophora colosalis, which I feel is correct given the information in the article.
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Re: Help on Licmophora ID

#13 Post by Hobbyst46 » Sat Aug 10, 2019 7:36 pm

Agreed. For publication, it is a reasonable option.

My curiosity is about the stria density. I re-read the paragraph by Belando et al about the stria density, and I have the impression that they claim the stria density of colosalis to be 23-27/10um. I failed to understand what density they attribute to the L. grandis. Yet, in the article by Claire Honeywill about diatoms in British waters (1998), she states that the density of stria in grandis is 22/10um (table 2, p264 in the article).

And since I personally believe that the stria are clearly visible in the valve view of your diatom, and given its length of 280um, there are 15 stria/10um at the most. The closest Licmophora species, per this feature, is L. abbreviata (16 stria/10um), but I am afraid that its length and form wo'nt fit.

DNA analysis is no amateur's playground. Streching my neck out a little bit more in this black cave (to me), would the number, location and pigment color of the chloroplasts aid in diatom identification ?

P.S. Just seen a very recent article by C. Lobban about three new Licmophora diatoms, all very long (200um) and all with 30-40 stria/10um. Found near Guam.
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Re: Help on Licmophora ID

#14 Post by 75RR » Sat Aug 10, 2019 7:57 pm

And since I personally believe that the stria are clearly visible in the valve view of your diatom, and given its length of 280um...
Looked up the details in my notebook for these images.

I tend to round up or down as the math when one multiplies the number of divisions given by the reticule, by the distance each division represents, is sometimes more 'accurate' than it actually is.

In this case the math gave 276µm. not enough to make a difference I suppose.
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Re: Help on Licmophora ID

#15 Post by Wes » Sun Aug 11, 2019 8:37 am

75RR wrote:
And since I personally believe that the stria are clearly visible in the valve view of your diatom, and given its length of 280um...
Looked up the details in my notebook for these images.

I tend to round up or down as the math when one multiplies the number of divisions given by the reticule, by the distance each division represents, is sometimes more 'accurate' than it actually is.

In this case the math gave 276µm. not enough to make a difference I suppose.
You have a stage micrometer, right? If so I can suggest to use ImageJ (its free), take an image of the micrometer (usually comes with 10 µm graduations) under the same conditions (objective, intermediate optics etc) as the object of interest. Then simply draw a straight line corresponding to exactly 10 microns in the micrometer image and set this as you global scale so you can then draw straight lines, curvy/irregular lines, even measure area etc in the image with your object of interest.

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Re: Help on Licmophora ID

#16 Post by 75RR » Sun Aug 11, 2019 7:32 pm

Wes wrote:
75RR wrote:
And since I personally believe that the stria are clearly visible in the valve view of your diatom, and given its length of 280um...
Looked up the details in my notebook for these images.

I tend to round up or down as the math when one multiplies the number of divisions given by the reticule, by the distance each division represents, is sometimes more 'accurate' than it actually is.

In this case the math gave 276µm. not enough to make a difference I suppose.
You have a stage micrometer, right? If so I can suggest to use ImageJ (its free), take an image of the micrometer (usually comes with 10 µm graduations) under the same conditions (objective, intermediate optics etc) as the object of interest. Then simply draw a straight line corresponding to exactly 10 microns in the micrometer image and set this as you global scale so you can then draw straight lines, curvy/irregular lines, even measure area etc in the image with your object of interest.
Thanks, will have a look
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