You could ask just Tatiana Shevchenko (my young friend). She work at IGS NAS of Ukraine... [email protected] 

Thank you for the contact.

Thank you very much for the detailed information. There is another question I have, connected to the topic. Is it possible to establish if the fossil cyst was created by heterotrophic or autotrophic species? The order Peridiniales is usually considered as heterotrophic and Gonyaulacales as autotrophic but it is not always true. I am especially interested in Heterosphaeridium sp. which according to your description represents a gonyaulacoid cyst. Such cysts does not occur in modern sediment so it is difficult to find out more information about it. However, I found a modern dinoflagellate Pfiesteria shumwayae that produces very similar cysts and is described as heterotrophic. Is that possible that the Heterosphaeridium sp. was also heterotrophic?

Hi Violka,

The principal difference between gonyaulacoid and peridinioid dinocysts is their tabulation.  In gonyaulacoids, the 1st apical plate is asymmetrical (the left and right lateral triple junctions are not in a plane parallel to the cingulum) and they tend to have one posterior intercalary  and one antapical plate.  In peridinioids, the 1st apical plate is longitudinally symmetrical, they typically lack posterior intercalaries and possess 2 antapical plates.  However, there are exceptions to this rule!

In my view Heterosphaeridium was a phototroph, and as with other areoligeracean gonyaulacoid dinocysts, seems to be well represented in littoral facies.  I can't think of any gonyaulacoid dinoflagellates presumed to be heterotrophic .  Although many modern peridinioid dinocysts do have a heterotropic feeding strategy, this is not true of all fossil peridinioids.  However, It is the protoperidinioid dinoflagellates that are usually considered to be entirely heterotrophic.

Hello Martin,

thank you for your help. My questions above are actually related to a particular problem. Perhaps I could explain it with more details. The cyst of mentioned Pfiesteria shumwayae (please see its description and photograph of the cyst here: http://en.citizendium.org/wiki/Pfiesteria_shumwayae) seems to me very similar to the cyst of Heteroshphaeridium bellii (Radmache et al., 2013). The Pfiesteria shumwayae (now called Pseudopfiesteria) is described as heterotrophic. It's cyst outlook suggests to me an autotrophic type. Other species of Pfiesteria (piscicida) is considered as heterotroph, which can temporarily be mixotrophic. This makes me feeling that this is really not possible to establis the type of feeding strategy fossil dinocyst producers.

The P. shumvayae is really interesting to me as it seems to be morphologically comparable to H. bellii. According to Litaker et al., 2005, '...the family Pfiesteriaceae is amended to include species with the following tabulation: 4-50, 0-2a, 5-60 0, 6c, PC, 5 þ s, 5000, 0p, and 20000 as well as an APC containing a pore plate (Po), a closing plate (cp), and an X plate; the tabulation is expanded to increase the number of sulcal plates and to include a new plate, the peduncle cover (PC) plate...'

I am not really familiar with this tabulation nomenclature. Would you be able to explain if this is the gonyaulacoid or peridinioid type? 

However, I lately realised that nutrients as phosphor and nitrogen are the same important for heterotrophs and autotrophs (is that right?). And this is where my first question came from. So perhaps it is not that important to me to know if the H. bellii was autotrophic or heterotrophic. But anyway I am still very curious :)

Hi Violka,

I personally wouldn't consider the processes or overall morphology of the cyst of P. shumvayae to be that similar to H bellii.  Although they both appear to be non-tabular, there are a lot of dinocysts that have this overall aspect.  The tabulation you mentioned should have been written: 4-5', 0-2a, 5-6'', 6c, PC, 5''', 0p, and 2'''', I'm not sure what Litaker et al means by 5 þ s.  This tabulation formula is probably closest to the standard peridinioid model.  All dinocysts need nutrients, C,H,N,O,P,S,Fe etc., where the heterotrophs get theirs from ingesting organic matter, phototrophs use sunlight as energy to utilise the nutrients

best wishes

M

Thank you very much for your explanation.

Oops, I meant all dinoflagellates need nutrients, not the dinocysts...

I am very sceptical about the cyst image. Doesn't look like a dinoflagellate cysts to me at all. Also, in the original description of the life cycle by Parrw&Burkholder 2003 there is no image of a cyst.

Obianuju P. Umeji · 16.75 · University of Nigeria

The two orders of Dinoflagellate cysts you mentioned can be  distinguished based on (1) Morphology-Shape, Horns and general ornamentation.  The Order: Peridiniales (from Peridinium) is ovoid with three horns one apical and two antapical. Many in this group have subdued horns anyway as is common in nature while some have one apical and one antapical horns, yet some do not have horns at all.Gonyaulacoid cysts (check your spelling) of the Order: Gonyaulacales (from Gonyaulax) are spherical. The may have one subdued apical process and one or two antapical  processes.

(2) Body tabulation which is for the expert and

(3) Deriving from the tabulation is the excystment opening called the archaeopyle. In the Peridiniales, it consist of precingular plates whereas in the Gonyaulacales it is apical or a combination with other plates, even epicystal where the cyst breaks into two at the equatorial plane.

There can not be a quick way to identify the cyst without going through a text-book in Palynology or Palaeopalynology, as the time saved in not learning the details of the group would be wasted in wrong identification.

Consult the  masterpiece, the book,  Paleopalynology by Alfred Traverse, 2007 Online Edition.

Obianuju P. Umeji

.

2 days ago

Hi Wiesława,

I would just add that a fairly easy way to determine if the cyst is of phototrophic or heterotrophic affinity is to use epifluorescence. If you have access to a microscope equipped with epifluorescence illumination, you can easily determine if your specimens contained Chl a, even on fossilized cysts over geological times.

Best,

Manuel

Hello Manuel. Thank you for your comment. This is very interesting. Would you be able to provide me with some more detailed information/publications about this topic? I will have this kind of microscope in few weeks to use so would be great to try to determine the Chl a. However, I wonder if the method will be suitable for samples as old as Cretaceous.

Hi Wiesława,

I guess a good reference paper for applications of epifluorescence in dinoflagellate studies would be: Lessard and Swift 1986, Dinoflagellates from the North Atlantic classified as phototrophic or heterotrophic by epifluorescence microscopy, J. Plankton Res., Vol.8 no.6 pp. 1209-1215.

Another interesting one is Brenner & Biebow 2001, Missing autofluorescence of recent and fossil dinoflagellate cysts - an indicator of heterotrophy? NEUES JAHRBUCH FUR GEOLOGIE UND PALAONTOLOGIE-ABHANDLUNGEN 219 (1-2): 229-240.

(Shoot me an email if you can't access those papers on your own; I'm sure it's fine to share for personal use but I don't think it would be right to upload them here since they are not my intellectual property).

I have never worked myself on Cretaceous material, and I am no expert on epifluorescence, but I heard that it is routinely observed in Mesozoic palynomorphs, depending on the state of thermal alteration.

So in short, if indeed your specimens show some epifluorescence, it is a pretty strong indication that the organism was photoautotrophic. On the other hand, if they don't, it means that either they were of heterotrophic affinity, or the specimens were thermally altered (so it would NOT rule out photoautotrophy). Either way, it is an additional, valuable line of evidence that you should use, especially since it is so quick and easy to check under the microscope!

Hope it helps,

Manuel

Yes, it helps. Thank you for the details.

Thank you very much Obianuju ! I had the same problem, which is solved now.