Rob,

I think your definitions are describing exactly the same thing -- an externally rounded pore through the central area of the valve, whose interior opening is variable, more or less complex.  And yes, stigmata is simply the plural of stigma.  Round et al., 1990, clearly opt for this usage.  In many specimens of Cymbellathe entire structure of the stigma is visible in the LM: assuming you are looking at the valve exterior, the stigma appears round at shallow focus, and elongates to a slit of greater or lesser length as you focus deeper.  I was looking at some C. proximaa few days ago that showed this effect very nicely.

Gomphonemaand Luticolashow stigmata also, of course.  I have a species of the former from the Rio Salado here in Phoenix in which the external round pore of the stigma widens on the interior to a strongly elongated transapical slit -- quite distinctive, but I am unable to name it.


Dick



________________________________
From: Rob <kimmich46@...>
To: diatom_forum@...
Sent: Sunday, August 14, 2011 10:45 AM
Subject: [diatom_forum] perforations


 
I've been working on some Cymbellas with different numbers of perforations near the central nodule.

Can one tell the difference between "stigma" and "stigmata" with the LM?

Are "stigmas" defined as very near the central nodule while "stigmatas" are defined as farther away? I found the following definitions on Jeff Stone's wiki site (see our Links folder):

Stigma
A perforation of the basal siliceous layer in raphe-bearing Pennales near the central nodule, with an unoccluded external opening and in some cases with a raised and convoluted structure of spongy or cracked appearance internally.

Stigmata
Perforation through the valve face whose external opening is rounded (or nearly so) and whose internal opening is slit-like or highly modified.

As an aside, it seems unfortunate that "stigmata" is used as a singular noun when in Greek it is the plural of "stigma". Maybe someone can enlighten me.

-Rob

Dick,

Thanks much for your evaluation -- makes sense to me too. I sent a note to Diatoms of the US about using Round's definitions, since their definitions are virtually the same as the ones from Jeff Stone.

-Rob

--- In diatom_forum@..., Richard Carter <rcarter68502@> wrote:

Rob,

I think your definitions are describing exactly the same thing -- an externally rounded pore through the central area of the valve, whose interior opening is variable, more or less complex.  And yes, stigmata is simply the plural of stigma.  Round et al., 1990, clearly opt for this usage.  In many specimens of Cymbellathe entire structure of the stigma is visible in the LM: assuming you are looking at the valve exterior, the stigma appears round at shallow focus, and elongates to a slit of greater or lesser length as you focus deeper.  I was looking at some C. proximaa few days ago that showed this effect very nicely.

Gomphonemaand Luticolashow stigmata also, of course.  I have a species of the former from the Rio Salado here in Phoenix in which the external round pore of the stigma widens on the interior to a strongly elongated transapical slit -- quite distinctive, but I am unable to name it.


Dick



________________________________
From: Rob <kimmich46@>
To: diatom_forum@...
Sent: Sunday, August 14, 2011 10:45 AM
Subject: [diatom_forum] perforations


 
I've been working on some Cymbellas with different numbers of perforations near the central nodule.

Can one tell the difference between "stigma" and "stigmata" with the LM?

Are "stigmas" defined as very near the central nodule while "stigmatas" are defined as farther away? I found the following definitions on Jeff Stone's wiki site (see our Links folder):

Stigma
A perforation of the basal siliceous layer in raphe-bearing Pennales near the central nodule, with an unoccluded external opening and in some cases with a raised and convoluted structure of spongy or cracked appearance internally.

Stigmata
Perforation through the valve face whose external opening is rounded (or nearly so) and whose internal opening is slit-like or highly modified.

As an aside, it seems unfortunate that "stigmata" is used as a singular noun when in Greek it is the plural of "stigma". Maybe someone can enlighten me.

-Rob

Diatoms of the US has just updated its glossary with the best definition for stigma yet, complete with an image [1]! It agrees with the use in Round (1990) and removes the confusion you will find in Jeff Stone's list or the Cal Academy glossary.

-Rob

[1] http://westerndiatoms.colorado.edu/glossary/letter/S

--- In diatom_forum@..., "Rob" <kimmich46@> wrote:

Dick,

Thanks much for your evaluation -- makes sense to me too. I sent a note to Diatoms of the US about using Round's definitions, since their definitions are virtually the same as the ones from Jeff Stone.

-Rob

--- In diatom_forum@..., Richard Carter <rcarter68502@> wrote:

Rob,

I think your definitions are describing exactly the same thing -- an externally rounded pore through the central area of the valve, whose interior opening is variable, more or less complex.  And yes, stigmata is simply the plural of stigma.  Round et al., 1990, clearly opt for this usage.  In many specimens of Cymbellathe entire structure of the stigma is visible in the LM: assuming you are looking at the valve exterior, the stigma appears round at shallow focus, and elongates to a slit of greater or lesser length as you focus deeper.  I was looking at some C. proximaa few days ago that showed this effect very nicely.

Gomphonemaand Luticolashow stigmata also, of course.  I have a species of the former from the Rio Salado here in Phoenix in which the external round pore of the stigma widens on the interior to a strongly elongated transapical slit -- quite distinctive, but I am unable to name it.


Dick



________________________________
From: Rob <kimmich46@>
To: diatom_forum@...
Sent: Sunday, August 14, 2011 10:45 AM
Subject: [diatom_forum] perforations


 
I've been working on some Cymbellas with different numbers of perforations near the central nodule.

Can one tell the difference between "stigma" and "stigmata" with the LM?

Are "stigmas" defined as very near the central nodule while "stigmatas" are defined as farther away? I found the following definitions on Jeff Stone's wiki site (see our Links folder):

Stigma
A perforation of the basal siliceous layer in raphe-bearing Pennales near the central nodule, with an unoccluded external opening and in some cases with a raised and convoluted structure of spongy or cracked appearance internally.

Stigmata
Perforation through the valve face whose external opening is rounded (or nearly so) and whose internal opening is slit-like or highly modified.

As an aside, it seems unfortunate that "stigmata" is used as a singular noun when in Greek it is the plural of "stigma". Maybe someone can enlighten me.

-Rob