Does Anyone Recognize This (Trilobite) Face?

[ClearLake]

I have a partial cephalon of a trilobite from the Galena Group (Late/Upper Ordovician) from NE Iowa that I obtained from Mike @minnbuckeye,  and am having trouble ID'ing.  Given the partial nature and somewhat poor preservation, an ID may not be possible, but the glabella seems distinctive enough that someone may recognize it even though I believe the eyes are missing.  I've removed some matrix from it, but thought I was about to do more damage than good if I went any further.  In reading through a variety of papers, the best match I can find is a Greenops species (maybe G. fitzpatracki or something similar) but these are Devonian in age so that's not it.  What are the Ordovician genera that have that type of face found in this area?  Big rounded glabella with distinctive furrows and pustules all over it.  Here are some pictures and I'm hoping some of our trilobite experts may recognize this one. I saw some Ordovician genera such as Pterygomeetopus and Ceraurus that are close but still don't seem to match best I can tell.  Any ideas will certainly be appreciated or hints to further papers I can search through.

 

Here is an overall image of the cephalon from the top.  The black bar is 1 cm.

 

Here is a bit closer image to show the granulal nature of the glabella.  The overall width is estimated at 1.5 cm and the length is right at 1 cm.

 

A profile view of the subject.

 

A full frontal again to demonstrate the overall shape.

 

Thanks for any and all ideas!!

 

 

Any ideas 

[Kane]

If I had to wager a guess, I might say Calyptaulax sp. on account of the expansive glabella and furrow positioning.

[ClearLake]

17 minutes ago, Kane said:

If I had to wager a guess, I might say Calyptaulax sp.

Thank you!  With that name in hand I found some much better pictures that do seem to look like my specimen.  I was in the neighborhood with Pterygometopus, I just needed some better examples than the old, poor reproductions I was looking at.