Which Pterygia ?

[claude54]

Thanks Manfred for your kind reply. I'm wondering if there is a secure way to identify the two species (fenestrata vs glans). At the beginning I was thinking that a finer reticulated sculpture could be a distinctive element to identify P. glans but it seems I'm wrong.  I enclose a picture representing a new Pterygia fenestrata where there are black bands and a different reticulated sculpture

<a href="http://img146.imageshack.us/i/pterygiafenestrata.jpg/" target="_blank"><img src="http://img146.imageshack.us/img146/2079/pterygiafenestrata.jpg" alt="http://img146.imageshack.us/img146/2079/pterygiafenestrata.jpg" style="border:0" /></a>

What's the key to recognize the two species? <img src="images/smiley/frown.gif" alt="" border="0" />