Which Pterygia ?

[claude54]

I'm in doubt about these Pterygia.
The first one seems to be fenestrata the second one crenulata.
The dimension respectively are 21.6 and 21.9 mm.
The locality is Papua New Guinea.
What's your opinion ?

<a href="http://img130.imageshack.us/i/pterygiasp.jpg/" target="_blank"><img src="http://img130.imageshack.us/img130/6605/pterygiasp.jpg" alt="http://img130.imageshack.us/img130/6605/pterygiasp.jpg" style="border:0" /></a>

[paul monfils]

Yes, that's a typical P. crenulata, with fine lines running both ways, creating a finely reticulated pattern. Quite different from the shell in the original image.

[paul monfils]

I think the first one is Pterygia glans.  Not sure on the other one.  The encircling lines are typical of P. undulosa but the pustulose sculpture is not.  P. undulosa is usually a rather smooth shell, and P. crenulata has very fine reticulated sculpture, not rounded "bumps" like this shell.  <span class="petit">--Last edited by Paul Monfils on 2010-04-08 05:38:16 --</span>

[claude54]

Thanks Paul for your steady help.
Could be the second one a hybrid of the two species?
I enclose a picture of another crenulata (I suppose! ) that I own, dimension 30.7 mm, locality Philippines

<a href="http://img168.imageshack.us/i/pterygiacrenulata.jpg/" target="_blank"><img src="http://img168.imageshack.us/img168/6474/pterygiacrenulata.jpg" alt="http://img168.imageshack.us/img168/6474/pterygiacrenulata.jpg" style="border:0" /></a>

[claude54]

This picture shows a different dimension of the sculpture, smaller in the specimen from Mayotte, I think it is always P. glans, the dimension is 23.8 mm, the second is the same you have already seen.

<a href="http://img709.imageshack.us/i/pterygiaglans.jpg/" target="_blank"><img src="http://img709.imageshack.us/img709/3756/pterygiaglans.jpg" alt="http://img709.imageshack.us/img709/3756/pterygiaglans.jpg" style="border:0" /></a>

The second picture show a group of pterygia coming from Philippine, dimension are 21.6, 20.6, 18.9, 17.1 could you confirm that they are undulosa?

<a href="http://img202.imageshack.us/i/pterygiaundulosa.jpg/" target="_blank"><img src="http://img202.imageshack.us/img202/2786/pterygiaundulosa.jpg" alt="http://img202.imageshack.us/img202/2786/pterygiaundulosa.jpg" style="border:0" /></a>

[manfred]

Dear Claude,
the Pterygia shells from the Philippines are indeed Pt. undulosa, but the Pterygia species from Mayotte is Pterygia fenestrata. Pterygia glans from Papua New Guinea is identified correctly.
Best regards
Manfred

[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" />