Pusula identification

[claude54]

Hi to all,
the following Triviidae was sold as Pusula solandri. After examining the shell I'm not so sure about that. In my opinion it should be Pusula radians.
What do you think?

See the images in the following links:
https://www.flickr.com/photos/61714007%4...538192497/

https://www.flickr.com/photos/61714007%4...744274981/

Regards,
Claudio

[paul monfils]

That's a tough one.  I have specimens of each species, plus a few I cannot assign to either species with certainty.  P. radians is supposed to have "a couple more ribs on the average than P. solandri" - not much help there when dealing with a single specimen.  P. radians tends to be more "flattened" than P. solandri.  In other words, the width to height ratio is greater in P. radians.  P. radians is described as having dark spots on the dorsum, but some P. solandri have such spots too.  How large is your specimen?  P. solandri seldom exceeds 15 mm, while P. radians often exceeds 20 mm.

[claude54]

Thanks Paul,
the specimen length is 17.9 mm, the width is 13.4 mm and the height is 9.9 mm.

[claude54]

Hi Paul,
I would like to add some more information.
The shell was found crawling on underside of rock at extreme low tide. The locality is Punta Paitilla - Panama City.
Now, in the last work of Dirk Fehse & J. Greco - Revision of the genus Pusula (2014) seems that the southwards distribution of Pusula solandri is in Bat Islands (North of Costarica) about 500 km away from Panama City; for Pusula radians Panama is one of the typical distribution.
After that...... I remain with my doubts

[claude54]

Hi Paul,
after reading more carefully the above mentioned book, I found probably the key to distinguish the two species.
About the Pusula solandri is stated that: "Labrum bears on on its inner margin on average 17 rather coarse denticles. The denticles are partly formed by the ribs others are just developed at the inner labral margin."
In the attached image you can see the difference between the two species.