Posted: Feb 16 2009

 Fissurella angusta (Gmelin, 1791), Narrow Keyhole Limpet

2/17/09 Bullas posted on LTS Forum:

Great job Marlo. The F.angusta have always troubled me. Here is what I've

come up with on them. Could be way off on my thoughts.
In the picture are Fissurella rosea,barbadensis,angusta that I have collected.

I went to Abbott/Morris 1995(4th edition) for the description of F.angusta.

They say- about 3/4 in long,rather flattish,somewhat pointed in front,brown

around orifice. The what I have as angusta in the picture is nothing like the

other two,so my question would be- if it's not a F.angusta then what did I find?

Marlo:

Locality data would be helpful. Detail quality not too good on the "Angusta"

shell, but I doubt that's it. Check the description of for D. listeri, although the

orifice doesn't fit.

Bullas:

Thanks Marlo- Hope this picture is better. They aren't D. listeri. They don't

have the line running across the ribs. These were collected at Jupiter Inlet,

attached under blowing rock" back in 1993. I don't have that much to go

by for ID but here's another one that has the pictures of F.rosea,

barbadensis and angusta -


The American Museum of Natural History-Guide to Shells. The picture

shows the angusta with the dark line around the orifice.

Susan J. Hewitt:

I would call these F. rosea. The black line would not be enough to change my mind on this.

Until you have handled literally hundreds (or thousands) of F. rosea shells, it is hard to believe how variable it is as a species, in color, in elevation, and in sculpture.

From my experience in the Leeward Islands I would say that F. angusta is usually pretty flat, often has a surprisingly small orifice compared to the size of the shell, and often is almost stellate in outline. It also often tends to run smaller than F. rosea does.

But some shells of F. angusta do seem to intergrade with some shells of F. rosea.

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