So once again the question of what species are valid and which are not has come up. In particular I am trying to sort out the species Tetragramma taffi versus T. malbosii. William Morgan in his book on Cretaceous Echinoids of Texas (2016) suggests that T. taffi are just mature T. malbosii. Those of us who have found large T. taffis will see a big difference (or is it just that they are in deed "big"?).
T. malbosii is well known in Europe and I have seen many postings of them that look just like what we find here in Texas. But I have yet to see an obvious T. "taffi" from anywhere other than here in the USA.
So can any of our fellow European echinoid collectors shed any light on the subject? Do you have anything there that resembles our T. taffi?
I'm attaching two photos of what I have identified as a T. malbosii and a T. taffi for reference. There are more photos in one of my albums here on the FF.
Tetragramma taffi
Tetragramma malbosii