Ian, in the 3 pictures below, you can easily see trident I have mentioned before. it is the spike in the upper border of the labellum, which makes kind of a trident fork with the two pseudo-teeth on the sides. This is typical of macrocarpum and it is diagnostic for the spacies. Furthermore, the central tooth must be very pointy, as some xtapiriceps might show a tridet, but normally the central tooth is not very pointy or it is very obtuse (sorry, could not find a picture of one)
regarding a link to learn about the Catasetum anatomy... must think more about it, as I do not recall any right now. You can join Catasetiane fans blogs (I only know one in Portuguese where you can learn a lot, it is from Brazil and you have many of the Catasetinae expert discussing there)
You can also follow George Carr's blog. This is not updated very often, but it has very good information.
You can also watch the photos, and probably start discussions in my Flickr Group:
Flickr: Catasetinae or on Robson's group:
Flickr: Catasetum
There is also a very good book (could be better, but it is the only one I know): The World of Catasetum by Arthur Holst <- out of print, but you can find used ones in Amazon or ebay.
In my case... it is more than 25 years dealing with Catasetum
I started growing orchids after I saw Catasetum pileatum var. imperiale the first time... many other Catasetinae grew wild around the house of my parents in Venezuela.
Catasetum macrocarpum (possibly xtapiriceps)
Linear Mode
