My condolences to his family on this awful news. For a vacation to visit the Fruit & Spice Park to end like this. Talk about being at the wrong place at the wrong time. It is one of those tragedies that really makes you think about things.
I cannot say I knew Andreas well, at all. We posted on some of the same threads about Eugenias, Garcinias, etc., so we shared some similar interests in plants and interacted a little. But, that does not mean I will not miss his presence on the Forum, a feeling which is nothing compared to what his family is feeling. From the news articles about him, he seemed like a good young man. I doubt anyone would have written about me as glowingly if I had died at that age, at least not if they were being truthful. I will make it a point to remember him and who he was.
I have a couple of plants that I would be willing to donate in his memory. They are only small seedlings, so they probably would not be able to be planted outdoors at the Houston Botanical Gardens for quite some time. I have a Psidium striatulum, since you requested Guava species. I also have a Eugenia repanda, since Andreas and I both commented on threads about Eugenias. I am not sure whether these species have the cold tolerance to withstand Houston's winters unprotected, but if they do, they might make a nice tribute.