OK found it!
"Lysmata rathbunae is found off eastern Florida (as opposed to the largely Carribean/Gulf L. wurdemanni). About the only external difference between the two is tail-fan patterning, and that is subtle. I have a picture of 1 of each species next to each other and in that context, the differences are quite apparent, but in an LFS
it would be difficult to tell. Basically L. rathbunae has a darker tail fan, with no visible striping, and a darker, more opaque body. L. rathbunae has no interest whatsoever in Aiptasia in my experience. I am not a taxonomist, and these are my lay interpretations of readings on the subject, as well as personal experience watching both varieties (or what I think are both varieties) in my tanks.
True L. wurdemanni has always eaten Aiptasia IME
, but it is fairly localized to their territory (about 1sq foot), so you need enough shrimp to cover the tank. It is reasonable to suspect that anything that will eat one Cnidarian will eat others as well, and their have been reports of L wurdemanni eating coral. I've not seen that, but I have never kept SPS
I believe much of the debate on their abilities is simply mis-identification (or overly well-fed shrimp -- they do not prefer Aiptasia over other more readily available foods). L. rathbunae are quite common in the trade, as they are collected in lobster traps in droves.
Tank raised L. wurdemanni are now available commercially via ORA. It would be nice if they grow them out on Aiptasia, but I doubt it."
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