There has been no improvement with the Chamaedorea costaricana seedlings in April. They still seem to be struggling to hold onto life with some green tissue left in the stems. I'm still a little puzzled about the cause of their ill health, particularly as they have been treated exactly the same as the other Chamaedorea seedlings, which all seem perfectly healthy and their cultural requirements should be very similar. I can only assume that whatever the cause happened some time ago and that they were never going to recover. It may be that they suffered more ill effects from the calcium deposits left by my misters or maybe they were unable to cope with the high humidity at the time. It may be as simple as rot that has spread through the pot. I think a pathogen or infestation is unlikely, as they would probably have spread to surrounding plants. I don't expect to be giving too many more photo updates on this species.