Len,
1.3 Dypsis sp. 'ambilanensis' - I'll take a pic of what was recently pointed out to me as D. psammophila according to J. Dransfield. Until I do, here's a blow up of the pic on the Discussion Page. The D. psamm that JD supposedly IDed has no red at all. The new spear is almost all black, and the petioles once it opens turn yellow, not red. The other differences are hard to write about. It's one of those, you have to be there and have seen both growing to get the feel.
1.4 Dypsis heteromorpha ??? - I'll have to find the pics of Daryl's plant again. I thought it had a fair amount of red "fuzz" on it. These have virtually no red at all. They are mostly just yellow and gray, and only one appears to be suckering. You can zoom in on the original photos for a better look. If you can find a pic of Daryl's, let me know. I remember that palm, but not that well. I thought it had a lot of color. This palm appears to be getting recurved leaves as well. Do you remember if Daryl's does?
1.5 Dypsis baronii Type - I have that same palm in SoCal. It came from JD Andersen as another one of those palms labeled as D. psammophila. Jerry has that same palm here in Hawaii as well. They are very different. Notice the new spear on the plant in Jeff's garden. It is almost white, then turning to light green. On Jerry's plant the new spear is jet black.
Here's that blow up of the first palm showing the colored petioles that D. psam does not have.