[Delphinus]

Reasonably certain. The tentacles are uniformly cylindrical with blunt ends (not a 100% ID, sometimes they can taper, but it just has a "classic" ritteri look to it, if that makes any sense). Plus it seems to be happy perched on top of a rock in the current and not wedged into a crevasse.

Colour isn't a good way to confirm ID because it can be fairly variable. My ritteri has a tan base, pinkish oral disk, which blends into yellow tips on the tentacles (mostly you just see the yellow though).

The column will tell you more. A sebae (H. malu or H. crispa) will be long and narrow and attaches very weakly, relying more on the verrucae as holdfasts, whereas a ritteri will attach on the bottom the pedal disk (similarly to a BTA) and rarely makes use of the verrucae. Plus the column on a sebae (H. malu or H. crispa in this case) usually has a "raw chicken skin" look to it because of the verrucae being so prominent and raised.

It's actually a very nice looking anemone. But just be warned it has a capacity to get very large on you. Also if it can "sense" any path upwards it will try to migrate up. (i.e., if it can touch a tank wall, don't be surprised if it tries to climb up on the glass and perch near the top of the tank.). What I've found works well is to have a halide directly overhead, and have it sit on top of a rock with nothing higher within "touching distance". Then it will "think" it's on the top of the reef and thus not want to wander because it's where it wants to be. Plus the halide will help keep it in place since they are light hungry. As long as it thinks it's as close to the light as possible it should stay put.