Au Ra physiology and other lore.

[Kedrah]

Pure speculation, but based on the hints we've been given and in-game characters, I'm assuming female Raen Auri names are going to follow a <Japanese name> <Nounverber> pattern.

It's stated they follow naming conventions similar to Doman names due to close relationships with them; the only major non-Auri Doman characters with full names so far are "Oboro Moonrise," "Tsubame Sunrise," and "Karasu Redbeak." "Yugiri Mistwalker" follows almost the exact pattern, except adding -er on the end (instead of "Yugiri Mistwalk").

Not sure if anyone else noticed this or what the naming conventions for male Raen Au Ra or how Xaela Auri names will be like at all, but I wanted to throw it out there.

It's not uncommon for characters in FFXIV to have an epithet, especially when they appear as an AI NPC in a duty. I'm thinking these are their style of epithet rather than any actual names. Considering these "surnames" are related in meaning to their given names (for example, Yugiri means "evening mist"), it seems more like an epithet to me.

I could be wrong of course, but it's just so different from the linguistic roots of their given names that it seems a little odd to be a surname.