[ANSTHRLD] Onamastics Question: Darthula

[Kathy Herndon]

I'm wondering if anyone knows the origin of the name Darthula.  I'm 
not trying to document it as period, just to find out what language, 
literary work, or whatever it was taken from.  It turns up 
periodically as a woman's name in 19th century America.  I thought it 
sounded vaguely Biblical, but it isn't listed in any index of Bible 
names I've found.

Are there any bored onamasticians out there who want to take this on?

Lady Rosamund Blaunchflur
Branch Herald, Barony of Northkeep
and Genealogical Putterer