Two that I couldn't remember earlier -
Slightly obscure (c.1761), in Giacomo Merchi's LE GUIDE DES ECOLIERS DE GUITARRE , Oeuvre VII
(mod. pub. Minkoff facsimile)
there are variations numbered to 30, of interest I think, but more like exercises (and Merchi's
guitar at this point was double-strung 5 course - though not so far down the road he advocated
single strings, though still only 5... though some Merchi duet pieces throw in some low G's which
suggest a 6th string rather than a down-tuned 5th - but I digress).
Rather more goodly and not so obscure are Salvador Castro's (Castro de Gistau)
Variations de las Folias D'Espagne, Oeuvre X (mod. pub. in a SPES facsimile pack)
numbered to 31 variations.
I'm sure there are some (not at all obscure) more that I've still to remember