duteous

Exception 3.—Final y is sometimes changed into e: as, duty + ous = duteous; beauty + ous = beauteous.

From New Word-Analysis by William Swinton

Thus you may earn your bread: this is your duteous work.

From The Fifth Queen And How She Came to Court by Ford Madox Ford

In yonder grave a Druid lies, Where slowly winds the stealing wave; The year’s best sweets shall duteous rise To deck its poet’s sylvan grave.

From The Poetical Works of William Collins With a Memoir by William Collins

And, now that I think o' th' lass, comrade, I am not so sure that a scolding wife is not well paid for by a duteous daughter.

From A Brother To Dragons and Other Old-time Tales by Amélie Rives

And Psyche, since had come no priestess there To trim the temple, in her pious care Forgat herself, and lent her duteous aid.

From The Poetical Works of Robert Bridges by Robert Bridges