Eidenmuller 2007 Question

[Matt28]

IN Eidenmuller's book, he says the genus name Monitor was declared a nomen deletum. I've never heard this term used before. I can venture a guess as to the literal meaning, but when specifically is a taxon considered a nomen deletum?

[HaroldD]

Eidenmuller is mistaken.  Is is the species name (for V. bengalensis) that was declared (ICZN opinion 540) a nomen deletum or nomen illegitum. The genus remains in syonymy.

[Matt28]

Thanks for the clarrification... but what exactly is a nomen deletum? I know what a nomen illegitum is. Are the two the same thing?