That's behind a paywall, unfortunately. However, the situation is: Willdenow published the name "Knoxia simplex" in 1818. Kunth published the name "Spermacoce diversifolia" in 1819, and cited Knoxia simplex as a synonym. Spermacoce diversifolia is therefore a superfluous name—a new name published for a taxon that already had a legitimate name. Consequently, Spermacoce diversifolia Kunth is illegitimate, and Crusea diversifolia (Kunth) W.R.Anderson is likewise illegitimate. In other words, this is a nomenclatural change, not a taxonomic change.
Sorry, guess I wasn't clear. I'm not proposing a deviation—I wanted to understand what the POWO taxonomy was based on and, since POWO does not provide that information, I thought it might be useful to any other curious parties for me to provide it here.
Los desacuerdos no intencionados ocurren cuando un grupo padre (B) se reduce al cambiar un grupo hijo (E) a otra parte del árbol taxonómico, provocando que las Identificaciones existentes del grupo padre sean interpretados como desacuerdos con las Identificaciones existentes del grupo hijo cambiado.
Identification
La ID 2 del taxón E será un desacuerdo no intencionado con la ID 1 del taxón B después del intercambio de ancestros
Si el adelgazamiento del grupo padre provoca más de 10 desacuerdos no intencionados, deberías dividir el grupo padre después de intercambiar el grupo hijo para substituir las identificaciones existentes del grupo padre (B) con identificaciones con las que no esté en desacuerdo.
The situation is described here: https://onlinelibrary.wiley.com/doi/abs/10.1002/tax.12183
That's behind a paywall, unfortunately. However, the situation is: Willdenow published the name "Knoxia simplex" in 1818. Kunth published the name "Spermacoce diversifolia" in 1819, and cited Knoxia simplex as a synonym. Spermacoce diversifolia is therefore a superfluous name—a new name published for a taxon that already had a legitimate name. Consequently, Spermacoce diversifolia Kunth is illegitimate, and Crusea diversifolia (Kunth) W.R.Anderson is likewise illegitimate. In other words, this is a nomenclatural change, not a taxonomic change.
https://www.tropicos.org/name/27905976
https://www.tropicos.org/name/100211544