Complex sentence: She wrote prose and poetry under her pseudonym "Pía-Rigán", an anagram of her given name, her work remained unpublished during her lifetime and was only anthologized and published posthumously.
Split into simpler sentences: She wrote prose and poetry under the pseudonym "Pía-Rigán", an anagram of her given name. Her work remained unpublished during her lifetime and was only anthologized and published posthumously.