Thanks Maroussia, for your comment. According to Phil McVey from Cornwall there is an interesting angle on how Pablo Neruda came to choose his pen-name:

"The Nobel Prize winner, Neftalí Ricardo Reyes Basoalto, took his pen-name (Pablo Neruda) from Jan Neruda. Interesting to note is how many literary articles state that he chose the name in homage to Neruda, the truth is a lot more prosaic. Even the Nobel Prize official website gets it wrong! Many people asked him why, and he never revealed this until his memoirs. The reason he chose Neruda? His father didn't like the idea of him being a poet, so he chose the name at random from a magazine for his first collection of poems! Only later did he realise how great a writer he had selected and he did pay homage to Neruda's grave when he visited Czechoslovakia."

In addition, he seems to have chosen Pablo after Paul Verlaine. Cesar Chelala