Answering my own question, after some research, the following correction was revealed:
I needed to create a file ...
$ sudo nano /etc/php/7.0/fpm/conf.d/20-xdebug.ini
with the following properties ...
zend_extension=xdebug.so
xdebug.remote_enable = 1
xdebug.remote_connect_back = 1
xdebug.remote_port = 9000
xdebug.scream=0
xdebug.cli_color=1
xdebug.show_local_vars=1
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