The relation of Arima is not in the map:
This borough is surrounded by Tunapuna–Piarco boundary, but not part of it.
Sources:
https://en.wikipedia.org/wiki/Arima
https://en.wikipedia.org/wiki/Tunapuna%E2%80%93Piarco
https://en.wikipedia.org/wiki/Regional_corporations_and_municipalities_of_Trinidad_and_Tobago