This species occurs from Japan to northeastern Australia. I am not aware of any records from Fiji or Tonga, but it is tiny (max length 19 mm with most adults in the 12-15 mm size range. They live in small tubes and cavities in rock and almost never come out, so they are easy to miss. They seem to be long-lived. I have several that I collected in Australia three years ago and they are still the same size. They typically come in two colors, green or black.
I have never seen T. spinosocarinatus reported for sale or as hitch-hikes, but I guess now I will have to add them to Roy's List.
Roy