What I'm trying to determine: is there a significant difference between the Types?

I determined the row frequencies, and set up a 2 x 3 contingency table.

G test 18.86, df 2, p-value 0.00008. Reject the Null hypothesis based on the p-value. (No relationship between Group type and classification level)

(I have never worked with contingency tables before, so any pointers gladly received!)

Now to the questions: Does it matter that there is such a large difference in the number of species by group?

Do I also need to determine phi?