They had no zippers. Real Gorn had zippers... just sayin' 
But I also went the 'different breed of same race' for something I am working on. There's even a bit of meta-canon that goes with that; originally, the species was called the 'Gorrin', but when the actors said it, it just sounded like 'Gorn' (I don't recall if it was actually changed int he script or not, but early drafts of the script had 'Gorrin').
So take your pick - The Gorrin is the race and 'Gorn' is a sub-species, or vice-versa. Doesn't matter.
In my personal writings I have them as a caste-based society with the different castes actually looking and behaving different. Solves all problems.

But I also went the 'different breed of same race' for something I am working on. There's even a bit of meta-canon that goes with that; originally, the species was called the 'Gorrin', but when the actors said it, it just sounded like 'Gorn' (I don't recall if it was actually changed int he script or not, but early drafts of the script had 'Gorrin').
So take your pick - The Gorrin is the race and 'Gorn' is a sub-species, or vice-versa. Doesn't matter.
In my personal writings I have them as a caste-based society with the different castes actually looking and behaving different. Solves all problems.