Tomatoville® Gardening Forums - Is there a 'dark grean leaf' gene?

I'm sure everybody has noticed that not all tomato varieties have the same leaf colour. Some are kinda light green, other 'normal' and some dark green (talking about same fertilization).
I noticed there is some special leaf type that only some black and green tomatoes have which is positively darker than normal and also has a different behaviour. One is that the classic magnesium deficiency symptoms are not the same (almost lack of interveinal yellowing, and also seem to have much much less Mg problems) and in general lacks any yellowing stage. So in case of a disease/pest it goes from green to brown with almost no yellowing in between like the rest.

Does anyone know what I'm talking about? Is there a known gene for this? (could be maybe a trait associated with a known gene for something else?)