It seems that it isn't just inhabitable Chunks (
http://aurora2.pentarch.org/index.php/topic,6063.0.html) that aren't listed as possible colony sites if they fall under your gravity range but also Dwarf Planets. Neither of these are listed under 'Available Colony Sites' or show up on the Galaxy Map (under the Col cost part of the 'Planet Types' EDIT: the 'dot' display seems to work for all of them correctly).
This means you have to look through all of the listings under F9, and if the NPRs use the colony sites tool to decide on new colonies they will probably skip them, putting them at a bit of an extra disadvantage
Also it seems that the Galaxy Map 'Planet Types' "Suitability x or less" lists don't include Col cost bodies of exactly x. As I have 3 Col cost 2.00 moons (2x Terrestrial, 1x Chunk) in my starting system and it only lists 1 (my home world I presume) on the "Suitability 2 or less" line and they seems to be included under the "4 or less" line.
EDIT: Hmm actually it seems that either my Col Cost 2.00 Chunk
OR my Col cost 3.43 Dwarf Planet
OR one of the 2 Terrestrials (1 moon + 1 planet both > Col cost 4 and less than 7, though there is also a Chunk moon! in that range as well so I'll just make a full list below as I can't figure out where it is going squiffy
) are listed under the "4 or less" so it seems to be a little more complex for the Galaxy Map vs the 'Available Colony Sites' screen issue.
Available bodies (Col cost <= 10):
B component:
Dwarf Planet (planet IV) 3.43
Terrestrial Planet (planet V) 0.00
Chunk Moon (planet VI) 2.00
2x Terrestrial Moon (planet VI) 2.00
Terrestrial Moon (planet VI) 2.85
C component:
Terrestrial Moon (planet II) 5.70
Chunk Moon (planet II) 6.63
Terrestrial Moon (planet II) 6.29
So I would expect to see on the Galaxy Map:
Suitability 2 or less 4
Suitability 4 or less 2
Suitability 7 or less 3
Suitability 10 or less 0
But I see:
Suitability 2 or less 1
Suitability 4 or less 4
Suitability 7 or less 1
Suitability 10 or less 0