The subject of a 'queen' is a hard one, as it is almost inexorably linked to the 'hive' concept.
Lets look at behaviour: do we ever see Shivans retreat? They throw ship after ship after ship at the GTVA. Sometimes they're badly outnumbered, but they don't run (that I can remember!). They are willing to die for their cause, whatever it is.
The queen-and-hive and the hive-mind concept works well with that. Neal Stephenson wrote that 'for ants, there are only two numebers: some and none'. In social or biological structure in which individual welfare is less developed than societal/biological welfare, 'some or none' is a valid model. Shivans can kill themselves wantonly, because individually they are 'none' and they need to die in larger numbers to become 'some'.
In a more individualised, less specialised society, one in which biological reproduction isn't centralised in a queen, any pair of individuals can produce offspring and thus continue the species. The problem with this is that individualised/unspeciaised species reproduce more slowly, due to the fact that there are no dedicated biological factories (queens). Slower reproduction means more incentive to live to reproduce. Shivans who were more individual would be more apt to retreat.
The final problem that comes into play is that collective biologies have is that there is not evolutionary pressure toward individual sentience. As has been pointed out in the Shivan Sociology thread, ants and bees and other collective biologies exhibit traits, practices and abilities found in individuals of generalised species (like humans). This is a case of the hive adapting to circumstances, not the individuals. Again, 'some or none' comes into play.
I'd like to think that somehow the Shivan's bucked the trend of hive biology. I think they started out as a hive biology but changed over time to adapt to a larger, more dangerous universe. Imagine that they are a hive species, but that the hives are smaller, maybe a few dozen or so. They aren't a hive mind, but more like a family unit. In such a system, the 'some or none' concept breaks down completely and real numbers, and therefor individual survival, becomes of benefit to the species. Small hives can specialise but the species as a whole becomes generalised, and thus more robust.
A step further, a mini-hive structure allows for a development of cooperation between hives. Eventually this cooperation becomes reliance and could lead to a hive-of-hives (nation) model. In this way, we can have biological 'queens' of hives, but avoid the it for the species. We can avoid the 'hive-mind' idea as well.
All of this dovetails nicely with my belief in a low-gravity, arboreal, insect-like development for Shivans.
ruhkferret on ICQ/AIM
"Your guy was a little SQUARE! You had to use your IMAGINATION! There were no multiple levels or screens. There was just one screen forever and you could never win the game. It just kept getting harder and faster until you died. JUST LIKE LIFE." --Ernie Cline