Ok,
There's enough core books now that I'm having trouble keeping track of everything. I'm looking for a way within the rules for people to ride large or bigger spiders. I could just hand wave it, but I'd rather find some way to make it legit, in case one of my players ends up asking to do so down the road (I prefer not to have things in my world that are 'npc only' if it's groups/peoples).
Now, I think the beast rider cavalier is closest, although that's limited to a specific class. I know they added some stuff with vermin companions with Ultimate Magic, but the spiders in there are small/medium (which is kind of annoying, since Scorpions are medium/large). But again, that limits it to a specific class. I'd rather not have everyone in the tribe be a druid or cavalier (although I'd be ok with them being popular).
Someone already started a thread about spider riding today! The pathfinder board is creating some funny similarities in thoughts.
http://paizo.com/threads/rzs2pgpf?Calling-all-spider-riders
Thanks for the redirect.
Read Handle Animal for Rear Wild Animal. The main thing you would need to add is the vermin section from Animal Companions.
Vermin Companions
Source: Ultimate Magic
Vermin companions follow the same rules as animal companions, advancing their Hit Dice and other abilities per Table: Animal Companion Base Statistics. Vermin companions can be trained as if they were animals using the Handle Animal skill.
Mindless: Vermin companions have no Intelligence score and possess the mindless trait. In spite of this, vermin companions may learn one trick, plus additional bonus tricks as noted on Table: Animal Companion Base Statistics. If a vermin animal companion gains an ability score increase (at 4 Hit Dice, 8 Hit Dice, and so on), the druid can apply this increase to the companion's Intelligence, changing it from — to 1, at which point the companion loses the mindless quality and is able to know up to 3 tricks per point of Intelligence, plus the additional bonus tricks, as per Handle Animal. Vermin companions have no skill points or feats as long as they have the mindless quality.
Trip: Because many vermin have multiple limbs, they are very difficult to trip. As a result, a CMD entry has been included for each, indicating the bonus to CMD such vermin receive against trip attacks.
Effectively, rearing from the wild gives vermin one trick and need to be "pushed" to do anything else. Until, the animal companion gains an Intelligence point. That's the rules.
You could always create a species of smart spiders to facilitate domestication.
cheers