Arachne (Spiderfolk)

You lose your extra arms racial ability. In exchange, you become Large size and your max burden is increased by 2. When attempting to move through 5ft wide spaces, it is considered difficult terrain for you and many humanoid buildings will struggle to accommodate you. You also suffer a -10 penalty to swimming checks, but you may climb through your spider climb ability at your normal speed instead of half speed.

In addition, you count as mounted for the purposes of abilities that require you to be mounted. This does not let you be a mount to other creatures.