super vs super()

class A
  attr_reader :stack

  def initialize
    @stack = Array.new
  end
end

class B < A
  attr_reader :name

  def initialize(args={})
    super
    @name = args.fetch(:name, nil)
  end
end

b = B.new({:name => 'Ruby'})

ArgumentError: wrong number of arguments (1 for 0)