Is there more than one type of tapered steerer?
Official website says that these are the only models available:


  1-1/8" STKM steel, 1-1/8" aluminum (-163g), XL 1-1/8" steel, XL 1-1/8"
  aluminum, 1.5" to 1-1/8" tapered aluminum (-123g), 1.5" aluminum
  (-146g)


Your fork is straight, the taper at the bottom is required for interference fitted crown race. I've measured straight Suntour XCM just in case and it has same dimensions as in the the question.