Okinawa Spiny Rat

沖繩裔鼠 / Okinawa Spiny Rat / オキナワトゲネズミ (Tokudaia muenninki)

Species information

Scientific name: Tokudaia muenninki
Japanese name: オキナワトゲネズミ
Chinese name: 沖繩裔鼠
English name: Okinawa spiny rat
Origin: Northern Okinawajima

Ecology and description

Okinawa spiny rat’s close relatives include the Amami spiny rat (Tokudaia osimensis), found on Amami Oshima, and the Tokunoshima spiny rat (Tokudaia tokunoshimensis), found on Tokunoshima.

Among the three, the Tokunoshima spiny rat is the largest in size, Okinawa spiny rat is medium, and Amami spiny rat is the smallest.

Their sex chromosomes are very interesting and different:

  • Amami spiny rat (T. osimensis 2n=25, XO/XO)
  • Tokunoshima spiny rat (T. tokunoshimemsis 2n=45, XO/XO)
  • Okinawa spiny rat (T. muenninki 2n=44, XX/XY)

Okinawa spiny rat inhabits forests dominated by Okinawa castanopsis. The population size is unknown, and there is significant predation pressure from invasive species (feral cats and dogs). Needle-like hairs of Okinawa spiny rat are often found in the feces of captured feral cats.

Field photographs taken during our tours, with observation dates

This species is very rare and elusive, making observation difficult. I have only seen a live individual once (in the video below).

Okinawa Spiny Rat (Tokudaia muenninki) [no date] A specimen of Okinawa spiny rat displayed at the old Ufugi Museum
A specimen of Okinawa spiny rat displayed at the old Ufugi Museum
Okinawa Spiny Rat (Tokudaia muenninki) Jun 27, 2019 A carcass of Okinawa spiny rat found in Kunigami, only the fur remained
Jun 27, 2019, Kunigami, A carcass of Okinawa spiny rat found, only the fur remained
Okinawa Spiny Rat (Tokudaia muenninki) [no date] Some of the hair of Okinawa spiny rat is flat and needle-like, possibly after being preyed upon by an owl
Some of the hair of Okinawa spiny rat is flat and needle-like, possibly after being preyed upon by an owl
Okinawa Spiny Rat (Tokudaia muenninki) Oct 17, 2020 A neighbor found the carcass of Okinawa spiny rat in the field, possibly brought by a predatory bird, Kunigami
Oct 17, 2020, Kunigami, A neighbor found the carcass of Okinawa spiny rat in the field, possibly brought by a predatory bird
Okinawa Spiny Rat (Tokudaia muenninki) Oct 17, 2020 The needle-like hair of the spiny rat is clearly visible
Oct 17, 2020, The needle-like hair of the spiny rat is clearly visible
Okinawa Spiny Rat (Tokudaia muenninki) [no date] The Amami spiny rat displayed at the Amami Wildlife Conservation Center, a QR code allows viewing of an ecological video
The Amami spiny rat displayed at the Amami Wildlife Conservation Center, a QR code allows viewing of an ecological video

Field videos recorded during our tours

Mar 20, 2023, Kunigami

Reference materials:
Research on Chromosomes of Tokudaia Species (2014)