Illacme is a genus of millipedes in the family Siphonorhinidae. It includes three species. Illacme plenipes was first described in 1928 from San Benito County, California, and rediscovered in 2005. In 2016, Illacme tobini was described based on a single male specimen collected in 2006 from Lange Cave, in Sequoia National Park, 240 km (150 mi) east of the known habitat for I. plenipes. In 2018, Illacme socal was discovered in Whiting Ranch Wilderness Park.

Illacme are detritovores and break down dead plant matter before eventually returning it to the soil.

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