C. yunnanensis specimens were collected by Yu-Tang Wang across the Chinese provinces of Guizhou and Yunnan, the latter of which gave the species its name.

[1][2] In 2018, a distinct form of the C. testudo species group was identified by entomologist Hiroyuki Yoshitomi from specimens collected in southwestern China which displayed novel genital characteristics.

The holotype of the species is a male specimen collected in Xima, Yunnan in 2014 by entomologist Yu-Tang Wang.

This is joined by large numbers of paratypes collected by Wang in Xima and other areas of Yunnan, including Ruili, Mengla, Daweishan.

and C. chayuensis due to the shared innovation of minuscule serrae (saw-like indentation) along the lower margin of the median lobe.

[3] Like other Caccothryptus beetles, it is commonly found in piles of dead, water-logged wood located along forest streams.