Scientists have discovered three new species of cockroaches in China.

The three new species - Pseudophoraspis clavellata, Pseudophoraspis recurvata and Pseudophoraspis incurvata - under the genus Pseudophoraspism have been documented for the first time in China.

Cockroaches belong to the family of Blaberidae, with more than 4,500 species found across the globe. Their fossil records date back to 400 million years, showing evidence that they are one of the greatest survivors of planet Earth.

The three newly-found species are some of the smallest members of the cockroach family. The adult can grow up to 3 cm in length, while the female of the largest species known, Blaberus giganteus, can reach up to 10 cm in length. The three species were discovered in China's Hainan, Yunnan and Guangxi Provinces respectively.

Until now, all the known species belonging to the genus Pseudophoraspis have been reported from Southeast Asia and South Asia, with Vietnam touted as the north boundary of the territory. But the new findings expand the reach of this genus northward.

"All of the known species were reported from Southeast Asia and South Asia, and the previously known boundary of this genus would be Vietnam. We found three new species from China, located in Hainan, Yunnan and Guangxi Provinces respectively, which extends the range of the genus Pseudophoraspis northward," Dr. Zongqing Wang, from Southwest University in China, said in a statement.

The findings of the study are published in the journal ZooKeys.