Houia
Houia is an extinct genus of dekatriatan, a clade of chelicerate arthropods. Fossils of Houia have been discovered in deposits of the Early Devonian period in Guangxi and Yunnan, both in China. The genus contains two species: H. guangxiensis, from the Pragian to Emsian epoch of Guangxi; and H. yueya, the type species, from the Lochkovian epoch of Yunnan. The name of the genus is derived from the Chinese character 鲎, meaning "horseshoe crab".
Houia yueya was originally described as a species of the xiphosuran genus Kasibelinurus in 2013, with its narrow opisthosoma being misinterpreted as incompletely preserved. The species name yueya comes from the Chinese characters 月 and 牙, referring to the crescentic shape of its carapace.
H. yueya was redescribed and replaced under its own genus, Houia, in 2015, being reinterpreted as a basal dekatriatan possessing both horseshoe crab and eurypterid-like features. Unlike most of dekatriatans like eurypterids and chasmataspidids, the metastoma of Houia is unusually enlarged, only being comparable by some mycteropoid eurypterids, and may have acted to crush more fortified prey. In 2021, a new species of Houia, H. guangxiensis, was described. Its species name derivates from the Chinese province in which it was discovered, Guangxi.