Houia

Houia is a genus of dekatriatan, a clade of chelicerate arthropods. Fossils of the single and type species, H. yueya, have been discovered in deposits of the Early Devonian period (Lochkovian epoch) in Yunnan, China. The name of the genus is derived from the Chinese character 鲎 (hòu), meaning "horseshoe crab".[1] The species name yueya comes from the Chinese characters 月 (yuè, meaning "Moon") and 牙 (yá, meaning "crescent"), referring to the crescentic shape of its carapace (the dorsal plate of the prosoma or head).[2]

Houia Temporal range: Lochkovian, 416–411.2 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Reconstruction of Houia yueya
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Clade:	Planaterga
Clade:	Dekatriata
Genus:	†Houia Selden, Lamsdell & Qi, 2015
Type species
†Houia yueya Lamsdell, Xue & Selden, 2013

Ventral structures of Houia yueya, showing metastoma (Mt).

Houia yueya was originally described as a species of the horseshoe crab genus Kasibelinurus (Kasibelinurus yueya) in 2013, with its narrow opisthosoma (the trunk section) being misinterpreted as incompletely preserved (lacking lateral regions).[3] It was redescribed and replaced under its own genus Houia in 2015, being reinterpreted as a basal dekatriatan possesses both horseshoe crab and eurypterid-like features (e.g crescentic carapace for the former, and metastoma for the latter).[1] Unlike most of the dekatriatans like eurypterids and chasmataspidids, the metastoma (ventral plate in front of opisthosoma) of Houia is unusually enlarged that only comparable by some mycteropoid eurypterids, and may have acted to crush harder prey items.[1]