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.^[1][2] The name of the genus is derived from the Chinese character 鲎 (hòu), meaning "horseshoe crab".^[1]

Houia Temporal range: Lochkovian–Emsian, 416–393.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Reconstruction of Houia yueya
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Chelicerata
Clade:	Planaterga
Clade:	Dekatriata
Genus:	†Houia Selden, Lamsdell & Qi, 2015
Type species
†Houia yueya Lamsdell, Xue & Selden, 2013
Species
†H. guangxiensis Wang et al., 2021 †H. yueya Lamsdell, Xue & Selden, 2013

Ventral structures of Houia yueya, showing metastoma (Mt)

Houia yueya was originally described as a species of the xiphosuran (horseshoe crab) genus Kasibelinurus (Kasibelinurus yueya) in 2013, with its narrow opisthosoma (the trunk section) being misinterpreted as incompletely preserved (lacking lateral regions).^[3] 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).^[4]

H. yueya was redescribed and replaced under its own genus, Houia, in 2015, being reinterpreted as a basal ("primitive") dekatriatan possessing both horseshoe crab and eurypterid-like features (e.g. crescentic carapace for the former, and metastoma for the latter). Unlike most of dekatriatans like eurypterids and chasmataspidids, the metastoma (ventral plate in front of opisthosoma) of Houia is unusually enlarged, only being comparable by some mycteropoid eurypterids, and may have acted to crush more fortified prey.^[1] 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.^[2]

References

1. Selden, Paul A.; Lamsdell, James C.; Qi, Liu (2015). "An unusual euchelicerate linking horseshoe crabs and eurypterids, from the Lower Devonian (Lochkovian) of Yunnan, China". Zoologica Scripta. 44 (6): 645–652. doi:10.1111/zsc.12124. S2CID 55264483.
2. Wang, Han; Lei, Xiaojie; Zhang, Haichun; Jarzembowski, Edmund A.; Xu, Honghe (2021). "New find of Houia (Arthropoda: Euchelicerata) from the Lower Devonian of Guangxi, South China". Geological Journal. 56 (12): 5910–5913. doi:10.1002/gj.4199. S2CID 237922832.
3. Lamsdell, James C.; Xue, Jinzhuang; Selden, Paul A. (2013). "A horseshoe crab (Arthropoda: Chelicerata: Xiphosura) from the Lower Devonian (Lochkovian) of Yunnan, China". Geological Magazine. 150 (2): 367–370. Bibcode:2013GeoM..150..367L. doi:10.1017/S0016756812000891. hdl:1808/14491. ISSN 0016-7568. S2CID 128448566.
4. Lamsdell, James C.; Xue, Jinzhuang; Selden, Paul A. (2013). "A horseshoe crab (Arthropoda: Chelicerata: Xiphosura) from the Lower Devonian (Lochkovian) of Yunnan, China". Geological Magazine. 150 (2): 367–370. Bibcode:2013GeoM..150..367L. doi:10.1017/S0016756812000891. hdl:1808/14491. S2CID 128448566.