Deanichthys

Deanichthys; Temporal range: Telychian, ; ~436 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Infraphylum:	Agnatha
Class:	†Galeaspida
Family:	†Dayongaspidae
Genus:	†Deanichthys; Zhang et al., 2026
Species:	†D. longpingi
Binomial name
	†Deanichthys longpingi; Zhang et al., 2026
Synonyms
	Deanaspis Lin et al., 2025 (preoccupied);

Deanichthys (meaning "De'an fish") is an extinct genus of jawless vertebrate from the Galeaspida which originated from the Silurian Xikeng Formation of De'an County, China. The type species is D. longpingi.

Discovery and naming

The holotype is specimen IVPP V26188, a head shield, and it was recovered from a previously unknown outcrop of the Xikeng Formation located within Baishui town, De'an County, China. The specimen was then provided to the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences by Professor Yi Wang.

The specimen was named as "Deanaspis" longpingi by Lin et al. 2025, who were unaware that the genus name was a junior homonym by being already preoccupied by a trilobite named in 1975. Zhang et al. (2026) created the replacement name Deanichthys.

Description and classification

Deanichthys shares traits found in members of both the Eugaleaspidiformes and the Xiushuiaspidae, including the longitudinal oval median dorsal opening in Eugaleaspidiformes and the long postbranchial division of the headshield found in members of the Xiushuiaspidae.

As a result of this assessment, Lin et al. (2025) placed Deanichthys within a new family named Deanaspidae. Zhang et al. (2026) instead placed Deanichthys within Dayongaspidae.

References

1 2 3 4 5 6 Lin, X.; Zan, C.; Gai, Z.; Zhu, M. (2025). "Deanaspis, a new genus of Galeaspida (jawless stem Gnathostomata) from the Silurian of Jiangxi, China, and its evolutionary implications". Journal of Systematic Palaeontology. 23 (1). 2460479. Bibcode:2025JSPal..2360479L. doi:10.1080/14772019.2025.2460479.
1 2 3 4 Zhang, Yumeng; Shan, Xianren; Lin, Xianghong; Gai, Zhikun; Donoghue, Philip C. J. (2026). "A New Dayongaspid Galeaspid from the Silurian of the Lower Yangtze Region: Implications for Biogeography and the Evolution of Key Adaptations in Galeaspids". Journal of Earth Science. 37 (1): 303–316. Bibcode:2026JEaSc..37..303Z. doi:10.1007/s12583-026-0504-6. hdl:1983/88b0135f-8ff4-47a5-95ef-d8be6b07a83c. ISSN 1674-487X.
↑ Hughes, C. P.; Ingham, J. K.; Addison, R. (1975-12-11). "The morphology, classification and evolution of the Trinucleidae (Trilobita)". Philosophical Transactions of the Royal Society of London. B, Biological Sciences. 272 (920): 537–604. Bibcode:1975RSPTB.272..537H. doi:10.1098/rstb.1975.0100. ISSN 0080-4622.

[Deanaspis-1] 1 2 3 4 5 6 Lin, X.; Zan, C.; Gai, Z.; Zhu, M. (2025). "Deanaspis, a new genus of Galeaspida (jawless stem Gnathostomata) from the Silurian of Jiangxi, China, and its evolutionary implications". Journal of Systematic Palaeontology. 23 (1). 2460479. Bibcode:2025JSPal..2360479L. doi:10.1080/14772019.2025.2460479.

[:1-2] 1 2 3 4 Zhang, Yumeng; Shan, Xianren; Lin, Xianghong; Gai, Zhikun; Donoghue, Philip C. J. (2026). "A New Dayongaspid Galeaspid from the Silurian of the Lower Yangtze Region: Implications for Biogeography and the Evolution of Key Adaptations in Galeaspids". Journal of Earth Science. 37 (1): 303–316. Bibcode:2026JEaSc..37..303Z. doi:10.1007/s12583-026-0504-6. hdl:1983/88b0135f-8ff4-47a5-95ef-d8be6b07a83c. ISSN 1674-487X.

[:0-3] Hughes, C. P.; Ingham, J. K.; Addison, R. (1975-12-11). "The morphology, classification and evolution of the Trinucleidae (Trilobita)". Philosophical Transactions of the Royal Society of London. B, Biological Sciences. 272 (920): 537–604. Bibcode:1975RSPTB.272..537H. doi:10.1098/rstb.1975.0100. ISSN 0080-4622.