Hemicorallium, Gray, 1867

Key to the Species of Hemicorallium View in CoL from the Hawaii and Western Pacific Region

1. Cortex (except tip or autozooids) color whitish or yellowish .................................................................................. 2

— Cortex color reddish or orangish .................................... 6

2. Autozooid mounds tall (> 2.0 mm in height)................ 3

— Autozooid mounds short (<2.0 mm in height)............ 4

3. Autozooid mounds more than 3.0 mm in height ............ ........................ H. jiaolongensis Hu, Zhang, and Xu, 2025

— Autozooid mounds 2.7 mm in height ............................... ................. H. variabile (Thomson and Henderson, 1906) View in CoL

4. Autozooid mounds more than 1.5 mm both in diameter and height, pale red in color....................................... .................................. H. guttatum Tu, Dai, and Jeng, 2016 View in CoL

— Autozooid mounds small and short (approximately 1.0 mm), whitish in color.................................................. 5

5. Branching rather bushy; double clubs present................. ....................................... H. boshuense (Kishinouye, 1903) View in CoL

— Branching lateral; double clubs absent ............................. .................................................... H. laauense ( Bayer, 1956) View in CoL

6. Autozooid mounds tall (> 2.5 mm in height), cortex red in color ........................................................................... ...................... H. indicodensum Hu, Zhang, and Xu, 2025

— Autozooid mounds short (<2.0 mm in height)............ 7

7. Autozooid mounds scarce, large (> 2.0 mm in diameter)...................................................................................... 8

— Autozooid mounds crowded, small (<2.0 mm in diameter) ................................................................................ 9

8. Autozooid mounds distributed biserially, sized approximately 2.0 mm both in diameter and height................... ..................................................... H. abyssale ( Bayer, 1956) View in CoL

— Autozooid mounds distributed on one side of the colony, sized more than 2.0 mm in diameter........................... ......... H. meraboshi Nonaka, Hanahara, and Kakui, 2023

9. Double clubs abundant ...................................................10

— Double clubs absent or rare............................................ 11

10. Autozooid mounds tall (0.9–2.0 mm in height); axis pinkish............................ H. sulcatum (Kishinouye, 1903) View in CoL

— Autozooid mounds short (approximately 1.0 mm in height); axis orange.............................................................. .......................... H. taiwanicum ( Tu, Dai, and Jeng, 2012) View in CoL

11. Eight-radiates abundant (> 60%).................................. 12

— Eight-radiates present but not abundant (<50%) ......16

12. Autozooid mounds tall (2.0–3.0 mm)............................... ..................................... H. halmaheirense (Hickson, 1907) View in CoL

— Autozooid mounds not tall (< 1.5 mm) .......................13

13. Spherical sclerite absent...................................................... ..................... H. muzikae Nonaka and Hayashibara, 2021 View in CoL

— Spherical sclerite present ................................................ 14

14. Spherical 8-radiate present................................................. ........................... H. aurantiacum Tu, Dai, and Jeng, 2016 View in CoL

— Spherical 8-radiate absent............................................... 15

15. Large irregular sclerite present; cortex and axis orangish............................................ H. reginae (Hickson, 1905) View in CoL

— Large irregular sclerite absent; cortex and axis red......... ......................................................... H. regale ( Bayer, 1956) View in CoL

16. Elongate multi-radiates dominant..................................... ......................................................... H. ryukyuense sp. nov.

— Elongate multi-radiates absent or rare.......................... 17

17. Almost cortex sclerites small (< 0.05 mm in length); cortex pinkish and axis pale purple................................... .................... H. tokiyasui Nonaka and Hayashibara, 2021 View in CoL

— Almost cortex sclerites large (> 0.05 mm in length); cortex and axis red............................................................... .......................... H. kaiyo Nonaka and Hayashibara, 2021 View in CoL