Note: When J. Agardh (1847: 16) established the genus Eucheuma, he treated the name as feminine, but later (1852a: 624–629) treated it as neuter, as have most subsequent authors. There are no obvious linguistic guidelines. The name Erythroclonium sonderi, without a description, was used by Harvey in his Australian exsiccata (1857c: no. 391).
Eucheuma arnoldii Weber-van Bosse, 1928: 421, pl. XIII: fig. 1 (type locality: Gisser Island [Pulau Geser], near Seram, Indonesia).
Eucheuma cupressoideum Weber-van Bosse, 1928: 421–422, pl. XIV: fig. 3 (type locality: Torres Strait, Australia).—S. Lee, 1966: 265, 271.— Johnson, 1967b: fig. 3.— Isaac, 1968: 4.— Lawson, 1980: 42.— Phang & Wee, 1991: 59.
INDIAN OCEAN DISTRIBUTION: Kenya, Malaysia, Singapore.
Note: The synonymy was proposed by Kraft (1972: 321).