Sarcodia platycarpa Harvey ex Grunow, 1874: 42–43 (type locality: Tonga).
Halymenia platycarpa (Harvey ex Grunow) J. Agardh, 1876: 135 (including Indian Ocean record).—G. Murray, 1887: 23.— J. Agardh, 1892: 53.— S. Dixit, 1970: 119.
INDIAN OCEAN DISTRIBUTION: Sri Lanka.
Note: Halymenia platycarpa is one of two unrelated foliose red algae, the other being Euryomma platycarpa Schmitz (q.v.), that are based on specimens bearing the manuscript name Sarcodia platycarpa and distributed by Harvey, first in his Ceylon exsiccata (1857a), with a query, and soon afterward in his Friendly Island exsiccata (1857b), without a query. In both exsiccatae S. platycarpa was assigned the number 52.A specimen from Tonga was described by Grunow (1874: 43) using Harvey's manuscript name, so that the valid name may be credited to Harvey ex Grunow. This species was transferred to Halymenia by J. Agardh (1876: 135). Subsequently, Schmitz (in Schmitz & Hauptfleisch, 1897d: 374), after examining a specimen of Sarcodia platycarpa from Sri Lanka, proposed a new genus to receive it, namely, Euryomma (placed by him in the Rhizophyllidaceae but assigned in this catalogue to the Solieriaceae in accordance with Kylin, 1932). Although Schmitz adopted Harvey's epithet, Euryomma platycarpa must be attributed directly to Schmitz.
The fact that J. Agardh confused the two species is immaterial because he cited Grunow and therefore the name Halymenia platycarpa must remain with the cryptonemiaceous alga. Kylin (1932: 30–31) discussed the confusion of the two species, but his taxonomic observations are marred by nomenclatural errors, among them an allegedly new, but in fact superfluous, combination, "Halymenia platycarpa (Harv.) Kylin''.