Thorea is a genus of fresh water algae in the division Rhodophyta (red algae). Thorea is a small alga with filaments up to 200 cm long, dark green in colour and not red as are marine Rhodophyta. The filaments have only as few secondary branches. Thorea is distributed throughout temperate and tropical regions. The genus was circumscribed by Jean Baptiste Bory de Saint-Vincent in Ann. Mus. Natl. Hist. Nat. vol.12 on page 126 in 1808. The genus name of Thorea is in honour of Jean Thore (1762–1823), who was a French botanist and physician who practiced medicine in the town of Dax.

Species

As accepted by WoRMS; Former species;

Thorea in UK

There is only one species of Thorea in the British Isles: Thorea hispida (Synonyms: Thorea anadina, T. lehmannii and T. ramosissima ). The first record of Thorea ramosissima in the British Isles is in Harvey's Manual (1841): Found in a pool in a bog in the County Donegal Mountains, going from Letterkenny to Dunfanaghy; July. These specimens are in the Ulster Museum (BEL: F42–F47), but proved to have been incorrectly identified and were specimens of Batrachospermum.