Florideophyceae is a class of exclusively multicellular
red algae.[3][4] They were once thought to be the only algae to bear
pit connections,[5] but these have since been found in the filamentous stage of the
Bangiaceae.[6] They were also thought only to exhibit apical growth, but there are genera known to grow by intercalary growth.[6] Most, but not all, genera have three phases to the
life cycle.[6] In the subclass Nemaliophycidae there are three orders, Balbianiales, Batrachospermales, and Thoreales, which lives exclusively in freshwater.[7]
According to molecular clock analysis, Florideophyceae diverged from other red algae about 943 (817–1,049) million years ago. It split into Hildenbrandiophycidae ca. 781 (681–879) mya, Nemaliophycidae ca. 661 (597–736) mya and Corallinophycidae ca. 579 (543–617) mya, and ca. 508 (442–580) mya the split between Ahnfeltiophycidae and Rhodymeniophycidae occurred.[1]
^Dawes, C. J.; Scott, F. M.; Bowler, E. (1961). "A Light- and Electron-Microscopic Survey of Algal Cell Walls. I. Phaeophyta and Rhodophyta". American Journal of Botany. 48 (10): 925–934.
doi:
10.2307/2439535.
JSTOR2439535.
^Le Gall L, Saunders GW (June 2007). "A nuclear phylogeny of the Florideophyceae (Rhodophyta) inferred from combined EF2, small subunit and large subunit ribosomal DNA: establishing the new red algal subclass Corallinophycidae". Mol. Phylogenet. Evol. 43 (3): 1118–30.
Bibcode:
2007MolPE..43.1118L.
doi:
10.1016/j.ympev.2006.11.012.
PMID17197199.