Florideophyceae

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]

Florideophyceae Temporal range: Neoproterozoic–present[1] Pha. Proterozoic Archean Had.
"Florideae" from Ernst Haeckel's Kunstformen der Natur, 1904
Scientific classification
Domain:	Eukaryota
Clade:	Archaeplastida
Division:	Rhodophyta
Subdivision:	Eurhodophytina
Class:	Florideophyceae Cronquist, 1960[2]
Subgroups
See text.

Classification

A Laurencia red alga from Hawaii

There are various classification schemes; see red algae. One option is to use the following:

Subclass Hildenbrandiophycidae

• Hildenbrandiales

Subclass Nemaliophycidae

• Acrochaetiales
• Balbianiales
• Balliales
• Batrachospermales
• Colaconematales
• Nemaliales
• Palmariales
• Entwisleiales
• Thoreales

Subclass Corallinophycidae

• Corallinales
• Corallinapetrales
• Rhodogorgonales
• Sporolithales

The subclass Corallinophycidae was introduced in 2007.^[8]

Subclass Ahnfeltiophycidae

• Ahnfeltiales
• Pihiellales

Subclass Rhodymeniophycidae

• Bonnemaisoniales
• Ceramiales
• Gelidiales
• Gigartinales
• Gracilariales
• Halymeniales
• Nemastomatales
• Peyssonneliales
• Plocamiales
• Rhodymeniales
• Acrosymphytales
• Atractophorales
• Catenellopsidales
• Sebdeniales

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]