Tetra/bisporangial conceptacles arranged in sori: Family Sporolithaceae (1)
Tetra/bisporangial conceptacles not arranged in sori: Family Corallinaceae (2)
(1) Family SPOROLITHACEAE
(1a) Tetra/bisporangial conceptacles 110-130 µm high and arise from a basal layer of elongated cells: Sporolithon sp. 1
(1b) Tetra/bisporangial conceptacles 60-70 µm high and do not arise from a basal layer of elongated cells: Sporolithon sp. 2
(2) Family CORALLINACEAE
(2a) Cells of contiguous filaments connected by cell fusions; tetra/bisporangial conceptacles uniporate: Subfamily Mastophoroideae (3)
(2b) Cells of contiguous filaments connected by cell fusions; tetra/bisporangial conceptacles multiporate: Subfamily Melobesioideae (4)
(3) Subfamily MASTOPHOROIDEAE
(3a) Thallus dimerous with palisade cells, postigenous filaments only around conceptacles: Lithoporella melobesioides
(3b) Thallus dimerous, tetra/bisporangial conceptacle diameter 260-360 µm: Spongites sp. 1
(3c) Thallus monomerous and non-coaxial, tetra/bisporangial conceptacle diameter 500-550 µm: Spongites sp. 2
(3d) Thallus monomerous, core filaments coaxial: Neogoniolithon sp.
(4) Subfamily MELOBESIOIDEAE
(4a) Vegetative initials as short or shorter than underlying cells, conceptacles nearly completely raised above thallus surface, conceptacle size 210-460 µm x 100-160 µm: Phymatolithon sp.
(4b) Conceptacles usually raised one half of their height above thallus surface, conceptacle size 350-600 µm x 170-200 µm: Meleobesioideae gen. et spec. indet.