Hildenbrandiales Explained

Hildenbrandiales is an order of crustose forms red alga which bear conceptacles^[1] and produce secondary pit-connections.^[2] They reproduce by vegetative gemmae^[3] as well as tetrasporangia, which are produced inside the conceptacles. The way in which the tetraspores are produced is unusual enough to justify the formation of this distinct order.^[1] Some members of the order are known from freshwater rivers as well.^[4]

Systematics

Hildenbradiales are difficult to discriminate on morphological grounds; tetrasporangia morphology is the only vaguely reliable character, but molecular techniques have indicated a monophyletic Apophlaea within a paraphyletic Hildenbrandia, with many Hildenbrandia species being recognized as non-monophyletic.^[5]

Notes and References

1. Pueschel . C.. Ultrastructural observations of tetrasporangia and conceptacles in Hildenbrandia (Rhodophyta: Hildenbrandiales). European Journal of Phycology. 17. 3. 333–341. 1982. 10.1080/00071618200650331.
2. Pueschel . C.. Secondary pit connections in Hildenbrandia (Rhodophyta, Hildenbrandiales). European Journal of Phycology. 23. 25–51. 1988. 10.1080/00071618800650031. free.
3. Sherwood . A. R.. Sheath . R. G.. Microscopic analysis and seasonality of gemma production in the freshwater red alga Hildenbrandia angolensis (Hildenbrandiales, Rhodophyta). Phycological Research. 48. 4. 241. 2000. 10.1111/j.1440-1835.2000.tb00220.x.
4. Khan . M.. On a fresh water Hildenbrandia Nardo. From India. Hydrobiologia. 44. 2–3. 237–240. 1974. 10.1007/BF00187272.
5. Sherwood . A. R.. Sheath . R. G.. Systematics of the Hildenbrandiales (Rhodophyta): Gene Sequence and Morphometric Analyses of Global Collections. Journal of Phycology. 39. 2. 409–422. 2003. 10.1046/j.1529-8817.2003.01050.x.