Английская Википедия:Hildenbrandia
Шаблон:Short description Шаблон:Automatic taxobox
Hildenbrandia is a genus of thalloid red alga comprising about 26 species. The slow-growing, non-mineralized thalli take a crustose form.[1] Hildenbrandia reproduces by means of conceptacles and produces tetraspores.
Morphology
Hildenbrandia cells are around 3–5 μm in diameter and the filaments are around 50–75 μm in height.[2]
The thallus comprises two layers: the hypothallus, which attaches to the rock, and the perithallus, a pseudoparenchymous layer comprising vertical filaments, which unlike coralline red algae is not further differentiated.[3][4] Шаблон:Further
Growth
Hildenbrandia comprises orderly layers of vertical oblong cells with thick vegetative cell walls, occasionally connected by secondary pit connections with pit plugs in the septal pores.[5] It grows at its margins, away from the centre, and is able to quickly repair any gaps arising by regenerating from a basal layer of cells.[6] As plants become more mature, they become multi-layered and strongly pigmented near their centres, whilst their single-layered margins begin to grow more slowly.[6] Multi-layered areas may develop in the margins; these will detach and float away as gemmae to form new colonies, leaving a single layer of cells beneath them once they separate from the host plant.[6]
Newly settled gemmae form rhizoids.[7]
Conceptacles develop in a haphazard manner; cells in conceptacle regions deform one another and become less regularly shaped as they grow larger.[5]
In a similar fashion to the coralline algae, the outer layer of the thallus is shed seasonally, presumably to avoid colonization by epiphytes.[8]
Taxonomy
The genus name of Hildenbrandia is in honour of Franz Xaver von Hildenbrand (1789-1849), who was an Austrian physician and botanist.[9]
The genus was circumscribed by Giovanni Domenico Nardo in Isis (Oken) vol.27 on page 675 in 1834.
Habitat
The freshwater species H. rivularis[6] and H. angularis[7] seems to form a clade,[10] and require an alkaline pH and hard water, preferring clean water.[11] Unlike most other freshwater red algae (which prefer running water), H. rivularis prefers still water, particularly shady lakes or ponds.[11] H. rubra and other marine species are found in brackish waters, but freshwater / gemma-bearing species cannot tolerate even moderate salinities.[12] The genus is often found in a symbiotic partnership with fungi.[13] Hildenbrandia has a remarkable tolerance to stresses including extreme temperatures, desiccation, and Ultra-violet light; it can be up and photosynthesizing near full capacity just minutes after being cooled to −17 °C or subjected to extreme salinities.[14]
Reproduction
Sexual reproduction has never been observed in any Hildenbrandia species.[12] It can reproduce by splitting into multiple colonies by fragmentation, or via stolons (i.e. sending out lateral branches) or gemmae.[6]
Marine Hildenbrandia, on the other hand, reproduce by means of tetraspores that are produced within the thallus by conceptacles.[7]
Systematics
The genus contains these species[15] (this list is out of date): Шаблон:Div col
- H. angolensis
- H. arracana
- H. canariensis
- H. crouanii
- H. crouaniorum
- H. dawsonii
- H. deusta
- H. expansa
- H. galapagensis
- H. kerguelensis
- H. lecannellieri
- H. lithothamnioides
- H. nardiana
- H. occidentalis
- H. pachythallos
- H. patula
- H. prototypus
- H. ramanaginaii
- H. rivularis
- H. rosea
- H. rubra
- H. sanjuanensis
- H. yessoensis
As of April 2022, the GBIF only accepts 6 species; Hildenbrandia crouaniorum Шаблон:Small, Hildenbrandia dawsonii, Hildenbrandia occidentalis Шаблон:Small, Hildenbrandia rivularis Шаблон:Small, Hildenbrandia rubra Шаблон:Small and Hildenbrandia sanjuanensis.[16]
Stonehenge
The presence of H. rivularis near Stonehenge has been put forward as a reason for the site's perceived mystical properties. Flint in the Blick Mead spring pools near to the henge takes on a pink hue a couple of hours after being taken out of water due to the presence of the algae. It is assumed that ancient hunter-gatherers would have seen the rocks as having magical properties and would have deemed the site worthy of interest.[17] [18]
References
External links
- Шаблон:Cite web an excellent, accessible overview of the genus.
- Images of Hildenbrandia at Algaebase
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite journal
- ↑ 5,0 5,1 Шаблон:Cite journal
- ↑ 6,0 6,1 6,2 6,3 6,4 Шаблон:Cite journal
- ↑ 7,0 7,1 7,2 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite book
- ↑ Шаблон:Cite journal
- ↑ 11,0 11,1 Шаблон:Cite journal
- ↑ 12,0 12,1 Шаблон:Cite journal
- ↑ Шаблон:Cite journal
- ↑ Шаблон:Cite book
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite web
- ↑ Шаблон:Cite journal