Aphanothece
Aphanothece castagnei Rbh.
Scientific classification
Domain:	Bacteria
Phylum:	Cyanobacteria
Class:	Cyanophyceae
Order:	Chroococcales
Family:	Aphanothecaceae
Genus:	Aphanothece C.Nägeli, 1849

Aphanothece is a polyphyletic genus with 63 accepted species.^[1] The name is derived from the Greek words, ‘aphanes’ and ‘theke’ which mean “invisible" and “box or sheath” respectively.^[2] This genera is cosmopolitan, found in soils, thermal springs^[1] and other benthic, freshwater, marine, hypersaline, and moist terrestrial environments.^[2] Morphology can vary,^[3] with both microscopic and macroscopic colonies large enough to be collected and preserved in herbarium records.^[2]

Morphology

The formerly combined genera Aphanothece and Anathece can be differentiated by the size of cells, ecology and colony morphology. Anathece rarely forms colonies large enough to see and has much smaller cells, while Aphanothece can have colonies several cm in diameter and tends to have larger cells. Aphanothece species occupy a broader range of microhabitats that can be planktonic, subaerophytic, metaphytic, epipelic, or benthic. While benthic Anathece have been reported, they are typically planktonic. Anathece colonies are less defined and colorless, Aphanothece colonies and mucilage can be found in shades of green, grey, blue, brown and yellow.^[3][1]

Ecology and Habitat

Aphanothece species live in freshwater ponds, lakes and coastal brackish environments.^[4] Some species are able to live in extremely thermophilic environments such as hot water springs.^[4] Aphanothece species also live in soil and on wet rocks, these species form sediments on the marine coasts.^[5]

In oil industry waste water, 40 species of algae including Aphanothece were observed to be growing in this environment by using organic molecules as nutrients in the summer and winter months.^[6]

Taxonomy

Aphanothece is a genus of cyanobacteria with complex taxonomy. Previously, the genus was only delineated morphologically since it was first described by Carl Nägeli in 1849, with Aphanothece microscopica Nägeli as the type species.^[1] By some accounts the genus has 29 accepted species,^[1] but work on the taxa since the 1990s reassigned species and divided the genus into three subgenera based on morphological and molecular methods: Aphanothece, Anathece and Cyanogastrum, which were later separated into their own genera.^[3]

In the most recent work on the classification of cyanobacteria orders and families, Anathece was moved to the Prochlorococcaceae family as its own genus.^[7] A formal review of every species in the taxa has not been conducted,^[7] as such a list of the 63 taxonomically accepted species in the AlgaeBase database are as follows, but are likely to change as more research is conducted.^[1]

References