Phyllosiphon
{{Short description|Genus of algae}}
{{Automatic taxobox
| image = Phyllosiphon arisari.jpg
| image_alt = Illustration of "Phyllosiphon arisari": A, leaf of "Arisarum vulgare" showing the infection ; B, algal branches in the petiole ; C, part of algal thallus with aplanospores ; D, aplanospores
| image_caption = Illustration of Phyllosiphon arisari: A, leaf of Arisarum vulgare showing the infection ; B, algal branches in the petiole ; C, part of algal thallus with aplanospores ; D, aplanospores
| taxon = Phyllosiphon
| authority = J.G.Kühn, 1878Kühn, J.G. (1878). Ueber eine neue parasitische Alge Phyllosiphon Arisari welche die Laubblaetter einer terrestrischen Pflanze ganz in derselben Weise befaellt, wie dies von parasitischen Pilzen bekannt ist. Sitzungsberichten der naturforschenden Gesellschaft zu Halle 1878: 25-26?.
| synonyms =
| synonyms_ref =
| type_species = Phyllosiphon arisari
| type_species_authority = J.G.Kühn
| subdivision_ranks = Species
| subdivision =
- Phyllosiphon alocasiae Lagerheim
- Phyllosiphon ari Procházková, Němková & Neustupa
- Phyllosiphon arisari J.G.Kühn
- Phyllosiphon coccidium H.Y.Song, Y.X.Hu, H.Zhu, Q.H.Wang, G.X.Liu & Z.Y.Hu
- Phyllosiphon deformans Mangenot
- Phyllosiphon duini K.Procházková, Y.Nemcová & J.Neustupa
- Phyllosiphon maximus Lagerheim
- Phyllosiphon philodendri Lagerheim
}}
Phyllosiphon is a genus of green algae in the class Trebouxiophyceae.Round, F. E. (1981). The Ecology of Algae. London: Cambridge University Press. pp. 398-400, [https://books.google.com/books?id=Rm08AAAAIAAJ&pg=PA398]. Unusually among the green algae, members of Phyllosiphon are often parasitic within the leaves of Araceae, causing necrosis. It has a mostly tropical to subtropical distribution, and is found primarily in the Mediterranean region, but has also been isolated in North America, Australia, Africa, and China.
Description
Most members of Phyllosiphon are parasitic green algae that inhabit the leaves of plants in the family Araceae. When inside the leaves, they cause yellowish-green spots; they remain greenish in color even when the leaf dries. Microscopically, the thallus of Phyllosiphon consists of branched, siphonal filaments which penetrate the space between leaf parenchyma cells. Asexual reproduction occurs from the formation of endospores, which fill the filaments. Endospores are about 3-6 μm in diameter and ellipsoidal.{{cite journal | doi=10.1127/nova_hedwigia/2015/0288 | title=Morphology and phylogeny of parasitic and free-living members of the genus Phyllosiphon (Trebouxiophyceae, Chlorophyta) | date=2015 | last1=Procházková | first1=Kateina | last2=Nmcová | first2=Yvonne | last3=Kulichová | first3=Jana | last4=Neustupa | first4=Jií | journal=Nova Hedwigia | volume=101 | issue=3–4 | pages=501–518 }}
A number of species of Phyllosiphon are free-living, but are phylogenetically in the same clade as parasitic Phyllosiphon species, and are therefore placed in the genus. When free-living, the cells are solitary and coccoid. Cells contain a single parietal, lobed chloroplast with{{cite journal|doi=10.7872/crya/v39.iss1.2018.23 |title=Phyllosiphon duini sp. Nov. (Trebouxiophyceae, Chlorophyta), a Species Isolated from a Corticolous Phototrophic Biofilm |date=2018 |last1=Procházková |first1=Kateřina |last2=Némcová |first2=Yvonne |last3=Neustupa |first3=Jiří |journal=Cryptogamie, Algologie |volume=39 |pages=23–34 }} or without pyrenoids, as well as oil droplets and carbohydrates.
Ecology
The species Phyllosiphon arisari Kühn induces necrosis in leaf tissue of Arisarum, after invading the intracellular space.{{cite journal|doi=10.1080/09670262.2011.590902 |title=Morphology, fine structure, life cycle and phylogenetic analysis of Phyllosiphon arisari , a siphonous parasitic green alga |date=2011 |last1=Aboal |first1=Marina |last2=Werner |first2=Olaf |journal=European Journal of Phycology |volume=46 |issue=3 |pages=181–192 |bibcode=2011EJPhy..46..181A }} Another species, Phyllosiphon ari, parasitizes leaves of Arum italicum.{{cite journal|doi=10.11646/phytotaxa.283.2.3 |title=Phyllosiphon ari sp. nov. (Watanabea clade, Trebouxiophyceae), a new parasitic species isolated from leaves of Arum italicum (Araceae)
|date=2016 |last1=Procházková |first1=Kateřina |last2=Němcová |first2=Yvonne |last3=Neustupa |first3=Jiří |journal=Phytotaxa |volume=283 |issue=2 |page=143 }} Five additional species have been described from the tropics, but have not been reported since.
When free-living, Phyllosiphon species inhabit a variety of terrestrial habitats, in particular subaerial biofilms on tree bark.