Homoeothrix

Generic name: HOMOEOTHRIX (Thuret ex Bornet et Flahault) Kirchner 1898, nom. cons. In Engler et Prantl, Nat.Pflanzenfam. 1(1a): 87.
Synonyms: AMPHITRIX Kützing ex Bornet et Flahault, 1886. Ann. Sci. Nat. Bot. 7, 3: 343.[AMPHITRIX Kützing (pro parte), characteribus mutatis, Phycologia generalis, p. 220, 1843 ex Bornet et Flahault, 1886: Chroolepus, Leptothrix, Hypheothrix ; LEPTOCHAETE Borzi, Morfologia e biologia delle Alghe ficocromacee, in N. Giornale bot. ital., vol XIV, p. 298, tab. XVI, fig. 6 - 8, 1882.]
Diagnosis:
Kirchner: Bornet et Flahault (1886) sub Amphithrix Kützing: Thallus crustiformis vel caespitosus, purpureus vel violaceus, e duobus stratis formatus : inferiore horizontaliter ex- panso, intricato, filamentoso, vel e cellulis minutis in lineas radiatas subseriatis contexto; superiore verticali, filis erectis simplicibus, hinc illinc in pilum mox evanescentem attenuatis constante. Vaginae tenues, arctissimae, continuae. Hormogonia solitaria vel seriata. Sporae...
Bornet et Flahault (1886) sub Leptochaete Borzi: Fila simplicia, saepius tenerrima, thallum indefinite crustiformem, tenuem, plerumque late effusum efficientia. Multiplicatio hormogoniis et conidiis chroococcoideis ex articulorum basalium
transmutatione ortis.
Type species: Homoeothrix juliana (Bornet et Flahault) Kirchner, 1898. - About 25 valid species. Heterogeneous genus, at least with two subgenera, Homoeothrix and Tapinothrix.
Descriptions:
Komárek (1992):
Filamentous; filaments solitary or in groups, heteropolar, attached with one end to the substrate (usually by a mucilaginous pad) and with free second end, erected or irregularly waved and creeping on the substrate, with simple, firm, thin sheath enveloping the trichome and open at the apex, colourless or coloured (yellow-brown, violet). Trichomes up to 15 um wide at the base, uniserial, simple, +/- straight or waved, from the widened base continually attenuated to the ends up to a thin
cellular hair (subg. Homoeothrix), or thin and cylindrical along the greatest part of a trichome and at the end hair-like elongated (Subg. Tapinothrix; probably different genera); at crosswalls usually constricted, rarely unconstricted; rarely false branching with one lateral branch, after division at necridic cells or between two vegetative cells (7; different genera 7). Cells shorter than wide or more or less isodiametric, rarely longer than wide before cell division, cylindrical or barrel-shaped, usually pale blue-green, olive-green or greyish, rarely (in large species) blue-green, without aerotopes; hair cells usually vacuolized. Heterocytes and akinetes absent.
Genotype differences, molecular data:
Reproduction strategies, life cycles, cell division:
Komárek (1992): Crosswise cell division by symmetric binary fission, only in special parts of a trichome (unclear or distinct meristematic zones - generic feature 7); cells grow into the original size before the next division (always 7). Reproduction by disintegration of an upper part of a trichome into motile hormogonia, after the separation of the hair. Hormogonia attach by one end to the substrate and germinate at the other ones.
Ultrastructure:
Taxonomic position, higher
hierarchy:
Cyanophyceae, Oscillatoriales, Ammatoideaceae
Notes to taxonomy, misinterpretations:
Ecology, ecophysiology, ecological significance:
Komárek (1992): All species are known from submerse biotopes. The majority of species grow on stones (on the upper or bottom sides) or epiphytic in streams (particularly in mountain creeks), in tarns, less on different substrates in other stagnant waters. One species is marine, few live endogloeic within mucilage of other algae. Almost all species are known from geographically limited areas.
Physiology and biochemistry:
Distribution, endemism, problematic citations:
Reference strain:
Infrageneric scheme, species concept:

List of species:
Homoeothrix endophytica (Lemmermann) Lemmermann 1907
Homoeothrix juliana (Bornet et Flahault) Kirchner 1898
Homoeothrix rubra (Crouan) ex Frémy 1926
Homoeothrix santolii Wawrik
Homoeothrix stagnalis (Hansgirg) Komárek et Kováčik 1987

Homoeothrix varians Geitler 1927


Unclear taxa
Amphithrix janthina Bornet et Flahault, 1886. Ann. Sci. Nat. Bot. 7, 3: 344
Amphithrix violacea Bornet et Flahault, 1886. Ann. Sci. Nat. Bot. 7, 3: 344
Homoeoethrix hansgirgii (Schmidle) Lemmermann 1910
Homoeothrix lyngbyoides Li 1984
Leptochaete capsosirae Frémy 1930
Leptochaete crustacea Borzi ex Bornet et Flahault, 1886. Ann. Sci. Nat. Bot. 7, 3: 342
Leptochaete fonticola Borzi ex Bornet et Flahault, 1886. Ann. Sci. Nat. Bot. 7, 3: 342
Leptochaete parasitica Borzi ex Bornet et Flahault, 1886. Ann. Sci. Nat. Bot. 7, 3: 342
Lyngbya lithophila Ercegović 1932

Keys:
List of stains:
Drawings:
Komárek 1992
Application technology:
Literature:
  2.1 taxonomy: Thuret ex Bornet et Flahault 1886, Kirchner 1898, Geitler 1932, Komárek & Kann 1973, Starmach 1980, Li 1984, Komárek & Kováčik 1987, Komárek 1992
  2.2 cytomorphology:
  2.3 16S rRNA sequencing:
  2.4 biology and life cycles:
  2.5 ecology: