Heterokont

In 1899, Luther created "Heterokontae" for some algae with unequal flagella, today called Xanthophyceae. Later, some authors (e.g., Copeland, 1956) would include other groups in Heterokonta, expanding its sense.

The origin of the other name of the group, "stramenopile", is explained by David (2002)[4] and Adl et al. (2005):[11]

Regarding the spelling of stramenopile, it was originally spelled stramenopile. The Latin word for straw is strāmĭnĕus (the macron ˉ indicates long vowels, while the breve ˇ indicates short vowels), -a, -um, adj. [stramen], made of straw—thus, it should have been spelled straminopile or straminipile (these corrections are based on the fact that the genitive of stramen required for the correct formation of a compound is straminis, and that the connective used since both parts are latin is i). However, Patterson (1989) clearly stated that this is a common name (hence, lower case, not capitalized) and, as a common name, it can be spelled as Patterson chooses. If he had stipulated that the name was a formal name, governed by rules of nomenclature, then his spelling would have been an orthogonal mutation and one would simply correct the spelling in subsequent publications (e.g. Straminopiles). But, it was not Patterson’s desire to use the term in a formal sense. Thus, if we use it in a formal sense, it must be formally described (and in addition, in Latin, if it is to be used botanically). However, and here is the strange part of this, many people liked the name, but wanted it to be used formally. So they capitalized the first letter, and made it Stramenopiles; others corrected the Latin spelling to Straminopiles.

As noted above, classification varies considerably. Originally, the heterokont algae were treated as two divisions, first within the kingdom Plantae and later the Protista:

Division Chrysophyta

Class Chrysophyceae (golden algae)

Class Bacillariophyceae (diatoms)

Division Phaeophyta (brown algae)

In this scheme, however, the Chrysophyceae is paraphyletic to both other groups. As a result, various members have been given their own classes and often divisions. Recent systems often treat these as classes within a single division, called the Heterokontophyta, Chromophyta, or Ochrophyta. This is not universal, however; Round et al. treat the diatoms as a division.

The discovery that oomycetes and hyphochytrids are related to these algae, rather than fungi, as previously thought, has led many authors to include these two groups among the heterokonts. Should it turn out that they evolved from colored ancestors, the heterokont group would be paraphyletic in their absence. Once again, however, usage varies. David J. Patterson named this extended group the stramenopiles, characterized by the presence of tripartite mastigonemes, mitochondria with tubular cristae, and open mitosis. He used the stramenopiles as a prototype for a classification without Linnaean rank. Their composition has been essentially stable, but their use within ranked systems varies.

Thomas Cavalier-Smith treats the heterokonts as identical in composition with the stramenopiles; this is the definition followed here. He has proposed placing them in a separate kingdom, the Chromalveolata, together with the haptophytes, cryptomonads, and alveolates. This is one of the most common revisions to the five-kingdom system, but has not been adopted, because Chromalveolata is not a monophyletic group. A few treat the Chromalveolata as identical in composition with the heterokonts, or list them as a kingdom Stramenopila.

Some sources divide the heterokonts into the autotrophic Ochrophyta and heterotrophic Bigyra and Pseudofungi.[12] However, some modifications to these classifications have been suggested.

The name Heterokonta can be confused with the (much older) name Heterokontae, which is generally equivalent to the Xanthophyceae, a limited subset of the Heterokonta.[13]

The simplified classification of the group according to Adl et al. (2012) is:[14]

Eukaryota

• SAR
  • Stramenopiles Patterson, 1989, emend. Adl et al., 2005
    • Opalinata Wenyon, 1926, emend. Cavalier-Smith, 1997 (Slopalinida Patterson, 1985)
    • Blastocystis Alexeev, 1911
    • Bicosoecida Grassé, 1926, emend. Karpov, 1998
    • Placidida Moriya et al., 2002
    • Labyrinthulomycetes Dick, 2001
    • Hyphochytriales Sparrow, 1960
    • Peronosporomycetes Dick, 2001 (Öomycetes Winter, 1897, emend. Dick, 1976)
    • Actinophryidae Claus 1874, emend. Hartmann 1926
    • Bolidomonas Guillou & Chrétiennot-Dinet, 1999 (Bolidophyceae in Guillou et al., 1999)
    • Chrysophyceae Pascher, 1914
    • Dictyochophyceae Silva, 1980
    • Eustigmatales Hibberd, 1981
    • Pelagophyceae Andersen & Saunders, 1993
    • Phaeothamniophyceae Andersen & Bailey, in Bailey et al., 1998
    • Pinguiochrysidales Kawachi et al., 2003
    • Raphidophyceae Chadefaud, 1950, emend. Silva, 1980
    • Synurales Andersen, 1987
    • Xanthophyceae Allorge, 1930, emend. Fritsch, 1935 (Heterokontae Luther, 1899, Heteromonadea Leedale, 1983, Xanthophyta Hibberd, 1990)
    • Phaeophyceae Hansgirg, 1886 (not Kjellman, 1891, not Pfitzer, 1894)
    • Schizocladia Henry et al., in Kawai et al., 2003 (Schizocladales Kawai et al., 2003) (M)
    • Diatomea Dumortier, 1821 (= Bacillariophyta Haeckel, 1878)
  • Alveolata
  • Rhizaria

Based on the following works of Ruggiero et al. 2015 & Silar 2016.[15][16][17]

Wikispecies has information related to Heterokonta

• Tree of Life Web Project: Stramenopiles