Heterotrich

Etymology

The term heterotrich derives from the ancient Greek (), meaning "another, different", and , (), meaning 'hair', because of the contrast between the regular somatic ciliation and that of the oral zone.

Ultrastructure

A number of ultrastructural details characterize the group. The cilia on the body are in dikinetids, in which either the anterior one or both kinetosomes may be ciliated, and which are associated with fibers composed of overlapping postciliary microtubules, called postciliodesmata and found only in this group and the closely related Karyorelictea. A series of oral polykinetids, each containing two or three rows of kinetosomes, support the membranelles. These run from the left to the anterior of the mouth, and often spiral out of the oral cavity. The macronucleus is divided by external microtubules, whereas in the Karyorelictea it forms by differentiation of micronuclei, and in all other ciliates it is divided by internal microtubules.

Pigmentation

Many species are highly pigmented, e.g. the blue Stentor coeruleus. In Blepharisma, the red pigment is associated with light sensitivity. Species of blue-pigmented Eufolliculina form extensive mats in the deep sea that have been called "blue mats".

Systematics

Early classification schemes by Otto Bütschli, Alfred Kahl, Emmanuel Fauré-Fremiet, and John O. Corliss classified the heterotrichs as a subgroup of spirotrichs. They included groups such as Armophorida, Odontostomatida, Licnophorida, Clevelandellida, and Plagiotomida within the Heterotrichea. However, more recent classification systems, which have incorporated information from molecular phylogenetics, place the above groups within the Intramacronucleata, because they are not closely related to the "core" heterotrichs at all. Almost all of the "true" heterotrichs belong to a single order, Heterotrichida.

In the classification scheme of Lynn (2008), the order Heterotrichida contains the following nine families:

• Blepharismidae Jankowski in Small & Lynn, 1985
• Chattonidiidae Villeneuve-Brachon 1940
• Climacostomidae Repak, 1972
• Condylostomatidae Kahl in Doflein & Reichenow, 1929
• Folliculinidae Dons, 1914
• Maristentoridae Miao, Simpson, Fu & Lobban 2005
• Peritromidae Stein, 1867
• Spirostomidae Stein, 1867
• Stentoridae Carus, 1863 Two new families were established in 2014 on the basis of molecular phylogenies:
• Gruberiidae
• Fabreidae

References

References

1. (2016-01-01). "Biocommunication of Ciliates". Springer International Publishing.
2. Bailly, Anatole. (1981-01-01). "Abrégé du dictionnaire grec français". Hachette.
3. Bailly, Anatole. "Greek-french dictionary online".
4. Lynn, Denis H.. (2008). "The Ciliated Protozoa: Characterization, Classification, and Guide to the Literature. 3rd Edition.". Springer.
5. (2014). "Phylogenetic relationships of the ciliate class Heterotrichea (Protista, Ciliophora, Postciliodesmatophora) inferred from multiple molecular markers and multifaceted analysis strategy". Molecular Phylogenetics and Evolution.
6. "Sunday Protist -- Blue Mats of the deep sea: Folliculinopsis".
7. NCBI: [https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=2528046 Pseudoblepharisma tenue] (species)
8. NCBI: [https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=2784338 Thiodictyon endosymbiont of Pseudoblepharisma tenue] (species)
9. (June 2021). "A microbial eukaryote with a unique combination of purple bacteria and green algae as endosymbionts.". Science Advances.