Katablepharid
| Katablepharid | |
|---|---|
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| Light (above) and transmission electron (below) micrographs of Roombia truncata | |
Scientific classification 
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| Domain: | Eukaryota |
| Clade: | Diaphoretickes |
| Phylum: | Cryptista |
| Subphylum: | Cryptophyta |
| Superclass: | Leucocrypta Cavalier-Smith 2004 stat. nov. 2015[4] |
| Class: | Leucocryptea Cavalier-Smith 2004[3] |
| Order: | Kathablepharidida Okamoto & Inouye 2005[2] |
| Family: | Kathablepharididae Vørs 1992 emend. Clay & Kugrens 1999[1] |
| Genus | |
| Synonyms | |
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The kathablepharids (also called katablepharids) are a group of heterotrophic flagellates (Protists)[6] the first species of which was described by Skuja in 1939 as Kathablepharis phoenikoston.[5] His spelling was challenged because of non-compliance with botanical nomenclatural conditions, hence the alternative spelling Katablepharis. As the organism was heterotrophic and usually regarded as 'protozoan', and to favour stability, Skuja's original spelling has largely prevailed. With an anterior pocket and ejectisomes, the kathablepharids were thought initially to be cryptomonads. There were a variety of differences with Cryptomonas and other typical cryptomonads = cryptophytes, such as the thickness, length, and beat pattern of the flagella, their phagotrophic habitat, differences in the ejectisomes, and various features of their ultrastructure. The distinctive characteristics of the group were established from electron microscopical studies by Clay and Kugrens[7] and Vørs.[8] More recently they have been tentatively grouped with the chromalveolates,[9] or distantly with the cryptophytes.[2]
Phylogeny[edit]
As of 2009, only five genera and ten species have been formally described. Dozens of other DNA sequences (both freshwater and marine) seem to represent further katablepharids which have not been cultured or formally described. They are currently placed in the Hacrobia, a tantative grouping of haptophytes, cryptophytes, katablepharids, telonemids, centrohelids, and perhaps biliphytes.[6]
| Hacrobia |
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Systematics[edit]
Taxonomic history[edit]
The botanist Heinrich Leonhards Skuja in 1939 described the family Kathablepharidaceae to accommodate colourless flagellates that had two divergent flagella and a longitudinal groove.[5] He included four genera in this family: Kathablepharis, Leucocryptos, Cryptaulax and Phyllomitus.[11] He considered katablepharids as closely related to cryptomonads, and placed them in class Cryptophyceae on the basis of morphological features seen through light microscopy.[12]
In 1992, the protozoologist Naja Vørs created the zoological variant of the family, Kathablepharidae and corrected the botanical variant as Katablepharidaceae,[a] redefined to only include three genera: Katablepharis, Leucocryptos and Platychilomonas.[11] However, she did not assign this family to any higher taxon, and instead treated it as incertae sedis protists, thereby removing them from Cryptophyceae.[15]
An alternative to Vørs' classification was proposed by the protozoologist Thomas Cavalier-Smith in 1993. Through observations of a single species Kathablepharis ovalis, he classified katablepharids as part of the phylum Opalozoa, on the basis of tubular mitochondrial cristae and the absence of ejectisomes that are characteristic of cryptomonads. He erected a new class Cyathobodonea and placed Kathablepharis and Leucocryptos in a new order Kathablepharida, defined by two anterior flagella encased by a surface sheath, lack of cytopharynx, and an anterior cytostome supported by four bands of microtubules.[16][17] The phylum Opalozoa was highly non-monophyletic, and in 1997 Cavalier-Smith separated katablepharids into a new phylum Neomonada which was another broad non-monophyletic assemblage. Katablepharids were placed in a new subphylum Isomita which also contained Telonemea.[18] Because this scheme was based on the observations on a single species K. ovalis, it was not considered valid.[15]
In 1999, Brec Clay and Paul Kugrens reviewed the systematics of katablepharids and rejected Cavalier-Smith's classification. Instead, they adopted Vørs' family, corrected the zoological spelling to Kathablepharididae, emended the diagnosis to include only Katablepharis and Leucocryptos, and postponed any higher classification until molecular phylogenetics could resolve their true placement.[1]
Eventually, molecular data revealed cryptophytes and katablepharids to be related. In 2004, Cavalier-Smith included both group as subphyla under the phylum Cryptista. For katablepharids, he proposed a new class Leucocryptea and subphylum Leucocrypta, named after Leucocryptos.[19] The following year, Noriko Okamoto and Isao Inouye interpreted the molecular and morphological gap between the two groups sufficient to propose them as two separate phyla. They also argued that the treatment of both groups as divisions (=botanical phylum) agrees with the widely accepted system where Cryptophyta is a division. They described higher taxa for both nomenclature codes: phylum Kathablepharida, class Kathablepharidea and order Kathablepharidida under zoological nomenclature, and division Katablepharidophyta, class Katablepharidophyceae and order Katablepharidales under botanical nomenclature.[20] In the following years, two new genera of katablepharids were described: Hatena in 2006[21] and Roombia in 2009.[6]
Following his own classification, Cavalier-Smith continued considering both groups as members of phylum Cryptista. In 2015, he lowered Leucocrypta to a superclass included within the subphylum Rollomonadia (equivalent to Cryptophyta), along with cryptomonads (under the name of Cryptomonada), and added additional subphyla Palpitia and Corbihelia to the phylum.[22]
Classification[edit]
There are five described genera of katablepharids:[21][6]
- Hatena Okamoto & Inouye 2006[21]
- Katablepharis Skuja 1939
- Leucocryptos Butcher 1967
- Platychilomonas Larsen & Patterson 1990
- Roombia Okamoto, Chantangsi, Horák, Leander & Keeling 2009[6]
Notes[edit]
- ^ According to the International Code of Botanical Nomenclature (ICBN) the spelling of Kathablepharis is incorrect and modified to Katablepharis (from Greek kata 'downwards', and blepharis 'eyelash'), but under the International Code of Zoological Nomenclature (ICZN) the original spelling is retained.[13] The spelling difference affects all higher taxa whose names are derived from this genus: the ICBN recognizes family Katablepharidaceae, order Katablepharidales, class Katablepharidophyceae and phylum Katablepharidophyta, while the ICZN recognizes family Kathablepharididae, order Kathablepharidida, class Kathablepharidea and phylum Kathablepharida.[14]
References[edit]
Citations[edit]
- ^ a b Clay & Kugrens 1999, p. 57.
- ^ a b Okamoto & Inouye 2005.
- ^ Cavalier-Smith 2004, p. 88.
- ^ Cavalier-Smith, Chao & Lewis 2015, p. 344.
- ^ a b c Skuja 1939.
- ^ a b c d e f g Okamoto et al. 2009.
- ^ Clay & Kugrens 1999.
- ^ Vørs 1992.
- ^ Reeb et al. 2009.
- ^ a b Kim & Graham 2008.
- ^ a b Vørs 1992, p. 384.
- ^ Clay & Kugrens 1999, p. 43.
- ^ Vørs 1992, p. 370.
- ^ Okamoto & Inouye 2005, p. 172.
- ^ a b Clay & Kugrens 1999, p. 56.
- ^ Cavalier-Smith 1993a.
- ^ Cavalier-Smith 1993b.
- ^ Cavalier-Smith 1997, p. 246.
- ^ Cavalier-Smith 2004, p. 77.
- ^ Okamoto & Inouye 2005, pp. 172–173.
- ^ a b c Okamoto & Inouye 2006.
- ^ Cavalier-Smith et al., p. 344.
Cited literature[edit]
- Cavalier-Smith, Thomas (1993a). "The Protozoan Phylum Opalozoa". Journal of Eukaryotic Microbiology. 40 (5): 609–615. doi:10.1111/j.1550-7408.1993.tb06117.x.
- Cavalier-Smith, Thomas (1993b). "Kingdom Protozoa and Its 18 Phyla". Microbiological Reviews. 57 (4): 953–994. doi:10.1128/mr.57.4.953-994.1993. PMC 372943. PMID 8302218.
- Cavalier-Smith, Thomas (1997). "Amoeboflagellates and Mitochondrial Cristae in Eukaryote Evolution: Megasystematics of the New Protozoan Subkingdoms Eozoa and Neozoa". Archiv für Protistenkunde. 147 (3–4): 237–258. doi:10.1016/S0003-9365(97)80051-6.
- Cavalier-Smith, Thomas (2004). "Chromalveolate Diversity and Cell Megaevolution: Interplay of Membranes, Genomes and Cytoskeleton". In Hirt, Robert P.; Horner, David S. (eds.). Organelles, Genomes and Eukaryote Phylogeny: An Evolutionary Synthesis in the Age of Genomics. Systematics Association special volume 68. CRC Press. pp. 86–126. ISBN 0-415-29904-7.
- Cavalier-Smith; Chao; Lewis (2015). "Multiple origins of Heliozoa from flagellate ancestors: New cryptist subphylum Corbihelia, superclass Corbistoma, and monophyly of Haptista, Cryptista, Hacrobia and Chromista". Molecular Phylogenetics and Evolution. 93: 331–362. doi:10.1016/j.ympev.2015.07.004. PMID 26234272.
- Clay, Brec; Kugrens, Paul (1999). "Systematics of the Enigmatic Kathablepharids, Including EM Characterization of the Type Species, Kathablepharis phoenikoston, and New Observations on K. remigera comb. nov". Protist. 150 (1): 43–59. doi:10.1016/S1434-4610(99)70008-8. PMID 10724518.
- Kim, Eunsoo; Graham, Linda E. (2008). "EEF2 analysis challenges the monophyly of Archaeplastida and Chromalveolata". PLOS ONE. 3 (7): e2621. Bibcode:2008PLoSO...3.2621K. doi:10.1371/journal.pone.0002621. PMC 2440802. PMID 18612431.
- Okamoto, Noriko; Inouye, Isao (2005). "The Katablepharids are a Distant Sister Group of the Cryptophyta: A Proposal for Katablepharidophyta Divisio Nova/Kathablepharida Phylum Novum Based on SSU rDNA and Beta-Tubulin Phylogeny". Protist. 156 (2): 163–179. doi:10.1016/j.protis.2004.12.003. PMID 16171184.
- Okamoto, Noriko; Inouye, Isao (2006). "Hatena arenicola gen. et sp. nov., a Katablepharid Undergoing Probable Plastid Acquisition". Protist. 157 (4): 401–419. doi:10.1016/j.protis.2006.05.011. PMID 16891155.
- Okamoto, Noriko; Chantangsi, Chitchai; Horák, Aleš; Leander, Brian S.; Keeling, Patrick J. (2009). "Molecular Phylogeny and Description of the Novel Katablepharid Roombia truncata gen. et sp. nov., and Establishment of the Hacrobia Taxon nov". PLOS ONE. 4 (9): e7080. Bibcode:2009PLoSO...4.7080O. doi:10.1371/journal.pone.0007080. PMC 2741603. PMID 19759916.
- Reeb, Valérie C.; Peglar, Michael T.; Yoon, Hwan Su; Bai, Jennifer Ruoyu; Wu, Min; Shiu, Philip; Grafenberg, Jessie L.; Reyes-Prieto, Adrian; Rümmele, Susanne E.; Gross, Jeferson; Bhattacharya, Debashish (2009). "Interrelationships of chromalveolates within a broadly sampled tree of photosynthetic protists". Molecular Phylogenetics and Evolution. 53 (1): 202–211. doi:10.1016/j.ympev.2009.04.012. PMID 19398025.
- Skuja, Heinrich-Leonhard (1939). "Beitrag zur Algenflora Lettlands II" [Contribution to the algal flora of Latvia II]. Acta Horti Botanici Universitatis Latviensis (in German). 11/12: 41–168.
- Vørs, Naja (1992). "Ultrastructure and autecology of the marine, heterotrophic flagellate Leucocryptos marina (Braarud) Butcher 1967 (Katablepharidaceae/Kathablepharidae), with a discussion of the genera Leucocryptos and Katablepharis/Kathablepharis". European Journal of Protistology. 28 (4): 369–389. doi:10.1016/S0932-4739(11)80001-5. PMID 23195337.