Taxonomic history The botanist
Heinrich Leonhards Skuja in 1939 described the family Kathablepharidaceae to accommodate colourless flagellates that had two divergent
flagella and a longitudinal groove. He included four genera in this family:
Kathablepharis,
Leucocryptos,
Cryptaulax and
Phyllomitus. He considered katablepharids as closely related to
cryptomonads, and placed them in class
Cryptophyceae on the basis of morphological features seen through
light microscopy. In 1992, the protozoologist Naja Vørs created the zoological variant of the family, Kathablepharidae and corrected the botanical variant as Katablepharidaceae, redefined to only include three genera:
Katablepharis,
Leucocryptos and
Platychilomonas. However, she did not assign this family to any higher taxon, and instead treated it as
incertae sedis protists, thereby removing them from Cryptophyceae. 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. 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. Because this scheme was based on the observations on a single species
K. ovalis, it was not considered valid. 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. Eventually, molecular data and
electron microscopy studies revealed
cryptomonads 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. 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. In the following years, two new genera of katablepharids were described:
Hatena in 2006 and
Roombia in 2009. 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. As of 2024, katablepharids are generally accepted as a subgroup of the Cryptista or Cryptophyta, instead of an independent phylum or division, together with cryptomonads.
Classification There are five accepted genera of katablepharids: •
Hatena •
Kathablepharis/
Katablepharis •
Leucocryptos •
Platychilomonas •
Roombia ==Notes==