The katablepharids, a group of heterotrophicflagellates, have been considered as part of the Cryptophyta since katablepharids were described in 1939. Although they differ from other cryptophytes and have even been proposed to be alveolates, early 21st century research suggests they are related to cryptophytes.
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.
^Noriko Okamoto and Isao Inouye (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". Protist156 (2): 163–79. doi:10.1016/j.protis.2004.12.003. PMID16171184.
^Reeb, Vc; Peglar, Mt; Yoon, Hs; Bai, Jr; Wu, M; Siu, P; Grafenberg, Jl; Reyes-Prieto, A; Rümmele, Se; Gross, J; Bhattacharya, D (May 2009). "Interrelationships of chromalveolates within a broadly sampled tree of photosynthetic protists.". Molecular Phylogenetics & Evolution53 (1): 202–11. doi:10.1016/j.ympev.2009.04.012. ISSN1055-7903. PMID19398025.