The cryptomonads-haptophytes assemblage is a proposed but disputed monophyletic grouping[1] of unicellular eukaryotes that are not included in the SAR supergroup. Several alternative names have been used for the group, including Hacrobia (derived from "ha-" referring to Haptophyta, "-cr-" referring to cryptomonads, and "-bia" as a general suffix referring to life);[2] CCTH (standing for Cryptophyta, Centrohelida, Telonemia and Haptophyta);[3] and "Eukaryomonadae".[4]
As of February 2012, it is unclear whether this group is monophyletic or not; results of phylogenetic studies are "often dependent on the selection of taxa and gene data set".[3] Two 2012 studies produced opposite results.[3][5]
In the past, heterokonts, haptophytes, and cryptomonads have sometimes been grouped together in a group known as chromists.[6] Though the heterokonts are now split out, Cryptophyta and Haptophyta are considered in some studies to be closely related[7][8] (and are sometimes simply referred to as the "Cryptophyta+Haptophyta" group).[9] A 2009 paper suggested that the Telonemia and centrohelids may form a clade with the cryptophytes and haptophytes.[10] The picobiliphytes may belong in this group but are too poorly known to be classified with confidence.[2]
Several recent studies have concluded that Haptophyta and Cryptophyta do not form a monophyletic group.[11] The former are a sister group to the SAR group, the latter cluster with the Archaeplastida (plants in the broad sense).[5] As of February 2012, it remains unclear whether the Hacrobia forms a monophyletic group.[3]
Another study[12] suggested the following arrangement: centrohelids are related to haptophytes and form the clade Haptista; Haptista is the sister group to SAR; Cryptista are related to Archaeplastida; and Haptista + SAR is the sister clade to Cryptista + Archaeplastida.
Based on work done by Silar 2016.[13][14]
Hacrobia Alveidia Haptista Centroheliozoa Haptophytina Rappemonada Haptomonada Cryptista s.l. Corbihelia Endohelia Corbistoma Cryptista s.s. Palpitia Rollomonadia Leucocrypta CryptomonadaThe cryptomonads-haptophytes assemblage is a proposed but disputed monophyletic grouping of unicellular eukaryotes that are not included in the SAR supergroup. Several alternative names have been used for the group, including Hacrobia (derived from "ha-" referring to Haptophyta, "-cr-" referring to cryptomonads, and "-bia" as a general suffix referring to life); CCTH (standing for Cryptophyta, Centrohelida, Telonemia and Haptophyta); and "Eukaryomonadae".
As of February 2012, it is unclear whether this group is monophyletic or not; results of phylogenetic studies are "often dependent on the selection of taxa and gene data set". Two 2012 studies produced opposite results.
