- Source: Ventrifilosa
Ventrifilosa (from Latin venter 'belly' and filum 'thread') is a highly diverse group of phagotrophic protists that glide through their flagella and emit filose pseudopods from their ventral side for feeding. Because of their mixture of amoeba and flagellate characteristics, they are amoeboflagellates. Members of this group are the Imbricatea, Sarcomonadea and Thecofilosea.
Morphology
Protists in the group Ventrifilosa ancestrally have a rigid extracellular theca on the dorsal side, and emit non-granular filose pseudopods from a ventral aperture. This aperture is called "cleft" when belonging to an amoeboflagellate, or "astropyle" when belonging to a phaeodarian.
The group includes descendants that have lost or modified some of these characteristics. For example, some have lost their pseudopods (such as the spongomonads and Ebria), some have lost their theca (such as Pseudopirsonia), and some have acquired axopodia (in Phaeodaria). The loss of flagella and scales has occurred in this group several times independently through evolution.
Taxonomy
The superclass Ventrifilosa was first described in 2012 by Cavalier-Smith to unite Thecofilosea and Imbricatea. However, the group proved to be polyphyletic because the sarcomonads were excluded. Later, in 2018, it was expanded to include Sarcomonadea, which belonged to the superclass Eoglissa before this change.
The current classification of Ventrifilosa recognizes 3 classes, 20 orders and 60 families.
Class Sarcomonadea Cavalier-Smith 1993 stat. nov. 1995 emend. 2018
?Family Katabiidae Cavalier-Smith 2012
Subclass Paracercomonada Cavalier-Smith 2018
Order Paracercomonadida Cavalier-Smith 2018
Subclass Pediglissa Cavalier-Smith 2012
Order Cercomonadida Poche 1913 emend. Cavalier-Smith
Order Glissomonadida Howe et al. 2009
Class Imbricatea Cavalier-Smith 2003 emend. 2018
Subclass Placonuda Cavalier-Smith 2012
Superorder Nudisarca Cavalier-Smith 2012
Order Variglissida Cavalier-Smith 2014
Order Marimonadida Cavalier-Smith & Bass 2011
Superorder Euglyphia Cavalier-Smith 2018
Order Euglyphida Copeland 1956 emend. Cavalier-Smith 1987
Order Zoelucasida Cavalier-Smith 2014
Superorder Discomonada Cavalier-Smith 2018
Order Discomonadida Cavalier-Smith 2014
Subclass Placoperla Cavalier-Smith 2012
Superorder Placofila Cavalier-Smith 2012
Order Thaumatomonadida Shirkina 1987
Order Discocelida Cavalier-Smith 1997
Superorder Perlatia Cavalier-Smith 2012
Order Spongomonadida Hibberd 1983
Order Perlofilida Cavalier-Smith 2012
Subclass Krakenia Cavalier-Smith 2018
Order Krakenida Dumack et al. 2017 ex Cavalier-Smith 2018
Class Thecofilosea Cavalier-Smith 2003 emend. 2012
Subclass Ventricleftia Cavalier-Smith 2018
Order Ventricleftida Cavalier-Smith 2011
Subclass Eothecia Cavalier-Smith 2012
Order Matazida Cavalier-Smith 2012
Order Ebriida Deflandre 1936
Order Cryomonadida Cavalier-Smith 1993
Subclass Phaeodaria Haeckel 1879
Order Eodarida Cavalier-Smith 2012
Order Opaloconchida Cavalier-Smith 2012
Subclass Tectosia Cavalier-Smith 2012
Order Tectofilosida Cavalier-Smith 2003