Cutosea () is a small group of marine life amoeboid proposed in 2016. It is a monotypic class of Amoebozoa containing the order Squamocutida (). Cutosean organisms are characterized by a cell coat of microscales separated from the cell membrane. Four genus, Armaparvus, Idionectes, Sapocribrum and Squamamoeba, belong to this group, distributed in three families.
Characteristics
The cells of cutosean
amoebae are surrounded by a continuous thin, somewhat flexible envelope, unique in structure because it is not attached to the cytoplasmic membrane. Below this envelope, they present oval microscales surrounded by a dense matrix. The small scales are not visible under a
light microscope.
The envelope is penetrated by one or many small pores, which allow sub
pseudopodia to occasionally protrude from the cell membrane,
for a very slow locomotion. Locomoting cells are flattened, oval or round in shape. All of their cells lack
cilia or
,
except for the uniciliate
of the amoeboflagellate
Idionectes.
Taxonomy
History
Cutosea is a
clade discovered through a 2016 phylogenetic study by Thomas Cavalier-Smith and his coauthors, published in the journal
Molecular Phylogenetics and Evolution. It is described as a class-level
taxonomic rank,
monotypic as it contains only one order
Squamamoebida. Additionally, it is grouped under the monotypic superclass
Cutosa. In traditional rank-based classifications, it is grouped within the
paraphyletic Lobosa, a subphylum of Amoebozoa that also contains
Tubulinea and
Discosea. Cutosean amoebae present a structurally unique cellular envelope, their
synapomorphy. Their names derive from the
Latin cutis, meaning 'skin', and
squama, meaning 'scale', referencing this envelope.
The Cutosea clade is supported by posterior phylogenetics and morphological studies, and has been accepted as of 2019 by the International Society of Protistologists, which revises the modern cladistic classification of .
Classification
Cutosea contains a total of four
species, distributed in four monotypic genera:
Evolution
Cutosea is a fully supported
clade within
Amoebozoa. It is the
sister group to
Conosa, which contains all the non-
Lobosa amoebozoans:
Variosea,
Archamoebea and
Eumycetozoa. Together, Cutosea and Conosa are the two members of the larger clade
Evosea.
The following
cladogram is based on a 2022 phylogenetic analysis:
External links
