The Archostemata are the smallest
suborder
Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...
of
beetle
Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
s, consisting of 50 living species in five families and over 200 described fossil species.
They are an ancient lineage with a number of primitive characteristics.
Antennae may be thread-shaped (filiform) or like a string of beads (moniliform). This suborder also contains the only beetles where both sexes are
paedogenic, ''
Micromalthus debilis''. Modern archostematan beetles are considered rare, but were more diverse during the
Mesozoic
The Mesozoic Era is the Era (geology), era of Earth's Geologic time scale, geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Period (geology), Periods. It is characterized by the dominance of archosaurian r ...
.
The term "Archostemata" is used more broadly by some authors to include both modern archostematans as well as
stem-group
In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...
beetles like "
protocoleopterans", which some modern archostematans closely resemble to due to their
plesiomorphic
In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral character shared by all members of a clade, which does not distinguish the clade from other clades.
Plesiomorphy, symplesiomorphy, apomorphy, an ...
morphology.
Genetic research suggests that modern archostematans are a
monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria:
# the grouping contains its own most recent co ...
group. Some genetic studies have recovered archostematans as the sister group of
Myxophaga.
A 2009 paper argued that the poor diversity of modern Archostemata, compared with the staggering evolutionary success of most other
Coleoptera
Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
lineages, could be due to the lower efficiency of the thoracic locomotor apparatus, the absence of
cryptonephric Malpighian tubules, and competition with other beetles more adapted to
angiosperms
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed within a fruit. T ...
.
[ ]
Taxonomy
There are five extant families.
* Family
Crowsoniellidae Iablokoff-Khnzorian, 1983
* Family
Cupedidae Laporte, 1838
* Family
Jurodidae Ponomarenko, 1985
* Family
Micromalthidae Barber, 1913
* Family
Ommatidae Sharp and Muir, 1912
Phylogeny
A partial phylogeny of Archostemata and early coleopterans, based on palaeontological data, from Boudinot et al. 2022.
According to Li et al. 2023;
archostematan families are in bold.
See also
*
List of subgroups of the order Coleoptera
References
External links
Tree of Life - Archostemata
{{DEFAULTSORT:Archostemata
Insect suborders
Extant Permian first appearances
Taxa named by Hermann Julius Kolbe