Apterygota

Apterygota Temporal range: Devonian–Present PreꞒ Ꞓ O S D C P T J K Pg N [1]
Petrobius maritimus (Archaeognatha: Machilidae)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Subclass:	Apterygota Brauer 1885[2]
Groups included
Archaeognatha[3] †Cercopoda[2] Zygentoma Tricholepidiidae ?
Cladistically included but traditionally excluded taxa
Pterygota

The name Apterygota is sometimes applied to a former

Characteristics

The primary characteristic of the apterygotes is they are primitively wingless. While some other insects, such as fleas, also lack wings, they nonetheless descended from winged insects but have lost them during the course of evolution. By contrast, the apterygotes are a primitive group of insects that diverged from other ancient orders before wings evolved. Apterygotes, however, have the demonstrated capacity for directed, aerial gliding descent from heights. It has been suggested by researchers that this evolved gliding mechanism in apterygotes might have provided an evolutionary basis from which winged insects would later evolve the capability for powered flight.^[5]

Apterygotes also have a number of other primitive features not shared with other insects. Males deposit sperm packages, or

Apterygotes possess small unsegmented appendages, referred to as "styli", on some of their abdominal segments, but play no part in locomotion. They also have long, paired abdominal cerci and a single median, tail-like caudal filament, or telson.^[6]

While all members of winged insects (

However, the Zygentoma are now considered more closely related to the Pterygota than to the Archaeognatha,[4] thus rendering even the amyocerate apterygotes paraphyletic, and resulting in the dissolution of Thysanura into two separate monophyletic orders.

References