Symphypleona

Symphypleona
Allacma fusca from forest near Cologne, Germany
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Hexapoda
Class:	Entognatha (disputed)
Subclass:	Collembola
Order:	Symphypleona
Superfamilies
Dicyrtomoidea Katiannoidea Sminthuroidea Sminthurididoidea Sturmioidea
Synonyms
Neopleona

The order Symphypleona is one of the three main groups of springtails (Collembola), tiny hexapods related to insects. When the springtails were still believed to be an order of insects, the Symphypleona were ranked as a suborder.

They can be best distinguished from the other springtail groups by their body shape. The Symphypleona are very round animals, almost spherical, and usually have long antennae. The Poduromorpha, by contrast, always have short legs and a plump body, but more oval in shape than the Symphypleona. The Entomobryomorpha contain the slimmest springtails, some with long and some with short legs and antennae, but always with a very slender body.

Systematics

The Symphypleona were always considered a highly distinct group of springtails, unlike the Entomobryomorpha and Poduromorpha which were in former times erroneously united in the paraphyletic "Arthropleona". However, occasionally the family Neelidae was separated as an order Neelipleona; this may be in error too, as other studies found the Neelidae very apomorphic relatives of the Sminthuridae, tiny, eyeless but with sensory fields all over their body instead. Consequently, the monotypic Neelipleona are abolished and the Neelidae are included in the Sminthuroidea by many authors. Others, however, include them in the Entomobryomorpha, while analysis of 18S and 28S rRNA sequence data suggests that they form the most ancient lineage of springtails instead, which would explain their peculiar apomorphies and revalidate the Neelipleona.

List of families

File:Sminthuridae.sp.jpg

Sminthurus nigromaculatus Sminthuridae

Includes fossil families.

Superfamily Sminthuridoidea

• Family Mackenziellidae
• Family Sminthuridae

Superfamily Katiannoidea

• Family Katiannidae
• Family Spinothecidae
• Family Arrhopalitidae
• Family Collophoridae

Superfamily Sturmioidea

• Family Sturmiidae

Superfamily Sminthuroidea

• Family Neelidae (disputed)
• Family Sminthuridae
• Family Bourletiellidae

Superfamily Dicyrtomoidea

• Family Dicyrtomidae

References

• Gao, Yan; Bu, Yun & Luan, Yun-Xia (2008): Phylogenetic Relationships of Basal Hexapods Reconstructed from Nearly Complete 18S and 28S rRNA Gene Sequences. Zool. Sci. 25(11): 1139-1145. doi:10.2108/zsj.25.1139 PMID 19267625 (HTML abstract)
• Haaramo, Mikko (2008): Mikko's Phylogeny Archive - Collembola. Version of 2008-MAR-11. Retrieved 2008-JUL-11.