Allotriocarida

Allotriocarida Temporal range: Upper Cambrian [1] 497–0  Ma PreꞒ Ꞓ O S D C P T J K Pg N
Mantis religiosa , a hexapod
Triops longicaudatus , a branchiopod
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Clade:	Pancrustacea
Clade:	Allotriocarida Oakley et al., 2013
Subphyla and classes
Branchiopoda Cephalocarida Hexapoda Remipedia

Allotriocarida is a clade of Pancrustacea, containing Hexapoda (all insects, springtails & their close relatives). It also contains three non-hexapod classes: Remipedia (blind, venomous crustaceans), Cephalocarida (translucent aquatic detrivores), and Branchiopoda (freshwater, non-decapod 'shrimp'). Newer studies also relocate Copepoda, which traditionally has belonged to the multicrustaceans, to the Allotriocarida. ^[2]

Allotriocarida is one of three major clades within Pancrustacea, being most closely related to its sister clade Multicrustacea (crabs, lobsters, barnacles, etc), and more distantly related to the superclass Oligostraca (seed shrimp, fish lice, and tongue worms). ^[3]

History

The idea of hexapods being 'terrestrial crustaceans' is relatively recent, coming from a 2005 molecular analysis study. ^[4]

A 2013 study restructured the relationships within Pancrustacea, and first proposed the name Allotriocarida. ^[5]

The most recent study of Allotriocarida in 2019 provides additional evidence suggesting that Hexapoda and Remipedia are likely more closely related to each other than to Cephalocarida or Branchiopoda. ^[6]

As of 2024, the existence of Allotriocarida as a monophyletic group within Pancrustacea is now much more widely accepted than the Atelocerata classification which dates back to the 19th century. This formerly-held belief was that hexapods and myriapods (centipedes, millipedes, etc.) are more closely related to each other than they are to the Multicrustacea, based on morphological similarities in their tracheae, but this proposition has been contradicted by the aforementioned modern molecular phylogenetic studies. The most recent understanding of Allotriocarida, as described in the 2019 study, ^[6] can be seen in the cladogram below.

Allotriocarida	Cephalocarida Branchiopoda Remipedia Hexapoda Protura Diplura Collembola Insecta

References

1. Walossek, Dieter (December 1993). "The Upper Cambrian Rehbachiella and the phylogeny of Branchiopoda and Crustacea". Lethaia. 26 (4): 318. Bibcode:1993Letha..26....1W. doi:10.1111/j.1502-3931.1993.tb01537.x.
2. Bernot, James P; Owen, Christopher L; Wolfe, Joanna M; Meland, Kenneth; Olesen, Jørgen; Crandall, Keith A (2023). "Major Revisions in Pancrustacean Phylogeny and Evidence of Sensitivity to Taxon Sampling". Molecular Biology and Evolution. 40 (8). doi:10.1093/molbev/msad175. PMC   10414812 . PMID   37552897.
3. WoRMS. "Allotriocarida". World Register of Marine Species .
4. Regier, Jerome C.; Shultz, Jeffrey W.; Kambic, Robert E. (February 22, 2005). "Pancrustacean phylogeny: hexapods are terrestrial crustaceans and maxillopods are not monophyletic". Proceedings of the Royal Society B: Biological Sciences. 272 (1561): 395–401. doi:10.1098/rspb.2004.2917. PMC   1634985 . PMID   15734694.
5. Oakley, Todd H.; Wolfe, Joanna M.; Lindgren, Annie R.; Zaharoff, Alexander K. (January 2013). "Phylotranscriptomics to Bring the Understudied into the Fold: Monophyletic Ostracoda, Fossil Placement, and Pancrustacean Phylogeny". Molecular Biology and Evolution. 30 (1): 215–233. doi:10.1093/molbev/mss216. PMID   22977117.
6. Lozano-Fernandez, Jesus; Giacomelli, Mattia; Fleming, James F.; Chen, Albert; Vinther, Jakob; Thomsen, Philip Francis; Glenner, Henrik; Palero, Ferran; Legg, David A.; Iliffe, Thomas M.; Pisani, Davide; Olesen, Jørgen (August 1, 2019). "Pancrustacean Evolution Illuminated by Taxon-Rich Genomic-Scale Data Sets with an Expanded Remipede Sampling". Genome Biology and Evolution. 11 (8): 2055–2070. doi:10.1093/gbe/evz097. PMC   6684935 . PMID   31270537 – via PubMed.