{{Short description|Group of segmented worms}} {{Automatic taxobox |image=Protodrilus (YPM IZ 072370) 002.jpeg |image_caption=''Protodrilus mirabilis'' |taxon=Protodriliformia|authority=Struck et al. 2015<ref name="Two adaptive routes Annelida"/>|subdivision_ranks=Orders and families|subdivision= *Polygordiidae *Protodrilida **Protodrilidae **Protodriloididae **Saccocirridae }} '''Protodriliformia''' is a clade of small marine polychaetes, comprised by the groups of meiofaunal interstitial worms Protodrilida and Polygordiidae, formerly considered "archiannelids". It is the most basal clade of Errantia.<ref name="Two adaptive routes Annelida"/><ref name="Handbook Zoology Annelida 1"/> ==Evolutionary history== Phylogenetic analysis of annelids has found Protodriliformia to be the earliest diverging clade of Errantia. At the same time, the other half of "archiannelid" worms, Orbiniida, was found to be the earliest diverging clade of Sedentaria. The convergence between these two groups occurred through progenesis and miniaturization, as a way to adapt to the marine interstitial ecosystem between sand grains (i.e. interstitium). This means that the larval or juvenile stages of a larger pleistoannelid ancestor temporarily inhabiting the interstitium stopped their somatic growth, became sexually mature and stayed in the interstitium permanently.<ref name="Two adaptive routes Annelida"/>
{{clade|style=font-size:90%;|label1=Pleistoannelida|1={{clade |label1=Errantia|1={{clade|label2='''Protodriliformia'''|2={{clade|2=Polygordiidae|label1=Protodrilida|1={{clade|2=Saccocirridae|1={{clade|1=Protodriloididae |2=Protodrilidae}}}}}}|barbegin2=green|1=Aciculata}} |label2=Sedentaria|2={{clade |1=Orbiniida|barend1=green |2=other Sedentaria }} }} |grouplabel1={{clade labels|label1={{font color|green|'Archiannelids'}}|top1=45%}} }}
==References== {{Reflist|refs=
<ref name="Two adaptive routes Annelida">{{cite journal|vauthors=Struck TH, Golombek A, Weigert A, Franke FA, Westheide W, Purschke G, Bleidorn C, Halanych KM|title=The evolution of annelids reveals two adaptive routes to the interstitial realm|journal=Curr Biol|date=3 August 2015|volume=25|issue=15|pages=1993–1999|doi=10.1016/j.cub.2015.06.007|pmid=26212885|doi-access=free|bibcode=2015CBio...25.1993S }}</ref>
<ref name="Handbook Zoology Annelida 1">{{cite book|chapter=Phylogeny|vauthors=Struck TH|doi=10.1515/9783110291582-002|title=Handbook of Zoology: Annelida|volume=1: Annelida Basal Groups and Pleistoannelida, Sedentaria I|veditors=Purschke G, Böggemann M, Westheide W|isbn=9783110291469|publisher=De Gruyter|date=2019|pages=37–68 }}</ref>
}}
{{Taxonbar|from=Q60982662}}
Category:Annelid unranked clades Category:Polychaetes
{{Annelid-stub}}