Platytrochozoa

The Platytrochozoa are a proposed basal clade of spiralian animals as the sister group of the Gnathifera. The Platytrochozoa were divided into the Rouphozoa and the Lophotrochozoa.^[1] A more recent study suggests that the mesozoans also belong to this group of animals, as sister of the Rouphozoa.^[2]

Spiralia	Gnathifera Platytrochozoa Rouphozoa Gastrotricha Platyhelminthes Mesozoa Lophotrochozoa

Platytrochozoa
Garden snail (Cornu aspersum) a basal platytrochozoan
Barentsia laxa colony (Entoprocta)
Scientific classification
Kingdom:	Animalia
Subkingdom:	Eumetazoa
Clade:	ParaHoxozoa
Clade:	Bilateria
Clade:	Nephrozoa
Clade:	Protostomia
Clade:	Spiralia
Clade:	Platytrochozoa Struck et al. 2014
Clade
Rouphozoa Lophotrochozoa Mesozoa?

An alternative phylogeny was given in 2019, with a basal grouping of Mollusca and Entoprocta named Tetraneuralia, and a second grouping of Nemertea and Platyhelminthes named Parenchymia as sister of Annelida. In this proposal, Lophotrochozoa would become roughly synonymous with Platytrochozoa, and Rouphozoa would be unsupported.^[3]

Protostomia	Ecdysozoa  Spiralia (s.l.) / Gnathifera  Lophotrochozoa /   Tetraneuralia    Mollusca Entoprocta     Gastrotricha  Lophophorata      Ectoprocta Phoronida Brachiopoda Annelida  Parenchymia    Platyhelminthes Nemertea  Platytrochozoa /  Spiralia (s.s.)  Gnathospiralia

In the 2022 study the Platytrochozoa clade is not recovered at all; spiralians (in this case identical with the Lophotrochozoa according to its definition) are divided into "Platyzoa s.l." (traditional Platyzoa expanded to include Bryozoa and Mesozoa) and Trochozoa clades:^[4]

Spiralia/	Platyzoa s.l. Bryozoa/Ectoprocta Entoprocta Cycliophora Gastrotricha Gnathifera Platyhelminthes Mesozoa Trochozoa Annelida Brachiozoa Nemertea Mollusca
Lophotrochozoa