All terminal taxa (turbellarian orders, neodermatan classes, and outgroup clades) are shown with equilateral triangles log-scaled in proportion to described species number (largely following [Martín-Durán and Egger, 2012]). Clades deemed to have equivocal or only preliminary support in these analyses are shown with a dashed subtending branch. Named clades discussed in the text are labeled. Clades with known homoplasy-free synapomorphies are labeled with an open square, whereas those with proposed synapomorphies showing inferred losses are labeled with a single diagonal line, and clades without any known synapomorphies are shown with a cross. Traits commonly referred to in discussions of platyhelminth phylogenetics are given to the right of the phylogeny; terminal taxa are shown filled in if any representatives have been reported in published studies to manifest the trait in question (although numerous reversals apparently occurring subsequent to the origin of a clade are not depicted), and clades for which no published observations are available are labeled with a question mark. The orders Prorhynchida and Gnosonesimida are given with a ‘*’ in the ‘Bulbous pharynx’ column to indicate that although the pharyngeal types manifested in these orders have been described under separate names (variable and coniform pharynx, respectively), both represent, by definition, a bulbous pharynx.
Line drawings in Figure 6 modified with permission from the following sources:
Gastrotricha (unspecified chatonotoid) – BIODIDAC database (http://biodidac.bio.uottawa.ca/)
Gnathostomulida (Gnathostomula peregrina) – Kirsteuer, 1969
Annelida (Hirudinea sp.) – BIODIDAC database (http://biodidac.bio.uottawa.ca/)
Prorhynchida (after Geocentrophora marcusi) – original
All others – Images modified from original illustrations provided courtesy of Janine Caira (Caira and Littlewood, 2013).