Clade for classes and Turbellarian orders from Nielson'94 p. 216.

               CL. TUR             #
       ==========2a*==B=============#     Or. Acoela
<<=1*==|               E            |
       |   =======2c*===L===========#     Or. Polycladida
       =2b*|             L          |
           |   ====2e*====A=========#     Or. Tricladida (planarians)
           =2d*|           R        |
               |   ==2g*====IA======#     Or. Rhabocoela
               =2f*|
                   |     ======4*==== Cl. Trematoda (endoparasitic flukes)
                   ==3*==|
                         |     ==6*== Monogenea (ectoparasites of aquatic vertebrates)
                         ==5*==|
                               ==7*== Cl. Cestoidea (endoparasitic tapeworms)

1: a) midventral mouth**, b) blind gut**, c) protonephridia**, d) coelom & blood vascular system absent**, e) ciliated epidermis**, f) multiciliated cells, g) epidermal gland cells extensive, h) monociliated sperm, i) hermaphroditic (unclear if valid trait), j) archoopheran reproductive system,
2a: a) lack gut**, b) simple pharynx**, c) lack protonephridia, d) no distinct gonads (gametes from parenchyma)
2b: a) rhabdites, b) biciliated sperm (present in all higher groups), c) gut cavity present, d) plicate pharynx,
2c: a) gut has multiple branches, b) pair of anterior tentacles (some), c) multiple gonads among branches of gut
2d: a) neoopheran reproductive system (present in all higher groups); b) lose typical 'spiral' cleavage
2e: a) gut has three branches
2f: a) bulbous pharynx,
2g: a) gut has single cavity
3: a) syncytial, non-ciliated epidermis, b) terminal mouth (also some rhabdocoels), c) paired intestinal cecae
4: a) oral & mid-ventral sucker, b) complex=indirect life cycle (1-2 intermediate hosts), c) anaerobic metabolism
5: a) distinct attachment hooks in larva
6: a) haptor, b) simple=direct life cycle** (no intermediate hosts)
7: a) scolex, b) strobila (=chain of proglottids), c) mouth & gut absent, d) reproductive system repeated in each proglottid, e) complex=indirect life cycle (1 or more intermediate hosts),

** possibly plesiomorphic (a primitive state, not unique to clade)

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