Introduction 1774 Dendrocoelum lacteum Bdellocephala punctata 1969 1999 2000 2003 2004 2006 2002 2002 2003 2003 2004 2004 2005 2006 Macrostomum lignano 2006a b M. lignano 1985 1996 2006 1985 2005 1969 The status of the acoels 2004a b 2001 2005 1985 1986 2004 What is a planarian? 2003 2004 1998 2002 2001 Stenostomum Microstomum It seems therefore desirable to agree on using less ambiguous denominations in scientific contexts, such as unequivocal scientific names, and to get rid of the term planarian. Overview of regeneration capacity in free-living flatworm groups 1 1985 1996 1985 1996 Fig. 1 green shades 1985 1996 2006  Catenulida Stenostomum Catenula 1900 1903a b 1927a 1929 1990 Stenostomum 1977 Catenula Acoela Polychoerus caudatus 1905 1907 1929 Paramecynostomum diversicolor 1913 1951 Amphiscolops langerhansi 1954 1955 1963a b Hofstenia giselae 1966 1967 H. giselae 1966 1967 A. langerhansi Pseudohaplogonaria sutcliffei 1991 Praesagittifera naikaiensis 2001 Convolutriloba longifissura C. longifissura 2001 Paratomella unichaeta 1959 C. retrogemma 1988 C. retrogemma 1988 1991 Nemertodermatida No account of regeneration potential or asexual reproduction has been given for animals from this taxon. Macrostomorpha Microstomum lineare Alaurina 1908 1927a 1986 1990 1991 Macrostomum 1927a Macrostomum tuba 1997 Macrostomum hystricinum marinum Macrostomum pusillum M. lignano 1999 2001 M. lignano 2006a b M. lignano M. lineare 1986 Polycladida Leptoplana Leptoplana alcynoe Letoplana alcinoi Leptoplana velutinus Thysanozoon brocchi Cryptocelis alba 1900a Leptoplana atomata 1901 1902 Leptoplana tremellaris L. alcinoi 1904a c 1905a 1939 L. tremellaris 1904a c Notoplana humilis 1998 T. brocchi 1900a 1939 Leptoplana saxicola Pucelis litoricola Planocera californica 1922a 1905 Leptoplana littoralis 1939 T. brocchi 1905 1922b 1939 1975 1976 1922b 1975 1976 1922b 1980 Cestoplana 1905b T. brocchi 2006 Lecithoepitheliata Prorhynchus stagnalis 1927a Geocentrophora baltica 1927 Geocentrophora sphyrocephala 1946 Prolecithophora 1957 Plagiostomum lemani 1894 Plagiostomum girardi 1900b Proseriata 1882 Monocelis fusca M. fusca Monocelis lineata Coelogynopora Archilopsis Itaspiella Bothriomolus 1966 Otomesostoma auditivum 1957 Bothrioplanida 1911 Bothrioplana semperi Tricladida 1814 Planaria nigra Polycelis nigra 1969 1930 1977 Phagocata velata Dugesia dorotocephala Polycelis auriculata Dendrocoelopsis lactea Dendrocoelopsis lactea Dendrocoelopsis ezensis Dendrocoelum lacteum Bdelloura Bdelloura candida Dugesia japonica Schmidtea mediterranea Rhabdocoela Mesostoma ehrenbergi 1913 Mesostoma productum Mesostoma lingua Mesostoma punctatum 1922 Phaenocora unipunctata Phaenocora megalops 1922 Dalyellia millportiana Gyratrix hermaphroditus 1927a Dalyellia viridis Typhloplana viridata Rhynchomesostoma rostratum 1928 Comparison of the regeneration capacity between free-living flatworm taxa Convolutriloba Stenostomum Microstomum Cestoplana M. lignano Bdelloura Macrostomum Macrostomum Microstomum Alaurina Macrostomum Asexual reproduction and regeneration 1 1969 2000 1969 2004 1974 2001 Stenostomum leucops 1929 Dugesia fissipara Dugesia paramensis 1951 Dugesia tahitiensis 2001 Why can some flatworm species regenerate while others cannot? 1991 2000 Heteromorphoses 1986 1992 2004 Dendrocoelum Bdellocephala 1969 M. lignano 2 2006a b M. lignano Fig. 2 a M. lignano b a c M. lignano arrowhead d c c d  M. lignano 2 1911 1913 1958 Ovaries restricting regeneration? Microstomum Macrostomum Stenostomum Stenostomum grande 1929 S. grande Vasa D. japonica M. lignano 1999 2005 vasa Stenostomum S. mediterranea 2003 Stenostomum Schmidtea Schmidtea Regeneration in juveniles Mesostoma 1922 H. giselae 1967 B. punctata 1942 1969 1957 O. auditivum 1928 G. sphyrocephala 1946 M. lignano 2006a b Similarities between postembryonic development and regeneration 1969 M. lignano 2001 2005 2006a b 2005 2006a b 3 2006a Fig. 3 M. lignano b d a b c d  M. lignano 3 4 4 2000 2000 2006a b Vasa 2005 M. lignano 2004 3 2006a b M. fusca 1966 1998 2004 4 4 1964 2006a b M. lignano 2006a b Fig. 4 M. lignano left right Regeneration M. lignano Starvation M. lignano  1964 M. lignano 4 Embryonic development and regeneration 2004 2002 2004 2000 2005 2001 1985 1996 5 4 2005 1966 2005 Fig. 5 a Pseudostylochus intermedius b M. lignano M. lignano  1986 1989 1992 5 P. nigra 1966 Nervous system and role of the brain for regeneration 2001 M. lignano 2006a b Macrostomum 6 D. japonica S. mediterranea 2002a 2003 2005 nou-darake D. japonica nou-darake 2002b nou-darake Fig. 6 M. lignano a b c b c b Arrowheads  M. hystricinum marinum M. pusillum 1997 M. lignano 6 1969 1998 1997 M. lineare S. leucops M. lignano 6 1950 1951a c 1950a b P. nigra Dugesia Schmidtea lugubris 1958 L. littoralis L. saxicola P. litoricola 1905 1922a 1965 S. lugubris P. nigra 1965 Dugesia M. lignano 2006a b M. lignano M. lignano Dendrocoelum 1939 1969 L. littoralis L. saxicola P. litoricola 1905 1922a Mesostoma 1922 Cestoplana T. brocchi 1905c 1939 Cestoplana 1905c M. lignano Notoplana acticola Planocera gilchristi 1976 Enchiridium punctatum 1976 1951 M. ehrenbergi 1913 Phaenocera 1922 G. sphyrocephala M. lignano 1946 M. lignano 1976 1976 2004 The totipotency of neoblasts M. lignano 2006a b 1902 Schmidtea lugubris S. mediterranea 1989 Macrostomum 2 2006a b 2006a b 1939 1976 M. lignano 2006a b 1969 Taenia crassiceps 1997 1894 Heteromorphoses 2 M. lignano 2 2006a b Macrostomum appendiculatum Bothrioplana bohemica 1911 S. leucops 1927b D. lacteum 1924 1969 1897 Planaria maculata Dugesia Girardia tigrina 1926 Leptoplana 1905a Mesostoma 1922 P. caudatus 1929 S. leucops 1927b M. lignano 2006a b 2003 1897 M. lignano 1967 H. giselae M. lignano 2006a b H. giselae Conclusion M. lignano