xvi
Ruppert and Barnes 1994; Nielsen 2001) or placed them together within Lophodeuterostomia
(Ruppert et al. 2004) or Radialia (Westheide and Rieger 2007). Many zoologists pointed to the
fact that the lophophorates combined the characters of protostomes and deuterostomes (e.g.
Zimmer 1973; Ivanov 1976; Willmer 1990; Ruppert and Barnes 1994; d’Hondt 1997). As a
result, Lophophorata (or members thereof) have often been placed at the base of the evolutionary bifurcation between Protostomia and Deuterostomia, being put closer either with the former or with the latter or being treated as a “transitory”, stem or sister group of Deuterostomia
(Marcus 1958; Hyman 1959; Hennig 1979; Dogiel 1981; Salvini-Plawen 1982; Willmer 1990;
Schram 1991; Ax 1995; Lüter and Bartolomaeus 1997; Sørensen et al. 2000; Brusca and
Brusca 2003; Westheide and Rieger 2007; see also discussions in Zrzavy et al. 1998;
Passamaneck and Halanych 2004; Helmkampf et al. 2008a, b; Gruhl 2008). For instance,
Anderson (2001) interpreted lophophorates to be protostomatous in origin, having acquired
morphological and embryological characters of deuterostomes as a result of convergent
evolution.
Molecular data are not supportive of Lophophorata as a monophyletic group. At present,
Bryozoa, Phoronida and Brachiopoda are included in the Lophotrochozoa or Spiralia within
Protostomia (Halanych et al. 1995; Halanych 1996, 2004; Mackey et al. 1996; Cohen and
Gawthrop 1996; Erber et al. 1998; Abouheif et al. 1998; Peterson and Eernisse 2001;
Waeschenbach et al. 2006; Baguña et al. 2008; Helmkampf et al. 2008a; Bourlat et al. 2008;
Dunn et al. 2008; Giribet et al. 2009; Jang and Hwang 2009; Hejnol et al. 2009; Sun et al.
2009, 2011; Mallatt et al. 2010, 2012; Edgecombe et al. 2011; Nesnidal et al. 2011; Shen et al.
2012, see also Giribet 2002, 2008; Passamaneck and Halanych 2004). However, their exact
positions within the Lophotrochozoa are still not resolved.
Zoologists have traditionally affi liated bryozoans with phoronids, treating them as sister
groups originating from pro(to)lophophorates or protophoronids or deriving Bryozoa from
Phoronida (i.e. considering early Phoronida as the stem group for Bryozoa) (Caldwell 1882;
Korschelt and Heider 1893; Borg 1926; Cori 1941; Marcus 1958; Hyman 1959; Brien 1960;
Farmer et al. 1973; Jebram 1973, 1986; Farmer 1977; Emig 1984; Malakhov 1995; Gorjunova
1996; Ruppert et al. 2004). Silén (1944, p. 100) wrote that phoronids are not “true ancestors of
the Bryozoa”, but there is “perhaps … a parallelism as to certain features of the two groups”.
Emig (1982, p. 79) considered brachiopods and bryozoans to be “blind branches” of a trunk
whose evolution resulted in the emergence of the phoronids, in his opinion the most advanced
lophophorates. In contrast, Beklemishev (1969) and d’Hondt (1986) viewed brachiopods as a
group separate from bryozoans and phoronids. Resurrecting the old view (see Van Beneden
1845; Leidy 1851; Allman 1856; Hatschek 1877), Nielsen (1971, 1995, 2000, 2001, 2002a, b)
united Bryozoa and Kamptozoa (Entoprocta) into a superphylum Bryozoa (see also Cuffey
1973) within the protostomes and considered Phoronida and Brachiopoda as related basal
deuterostomes. Recently, however, this author included Brachiozoa (Brachiopoda + Phoronida)
in the Spiralia (Nielsen 2012; see also below).
Molecular studies and a combined “morphomolecular” analysis usually also place Bryozoa
apart from Phoronida and Brachiopoda (whether uniting phoronids and brachiopods or setting
them apart) (Halanych et al. 1995; Halanych 1996; Cohen and Gawthrop 1996; Mackey et al.
1996; Littlewood et al. 1998; Zrzavý et al. 1998; Abouheif et al. 1998; Cohen et al. 1998;
Winnepenninckx et al. 1998; Cohen 2000; Peterson and Eernisse 2001; Waeschenbach et al.
2006; Baguña et al. 2008; Dunn et al. 2008; Bleidorn et al. 2009; Hejnol et al. 2009; Hausdorf
et al. 2010; Mallatt et al. 2012; Edgecombe et al. 2011; Nesnidal et al. 2011; see also discussion in Gruhl 2008; Giribet et al. 2009). Also, different authors refute (Mallatt et al. 2010,
2012) or, on the contrary, support (Hausdorf et al. 2007, 2010; Helmkampf et al. 2008a; Hejnol
et al. 2009; Bleidorn et al. 2009; Witek et al. 2009; Philippe et al. 2011; Edgecombe et al. 2011)
a close relationships between bryozoans and entoprocts (see also Abouheif et al. 1998; Baguñá
et al. 2008; Giribet et al. 2009; Nesnidal et al. 2011; Fuchs 2011). Recently Bryozoa, Entoprocta
and Cycliophora have been united under the name Polyzoa (Cavalier-Smith 1998; Hejnol et al.
2009; summarized in Hejnol 2010; Nielsen 2012).
Introduction
Ruppert and Barnes 1994; Nielsen 2001) or placed them together within Lophodeuterostomia
(Ruppert et al. 2004) or Radialia (Westheide and Rieger 2007). Many zoologists pointed to the
fact that the lophophorates combined the characters of protostomes and deuterostomes (e.g.
Zimmer 1973; Ivanov 1976; Willmer 1990; Ruppert and Barnes 1994; d’Hondt 1997). As a
result, Lophophorata (or members thereof) have often been placed at the base of the evolutionary bifurcation between Protostomia and Deuterostomia, being put closer either with the former or with the latter or being treated as a “transitory”, stem or sister group of Deuterostomia
(Marcus 1958; Hyman 1959; Hennig 1979; Dogiel 1981; Salvini-Plawen 1982; Willmer 1990;
Schram 1991; Ax 1995; Lüter and Bartolomaeus 1997; Sørensen et al. 2000; Brusca and
Brusca 2003; Westheide and Rieger 2007; see also discussions in Zrzavy et al. 1998;
Passamaneck and Halanych 2004; Helmkampf et al. 2008a, b; Gruhl 2008). For instance,
Anderson (2001) interpreted lophophorates to be protostomatous in origin, having acquired
morphological and embryological characters of deuterostomes as a result of convergent
evolution.
Molecular data are not supportive of Lophophorata as a monophyletic group. At present,
Bryozoa, Phoronida and Brachiopoda are included in the Lophotrochozoa or Spiralia within
Protostomia (Halanych et al. 1995; Halanych 1996, 2004; Mackey et al. 1996; Cohen and
Gawthrop 1996; Erber et al. 1998; Abouheif et al. 1998; Peterson and Eernisse 2001;
Waeschenbach et al. 2006; Baguña et al. 2008; Helmkampf et al. 2008a; Bourlat et al. 2008;
Dunn et al. 2008; Giribet et al. 2009; Jang and Hwang 2009; Hejnol et al. 2009; Sun et al.
2009, 2011; Mallatt et al. 2010, 2012; Edgecombe et al. 2011; Nesnidal et al. 2011; Shen et al.
2012, see also Giribet 2002, 2008; Passamaneck and Halanych 2004). However, their exact
positions within the Lophotrochozoa are still not resolved.
Zoologists have traditionally affi liated bryozoans with phoronids, treating them as sister
groups originating from pro(to)lophophorates or protophoronids or deriving Bryozoa from
Phoronida (i.e. considering early Phoronida as the stem group for Bryozoa) (Caldwell 1882;
Korschelt and Heider 1893; Borg 1926; Cori 1941; Marcus 1958; Hyman 1959; Brien 1960;
Farmer et al. 1973; Jebram 1973, 1986; Farmer 1977; Emig 1984; Malakhov 1995; Gorjunova
1996; Ruppert et al. 2004). Silén (1944, p. 100) wrote that phoronids are not “true ancestors of
the Bryozoa”, but there is “perhaps … a parallelism as to certain features of the two groups”.
Emig (1982, p. 79) considered brachiopods and bryozoans to be “blind branches” of a trunk
whose evolution resulted in the emergence of the phoronids, in his opinion the most advanced
lophophorates. In contrast, Beklemishev (1969) and d’Hondt (1986) viewed brachiopods as a
group separate from bryozoans and phoronids. Resurrecting the old view (see Van Beneden
1845; Leidy 1851; Allman 1856; Hatschek 1877), Nielsen (1971, 1995, 2000, 2001, 2002a, b)
united Bryozoa and Kamptozoa (Entoprocta) into a superphylum Bryozoa (see also Cuffey
1973) within the protostomes and considered Phoronida and Brachiopoda as related basal
deuterostomes. Recently, however, this author included Brachiozoa (Brachiopoda + Phoronida)
in the Spiralia (Nielsen 2012; see also below).
Molecular studies and a combined “morphomolecular” analysis usually also place Bryozoa
apart from Phoronida and Brachiopoda (whether uniting phoronids and brachiopods or setting
them apart) (Halanych et al. 1995; Halanych 1996; Cohen and Gawthrop 1996; Mackey et al.
1996; Littlewood et al. 1998; Zrzavý et al. 1998; Abouheif et al. 1998; Cohen et al. 1998;
Winnepenninckx et al. 1998; Cohen 2000; Peterson and Eernisse 2001; Waeschenbach et al.
2006; Baguña et al. 2008; Dunn et al. 2008; Bleidorn et al. 2009; Hejnol et al. 2009; Hausdorf
et al. 2010; Mallatt et al. 2012; Edgecombe et al. 2011; Nesnidal et al. 2011; see also discussion in Gruhl 2008; Giribet et al. 2009). Also, different authors refute (Mallatt et al. 2010,
2012) or, on the contrary, support (Hausdorf et al. 2007, 2010; Helmkampf et al. 2008a; Hejnol
et al. 2009; Bleidorn et al. 2009; Witek et al. 2009; Philippe et al. 2011; Edgecombe et al. 2011)
a close relationships between bryozoans and entoprocts (see also Abouheif et al. 1998; Baguñá
et al. 2008; Giribet et al. 2009; Nesnidal et al. 2011; Fuchs 2011). Recently Bryozoa, Entoprocta
and Cycliophora have been united under the name Polyzoa (Cavalier-Smith 1998; Hejnol et al.
2009; summarized in Hejnol 2010; Nielsen 2012).
Introduction