The Acoela: On their kind and kinships, especially with nemertodermatids and xenoturbellids (Bilateria incertae sedis)

Organisms Diversity and Evolution

Volumn 13, Issue 2, 2013, Pages 267-286

  Achatz, Johannes G ^a,b   Chiodin, Marta ^a   Salvenmoser, Willi ^b   Tyler, Seth ^c   Martinez, Pedro ^a,d  

^a UNIVERSITY OF BARCELONA   (Spain)

^b UNIVERSITY OF INNSBRUCK   (Austria)

^c UNIVERSITY OF MAINE   (United States)

^d INSTITUCIÓ CATALANA DE RECERCA I ESTUDIS AVANÇATS ICREA   (Spain)

Author keywords

Acoelomorpha; Development; Morphology; Phylogeny; Systematics; Xenoturbella

Indexed keywords

CLADISTICS; DIGESTIVE SYSTEM; EUKARYOTE; KINSHIP; MORPHOLOGY; PHYLOGENY; TAXONOMY;

ACOELA; ACOELOMORPHA; ANIMALIA; BILATERIA; BILATERIA INCERTAE SEDIS; NEMERTODERMATIDA; PLATYHELMINTHES; XENOTURBELLA; XENOTURBELLIDA;

EID: 84878640630     PISSN: 14396092     EISSN: 16181077     Source Type: Journal    
DOI: 10.1007/s13127-012-0112-4     Document Type: Review

References (194)

1. Abildgaard, P. C. (1806). Zoologica danica seu animalium Danicae et Norwegiae rariorum ac mines notorum descriptorum et historia. In O. F. Müller (Ed.), Zoologica Danica 4 (p. 26). Copenhagen (Havnia): N. Mölleri.
2. Achatz, J. G., Hooge, M., Wallberg, A., Jondelius, U., & Tyler, S. (2010). Systematic revision of acoels with 9 + 0 sperm ultrastructure (Convolutida) and the influence of sexual conflict on morphology. Journal of Zoological Systematics and Evolutionary Research, 48(1), 9-32.
3. Åkesson, B., Gschwentner, R., Hendelberg, J., Ladurner, P., Müller, J., & Rieger, R. (2001). Fission in Convolutriloba longifissura: Asexual reproduction in acoelous turbellarians revisited. Acta Zoologica (Copenhagen), 82(3), 231-239. (Pubitemid 33669476)
4. Apelt, G. (1969). Fortpflanzungsbiologie, Entwicklungszyklen und vergleichende Frühentwicklung acoeler Turbellarien. Marine Biology (Berlin), 4, 267-325.
5. Ax, P., & Dörjes, J. (1966). Oligochoerus limnophilus nov. spec., ein Kaspisches Faunenelement als erster Süsswasservertreter der Turbellaria Acoela in Flüssen Mitteleuropas. Internationale Revue der Gesamten Hydrobiologie, 51, 15-44.
6. Baguñà, J., & Riutort, M. (2004). The dawn of bilaterian animals: the case of acoelomorph flatworms. Bioessays, 26(10), 1046-1057. (Pubitemid 39424808)
7. Barneah, O., Brickner, I., Hooge, M., Weis, V. M., & Benayahu, Y. (2007). First evidence of maternal transmission of algal endosymbionts at an oocyte stage in a triploblastic host, with observations on reproduction in Waminoa brickneri (Acoelomorpha). Invertebrate Biology, 126(2), 113-119. (Pubitemid 47258874)
8. Bartolomaeus, T., & Balzer, I. (1997). Convolutriloba longifissura, nov. spec. (Acoela) - first case of longitudinal fission in Plathelminthes. Microfauna Marina, 11, 7-18.
9. Bery, A., Cardona, A., Martinez, P., & Hartenstein, V. (2010). Structure of the central nervous system of a juvenile acoel, Symsagittifera roscoffensis. Development Genes and Evolution, 220(3-4), 61-76.
10. Bery, A., & Martinez, P. (2011). Acetylcholinesterase activity in the developing and regenerating nervous system of the acoel Symsagittifera roscoffensis. Acta Zoologica (Copenhagen), 92(4), 383-392.
11. Boone, M., Willems, M., Claeys, M., & Artois, T. (2011). Spermatogenesis and the structure of the testes in Isodiametra pulchra (Isodiametridae, Acoela). Acta Zoologica (Copenhagen), 92(2), 101-108.
12. Bourlat, S. J., Juliusdottir, T., Lowe, C. J., Freeman, R., Aronowicz, J., Kirschner, M., et al. (2006). Deuterostome phylogeny reveals monophyletic chordates and the new phylum Xenoturbellida. Nature (London), 444(7115), 85-88. (Pubitemid 44684760)
13. Bourlat, S. J., Nielsen, C., Lockyer, A. E., Littlewood, D. T. J., & Telford, M. J. (2003). Xenoturbella is a deuterostome that eats molluscs. Nature (London), 424(6951), 925-928. (Pubitemid 37051680)
14. Bourlat, S. J., Rota-Stabelli, O., Lanfear, R., & Telford, M. J. (2009). The mitochondrial genome structure of Xenoturbella bocki (phylum Xenoturbellida) is ancestral within the deuterostomes. BMC Evolutionary Biology, 9(107), 1-14.
15. Boyer, B. C., Henry, J. Q., & Martindale, M. Q. (1996). Modified spiral cleavage: The duet cleavage pattern and early blastomere fates in the acoel turbellarian Neochildia fusca. Biological Bulletin Wood's Hole, 191(2), 285-286. (Pubitemid 27011795)
16. Bresslau, E. (1909). Die Entwicklung der Acoelen. Verhandlungen der Deutschen Zoologischen Gesellschaft Leipzig, 19, 314-324.
17. Brüggemann, J. (1985a). Ultrastructure and formation of the bursa mouthpiece of Philocelis cellata (Plathelminthes[Platyhelminthes], Acoela). Hydrobiologia, 128(1), 23-30.
18. Brüggemann, J. (1985b). Ultrastruktur und Bildungsweise penialer Hartstrukturen bei freilebenden Plathelminthen. Zoomorphology (Berlin), 105(3), 143-189.
19. Bueno, D., Baguñà, J., & Romero, R. (1997). Cell-, tissue-, and position-specific monoclonal antibodies against the planarian Dugesia (Girardia) tigrina. Histochemistry and Cell Biology, 107(2), 139-149. (Pubitemid 27110112)
20. Bush, L. (1975). Biology of Neochilda fusca n. gen. n. sp. from Northeastern Coast of United-States (Platyhelminthes - Turbellaria). Biological Bulletin Wood's Hole, 148(1), 35-48.
21. Carranza, S., Baguñà, J., & Riutort, M. (1997). Are the platyhelminthes a monophyletic primitive group? An assessment using 18S rDNA sequences. Molecular Biology and Evolution, 14(5), 485-497. (Pubitemid 27200479)
22. Chiodin, M., Achatz, J. G., Wanninger, A., & Martinez, P. (2011). Molecular Architecture of Muscles in an Acoel and Its Evolutionary Implications. Journal of Experimental Zoology Part B Molecular and Developmental Evolution, 316B(6), 427-439.
23. Costello, H. M., & Costello, D. P. (1938). Copulation in the Acoelous Turbellarian Polychoerus carmelensis. Biological Bulletin Wood's Hole, 75, 85-98.
24. Costello, H. M., & Costello, D. P. (1939). Egg laying in the acoelous Turbellarian Polychoerus carmelensis. Biological Bulletin Wood's Hole, 76, 80-89.
25. Crezée, M. (1975). Monograph of the Solenofilomorphidae (Turbellaria: Acoela). Internationale Revue der Gesamten Hydrobiologie, 60(6), 769-845.
26. Davidson, E. H. (2011). Evolutionary bioscience as regulatory systems biology. Developmental Biology, 357(1), 35-40. doi: 10.1016/j.ydbio.2011.02.004.
27. De Mendoza, A., & Ruiz-Trillo, I. (2011). The Mysterious Evolutionary Origin for the GNE Gene and the Root of Bilateria. Molecular Biology and Evolution, 28(11), 2987-2991. doi: 10.1093/Molbev/Msr142.
28. De Mulder, K. (2009). Molecular characterization of the exceptional stem cell system of flatworms. Dissertation, University of Ghent, Belgium.
29. De Mulder, K., Kuales, G., Pfister, D., Willems, M., Egger, B., Salvenmoser, W., et al. (2009). Characterization of the stem cell system of the acoel Isodiametra pulchra. BMC Developmental Biology, 9. doi: 10.1186/1471-213x-9-69.
30. De Robertis, E. M. (2008). Evo-Devo: Variations on ancestral themes. Cell, 132(2), 185-195. doi: 10.1016/J.Cell.2008.01.003. (Pubitemid 351172437)
31. Doe, D. A. (1981). Comparative ultrastructure of the pharynx simplex in Turbellaria. Zoomorphology (Berlin), 97(1-2), 133-192.
32. Dörjes, J. (1966). Paratomella unichaeta nov. gen. nov. spec., Vertreter einer neuen Familie der Turbellaria Acoela mit asexueller Fortpflanzung durch Paratomie. Veröffentlichungen des Institutes für Meeresforschung Bremerhafen Sonderberichte, 2, 187-200.
33. Dörjes, J. (1968). Die Acoela (Turbellaria) der Deutschen Nordseekuste und ein neues System der Ordnung. Zeitschrift fuer Zoologische Systematik und Evolutionsforschung, 6, 56-452.
34. du Bois-Reymond Marcus, E. (1955). On Turbellaria and Polygordius from the Brazilian coast. Boletim da Faculdade de Filosofia Ciencias e Letras Universidade de Sao Paulo Zoologica, 20, 19-65.
35. Egger, B., Gschwentner, R., & Rieger, R. (2007). Free-living flatworms under the knife: past and present. Development Genes and Evolution, 217(2), 89-104. (Pubitemid 46206502)
36. Egger, B., Steinke, D., Tarui, H., De Mulder, K., Arendt, D., Borgonie, G., et al. (2009). To Be or Not to Be a Flatworm: The Acoel Controversy. Plos One, 4(5), doi: 10.1371/journal.pone.0005502.
37. Ehlers, U. (1985). Das Phylogenetische System der Plathelminthes. Stuttgart: Gustav Fischer.
38. Ehlers, U. (1992a). On the fine structure of Paratomella rubra Rieger & Ott (Acoela) and the position of the taxon Paratomella Dörjes in a phylogenetic system of the Acoelomorpha (Plathelminthes). Microfauna Marina, 7, 265-293.
39. Ehlers, U. (1992b). Pulsatile bodies in Anaperus tvaerminnensis (Luther, 1912) (Acoela, Plathelminthes) are degenerating epidermal cells. Microfauna Marina, 7, 295-310.
40. Ehlers, U. (1992c). Dermonephridia-modified epidermal cells with a probable excretory function in Paratomella rubra (Acoela, Plathelminthes). Microfauna Marina, 7, 253-264.
41. Ehlers, U. (1997). Ultrastructure of the statocysts in the apodous sea cucumber Leptosynapta inhaerens (Holothuroidea, Echinodermata). Acta Zoologica (Copenhagen), 78(1), 61-68. (Pubitemid 27203535)
42. Faubel, A., & Kolasa, J. (1978). On the anatomy and morphology of a freshwater species of Acoela (Turbellaria): Limnoposthia polonica (Kolasa et Faubel, 1974). Bulletin de l'Academie Polonaise des Sciences Serie des Sciences Biologiques, 26(6), 393-397.
43. Fransen, M. E. (1980a). Ultrastructure of coelomic organization in annelids. 1. Archiannelids and other small polychaetes. Zoomorphologie (Berlin), 95(3), 235-249.
44. Fransen, M. E. (1980b). Variations in the lining of the polychaete body cavity. American Zoologist, 20(4), 751-751.
45. Franzén, A., & Afzelius, B. A. (1987). The ciliated epidermis of Xenoturbella bocki (Platyhelminthes, Xenoturbellida) with some phylogenetic considerations. Zoologica Scripta, 16(1), 9-17.
46. Freudenstein, J. V. (2005). Character, states and homology. Systematic Biology, 54(6), 965-973. doi: 10.1080/10635150500354654.
47. Gaerber, C. W., Salvenmoser, W., Rieger, R. M., & Gschwentner, R. (2007). The nervous system of Convolutriloba (Acoela) and its patterning during regeneration after asexual reproduction. Zoomorphology (Berlin), 126(2), 73-87. doi: 10.1007/S00435-007-0039-Z. (Pubitemid 47221317)
48. Graff, L. V. (1882). Monographie der Turbellarien. I. Rhabdocoelida. Leipzig: Wilhelm Engelmann.
49. Graff, L. V. (1891). Die Organisation der Turbellaria Acoela. Leipzig: Wilhelm Engelmann.
50. Graff, L. v. (1904-08). Acoela und Rhabdocoelida. In H. G. Bronn (Ed.), Klassen und Ordnungen des Thier-Reichs (Vol. 4, pp. 1732-2597). Leipzig: C. F. Winter'sche Verlagshandlung.
51. Graff, L. V. (1905). Turbellaria I. Acoela. In F. E. Schulze (Ed.), Das Tierreich 23 (pp. 23-34). Berlin: Königliche Preussische Akademie der Wissenschaften.
52. Gschwentner, R., Ladurner, P., Nimeth, K., & Rieger, R. (2001). Stem cells in a basal bilaterian: S-phase and mitotic cells in Convolutriloba longifissura (Acoela, Platyhelminthes). Cell & Tissue Research, 304(3), 401-408. (Pubitemid 32480571)
53. Hanson, E. D. (1960). Asexual reproduction in acoelous Turbellaria. Yale Journal of Biology and Medicine, 33(2), 107-111.
54. Harzsch, S., & Wanninger, A. (2010). Evolution of invertebrate nervous systems: the Chaetognatha as a case study. Acta Zoologica (Copenhagen), 91(1), 35-43. doi: 10.1111/J.1463-6395.2009.00423.X.
55. Haszprunar, G. (1996). Plathelminthes and Plathelminthomorpha - paraphyletic taxa. Journal of Zoological Systematics and Evolutionary Research, 34(1), 41-47.
56. Hejnol, A., & Martindale, M. Q. (2008a). Acoel development supports a simple planula-like urbilaterian. Philosophical Transactions of the Royal Society B-Biological Sciences, 363(1496), 1493-1501. doi: 10.1098/Rstb.2007. 2239. (Pubitemid 351363991)
57. Hejnol, A., & Martindale, M. Q. (2008b). Acoel development indicates the independent evolution of the bilaterian mouth and anus. Nature (London), 456(7220), 382-U345. doi: 10.1038/Nature07309.
58. Hejnol, A., & Martindale, M. Q. (2009). Coordinated spatial and temporal expression of Hox genes during embryogenesis in the acoel Convolutriloba longifissura. BMC Biology, 7. doi: 10.1186/1741-7007-7-65.
59. Hejnol, A., Obst, M., Stamatakis, A., Ott, M., Rouse, G. W., Edgecombe, G. D., et al. (2009). Assessing the root of bilaterian animals with scalable phylogenomic methods. Proceedings of the Royal Society B-Biological Sciences, 276(1677), 4261-4270. doi: 10.1098/Rspb.2009.0896.
60. Hendelberg, J. (1969). On the development of different types of spermatozoa from spermatids with two flagella in the Turbellaria with remarks on the ultrastructure of the flagella. Zoologiska Bidrag fran Uppsala, 38, 2-50.
61. Hendelberg, J. (1977). Comparative morphology of turbellarian spermatozoa studied by electron microscopy. Acta Zoologica Fennica, 149-162.
62. Hendelberg, J., & Åkesson, B. (1988). Convolutriloba retrogemma gen. et sp. n., a turbellarian (Acoela, Platyhelminthes) with reversed polarity of reproductive buds. Progress in Zoology, 36, 321-327.
63. Hendelberg, J., & Hedlund, K. O. (1974). On the morphology of the epidermal ciliary rootlet system of the acoelous turbellarian Childia groenlandica. Zoon (Uppsala), 2(1), 13-24.
64. Hennig, W. (1950). Grundzüge einer Theorie der Phylogenetischen Systematik. Berlin: Deutscher Zentral Verlag.
65. Hennig, W. (1965). Phylogenetic Systematics. Annual Review of Entomology, 10, 97-116.
66. Henry, J. Q., Martindale, M. Q., & Boyer, B. C. (2000). The unique developmental program of the acoel flatworm, Neochildia fusca. Developmental Biology, 220(2), 285-295. (Pubitemid 30228153)
67. Holland, N. D. (2003). Early central nervous system evolution: An era of skin brains? Nature Reviews Neuroscience, 4(8), 617-627. doi: 10.1038/Nrn1175. (Pubitemid 37280157)
68. Hooge, M. D. (2001). Evolution of body-wall musculature in the Platyhelminthes (Acoelomorpha, Catenulida, Rhabditophora). Journal of Morphology, 249(3), 171-194. (Pubitemid 32828062)
69. Hooge, M. D., Haye, P. A., Tyler, S., Litvaitis, M. K., & Kornfield, I. (2002). Molecular systematics of the Acoela (Acoelomorpha, Platyhelminthes) and its concordance with morphology. Molecular Phylogenetics and Evolution, 24(2), 333-342. (Pubitemid 35008244)
70. Hooge, M. D., & Rocha, C. E. F. (2006). Acoela (Acoelomorpha) from the northern beaches of the state of São Paulo, Brazil, and a systematic revision of the family Otocelididae. Zootaxa, 1335, 1-50. (Pubitemid 46063554)
71. Hooge, M. D., & Tyler, S. (2005). New tools for resolving phylogenies: a systematic revision of the Convolutidae (Acoelomorpha, Acoela). Journal of Zoological Systematics and Evolutionary Research, 43(2), 100-113. (Pubitemid 40764328)
72. Hrouda, M. (2007). Molecular Analysis of the Evolution of Bilaterian Body Axes: Wnt and Bmp-signaling in Isodiamtera pulchra and Macrostomum lignano (Acoelomorpha, Macrostomorpha; Platyhelminthes). Dissertation, University of Innsbruck, Austria.
73. Hyman, L. H. (1937). Reproductive system and copulation in Amphiscolops langerhansi (Turbellaria acoela). Biological Bulletin Wood's Hole, 72, 319-326.
74. Hyman, L. H. (1951). The Invertebrates: Platyhelminthes and Rhynchocoela. The acoelomate Bilateria (Vol. 2). New York: McGraw Hill Book Co.
75. Hyman, L. H. (1959). The Invertebrates: Smaller Coelomate Groups (Vol. 5). New York: McGraw Hill Book Co.
76. Israelsson, O. (1999). New light on the enigmatic Xenoturbella (phylum uncertain): ontogeny and phylogeny. Proceedings of the Royal Society of London Series B Biological Sciences, 266(1421), 835-841. (Pubitemid 29204214)
77. Jägersten, G. (1972). Evolution of the metazoan life cycle. A comprehensive theory. London and New York: Academic Press.
78. Jennings, J. B. (1971). Parasitism and commensalism in the Turbellaria. Adv Parasitology, 9, 1-32.
79. Jondelius, U., Larsson, K., & Raikova, O. (2004). Cleavage in Nemertoderma westbladi (Nemertodermatida) and its phylogenetic significance. Zoomorphology (Berlin), 123(4), 221-225. doi: 10.1007/S00435-004-0105-8. (Pubitemid 40047500)
80. Jondelius, U., Ruiz-Trillo, I., Baguñà, J., & Riutort, M. (2002). The Nemertodermatida are basal bilaterians and not members of the Platyhelminthes. Zoologica Scripta, 31(2), 201-215. (Pubitemid 34285649)
81. Jondelius, U., Wallberg, A., Hooge, M., & Raikova, O. I. (2011). How the worm got its pharynx: phylogeny, classification and Bayesian assessment of character evolution in Acoela. Systematic Biology, 60(6), 845-871. doi: 10.1093/Sysbio/Syr073.
82. Karling, T. G. (1974). On the anatomy and affinities of the turbellarian orders. In N. W. Riser & M. P. Morse (Eds.), Biology of the Turbellaria (pp. 1-16). New York: McGraw-Hill.
83. Klauser, M. D., Smith, J. P. S., III, & Tyler, S. (1986). Ultrastructure of the frontal organ in Convoluta and Macrostomum spp.: significance for models of the turbellarian archetype. Hydrobiologia, 132, 47-52.
84. Knauss, E. B. (1979). Indication of an anal pore in Gnathostomulida. Zoologica Scripta, 8(3), 181-186.
85. Kristensen, R. M., & Funch, P. (2000). Micrognathozoa: a new class with complicated jaws like those of Rotifera and Gnathostomulida. Journal of Morphology, 246(1), 1-49.
86. Ladurner, P., Pfister, D., Seifarth, C., Schärer, L., Mahlknecht, M., Salvenmoser, W., et al. (2005). Production and characterisation of cell- and tissue-specific monoclonal antibodies for the flatworm Macrostomum sp. Histochemistry and Cell Biology, 123(1), 89-104. (Pubitemid 40386270)
87. Ladurner, P., & Rieger, R. (2000). Embryonic muscle development of Convoluta pulchra (Turbellaria - Acoelomorpha, Platyhelminthes). Developmental Biology, 222(2), 359-375. (Pubitemid 30416374)
88. Lanfranchi, A. (1990). Ultrastructure of the epidermal eyespots of an acoel platyhelminth. Tissue & Cell, 22(4), 541-546. (Pubitemid 20278652)
89. Lundin, K. (1998). The epidermal ciliary rootlets of Xenoturbella bocki (Xenoturbellida) revisited: new support for a possible kinship with the Acoelomorpha (Platyhelminthes). Zoologica Scripta, 27(3), 263-270. (Pubitemid 28374062)
90. Lundin, K. (2001). Degenerating epidermal cells in Xenoturbella bocki (phylum uncertain), Nemertodermatida and Acoela (Platyhelminthes). Belgian Journal of Zoology, 131, 153-157.
91. Lundin, K., & Hendelberg, J. (1996). Degenerating epidermal bodies («pulsatile bodies») in Meara stichopi (Plathelminthes, Nemertodermatida). Zoomorphology (Berlin), 116(1), 1-5. (Pubitemid 126443348)
92. Luther, A. (1912). Studien über acöle Turbellarien aus dem Finnischen Meerbusen. Acta Societatis pro Fauna et Flora Fennica, 36(5), 1-60.
93. Mainitz, M. (1983). Gnathostomulida. In Reproductive biology of invertebrates. Volume 1. Oogenesis, oviposition, and oosorption (pp. 169-180). Chichester, New York etc.: John Wiley & Sons
94. Mallatt, J., Craig, C. W., & Yoder, M. J. (2010). Nearly complete rRNA genes assembled from across the metazoan animals: Effects of more taxa, a structure-based alignment, and paired-sites evolutionary models on phylogeny reconstruction. Molecular Phylogenetics and Evolution, 55(1), 1-17. doi: 10.1016/J.Ympev.2009.09.028.
95. Mamkaev, Y. V. (1967). Essays on the morphology in acoelous Turbellaria. Trudy zool. Inst. Leningr., 44, 26-108.
96. Marcus, E. (1947). Turbellarios marinhos do Brasil. Boletim Faculdade de Filosophia e Letras Universidade de Sao Paulo Zoologica, 12, 99-215.
97. Marcus, E. (1948). Turbellaria do Brasil. Boletim da Faculdade de Filosofia Ciencias e Letras Universidade de Sao Paulo Zoologica, 13, 111-243.
98. Marcus, E. (1949). Turbellaria brasileiros (7). Boletim da Faculdade de Filosofia Ciencias e Letras Universidade de Sao Paulo Zoologica, 14, 7-155.
99. Marcus, E. (1950). Turbellaria Brasileiros (8). Boletim da Faculdade de Filosofia Ciencias e Letras Universidade de Sao Paulo Zoologica, 15, 5-191.
100. Marcus, E. (1951). Turbellaria Brasileiros. Boletim da Faculdade de Filosofia Ciencias e Letras Universidade de Sao Paulo Zoologica, 16, 1-215.
101. Marcus, E. (1952). Turbellaria Brasileiros (10). Boletim da Faculdade de Filosofia Ciencias e Letras Universidade de Sao Paulo Zoologica, 17, 5-187.
102. Marcus, E. (1954). Turbellaria Brasileiros. Papéis Avulsos Departamento de Zoologia Secretaria de Agricultura São Paolo, 11, 419-489.
103. Marcus, E., & Macnae, W. (1954). Architomy in a species of Convoluta. Nature (London), 173, 130.
104. Mark, E. L. (1892). Polychoerus caudatus, nov. gen. et nov. sp. (Festschrift zum 70. Geburtstage Rudolf Leuckarts). Leipzig: Wilhelm Engelman.
105. Marlétaz, F., Gilles, A., Caubit, X., Perez, Y., Dossat, C., Samain, S., et al. (2008). Chaetognath transcriptome reveals ancestral and unique features among bilaterians. Genome Biology, 9(6), doi: 10.1186/Gb-2008-9-6-R94. (Pubitemid 351984749)
106. Marlow, H. Q., Srivastava, M., Matus, D. Q., Rokhsar, D., & Martindale, M. Q. (2009). Anatomy and development of the nervous system of Nematostella vectensis, an Anthozoan Cnidarian. Developmental Neurobiology, 69(4), 235-254. doi: 10.1002/Dneu.20698.
107. Moreno, E., De Mulder, K., Salvenmoser, W., Ladurner, P., & Martinez, P. (2010). Inferring the ancestral function of the posterior Hox gene within the bilateria: controlling the maintenance of reproductive structures, the musculature and the nervous system in the acoel flatworm Isodiametra pulchra. Evolution & Development, 12(3), 258-266. doi: 10.1111/J.1525-142x.2010. 00411.X.
108. Moreno, E., Nadal, M., Baguñà, J., & Martinez, P. (2009). Tracking the origins of the bilaterian Hox patterning system: insights from the acoel flatworm Symsagittifera roscoffensis. Evolution & Development, 11(5), 574-581. doi: 10.1111/J.1525-142x.2009.00363.X.
109. Moreno, E., Permanyer, J., & Martinez, P. (2011). The origin of patterning systems in bilateria-insights from the Hox and ParaHox genes in Acoelomorpha. Genomics Proteomics Bioinformatics, 9(3), 65-76. doi: 10.1016/S1672-0229(11)60010-7.
110. Mwinyi, A., Bailly, X., Bourlat, S. J., Jondelius, U., Littlewood, D. T. J., & Podsiadlowski, L. (2010). The phylogenetic position of Acoela as revealed by the complete mitochondrial genome of Symsagittifera roscoffensis. BMC Evolutionary Biology, 10. doi: 10.1186/1471-2148-10-309.
111. Pardos, F. (1988) Fine structure and function of pharynx cilia in Glossobalanus minutus Kowalewsky (Enteropneustea). Acta Zoologica (Copenhagen), 69(1), 1-12.
112. Pedersen, K. J., & Pedersen, L. R. (1986). Fine ultrastructural observations on the extracellular matrix (ECM) of Xenoturbella bocki Westblad, 1949. Acta Zoologica (Copenhagen), 67(2), 103-113.
113. Pedersen, K. J., & Pedersen, L. R. (1988). Ultrastructural observations on the epidermis of Xenoturbella bocki Westblad, 1949; with a discussion of epidermal cytoplasmic filament systems of invertebrates. Acta Zoologica (Copenhagen), 69(4), 231-246.
114. Peterson, K. J., Cameron, R. A., Tagawa, K., Satoh, N., & Davidson, E. H. (1999). A comparative molecular approach to mesodermal patterning in basal deuterostomes: the expression pattern of Brachyury in the enteropneust hemichordate Ptychodera flava. Development (Cambridge), 126(1), 85-95. (Pubitemid 29045902)
115. Petrov, A., Hooge, M., & Tyler, S. (2004). Ultrastructure of sperms in Acoela (Acoelomorpha) and its concordance with molecular systematics. Invertebrate Biology, 123(3), 183-197. (Pubitemid 39483888)
116. Petrov, A., Hooge, M., & Tyler, S. (2006). Comparative morphology of the bursal nozzles in acoels (Acoela, Acoelomorpha). Journal of Morphology, 267(5), 634-648. (Pubitemid 43666491)
117. Philippe, H., Brinkmann, H., Copley, R. R., Moroz, L. L., Nakano, H., Poustka, A. J., et al. (2011). Acoelomorph flatworms are deuterostomes related to Xenoturbella. Nature (London), 470(7333), 255-258.
118. Pleijel, F. (1995). On character coding for phylogeny reconstruction. Cladistics, 11(3), 309-315.
119. Popova, N. V., & Mamkaev, Y. V. (1985). Ultrastructure and primitive features of the eyes of Convoluta convoluta (Turbellaria Acoela). Doklady Akademii Nauk SSSR, 283(3), 756-759.
120. Raikova, O. I., Falleni, A., & Justine, J.-L. (1997). Spermiogenesis in Paratomella rubra (Platyhelminthes, Acoela): ultrastructural, immunocytochemical, cytochemical studies and phylogenetic implications. Acta Zoologica (Copenhagen), 78(4), 295-307. (Pubitemid 27526402)
121. Raikova, O. I., Reuter, M., Gustafsson, M. K. S., Maule, A. G., Halton, D. W., & Jondelius, U. (2004a). Evolution of the nervous system in Paraphanostoma (Acoela). Zoologica Scripta, 33(1), 71-88. (Pubitemid 38162372)
122. Raikova, O. I., Reuter, M., Gustafsson, M. K. S., Maule, A. G., Halton, D. W., & Jondelius, U. (2004b). Basiepidermal nervous system in Nemertoderma westbladi (Nemertodermatida): GYIRFamide immunoreactivity. Zoology, 107(1), 75-86. doi: 10.1016/J.Zool.2003.12.002. (Pubitemid 40427893)
123. Raikova, O. I., Reuter, M., Jondelius, U., & Gustafsson, M. K. S. (2000a). The brain of the Nemertodermatida (Platyhelminthes) as revealed by anti-5HT and anti-FMRFamide immunostainings. Tissue & Cell, 32(5), 358-365.
124. Raikova, O. I., Reuter, M., Jondelius, U., & Gustafsson, M. K. S. (2000b). An immunocytochemical and ultrastructural study of the nervous and muscular systems of Xenoturbella westbladi (Bilateria inc. sed.). Zoomorphology (Berlin), 120(2), 107-118.
125. Raikova, O. I., Reuter, M., & Justine, J.-L. (2001). Contributions to the phylogeny and systematic of the Acoelomorpha. In D. T. J. Littlewood & R. A. Bray (Eds.), Interrelationships of the Platyhelminthes (Vol. 60, pp. 13-23). London & New York: Systematics Association Special Volume Series.
126. Raikova, O. I., Reuter, M., Kotikova, E. A., & Gustafsson, M. K. S. (1998). A commissural brain! The pattern of 5-HT immunoreactivity in Acoela (Plathelminthes) [Platyhelminthes]. Zoomorphology (Berlin), 118(2), 69-77. (Pubitemid 128097516)
127. Ramachandra, N. B., Gates, R. D., Ladurner, P., Jacobs, D. K., & Hartenstein, V. (2002). Embryonic development in the primitive bilaterian Neochildia fusca: Normal morphogenesis and isolation of POU genes Brn-1 and Brn-3. Development Genes and Evolution, 212(2), 55-69. (Pubitemid 36075534)
128. Reisinger, E. (1960). Was ist Xenoturbella? Zeitschrift fuer Wissenschaftliche Zoologie, 164, 188-198.
129. Reisinger, E. (1961). Allgemeine Morphologie der Metazoen. Morphologie der Coelenteratcn, acoelomaten und pseudocoelomaten Würmer. Fortschritte der Zoologie, 13, 1-82.
130. Remane, A. (1963). The evolutionary origin of the coelom. In E. C. Dougherty (Ed.), The lower Metazoa. Los Angeles: University of California Press.
131. Reuter, M., Raikova, O. I., & Gustafsson, M. K. S. (1998). An endocrine brain? The pattern of FMRF-amide immunoreactivity in Acoela (Plathelminthes). Tissue & Cell, 30(1), 57-63. (Pubitemid 28142343)
132. Reuter, M., Raikova, O. I., & Gustafsson, M. K. S. (2001a). Patterns in the nervous and muscle systems in lower flatworms. Belgian Journal of Zoology, 131, 47-53.
133. Reuter, M., Raikova, O. I., Jondelius, U., Gustafsson, M. K. S., Maule, A. G., & Halton, D. W. (2001b). Organisation of the nervous system in the Acoela: An immunocytochemical study. Tissue & Cell, 33(2), 119-128. (Pubitemid 32457842)
134. Richter, S., Loesel, R., Purschke, G., Schmidt-Rhaesa, A., Scholtz, G., Stach, T., et al. (2010). Invertebrate neurophylogeny: suggested terms and definitions for a neuroanatomical glossary. Frontiers in Zoology, 7, 29.
135. Rieger, R. M. (1980). A new group of interstitial worms, Lobatocerebridae nov. fam. (Annelida) and its significance for metazoan phylogeny. Zoomorphologie (Berlin), 95(1), 41-84.
136. Rieger, R. M. (1985). The phylogenetic status of the acoelomate organization within the Bilateria: a histological perspective. In S. Conway Morris, J. D. George, R. Gibson, & H. M. Platt (Eds.), The origins and relationships of lower invertebrates (Vol. 28, pp. 101-122). Oxford: Clarendon Press.
137. Rieger, R. M. (1986). Über den Ursprung der Bilateria: die Bedeutung der Ultrastrukturforschung für ein neues Verstehen der Metazoenevolution. Verhandlungen der Deutschen Zoologischen Gesellschaft, 79, 31-50.
138. Rieger, R. M., & Ladurner, P. (2003). The significance of muscle cells for the origin of mesoderm in Bilateria. Integrative and Comparative Biology, 43(1), 47-54. (Pubitemid 36953166)
139. Rieger, R. M., Tyler, S., Smith, J. P. S., III, & Rieger, G. E. (1991). Platyhelminthes: Turbellaria. In F. W. Harrison & B. J. Bogitsh (Eds.), Microscopic Anatomy of Invertebrates. Volume 3. Platyhelminthes and Nemertinea (Vol. 3, pp. 7-140). New York: Wiley-Liss Inc.
140. Riser, N. W. (1987). Nemertinoides elongatus gen. n., sp. n. (Turbellaria: Nemertodermatida) from coarse sand beaches of the western north Atlantic. Proceedings of the Helminthological Society of Washington, 54(1), 60-67.
141. Ruiz-Trillo, I., Riutort, M., Littlewood, D. T. J., Herniou, E. A., & Baguñà, J. (1999). Acoel flatworms: earliest extant bilaterian metazoans, not members of Platyhelminthes. Science (Washington DC), 283(5409), 1919-1923. (Pubitemid 29144210)
142. Ruiz-Trillo, M., Riutort, M., Fourcade, H. M., Baguñà, J., & Boore, J. L. (2004). Mitochondrial genome data support the basal position of Acoelomorpha and the polyphyly of the Platyhelminthes. Molecular Phylogenetics and Evolution, 33(2), 321-332. (Pubitemid 39175116)
143. Ruppert, E. E., Fox, R. S., & Barnes, R. D. (2004). Invertebrate Zoology, a Functional Evolutionary Approach (7. ed.). Belmont, California; London: Thomson Brooks/Cole.
144. Salvenmoser, W., Egger, B., Achatz, J. G., Ladurner, P., & Hess, M. W. (2010). Electron Microscopy of Flatworms: Standart and Cryo-Preparation Methods. In T. Müller-Reichert (Ed.), Methods in Cell Biology (Vol. 96, pp. 307-330): Academic Press.
145. Salvini-Plawen, L. (1978). On the origin and evolution of the lower Metazoa. Zeitschrift fuer Zoologische Systematik und Evolutionsforschung, 16(1), 40-88.
146. Schärer, L., Littlewood, D. T. J., Waeschenbach, A., Yoshida, W., & Vizoso, D. B. (2011). Mating behavior and the evolution of sperm design. Proceedings of the National Academy of Sciences of the United States of America, 108(4), 1490-1495. doi: 10.1073/Pnas.1013892108.
147. Schimkewitsch, W. (1891). Versuch einer Klassiffikation des Tierreichs. Biologisches Zentralblatt, 11, 291-295.
148. Schuchert, P., & Rieger, R. M. (1990). Ultrastructural observations on the dwarf male of Bonellia viridis (Echiura). Acta Zoologica (Copenhagen), 71(1), 5-16.
149. Semmler, H., Bailly, X., & Wanninger, A. (2008). Myogenesis in the basal bilaterian Symsagittifera roscoffensis (Acoela). Frontiers in Zoology, 5(14).
150. Semmler, H., Chiodin, M., Bailly, X., Martinez, P., & Wanninger, A. (2010). Steps towards a centralized nervous system in basal bilaterians: insights from neurogenesis of the acoel Symsagittifera roscoffensis. Development Growth & Differentiation, 52(8), 701-713.
151. Sempere, L. F., Cole, C. N., McPeek, M. A., & Peterson, K. J. (2006). The phylogenetic distribution of metazoan microRNAs: insights into evolutionary complexity and constraint. Journal of Experimental Zoology Part B Molecular and Developmental Evolution, 306B(6), 575-588. (Pubitemid 44950649)
152. Sempere, L. F., Martinez, P., Cole, C., Baguna, J., & Peterson, K. J. (2007). Phylogenetic distribution of microRNAs supports the basal position of acoel flatworms and the polyphyly of Platyhelminthes. Evolution & Development, 9(5), 409-415. (Pubitemid 47383641)
153. Shannon, T., III, & Achatz, J. G. (2007). Convolutriloba macropyga sp. nov., an uncommonly fecund acoel (Acoelomorpha) discovered in tropical aquaria. Zootaxa, 1525, 1-17. (Pubitemid 47094514)
154. Sikes, J. M., & Bely, A. E. (2008). Radical modification of the A-P axis and the evolution of asexual reproduction in Convolutriloba acoels. Evolution & Development, 10(5), 619-631.
155. Sikes, J. M., & Bely, A. E. (2010). Making heads from tails: development of a reversed anterior-posterior axis during budding in an acoel. Developmental Biology, 338(1), 86-97.
156. Smith, J. P. S. (1981). Fine-structural anatomy of the parenchyma in the Acoela and Nemertodermatida (Turbellaria). Dissertation, University of North Carolina, Chapel Hill.
157. Smith, J. P. S., & Tyler, S. (1985a). The acoel turbellarians: kingpins of metazoan evolution or a specialized offshoot. In S. Conway Morris, J. D. George, R. Gibson, & H. M. Platt (Eds.), The origins and relationships of lower invertebrates (Vol. 27, pp. 123-142). Oxford: Clarendon Press.
158. Smith, J. P. S., & Tyler, S. (1985b). Fine-structure and evolutionary implications of the frontal organ in Turbellaria Acoela. 1. Diopisthoporus gymnopharyngeus sp. n. Zoologica Scripta, 14(2), 91-102.
159. Smith, J. P. S., & Tyler, S. (1986). Frontal organs in the
160. Smith, J. P. S., Tyler, S., & Rieger, R. M. (1986). Is the Turbellaria polyphyletic? Hydrobiologia, 132, 13-21.
161. Smith, J. P. S., Tyler, S., Thomas, M. B., & Rieger, R. M. (1982). The morphology of turbellarian rhabdites: phylogenetic implications. Transactions of the American Microscopical Society, 101(3), 209-228.
162. Stach, T., Dupont, S., Israelson, O., Fauville, G., Nakano, H., Kanneby, T., et al. (2005). Nerve cells of Xenoturbella bocki (phylum uncertain) and Harrimania kupfferi (Enteropneusta) are positively immunoreactive to antibodies raised against echinoderm neuropeptides. Journal of the Marine Biological Association of the United Kingdom, 85(6), 1519-1524. (Pubitemid 41607464)
163. Steinböck, O. (1966). Die Hofsteniiden (Turbellaria Acoela). Grundsätzliches zur Evolution der Turbellarien. Zeitschrift für Zoologische Systematik und Evolutionsforschung, 4, 58-195.
164. Sterrer, W. (1998). New and known Nemertodermatida (Platyhelminthes- Acoelomorpha) - a revision. Belgian Journal of Zoology, 128(1), 55-92. (Pubitemid 128487342)
165. Struck, T. H., Paul, C., Hill, N., Hartmann, S., Hoesel, C., Kube, M., et al. (2011). Phylogenomic analyses unravel annelid evolution. Nature (London), 471(7336), 95-98.
166. Taguchi, S., Tagawa, K., Humphreys, T., & Satoh, N. (2002). Group B Sox genes that contribute to specification of the vertebrate brain are expressed in the apical organ and ciliary bands of hemichordate larvae. Zoological Science (Tokyo), 19(1), 57-66. (Pubitemid 34881820)
167. Tekle, Y. I., Raikova, O. I., Ahmadzadeh, A., & Jondelius, U. (2005). Revision of the Childiidae (Acoela), a total evidence approach in reconstructing the phylogeny of acoels with reversed muscle layers. Journal of Zoological Systematics and Evolutionary Research, 43(1), 72-90. (Pubitemid 40256965)
168. Tekle, Y. I., Raikova, O. I., Justine, J.-L., & Jondelius, U. (2007). Ultrastructure and tubulin immunocytochemistry of the copulatory stylet-like structure in Childia species (Acoela). Journal of Morphology, 268(2), 166-180. (Pubitemid 46340258)
169. Telford, M. J., Lockyer, A. E., Cartwright-Finch, C., & Littlewood, D. T. J. (2003). Combined large and small subunit ribosomal RNA phylogenies support a basal position of the acoelomorph flatworms. Proceedings of the Royal Society of London Series B-Biological Sciences, 270(1519), 1077-1083. doi: 10.1098/Rspb.2003.2342. (Pubitemid 36605643)
170. Todt, C. (2009). Structure and evolution of the pharynx simplex in acoel flatworms (Acoela). Journal of Morphology, 270(3), 271-290.
171. Todt, C., & Tyler, S. (2007). Ciliary receptors associated with the mouth and pharynx of Acoela (Acoelomorpha): a comparative ultrastructural study. Acta Zoologica (Copenhagen), 88(1), 41-58. (Pubitemid 44968044)
172. Tyler, S. (1979). Distinctive features of cilia in metazoons and their significance for systematics. Tissue & Cell, 11(3), 385-400.
173. Tyler, S. (2001). The early worm: origins and relationships of the lower flatworms. In D. T. J. Littlewood & R. A. Bray (Eds.), Interrelationships of the Platyhelminthes (Vol. 60, pp. 3-12). London & New York: Systematics Association Special Volume Series.
174. Tyler, S., Grimm, J. K., & Smith, J. P. S. (1989). Dynamics of epidermal wound repair in Acoel Turbellarians - the Role of Pulsatile Bodies. American Zoologist, 29(4), A115-A115.
175. Tyler, S., & Rieger, R. M. (1974). Uniflagellate spermatozoa in Nemertoderma (Turbellaria) and their phylogenetic significance. Science (Washington DC), 188, 730-732.
176. Tyler, S., & Rieger, R. M. (1977). Ultrastructural evidence for the systematic position of the Nemertodermatida (Turbellaria). Acta Zoologica Fennica, 194-207.
177. Tyler, S., & Rieger, R. M. (1999). Functional morphology of musculature in the acoelomate worm, Convoluta pulchra (Plathelminthes). Zoomorphology (Berlin), 119(3), 127-141. (Pubitemid 129496424)
178. Tyler, S., Schilling, S., Hooge, M., & Bush, L. F. (2012). Turbellarian taxonomic database. Version 1.7. http://turbellaria.umaine.edu.
179. Uljanin, W. N. (1870). Die Turbellarien der Bucht von Sebastopol. Arbeiten der 2. Versammlung russischer Naturforscher zu Moskau, 1869, 1-96.
180. Ulrich, W. (1951). Vorschlage zu einer Revision der Grosseinteilung des Tierreiches. Verhandlungen der Deutschen Zoologischen Gesellschaft, 1950, 244-271.
181. Wallberg, A. (2012). The Stylet - Diversity and Systematics of Acoela and Nemertodermatida. http://acoela.myspecies.info.
182. Wallberg, A., Curini-Galletti, M., Ahmadzadeh, A., & Jondelius, U. (2007). Dismissal of Acoelomorpha: Acoela and Nemertodermatida are separate early bilaterian clades. Zoologica Scripta, 36(5), 509-523. (Pubitemid 47373559)
183. Webster, B. L., Copley, R. R., Jenner, R. A., Mackenzie-Dodds, J. A., Bourlat, S. J., Rota-Stabelli, O., et al. (2006). Mitogenomics and phylogenomics reveal priapulid worms as extant models of the ancestral Ecdysozoan. Evolution & Development, 8(6), 502-510. (Pubitemid 44657063)
184. Westblad, E. (1940). Studien über skandinavische Turbellaria Acoela. 1. Arkiv för Zoologi, 32A(20), 1-28.
185. Westblad, E. (1942). Studien über skandinavische Turbellaria Acoela. 2. Arkiv för Zoologi, 33A(14), 1-48.
186. Westblad, E. (1945). Studien über skandinavische Turbellaria Acolea. 3. Arkiv för Zoologi, 36A(5), 1-56.
187. Westblad, E. (1946). Studien über skandinavische Turbellaria Acoela. 4. Arkiv för Zoologi, 38A(1), 1-56.
188. Westblad, E. (1948). Studien über Skandinavische Turbellaria Acoela. 5. Arkiv för Zoologi, 41A(7), 1-82.
189. Westblad, E. (1949). Xenoturbella bocki n. g., n. sp. a peculiar, primitive turbellarian type. Arkiv för Zoologi, 1, 11-29.
190. Westheide, W., & Rieger, R. M. (2007). Systematik-Poster: Zoologie. Heidelberg: Spektrum Akademischer Verlag.
191. Wiens, J. J. (2001). Character analysis in morphological phylogenetics: Problems and solutions. Systematic Biology, 50(5), 689-699.
192. Winsor, L. (1988). A new acoel (Convolutidae) from the north Queensland coast, Australia. Progress in Zoology, 36, 391-394.
193. Xiang, Q. Y., & Thomas, D. T. (2008). Tracking character evolution and biogeographic history through time in Cornaceae - Does choice of methods matter? Journal of Systematics and Evolution, 46(3), 349-374. doi: 10.3724/Sp.J.1002.2008.08056.
194. Yamasu, T. (1991). Fine-structure and function of ocelli and sagittocysts of acoel flatworms. Hydrobiologia, 227, 273-282.