Abstract
Additional evidence has been obtained that demonstrates the low capacity of ascidians to polyploidize. The evolution of ascidians appears to have been accompanied by a decrease of chromosome number within the Phlebobranchiata, and by both a decrease and increase of chromosome number in the other two suborders, Aplousobranchiata and Stolidobranchiata. There are indications that the basic chromosome number, 2n=32, of Stolidobranchiata is of very early origin within the class Ascidiacea.
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Literature Cited
Bancroft, F.W.: Ovogenesis in Distaplia occidentalis Ritter, with remarks on other species. Bull. Mus. comp. Zool. Harv. 35, 59–112 (1899)
Colombera, D.: I cromosomi di Botryllus schlosseri (Ascidiacea). Ricerca scient. 33, 443–448 (1963)
—: I cromosomi di Botryllus schlosseri e Botrylloides leachi (Ascidiacea). Boll. Zool. 34, p. 105 (1967)
—: Il numero dei cromosomi in alcune popolazioni di Ascidiacei. Boll. Zool. 35, p. 446 (1968)
—: The karyology of the colonial ascidian Botryllus schlosseri Pallas. Caryologia 22, 339–350 (1969)
—: A squash method for chromosomes of ascidians (Tunicata). Caryologia 23, 113–115 (1970)
—: Number and morphology of chromosomes in three geographic populations of Ascidiella aspersa (Ascidiacea). Mar. Biol. 11, 149–151 (1971a)
—: The chromosomes of ascidians. Boll. Zool. 38, 187–191 (1971b)
—: The karyology of Clavelina lepadiformis Müller (Ascidiacea). Caryologia 24, 59–64 (1971c)
—: Pre-anaphase separation of daughter kinetochores in ascidian embryos. Caryologia 26, 35–41 (1973)
— e G. Benetton: L azione della colchicina sulle mitosi embrionali di Botryllus schlosseri. Boll. Zool. 36, p. 372 (1969)
— and M. Sala: The male chromosomes of Diplosoma listerianum. Caryologia 25, 409–415 (1972)
Colombera, D. and M. Tenca: The karyology of Ascidia mentula Müller. Cytologia. (In press).
Crampton, H.E.: Early stages in the development of Molgula. Am. Nat 32, p. 126 (1898)
Floderus, M.: Ueber die Bildung der Follikelhüllen bei der Ascidien. Z. wiss. Zool. 61, 163–260 (1896)
Hill, B.A.: Notes on the fecundation of the egg of Sphaerechinus granularis, and on the maturation and fertilization of the egg of Phallusia mammillata. Q. J1 microsc. Sci. 150, 315–330 (1895)
Matthey, R.: Cytologie de la parthénogénèse chez Pycnocelus surinamensis L. Revue stisse Zool. 52, 1–109 (1945)
Minganti, A.: Ricerche citologiche sugli ibridi di ascidie. Atti Accad. naz. Lincei Rc. (Ser. 8) 12, 125–127 (1952)
—: I cromosomi nei tunicati. Boll. Zool. 23, 299–315 (1956)
—: Ricerche su ibrídi dí ascidie. Boll. Zool. 34, 142–143 (1967)
Minouchi, O.: Notiz über die Chromosomen von Thethyum plicatum Les. Z. Zellforsch. mikrosk. Anat. 23, 790–794 (1936)
Taylor, K.M.: The chromosomes of some lower chordates. Chromosoma 21, 181–188 (1967)
Zwillenberg, L.O. and H.H.L. Zwillenberg: Chromosome counts in tunicates and a modified method for making permanent squash preparations. Nature, Lond. 173, 876–877 (1954)
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Communicated by B. Battaglia, Padua
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Colombera, D. Chromosome number within the class Ascidiacea. Mar. Biol. 26, 63–68 (1974). https://doi.org/10.1007/BF00389087
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DOI: https://doi.org/10.1007/BF00389087