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Hokkaido University Collection of Scholarly and Academic Papers >
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Peer-reviewed Journal Articles, etc >
The Internal-Brooding Apparatus in the Bryozoan Genus Cauloramphus (Cheilostomata: Calloporidae) and Its Inferred Homology to Ovicells
| Title: | The Internal-Brooding Apparatus in the Bryozoan Genus Cauloramphus (Cheilostomata: Calloporidae) and Its Inferred Homology to Ovicells |
| Authors: | Ostrovsky, Andrew N. Browse this author | | Dick, Matthew H. Browse this author →KAKEN DB | | Mawatari, Shunsuke F. Browse this author →KAKEN DB |
| Keywords: | Bryozoa | | Cauloramphus | | ovicell | | internal brooding | | evolution | | homology |
| Issue Date: | Dec-2007 |
| Publisher: | Zoological Society of Japan |
| Journal Title: | Zoological Science |
| Volume: | 24 |
| Issue: | 12 |
| Start Page: | 1187 |
| End Page: | 1196 |
| Publisher DOI: | 10.2108/zsj.24.1187 |
| Abstract: | We studied by SEM the external morphology of the ooecium in eight bryozoans of the genus Cauloramphus Norman, 1903 (Cheilostomata, Calloporidae): C. spinifer, C. variegatus, C. magnus, C. multiavicularia, C. tortilis, C. cryptoarmatus, C. niger, and C. multispinosus, and by sectioning and light microscopy the anatomy of the brooding apparatus of C. spinifer, C. cryptoarmatus, and C. niger. These species all have a brood sac, formed by invagination of the non-calcified distal body wall of the maternal zooid, located in the distal half of the maternal (egg-producing) autozooid, and a vestigial, maternally budded kenozooidal ooecium. The brood sac comprises a main chamber and a long passage (neck) opening externally independently of the introvert. The non-calcified portion of the maternal distal wall between the neck and tip of the zooidal operculum is involved in closing and opening the brood sac, and contains both musculature and a reduced sclerite that suggest homology with the ooecial vesicle of a hyperstomial ovicell. We interpret the brooding apparatus in Cauloramphus as a highly modified form of cheilostome hyperstomial ovicell, as both types share 1) a brood chamber bounded by 2) the ooecium and 3) a component of the distal wall of the maternal zooid. We discuss Cauloramphus as a hypothetical penultimate stage in ovicell reduction in calloporid bryozoans. We suggest that the internal-brooding genus Gontarella, of uncertain taxonomic affinities, is actually a calloporid and represents the ultimate stage in which no trace of the ooecium remains. Internal brooding apparently evolved several times independently within the Calloporidae. |
| Type: | article |
| URI: | http://hdl.handle.net/2115/56381 |
| Appears in Collections: | 理学院・理学研究院 (Graduate School of Science / Faculty of Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: Matthew Hill Dick
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