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The internal-brooding apparatus in the bryozoan genus Cauloramphus (Cheilostomata : Calloporidae) and its inferred homology to ovicells. / Ostrovsky, Andrew N.; Dick, Matthew H.; Mawatari, Shunsuke F.
In: Zoological Science, Vol. 24, No. 12, 12.2007, p. 1187-1196.Research output: Contribution to journal › Article › peer-review
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TY - JOUR
T1 - The internal-brooding apparatus in the bryozoan genus Cauloramphus (Cheilostomata
T2 - Calloporidae) and its inferred homology to ovicells
AU - Ostrovsky, Andrew N.
AU - Dick, Matthew H.
AU - Mawatari, Shunsuke F.
PY - 2007/12
Y1 - 2007/12
N2 - 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.
AB - 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.
KW - Bryozoa
KW - Cauloramphus
KW - Evolution
KW - Homology
KW - Internal brooding
KW - Ovicell
UR - http://www.scopus.com/inward/record.url?scp=39149139036&partnerID=8YFLogxK
U2 - DOI: 10.2108/zsj.24.1187
DO - DOI: 10.2108/zsj.24.1187
M3 - Article
C2 - 18271635
VL - 24
SP - 1187
EP - 1196
JO - Zoological Science
JF - Zoological Science
SN - 0289-0003
IS - 12
ER -
ID: 5055292