CLADISTIC CLASSIFICATION OF CELLEPORID BRYOZOANS USING LARVAL AND METAMORPHIC CHARACTERS.

通过对蜂窝虫幼虫形态特征的分析，确定了6个重要的分类学特征：1)冠，2)苍白上皮，3)口腔上皮，4)交代囊，5)梨状器官，6)间质。其中，对北海道7种麻孢虫的白质、口腔上皮和交代囊3个稳定性状进行了研究。这3个性状的极性转换结果表明，伪细孢虫属来源于细孢虫属。然而，在Celleporina的种中，这三个性状的转化序列并不重合。然后应用外群比较来确定哪个特征反映了celleporids的真实系统发育。由于Cellepora、Galeopsis和Lagenipora这三个属尚未明确，因此暂定作为外群。得到的三个梯形图不一致。在目前的研究中，我无法得到任何关于哪个枝状图包含一个真正的系统图的答案，因为没有数据表明三个属中哪一个是celleporids的外群。因此，本研究完成了对北海道麻虫幼虫的特征分析，但没有得到麻虫幼虫的枝状图和系统分布图。对于没有适当外群的分类单元的枝系分类，需要用外群比较以外的方法来确定转换序列的极性。

Character analysis for the morphology of celleporids larvae distinguished six taxonomically important characters as follows: 1)corona, 2)pallial epithelium, 3)oral epithelium, 4)metasomal sac, 5)pyriform organ, and 6)messenchyme. Among them, three stable characters, pallial and oral epithelium and metasomal sac, were examined in the seven species of celleporids from Hokkaido. The polarity of the three characters transformed among the celleporids revealed that Pseudocelleporina was derived from the species of Celleporina. Among the species in Celleporina, however, the transformation series of the three characters did not coincide with each other. An out-group comparison was then applied to determine which character reflected a true phylogeny of the celleporids. Since the closest relative of celleporids has not been specified, three genera, Cellepora, Galeopsis, and Lagenipora were tentatively chosen as the out-groups. Three cladograms obtained did not agree with each other. In the present study, I was not able to get any answer to the question which cladogram involved a true phylogram, because there was no data to show which one of the three genera was the out-group of celleporids. As a result, present study anyhow accomplished the character analysis of celleporid larvae, but resulted neither cladograms nor phylograms of the species from Hokkaido. For cladistic systematics of a taxon without any appropriate out-group, a method other than the out-group comparison is needed to determine the polarity of a transformation series of characters.