Phylogenetic position of the marine ciliate, Cardiostomatella vermiforme (Kahl, 1928) Corliss, 1960 inferred from the complete SSrRNA gene sequence, with establishment of a new order Loxocephalida n. ord. (Ciliophora, Oligohymenophorea)

摘要

The small subunit rRNA (SSrRNA) gene was sequenced for Cardiostomatella vermiforme, a large marine ciliate the systematic position of which is uncertain but which has been regarded as a scuticociliate for about forty years. The present work indicates that this organism, together with a closely related species, Dexiotrichides pangi, always form a separate assemblage as a sister group to the scuticociliates sensu stricto. The fact that the clade comprising Cardiostomatella and Dexiotrichides branches between the typical scuticociliates and Hymenostomatia, and shares a series of morphological and morphogenetical characters with both, supports the conclusion that it belongs to an intermediate group between the two. We suggest that this group represents a new order, Loxocephalida n. ord. within the subclass Scuticociliatia, which possibly contains all taxa within the families Loxocephalidae and Cinetochilidae and with Loxocephalidae as the type family. (c) 2006 Elsevier GrnbH. All rights reserved.