Cerianthids (Anthozoa, Cnidaria) from Bengual Upwelling Region. 2. Cerianthus malakhovi and composition of the genus Cerianthus

摘要

The new species, Cerianthus malakhovi Molodtsova, from Bengual upwelling is described. Some features of microscopic anatomy and the cnidom of Cerianthus malakhovi Molodtsova are discussed. In Cerianthus malakhovi Molodtsova none of the mesenterial pairs does reach the gastral cavity bottom. This feature distinguishes the new species from C. moriensenii Carlgren 1924, C. punctatus Uchida 1979, C. japonicus Carlgren 1924, C. sulcatus McMurrich 1910, C. membranaceus (Spallanzani 1784), C. misakiensisNakamoto 1923, C. lloydii Gosse 1859, and C. vogti Danielssen 1890. Cerianthus malakhovi Molodtsova has several well-developed craspedonemes in the aboral part of the ciliated tract on each mesentery except deriotives in contrast with C. lloydii Gosse 1859, C. taedus McMurrich 1910, C. tenebrarum Alcock 1893, and C. valdivae Carlgren 1912. The new species differ from C. lloydii Gosse and C. valdivae Carlgren by the presence of the unpaired directive tentacle in the labial set. The composition of the genus Cerianthus is discussed and a key to identifying eleven valid species is given. The analysis of the type specimens C. borealis Verrill 1873 and C. nobilis Haddon et Shackelton 1894 showed that these species should be refereed to the genus Pachycerianthus Roule 1904.