Cribrimorph and Other Cauloramphus Species (Bryozoa: Cheilostomata) from the Northwestern Pacific

We provide original descriptions for nine new species in the cheilostome bryozoan genus Cauloramphus (C. gracilis, C. Ordinarius, C. amphidisjunctus, C. cheliferoides, C. oshurkovi, C. infensus, C. parvus, C. peltatus, and C. ascofer) and a redescription of C. disjunctus Canu and Bassler, 1929. We delineate a group of eight species, here termed the ‘C. disjunctus clade,’ that have the opesial spine joints calcified to a greater or lesser extent in mature zooids; most also have paired, hypertrophied avicularia. This group includes C. amphidisjunctus, C. cheliferoides, C. infensus, C. parvus, C. peltatus, and C. ascofer in the Aleutian Islands, Alaska; C. oshurkovi in the Commander Islands; and C. disjunctus in Japan. High levels of apparent endemism in two unrelated bryozoan genera (Cauloramphus and Monoporella), and geographical population differentiation in C. ascofer indicating ongoing allopatric speciation, suggest high speciation rates for deep benthic bryozoans in the western Aleutians. A phylogenetic hypothesis for the C. disjunctus clade indicates that populations of Cauloramphus dispersed between the Aleutians and Asia on at least three separate occasions, and that the polarity of at least two of these dispersal events was from the Aleutians to Asia.

[1]  A. M. Norman.  Notes on the natural history of east Finmark. Polyzoa. , 2009 .

[2]  F. Canu.  Bryozoa of the Philippine Region , 2009 .

[3]  S. Lidgard,et al.  The origin of ascophoran bryozoans was historically contingent but likely , 2009, Proceedings of the Royal Society B: Biological Sciences.

[4]  G. J. Allman.  A Monograph of the Fresh-Water Polyzoa, Including all the Known Species, both British and Foreign , 2009 .

[5]  M. Dick,et al.  The Internal-Brooding Apparatus in the Bryozoan Genus Cauloramphus (Cheilostomata: Calloporidae) and Its Inferred Homology to Ovicells , 2007, Zoological science.

[6]  M. Dick,et al.  Diversity and taxonomy of intertidal Bryozoa (Cheilostomata) at Akkeshi Bay, Hokkaido, Japan , 2007 .

[7]  George L. Hunt,et al.  Oceanography and ecology of the Aleutian Archipelago: spatial and temporal variation , 2005 .

[8]  M. Dick,et al.  Intertidal Bryozoa (Cheilostomata) of the Kodiak vicinity, Alaska , 1988 .

[9]  S. Mawatari,et al.  Studies on Japanese Anascan Bryozoa 9 : Division Malacostega (7) , 1984 .

[10]  G. L. Snyder,et al.  Preliminary Report on the Geology of the Aleutian Islands. , 1954, Science.

[11]  M. Dick.  Unexpectedly High Diversity of Monoporella (Bryozoa: Cheilostomata) in the Aleutian Islands, Alaska: Taxonomy and Distribution of Six New Species , 2008, Zoological science.

[12]  T. Hamilton,et al.  Glacial Geology of the Aleutian Islands: Based on the contributions of Robert F. Black , 1986 .

[13]  J. D'hondt.  Contribution à la systématique des Bryozoaires Eurystomes. Apport récents et nouvelles propositions , 1985 .

[14]  R. S. Bassler,et al.  The bryozoan fauna of the Galapagos Islands , 1930 .

[15]  R. S. Bassler,et al.  Fossil and Recent Bryozoa of the Gulf of Mexico region , 1928 .

[16]  A. Ortmann.  Die Japanische Bryozoenfauna. Bericht uber die von Herrn Dr. L. Doderlein in Jahre 1880-1881 gemachten Sammlungen , 1890 .

[17]  Rev. Thomas Hincks B.A. F.R.S..  VIII.—On Polyzoa from Iceland and Labrador , 2022 .