Chelyosoma columbianum Huntsman, 1912

Sanamyan, K. E. & Sanamyan, N. P., 2006, Deep-water ascidians (Tunicata: Ascidiacea) from the northern and western Pacific, Journal of Natural History 40 (5 - 6), pp. 307-344 : 309

Chelyosoma columbianum Huntsman, 1912

Chelyosoma columbianum Huntsman 1912, p 124 ; Ritter 1913, p 486; Van Name 1945, p 208; Sanamyan 1998, p 110.

Material examined

St. 6089, 170 m, 25 specimens.

Remarks

All newly recorded specimens are identical to the one from the Commander Islands ( Sanamyan 1998). They all have two central plates connected by short muscles, and 8–11 marginal plates. None of the 25 examined specimens had intermediate plates that Huntsman (1912) recorded for this species. Huntsman (1912) stated that C. columbianum may be readily distinguished from C. productum Stimpson, 1864 by the presence of short muscles connecting the two central plates. Ritter (1913) based his assignation of specimens from the Strait of Juan de Fuca to C. columbianum solely on this feature. However, it is possible that the muscles between the central plates have been overlooked in those specimens assigned to C. productum and it may not differ from C. columbianum . Unfortunately no specimens clearly referable to C. productum (with elongated body and more numerous marginal plates) were available to confirm this view. The present species cannot be confused with the other north Pacific species of Chelyosoma , which either have a single central plate ( C. macleayanum Broderip and Sowerby, 1830 and C. orientale Redikorzev, 1911 ), or lack the plates on the disk ( C. inaequale Redikorzev, 1913 ).