Halocynthia igaboja Oka, 1906

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 : 333-335

Halocynthia igaboja Oka, 1906

Halocynthia igaboja Oka 1906, p 45 ; Van Name 1945, p 362 (synonymy); Lambert and Sanamyan, 2001, p 1776.

Material examined

St. 6089, 170 m, four specimens; St. 6098, 200 m, three specimens.

Remarks

This species belongs to a group of several similar species which differ from each other mainly in external appearance, length of siphons, and shape and distribution of the spines on the test. The group includes several species described from Japan: H. hilgendorfi (Traustedt, 1885) , H. oaestoni Oka, 1906 , H. ritteri Oka, 1906 , H. igaboja Oka, 1906 , H. cactus Oka, 1932 , and the east Pacific species H. okai Ritter, 1907 . Although these species have been discussed by almost all ascidian taxonomists it is not clear if they are synonyms or a group of sibling species. Only one species has a recorded range from Alaska to California, but several are sympatric from northern Japan to the Korea Strait ( Lambert and Sanamyan, 2001). Huntsman (1912) synonymized H. okai with H. igaboja and the latter name is applied to the east Pacific specimens ( Van Name 1945; Lambert and Sanamyan 2001). East and west Pacific populations appear to be separated: the species is abundant in Alaska Bay and the eastern Aleutian Islands (we found it in dredged material collected by every expedition to that region), but not recorded in the west Pacific north of Japan and appears to be absent in Russian waters. Therefore, although H. okai may be distinct from H. igaboja , the question can be resolved only by comparison of further material.