Taxonomy and regeneration of a newly recorded Polychaete Capitella teleta (Annelida, Capitellidae) in the coastal water of Shandong, China

Abstract

The polychaete species of Capitella are widely distributed in the China seas, however little is known about Capitella taxonomy, and specimens collected from China have been identified as Capitella capitata (Fabricius, 1780) for more than 50 years. C. capitata was considered to be Arctic and subarctic in distribution, therefore the records of C. capitata in the China seas probably represent other species. A taxonomic study based on the samples collected from the northeast coastal water of Shandong Province reveals a different species, Capitella teleta Blake et al., 2009, which is recorded in the China seas for the first time. Morphologically, C. teleta can be easily distinguished from C. capitata by the absence of neuropodial capillaries on chaetigers 8 and 9. The identity of C. teleta is further supported by genetic distance and phylogenetic analyses assessed from mitochondrial cytochrome c oxidase subunit I (COI) gene. In addition, the regeneration feature of C. teleta was studied through whole mount immunohistochemistry and chemical staining. After amputation, the wound of C. teleta was healed within 24 h, forming a significant regeneration blastema by 3 days post amputation (dpa). By 5 dpa, muscle tissues regenerated, nerve fibers also extended. By 7 dpa, neurites and muscle tissues are both significantly regenerated. Notably, there are more than ten segments regenerated until 16 dpa. As a highly opportunistic species, Capitella teleta is distributed in China, Japan, Korea, North America, and the Mediterranean. It is expected to be an excellent model for studying developmental genetics and evolution of regeneration.