Molecular identification and larval morphology of spionid polychaetes (Annelida, Spionidae) from northeastern Japan Author Abe, Hirokazu https://orcid.org/0000-0002-7753-9368 Department of Biology, Center for Liberal Arts & Sciences, Iwate Medical University, Idaidori 1 - 1 - 1, Yahaba-cho, Shiwa-gun, Iwate 028 - 3694, Japan habe@iwate-med.ac.jp Author Sato-Okoshi, Waka Laboratory of Biological Oceanography, Graduate School of Agricultural Science, Tohoku University, Aramaki-Aza-Aoba 468 - 1, Aoba-ku, Sendai 980 - 8572, Japan text ZooKeys 2021 2021-02-04 1015 1 86 http://dx.doi.org/10.3897/zookeys.1015.54387 journal article http://dx.doi.org/10.3897/zookeys.1015.54387 1313-2970-1015-1 F6BD92139DB74564AA003C61B2F43B2D AF1641758561525C8D40BBF3F895FA8A Scolelepis sp. 1 Fig. 4J, K Larval morphology. Thick and fusiform in overall shape. Prostomium pointed anteriorly as a small process, tip of prostomium terminates in retractile, muscular tip. Lateral parts of peristomium clearly demarcated from prostomium, forming large peristomial umbrella. Peristomial umbrella carrying well-developed prototroch. Short palps developed in late larvae, attached on lateral-most parts of peristomium. Two pairs of red eyes arranged in an approximately straight line. Pharynx pigmented orange and the gut pigmented brown. Pygidium broad and spherical. Remarks. Adult individuals of this species were collected from muddy sediments at 22 m depth in Onagawa Bay in December 2011 by using a Smith-McIntyre grab sampler. These adults were morphologically identified as Scolelepis , but they were not identified to species level as these specimens were all incomplete and in poor condition. As the 18S and 16S rRNA gene sequences obtained in the present study did not match any available Scolelepis sequences (Figs 2 , 3 ), this species was referred to Scolelepis sp. 1. Planktonic larvae of this species were collected in Onagawa Bay in October during the study period. The larvae and adults were confirmed to match using molecular data (Fig. 3 ).