Lacydoniidae (Annelida) Off the Coast of North-eastern Japan: A Descriptionof Lacydonia japonica sp. nov.

摘要

Lacydonia japonica sp. nov. (Annelida, Lacydoniidae) is described based onmaterial found in sediments collected off the Pacific coast of northern Honshu, Japan, atdepths of 262 m and 407 m. The sediments were obtained by a remotely operated vehicleequipped with a suction sampler during a Tohoku Ecosystem-Associated Marine Sciences(TEAMS) project in 2019. Lacydonia japonica sp. nov. belongs to theeyeless group of lacydoniids and is discriminated from the morphologically most similarcongener, Lacydonia papillata Uschakov, 1958 by its reddish pigments onboth the dorsal and ventral parapodial cirri and four pigment spots on the pygidium. Toassess the phylogenetic position of the new species among other lacydoniids for whichsequence data are available in public databases, analyses were performed using themitochondrial cytochrome c oxidase subunit I (COI) and16S rRNA, as well as the nuclear 18S rRNA and 28S rRNA genes. We additionally obtainedsome lacydoniids by sledging off western Japan, but these were severely fragmented andbroken during collection. Using the paucity of morphological data, they were leftunidentified as Lacydonia sp. but included in the molecular analyses.Genetic distances between Lacydonia eliasoni Hartmann-Schröder, 1996,Lacydonia japonica, and Lacydonia sp. off westernJapan were 10.4–17.1% uncorrected p-distance (11.3–18.6% K2P) in terms of658-bp COI sequences.