A report of four unrecorded species of opisthobranch molluscs from Korea Author Jung, Daewui Author Lee, Jongrak Author Kim, Chang-Bae text Journal of Species Research 2014 2014-02-28 3 1 1 6 http://dx.doi.org/10.12651/jsr.2014.3.1.001 journal article 10.12651/JSR.2014.3.1.001 2713-8615 8120252 Genus Pleurobranchus Cuvier, 1804 Diagnosis. Retractable conical tubercles on mantle. Gills with double row of alternated tubercles on rhachis. Large internal shell, about half of body length. External penial sheath non-retractable, surrounding genital opening ( Thompson, 1976 ).