Phyllidia carlsonhoffi  Brunckhorst, 1993

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Phyllidia carlsonhoffi is characterized by alternating large conical and small rounded tubercles (not joined as ridges), and a median black line on the foot sole.
I misidentified this 2 mm specimen on 13 July 2011 as juvenile Phyllidia carlsonhoffi because of the large isolated conical tubercles.
On 21 May 2012 I saw some of the small yellowish feet, and realized it is a juvenile sea cucumber, a Pearsonothuria graeffei (Semper, 1868)!
Pretty similar are:
Phyllidia varicosa which also has a median black line on the foot sole. It differs by its notal ridges and compound blue-grey tubercles.
Phyllidia tula which also has a median black line on the foot sole. It is more tuberculate with a graduated series of tubercles which decreases in size from very large in the centre to tiny and closely packed at the margin.
Phyllidia madangensis lacks the alternating smaller tubercles, its larger tubercles are sparsely scattered, and it lacks markings on the foot sole, unique is a small tubercle immediately in front of each rhinophoral pocket.
More information on Phyllidia carlsonhoffi are on Bill Rudman's Sea-Slug Forum!
How to cite:
Köhler, E. (2017), published 26 February 2017, Phyllidia carlsonhoffi  Brunckhorst, 1993
available from https://www.Philippine-Sea-Slugs.com/Nudibranchia/Euctenidiacea/Phyllidia_carlsonhoffi.htm