Confidence: It's likely to be this, but I can't be certain.
Notes: Xantho incisus, as it used to be called, is distinguished from Xantho pilipes which has a dense fringe of hairs on all the walking leg segments.
gives the current name for this species as Xantho hydrophilus, but WORMS gives the accepted name for X. incisus as Lophozozymus incisus, http://www.marinespecies.org/aphia.php?p=taxdetails&id=148461
and lists X. hydrophilus as a separate species. http://www.marinespecies.org/aphia.php?p=taxdetails&id=107440