Phyllidiella rosans (Bergh, 1873)
|Maximum size: about 38 mm
has a black notum with 5-7 smooth, longitudinal, pink ridges that
may be continuous or interrupted. In all or most Hawaiian animals, the
central ridges coalesce to form complete or partial rings
in the center of the notum. (Note 1) The mantle
is edged in pink. The
rhinophores are black.
This is a
rarely-seen phyllidiid that has been found in the open in rocky
areas as well as inside caverns. It lives in moderately protected to
highly exposed habitats from 5-37 m (16-120 ft). Scott Johnson reports
it feeding on an yellow sponge.
Big Island, Maui, Lanai, Oahu and Niihau: widely distributed in
the species illustrated as Phyllidia
sp. and listed as Phyllidia nigra
Pease, 1868c in Kay, 1979 (the photo of the latter is probably of Phyllidiopsis sphingis). It is
referred to as the "rosy Phyllidia" in Hoover, 1998 & 2006.
Photo: PF: 16
mm: Makena, Maui; Nov. 1989.
Observations and comments:
1: Since P. rosans from elsewhere in the
Indo-Pacific lack this feature, there's some chance that the
Hawaiian population might prove to be endemic when DNA is examined.