young, 3.5 mm
Dendrodoris krusensternii (Gray, 1850)
|Maximum size: about 38 mm.
The notum of this species is covered with fleshy tubercles of varying
sizes except in 3-4 paired areas on either side of the mid-line where
it is smooth. The body is translucent brown with a variable
amount of white spotting. Within each of the smooth areas is one large
(or, sometimes, several small) iridescent
blue spots. (Note 1) The rhinophores are gold to brown with white tips and brown
stalks while the gills are translucent cream with dark brown edges. The
tubercles become more elaborate in larger animals.
is a moderately rare species that has been found in protected to
highly exposed rocky habitats from 1-110 m (3-361 ft). It lays a
Big Island, Maui, Oahu, Kauai and Midway: widely distributed in the Indo-Pacific.
Taxonomic notes: This species was first recorded in Hawaii off Hale'iwa, Oahu by Terry Gosliner in
1972 (dredged). It's listed in many sources as Dendrodoris denisoni (Angas, 1864). (Note 2)
Photo: PF: 30
mm: Midway Atoll: June 7, 1993.
Observations and comments:
1: The blue spots on a gold background aren't as precisely matched to the blue and gold ocelli found in the sea hares Stylocheilus
striatus and Phycophila euchlora as are the markings in some other possible mimics.
But, perhaps they are close enough so that D. krusensternii is
still deriving some benefit from the resemblance (since the sea hares
are known to concentrate toxins from the cyanobacteria they eat)?
Note 2: There's some chance that animals with single blue spots in their lateral depressions and many light
pustules on the tips of their tubercles might turn out to be different
from animals with multiple blue spots in their lateral depressions and
few light pustules on the tips of their tubercles.