on food hydroid
with egg masses
Doto sp. #2
|Maximum size: about 5 mm.
a small species with evenly tuberculate cerata. The body
is cream liberally blotched with black. The digestive gland showing
through the cerata is orange to dusky pink while the tubercles have black cores. The
tubercles are frosted with white (with a few denser white spots). The
rhinophore tips are white with a few opaque white spots and the rhinophore sheaths are black with
Doto sp. #2 is known from at least ten animals found on what appears to be Pennaria disticha
in a heavily shaded micro-habitat at a protected to moderately
protected harbor location. They were at a depth of less than 1 m (3 ft).
(Hai Van On, pers. com.) It feeds on what is probably Pennaria disticha
and lays a white, flattened, irregularly convoluted egg mass on its
host. Pairs of animals coil around the host hydroid when laying eggs. (Note 1).
Big Island: possibly known from Indonesia.
It was first
recorded in Hawaii from Kawaihae Harbor, Big Island by Hai Van On on April 28, 2019. (Note 2)
Photo: Hai Van On: about 5 mm: Kawaihae Harbor, Big Island; April 28, 2019.
Observations and comments:
1: The presence of paired animals with typical Doto egg masses on what appears to be Pennaria disticha
suggests that it feeds on that species. Also, the presence of
"dark-zone" octocoral polyps in some of the uncropped photos suggests a
heavily shaded micro-habitat.
Note 2: This species appears close to "Doto sp.
5" in Gosliner, et. al. (2018). However, it differs from it in
the color of its rhinophores and its host hydroid. It seems closer to the 15 mm Indonesian animal illustrated as "Doto sp. 18" at Seaslug World.
The white line on the edge of the rhinophore sheath is less well defined
in the Indonesian animal but that difference could be due to ontogeny. Based on its host hydroid, there's also some
possibility that it's introduced (if its host is actually P. disticha).