young, 2.5 mm
Placida kevinleei McCarthy, Krug & Valdes, 2017
|Maximum size: 6 mm.
species has an orange body with a few small cream flecks. The
distal half of the cerata, the ventral surfaces of the rhinophores and
the sides of the head are velvet-black. The rhinophores have a diffuse
dorsal white stripe confined to their bases (in contrast to the
similar-appearing Placida barackobamai in which the rhinophores have sharply bounded white stripes extending their full length). (Note 1)
is a rare species found in moderately exposed to highly
exposed rocky habitats at depths of 1-2 m (4-6 ft). According to
McCarthy, et. al. (2017), it's been found to feed primarily on the
filamentous green alga Derbesia sp. (Note 2)
Distribution: Big Island, Maui and Kauai: also known from Japan (probably widely distributed in the western & central Pacific).
Taxonomic notes: It was previously lumped (with Placida barackobamai) under the circumtropical species Placida cremoniana
(Trinchese, 1893). The latter, however, was recently found to be a
species complex as reported in McCarthy, J.B., P.J. Krug & A.
Valdes, 2017. It was first
recorded in Hawaii from Kalepolepo, Maui by PF on Nov. 18, 1991.
Photo: PF: 5 or 6 mm: Kalepolepo, Maui; Nov.18, 1991.
Observations and comments:
1: Although the basic pattern remains constant, the amount of black pigment on the rhinophores may increase with age.
McCarthy, et. al. (2017) suggests that its distinctive color pattern
is aposematic coloration associated with the retention of toxins from
food algae. However, some of our animals may have been taken in beds of Sargassum echinocarpum and/or Sargassum polyphyllum.
If that proves to be its primary habitat, perhaps the orange and black
coloration actually evolved as camouflage when crawling on Sargassum spp.? Presumably, the filamentous Derbesia is growing on or under the larger algae...