young, about 60 mm
Pleurobranchus grandis Pease, 1868
|Maximum size: about 300 mm.
(Hoover, 2006); perhaps as large as 800 mm (Kay, 1979).
this species is covered with a tile-like pattern of
flattened tubercles composed of rings of smaller tubercles surrounding
larger central ones. Most mature Hawaiian animals range from dark red
brown to deep violet (cream and cream-spotted forms that are
common elsewhere in the Indo-Pacific are rare in Hawaii). Very young
animals are cream with violet-brown tipped tubercles that are
less developed than in mature animals.
Clusters of tubercles are separated by a network of white lines that
disappear as the animal matures.
Natural history: On
Maui, Pleurobranchus grandis
is a moderately rare species that we've found at moderately exposed to
rocky sites at depths of 5-10 m (15-33 ft) as well as in moderately
protected sand habitats at 18 m (60 ft). However, it's listed as
common at depths of about 30 m (98 ft)" in Kay, 1979 and has also been
to depths of 74
m (243 ft) by HURL submersibles. Rarely, it can be found in tide pools.
Like Pleurobranchus forskalii,
it usually carries the posterior portion of its mantle in a siphon-like
fold (see photo).
Maui, Oahu and Kauai: Widely distributed in the Indo-Pacific.
Pease, 1864 in Kay, 1979 appears to refer to this species. Goodheart, et. al. (2015) tentatively lists Pleurobranchus violaceus Pease, 1863 as a synonym of P. grandis. However, it also seems possible that Pease's animals were Pleurobranchus peronii (due to ambiguity in the description and the likely depth of collection). It's listed as Pleurobranchus
sp. 2 in Hoover, 1998 and is referred to as the "tiled pleurobranch" in
Hoover, 1998 & 2006.
Johnson: about 150 mm: found by Stan Jazwinski; Kihei, Maui; Aug., 1977.
Observations and comments:
1: ( )