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Additional Photos
shell sculpture
underside
young, 1.5 mm
extensive granules
shell
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Retusa sp. #2
Maximum size: 3.8 mm.
Identification:
The
shell
of
this species has an involute apex plus fine axial ribs and
spiral striae. The animal is translucent cream with small
greenish-yellow granules embedded in its tissue. The granules appear to
become more prominent with age and the eye spots less prominent. The
shell profile may be variable. (Note 1)
Natural history:
Retusa sp. #2 is
known from only three live animals: one found in a sand sample
taken
off Keehi
Lagoon, Oahu; one taken in an algae wash at about 1 m (3 ft) at
Hekili Point, Maui and one taken in an algae wash at about 1 m (3 ft) near
mangroves at Coconut Island on Oahu. Two shells have been found in sand
samples from
depths of 10-20
m (33-66 ft) on Maui. The coconut Island animal produced an unusually
strong mucous "drag-line."
Distribution:
Big Island, Maui and Oahu.
Taxonomic notes:
There
is
some question whether this is actually a Retusa, pending further work. It was first recorded in Hawaii from a sand
sample collected at Black Rock,
Maui by CP (shell only). This
first live animal was probably recorded off Keehi Lagoon; Oahu by
the 2006 CREEF
expedition on Oct. 7, 2006.
Photo: CP: 2.6 mm: Hekili Point, Maui; Feb. 20, 2018.
Observations and comments:
Note
1: The illustrated shell from
Wahikuli (see photo) is a bit more slender than the others. So, there's
some chance that it may be a separate species. Shell profile could also change with growth.
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