|Maximum size: 11 mm shell
The shell of this species is highly flattened with the apex set well to
the left of the midline and the posterior ribs noticeably better
developed than the anterior ribs. (Note 1).
Shells of Siphonaria sp. #1
are moderately common in beach drift. Live animals are moderately common
at moderately exposed rocky sites. They are usually found lower in the
intertidal than Siphonaria normalis.
Big Island, Maui, Kahoolawi and Oahu.
This species probably corresponds to Siphonaria normalis form chirura as illustrated in Pilsbry, 1921 and Edmondson, 1946.
largest 11 mm: composite photo, two shells; beach drift, Mokuleia Bay,
Maui; fall, 1984.
Observations and comments:
1: While shells of Siphonaria normalis vary
considerably from site to site but are fairly uniform at a given site,
the shells of Siphonaria sp.
#1 are consistent in form throughout coastal Maui where they are
sympatric with the "typical" form of S.
normalis at each location. This
may support the suggestion that it's a distinct species.