Posted: May 1 2017
Olivella mutica (Say, 1822), Variable Dwarft Olive
O. mutica and O. pusilla (Marrat, 1871) were discussed and
compared on LTS in Dec 2006. This discussion is inserted
below. Much of the content has been consolidated and is
reflected in the presentation of O. pusilla.
Tom Watters asked after reviewing photos of O. pusilla
posted on LTS:
"Ok, so what are the key differences between O. pusilla and
"I don't know why, but O. mutica is poorly treated.
Apparently, Redfern did not find it in the Bahamas.
DeJong and Coomans did not report it from Curacao,
Aruba and Bonaire. Gunther Sterba does not even mention
it in his Olividae A Collectors Guide. Abbott does treat it.
So, let's see what he reported and compare it with O. pusilla.
The adjacent slides and following text discuss Abbott's and
my perception of the differences between these two taxa.
Sutures: Abbot does not mention the sutures of O. mutica,
but indicates that those of O. pusilla are narrowly channeled.
To me, both appear to have deep, open, well defined
sutures. However, the sutures of O. pusilla are very often
partially hidden by an elevated, translucent ridge (collar) that
runs around the top of each whorl.
Here's what I see:
Patterning: The color patterning of O. mutica is very
characteristic in most specimens. On the body whorl there
is a color band just below the suture with a jagged lower
edge. Then, there is a narrow, white or lighter colored band
(sometimes with pattering). Then comes a wide band of
color that extends down to the top of the fasciole where
there is another narrow, white or lighter colored band.
Overall shape: I'd describe O. mutica as more globose than
Abbott's description of O. pusilla as being "subelliptical to
Columella: The columella of O. mutica looks to me as
distinctly concave versus almost straight in O. pusilla."
Click here for numerous images of Olivella mutica.
Here's a direct comparison of a live O. pusilla and a live O. mutica:
O. pusilla from Mosquito Lagoon, Brevard County, FL O. mutica from Little Talbot Island State Park,
Photo by Marlo Krisberg Duval County, FL. This photo from the Jacksoville
Shell Club site. I believe photo is by Bill Frank