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

mutica?"

Marlo:

"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

bullet-shaped."

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