Lima anatomy & Species ID

In studying some live Lima collected over the weekend I am trying to ascertain
a few details...
Since I have not found in any of my literature good anatomical information
concerning Lima I am throwing this out to all of you for your help.

Species:  Somewhat resembles Lima pellucida

Where:     South Texas (South Padre Island)  from an inter-tidal rock pile.
Quantity:  3 currently, in addition to 4 specimens 2 weeks ago.

Description
1)  Size:  They are all well under 1", most 1/2" or less.
This size is consistent for specimens collected at this location over the last
3 years.
2)  Shell:  Valves have very little, almost no inflation and are thin, shell
opaque white,
relatively smooth possessing light radial ornamentation, having a light golden
periostracum,
larger shells becoming increasingly elongated.
3)  Animal:  The tentacles are a lavender to pink color.
Of the 3 specimens, the largest has a distinct anatomical difference from the
other two.
In the center of the specimen there is a large organ, possibly the heart or
reproductive gonads.
In the large specimen it is a beautiful red-orange color.
It is rather globular and similar in shape to a mammalian heart.
In the other 2 specimens it is a pale cream-tan color, is differently shaped,
elongated coming to a point and smaller. shaped more a classic Pelecypod foot.

Here are the uncertainly on my part.
1)  Do Lima have separate sexes?  Are they Gonochoristic, hermaphroditic,
viviparous?
2)  The animal coloration is consistent with which species?

Currently the specimens are refrigerated in hypertonic suspension pending
further dissection.  They can be photographed as needed.
I will be happy to e-mail a photo to anyone interested in helping on this.

Thanks,
Leslie Allen Crnkovic
HARF/IMCS