Andy,
Your welcome message to Wolfgang (which I would like to reiterate -
Welcome to the group Wolfgang!) reminded me of a narrow taxonomic
question that has been recurring to me for some time, and which
hopefully might have a dull answer lurking in the pages of some
obscure ICZN manual.  Generally, the gender suffix on a species name
(typically an adjective) matches that of the genus name (the noun it
modifies).  However, in many cases that is not true, for example:
Cypraea cervus, Cypraea ovum, Pterygia conus, Phalium pila, Conus
granum, Conus terebra, Marginella prunum, Modulus tectum, Natica
vitellus.  I have noticed that in many cases where the two endings do
not match in gender (including the examples above), the specific name
is not actually an adjective, but rather a second noun used as an
adjective.  (We do this all the time in english - bicycle rack,
telephone pole, coffee cup, shell collection.)  So, this leads me to
suspect there must be some rule governing this situation, whereby a
noun used as an adjective retains its own gender, rather than
matching the gender of the primary noun.  SO - my question is - is
there?
Regards,
Paul M.
Rhode Island