Hallo, all,
 
the Englishmen or Americans don't have any problems with the gender of nouns.
They simply say "the" - "the man, the wife, the child".
In other languages (Greek, Latin or German - where I am at home), has every noun
his definite gender, what has also a cultural background.
An example: For the people in the nord of Europe, where the sun is only mild
shining, appears she to the people like a good mother who lovingly takes
everithing to flourishing on the earth - well feminin, the moon however cold and
unfriendly - masculine (die Sonne, der Mond).
In the south of Europe (France, Italy, Greece), where the sun shuts hard with
her rays and all growth brings to drying up she has a male character like a
bright hero or God (le soleil, le sole, o ilios [Helios]) and the moon soft and
affectionate, female or like child-neuter (la luna, to fengari).
Our Greek friends on Crete (Iraklion) laughed as we them told, in the German
language the sun is a woman and the moon a man.
It is well not at all easy to recognize, the gender of a foreign-language noun
(particularly if they come from the Greek or Old- Greek). Like  A. Rindsberg
wrote, - one must have a good dictionary.
Which gender have then names like Helix, Cerastoderma, Calliostoma?
"Helix" = gr. "i elix (helix)" fem. - (cycle, spiral, tendril, - the winding
shell),
"-derma" = gr. "to derma" neutr. - (hide, leather),
"-stoma" = gr. "to stoma" neutr. - (mouth, opening).
We see, the advice to the ending -a for feminine doesn't help with Greek names,
apply to Latin names and also there not always.
Patty Jansen believes, the old guys had a much better understanding of ancient
Latin and Greek than we do. Likes to be! But then PILSBRY 1895 wouldn't have
written "Metafruticicola pellita", as he transferred the species-name Helix
pellita FERUSSAC as typus to Metafruticicola IHERING, 1892.
"Helix pellita" was correct, because Helix is feminine. "Metafruticicola
pellita" must be writen "Metafruticicola pellitus", because the Latin ending
"-cola" (like in "agricola" = farm worker, famer) is masculine regardless of the
ending "-a".
See also ICZN, Art. 30, c Example: "Compound Latin names ending in "-cola", such
as 'Sylvicola', are treated as masculine."
To it: We have in Crete three or four endemic species to Metafruticicola.
The most frequent is:
Metafruticicola lectus (FERUSSAC, 1819), everywhere,
Metafruticicola pellitus (FERUSSAC, 1819) in East-Crete,
Metafruticicola noverca (L. PFEIFFER, 1853), also everywhere.
You ask: Why noverca (with ending -a)? - Noverca  (lat. = stepmother) is not an
adjective but a noun without flexible ending, according to ICZN Art. 31b/i a
"noun in apposition".
Greetings!
Gert