Dear Harry, Steve, and David C.,
Thanks for your responses! I was unaware of the Petuch taxon (there was a mention of an upcoming shell
book on southeast Florida, which would be useful).
Examination with my 15X lens reveals some rotation at the point of emergence on my specimen, although it's hard to see how much.
Both Harry and David use the spelling "Amalthina." Is that a typo or is the common use of "Amathina" incorrect?
Amathina tricarinata occurs very frequently in the Pacific in my limited experience. Is the Florida counterpart common in some vicinities? Maybe the comparison of some soft parts will be helpful in determining whether the Florida residents are from an immigrant.
David Kirsh
Durham, NC
-----Original Message-----
>From: David Campbell <[log in to unmask]>
>Sent: Jun 20, 2011 1:24 PM
>To: [log in to unmask]
>Subject: Re: [CONCH-L] brain-teaser from Boca
>
>Iselica is another genus, widely placed in the general vicinity of
>capulids (typically as Fossaridae), but is actually a heterobranch
>akin to Amalthina.
>
>On Mon, Jun 20, 2011 at 7:16 AM, Harry G. Lee <[log in to unmask]> wrote:
>> Brilliant - absolutely brilliant, David.
>>
>> I'll betcha you have Cyclothyca pacei Petuch, 1987. It seems to prosper on
>> the shells of living pectinids and Spondylus americanus. According to the
>> original description, in which the genus name is consistently misspelled
>> "Cyclotheca," the favored "host" was reported as Chlamys imbricata [=
>> Caribachlamys pellucens (Linnaeus, 1758) of yesterday's forum].
>>
>> Cyclothyca was placed in the Capulidae by Petuch, whereas the affinities of
>> the much larger Amalthina tricarinata (Linné, 1767) seem to be with the only
>> remotely-related Heterobranchia.
>>
>> But wait! I have just examined some juvenile C. pacei shells and discovered
>> that, like the Heterobranchia, they are heterostrophic. That is, the
>> embryonic shell is sinistral, and the axis of coil rotates through about 270
>> degrees at the metamorphosis to the teleoconch. The shells of the two
>> nominal taxa are in fact very close! So close that, allowing for differences
>> in size, and accounting for the natural variability of shell form induced by
>> irregularities of substrate topology, they could be the same species!
>>
>> I find it strange that a snail like Cyclothyca pacei has only recently come
>> to our attention in SE Florida. Could it be that it is just an ecophenotype
>> descended from an immigrant A. tricarinata? The latter is known to be
>> associated with oysters and pen shells in Japan. Maybe, when introduced to,
>> say, Biscayne Bay in bilge from one of the Japanese merchant fleet water
>> sometime in the mid- or late 20th Century, it took up with the most
>> available hosts in the vicinity?
>>
>> In any event the resemblance between "Cyclothyca" pacei Petuch and
>> Cyclothyca Stearns 1890 [Type species C. corrugata Stearns, 1890] is
>> infinitesimal compared to it and A. tricarinata.
>>
>> You have opened a Pandora's Box, David - mostly attributable to an eclectic
>> taste in gastropod shells and a "photogenic" memory of iconographies.
>>
>> Harry
>>
>>
>> On 6/19/2011 11:52 PM, David Kirsh wrote:
>>
>> Recently, I collected from drift in Boca Raton, Florida and came across a
>> 4mm cap-like shell I thought I knew. The name had "tri-" in it, and possibly
>> "Ama-" something...couldn't find it in Abbott (1974) or Colin Redfern's
>> Bahamas book or Harry's Marine Shells of NE Florida. I felt slight
>> shame..."I ought to know this one."
>>
>> As I was taking photos of it, my flash must have jarred loose that it is
>> supposed to be parasitic on other shells. Somehow that led me to crack open
>> Okutani's Marine Mollusks in Japan and there it was: Amathina tricarinata
>> (Linnaeus, 1767).
>>
>> Now that I'm a little reassured that my memory isn't totally gone, I'd like
>> to know if others have found this species in the western Atlantic.
>>
>> David Kirsh
>> Durham, NC
>>
>> "It's no wonder that truth is stranger than fiction.
>> Fiction has to make sense." - Mark Twain
>>
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>>
>>
>>
>> --
>> Harry G. Lee MD
>> 4132 Ortega Forest Drive
>> Jacksonville, FL
>> USA
>> (904) 389 4049
>> [log in to unmask]
>> [log in to unmask]
>
>
>
>--
>Dr. David Campbell
>The Paleontological Research Institution
>1259 Trumansburg Road
>Ithaca NY 14850
>
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