Thanks for help on this maddening complex.  Surely you mean riisei and angustior, not ziczac, in two spots in your observations on ziczac.
>
> From: marlo <[log in to unmask]>
> Date: 2005/10/24 Mon PM 03:24:54 EDT
> To: [log in to unmask]
> Subject: Florida Nodilittorina
>
> I'm integrating the Florida material a generous friend gave me into my
> extensive collection of Florida marine seashells.  Both our collections span
> about 15 years of field collecting and all of Florida.  Many names have
> changed and species ranges redefined.  So, the effort requires many
> extensive reexaminations.  Currently, I'm working with some common
> Nodilittorina (I rely on Common and Scientific Names of Aquatic
> Invertebrates from the United States and Canada:  Mollusks, 2nd Ed., 1998,
> American Fisheries Society Special Publication 26, Bethesda, Maryland, for
> genus names.)  Abbott's American Seashells and Redfern's Bahamian Seashells
> are the two principle references I utilize.  Most current references rely
> upon Bandel, K. & D. Kadolsky. 1982, Western Atlantic species of
> Nodilittorina.  The Veliger 25(1):1-42, a copy of which I do not have and
> have not read.  The species presenting the identification problem are
> angustior, interrupta, lineolata, mordax, riisei, and ziczac.  Four of these
> (interrupta, lineolata, mordax, riisei) are essentially indistinguishable.
> To resolve the issue I reviewed several references and have concluded as
> follows.
>
> Abbott's reference to lineolata is in error and is most probably riisei.
> Lineolata is now considered restricted to Brazil/Uruguay.
>
> Abbott does not list mordax, which is consistent with Redfern's comments
> that it is found in the Bahama's and Curacao.  Mordax is considered as
> indistinguishable from riisei, with riisei ascribed to Florida, Nicaragua
> and Cuba.  These two may one day found to be the same.
>
> This brings us to interrupta, which Harry Lee considers to be the Florida
> species rather than riisei.  Harry is not often wrong, but Bandel and
> Kadolsky placed interrupta in Jamaica, Haiti, Antilles, Costa Rica and
> Columbia.
>
> Neither Mollusks, 2nd Ed. or The Academy of Natural Sciences of
> Philadelphia's Malacolog include interrupta or mordax as occurring in North
> America.  Both list riisei.
>
> Therefore, I'm confronted with three species to separate and identify -
> angustior, riisei, and ziczac.  Here's my collecting data and observations.
>
>
> Angustior.  Samples found from Sebastian Inlet south to Dade County, the
> Keys, none along west coast, then from Taylor County in the eastern
> panhandle west to Pensacola.  Harry Lee considers angustior essentially
> indistinguishable from riisei (his interrupta).  Redfern distinguishes
> mordax(indistinguishable from riisei) from angustior with mordax having one
> white band at bottom of interior of mouth and angustior as having two bands.
> I have not found this to be a consistent distinguisher.  Redfern notes that
> angustior has a stronger cord around the bottom of the body whorl giving it
> a sharper angled profile (than riisei, and ziczac) and causing a notch to
> appear on the inside of the lip.  He also describes angustior's teleoconch
> whorls as only slightly convex.  In my observations riisei's teleoconch
> whorls are consistently more convex than angustior's.  I'd characterize
> angustior as almost straight sided, riisei as somewhat convex, and ziczac as
> distinctly convex.  As a result angustior appears more narrow with a high
> spire and  ziczac appears rounded and stout, with riisei falling in between
> and often too close to angustior to distinguish on this characher.
>
> Riisei.  Samples found all along Florida's east coast from Nassau County
> south to Dade County.  None in the Florida Keys (Monroe County).  On west
> coast of Florida from Collier County north to Tarpon Springs, then in the
> panhandle from Franklin County west to Santa Rosa County.  Riisei's cord
> around the bottom of the body whorl less pronounced than angustior and does
> not create a notch to appear on the inside of the lip.  Profile of
> teleoconch more convex than angustior.
>
> Ziczac.  Samples found along Florida east coast from Sebastian Inlet south
> to Dade County and the Florida Keys.  None on west coast.  Ziczac easily
> distinguished from riisei and ziczac.  It is larger (20mm vs 16/17), profile
> of teleoconch distinctly more convex, cord around the bottom of the body
> whorl indistinct and as Redfern notes its appearance is predominantly
> grayish white with much narrower oblique brown lines.  Also, when looking at
> the shell from the mouth side, count the spiral groves from the top of the
> lip to the suture.  Ziczac has about 24 finer groves than riisei's and
> ziczac's 8 to 10 wider and deeper grooves.
>
> So, this is how I've attempted to distinguish among three Florida
> Nodilittorina.  I'm soliciting comments and critique from others who have
> experience with them.
>
> marlo
> merritt island, FL
>
>
> Marlo
>
>
>

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