Dear Richie,

Thanks for the idea!

There are several specimens of each before me.  The resemblance to of my
Ithaca shells to Stenotrema, particularly S. hirsutum, is uncanny!

My shells vary very little in size, averaging about seven mm, which is not
unusual for samples of S. hirsutum. The dorsal aspect of equal-sized S.
hirsutum and my Ithaca shells is uncannily similar - same number of whorls
and a hairy surface.  The whorls match nicely until the last, which is more
rapidly-expanding and rapidly-descending in the Ithaca shells.  These
shells also have longer, less densely-placed, hairs and are darker in
color, but, as you know, these characters may be variable or evanescent.

The ventral aspects of the two present a stark contrast.  The Ithaca shells
have a deep umbilicus that penetrates to the first whorl.  Its diameter is
about 1/7 that of the shell's base.  The abapical (basal) aspect of the
outer lip descends conspicuously below the transverse ("horizontal") plane
of the Ithaca shells, whereas it is on the same plane in S. hirsutum.

I have to admit, there is no sign of thickening of the basal outer lip (T.
hispida) or reflection of the lip (S. hirsutum), indicating maturity, in
any of my several shells, and I have no immature S. hirsutum for
comparison.  Nonetheless, the two are distinguishable based on the
available material.

I have never found S. hirsutum is a "stressed" habitat, and it is seldom
abundant. This was not the case at the Ithaca station.

I'll have to post images of these shells on the Jax website to illustrate
this conchology.

Harry


At 01:06 AM 11/29/2004, you wrote:
>Harry,
>
>Digging into the literature covering New York State (NYS) terrestrial
>mollusks reveals some interesting information.
>
>First, as you know, juvenile Stenotrema hirsutum (Say, 1817) exhibit
>perfunctory characteristics of Trichia hispida.  Immature Stenotrema
>hirsutum tend to have the same fussy periostracum of Trichia
>hispida.  Without a picture, or size and shape information about your
>shell, I cannot firmly discuss any similarities. The literature, though,
>leads me question whether T. hispida has been introduced to NYS.
>
>There are multiple records of S. hirsutum in western NYS (Robertson,
>I.C.S. and Blakeslee, C.L., 1948. The Mollusca of the Niagara Frontier
>Region and Adjacent Territory. p. 14).
>
>In the bible for North American land shells (Pilsbry, H.A., 1940. Land
>Mollusca of North America. Vol. I, No.2. p.662) the first record for
>Stenotrema hirsutum in New York State is Ithaca!
>
>Essentially, S. hirsutum is found throughout a swath of NYS, north of our
>hometown, from Dutchess County, diagonally northwest to Erie County in the
>western part of the state.
>
>I could be totally wrong, but it may be worth a second look to see if in
>fact what you have is immature Stenotrema hirsutum.  Certainly if your
>shells are mature, umbilicate, and with a depressed convex spire, then
>more than likely you have an important record for an alien species in New
>York State.
>
>Rich

Harry G. Lee
Suite 500
1801 Barrs St.
Jacksonville, FL 32204
USA
Voice: 904-384-6419
Fax: 904-388-6750
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Visit the Jacksonville Shell Club Home Page at:
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