I have no knowledge of my own to add. But Rich Goldberg had an article in
Conchologists of America Bulletin (then so-named) December 1982, No. 28
page 9 that re-defined porcellana as western Atlantic, (it had been thought
eastern Pacific), accola as eastern Pacific, reportedly intertidal, and
tessellata as a valid species from eastern Pacific deep water. Reportedly,
quoting Roth & Emerson (Nautilus, vol. 96 No. 4 Oct 29, 1982) it differs by
"consistently smaller size, rows of spots covering about 90% of the shell's
surface" among other things.

In my own collection I have something labeled "tessellata f. accola?" which
gives an idea of my level of conviction.

John Wolff


At 08:34 PM 8/6/2005, you wrote:

>Identifying mollusks from web pictures (and popular booklets) is very
>problematic.  I am not a marginellid specialist but the literature does
>appear to be confusing.  For many years P. tessellata (Lamarck) was thought
>to be a Western Atlantic species.  Persicula accola was described by Roth &
>Coan, 1968, for the Panamic species.  Later, P. tessellata was found to
>actually be a Panamic species and now the question is, as you point out,
>whether or not it is specifically (or subspecifically) distinct from P.
>accola.  When Roth & Emerson in 1982 discovered the correct location for P.
>tessellata, they wrote a paper on various species of Persicula. Roth and
>Emerson describe differences between the two and indicate that they come
>from different depths and bottom conditions. Their paper ends with the
>statement: "In summary, Persicula tessellata (Lamarck, 1822) and Persicula
>accola Roth & Coan, 1968, are similar eastern Pacific species occurring in
>then same part of western Panama."
>
>Sorry I cannot be of more help.
>
>Dick Petit

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