Posted: Aug 16 2009

 Miralda havanensis (Pilsbry and Aguayo, 1933)

On Aug 16, 2009 Marlo posted on Conch-L:

"Miralda havanensis is not exactly rare, but it is not common. I have records of this species only from east Florida except for one record of this shell from Florida's west coast. I was wondering if anyone has first-hand knowledge of any finds on Florida's west coast."

In response
Harry Lee reported:

"I have specimens from 60 feet, 9 mi. W. Egmont Key collected by Peggy Williams, on 9/23/89 and from Raccoon Key, Monroe Co. by Phil Poland on 9/21/98, but the bulk of my material comes from warmer waters: Bahamas, Cayman Is., Tobago, Aruba, and Caribbean Panama (Trish Hartmann!). If you add Cuba, the type locality of Odostomia (Miralda) havanensis), Guadeloupe (Folin), Panama again (Olsson and McGinty, 1958: 44; pl. 1, fig. 8), Yucatan (Vokes and Vokes, 1984: 32, 59), and Odé (1993: 58-59), who recorded 11 lots (as Lia decorata) from off the Texas coast (most from Flower Garden Banks), a pretty much circum-Caribbean pattern with penetration up the east Florida coast and well into the Gulf of Mexico emerges."

Harry later added:

Excellent production, Marlo! This specimen (and its photography) greatly exceeds anything in my collection.

Virtually all you say about the shell is quite accurate and informative.

Not to nit-pick, but I think it is important to point out that the coiling axis of the first portion of the protoconch is actually about 20 degrees removed from perpendicular to that of the teleoconch. That is, it's directed to the NW in the topology of the apertural view you present. That means this early shell is sinistral in coil, as are the majority, possibly all, the Pyramidelloidea (pyrams) at that stage of growth. In passing from early protoconch to teleoconch, this shell's axis of growth passed through about 110 degrees of rotation. A change in growth pattern like this (> 90 degrees) is termed "heterostrophy." The shells of some pyrams actually rotate this axis 180 degrees. The latter are termed "coaxially heterostrophic," whereas all other pyrams, including this species, are called "heteroaxially heterostrophic."


Marlo writes: I struggled for about a half hour as to whether to use the term heterostrophic, but while the definition seemed easy enough (the whorls of the protoconch coil in the opposite direction to those of the teleconch), I just couldn't grasp how to describe it since it is not visually apparent in these photos with the tip of the protoconch out of sight sunken in the apex. Thanks for the additional explanation.

Tom Watters:

I have specimens from Biscayne Bay, Bonefish Key, Sambo Reef, Belize, and Grenada. An outstanding species for those not familiar with "micro-molluscs."

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