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Specimen of the Week – Acantholabia floridana from Fossil Park, Florida

27 May

Back in July, 1995, I made my first visit to Fossil Park in St. Petersburg, Florida, a park known locally for its baseball fields, bike paths, pool, and other standard family-oriented recreational facilities. Of course, my reason for wanting to visit was based on the park’s name, referencing the fact that it was the original locality from which Olsson and Harbison wrote their famous 1953 book on the Caloosahatchee fauna of North St. Petersburg. According to their book, the Caloosahatchee shells at this site were not a natural outcrop, but were probably transplanted from nearby pits that were dug back in the 1920’s.

There are not many fossil shells to be found today at the park — in the water-filled ditch surrounding one side of the park, there seems to be a layer of young, possibly Fort Thompson era, shells. However, as is true with much of south Florida, crushed shells can be found virtually everywhere if you look hard enough. As we were walking along, I had my eye on the bike path next to the walkway, which was lined with small crushed shells. To my great surprise, I spotted a specimen of Acantholabia floridana Olsson and Harbison, 1953, a species I did not heretofore have in my collection, and a species that was in fact originally described from the St. Pete deposits at Fossil Park. That second fact alone made it an incredibly memorable find for me.

As luck would have it, there was some roadwork going on at a street corner on the edge of the park, with construction workers digging holes right through the pavement. Wandering over that direction, we found several large specimens of Siphocypraea problematica as well, and some other larger shells. However, I will always remember the visit for my somewhat miraculous find of this small extinct muricid with the large labral tooth. I never found any more specimens on future visits to the park, although I later lived just a few miles away from it.

Acantholabia floridana, Fossil Park, St. Petersburg, FL

Acantholabia floridana from type locality, Fossil Park, St. Petersburg, FL

Dr. Emily Vokes mentioned in her 1992 review of the genus Acantholabia that she only knew of three specimens of A. floridana (two type specimens from St. Petersburg, and one specimen questionably referred to the species from the older Tamiami Formation of Mule Pen quarry). However, Ed Petuch has figured at least one specimen from spoil banks of Caloosahatchee age along the Miami Canal. Dr. Petuch also named a new species from the Pinecrest Beds of Sarasota, A. sarasotaensis, which can be distinguished from A. floridana by its “higher spire and…more angulate shoulder” (Vokes, 1992, p.92). While Dr. Vokes mentioned only having 7 specimens of this second species in the Tulane collection back in 1992, I hesitate to call it rare based on the Tulane collection figures alone, since I hardly ever collected at the APAC quarry and yet still have at least 3 specimens referable to the species in my collection.

Acantholabia sarasotaensis, APAC Quarry, Sarasota, FL

Acantholabia sarasotaensis, APAC Quarry, Sarasota, FL (siphonal canal is broken on the large specimen on the right)

Where things get interesting, or perhaps just confusing, is that there are also specimens of Acantholabia from the Sarasota beds that — to me — resemble A. floridana far more than they do A. sarasotaensis. Yet literature does not indicate that the two species overlapped in occurrence (aside the unusual specimen documented from Mule Pen Quarry). It is also difficult to say from what level these other specimens came, since most people (including myself) generally collected from spoil piles in the pit. The Florida Museum of Natural History lists 31 specimens (mostly donated by amateur collectors) labeled as “Acantholabia floridana” in its collections from Sarasota, versus only 19 specimens labeled as “Acantholabia sarasotaensis” (search their collections online here), so only further examination of specimens outside my private collection will solve the mystery for me.

I should note, however, that it used to be common practice for amateur collectors to use the Olsson and Harbison book, which primarily figured Caloosahatchee Formation species, to identify their specimens from the older Pinecrest Beds of Sarasota. This is because prior to Dr. Petuch’s work, there were few other resources available for amateurs to reference. I used to see this quite frequently back in the late 1980’s / early 1990’s, in that amateur collectors would label their specimens of Chicoreus floridanus as either “Murex salleanus” or “Murex brevifrons” based on incorrect species attributions appearing in the Olsson and Harbison book. Now today, the pendulum has swung in a completely different direction, and I instead frequently observe my fellow amateurs blindly following  the proliferation of species names, and labeling their specimens with the latest and greatest names, without truly understanding what makes each of the proposed new taxa distinct (or not). More on that when I blog about the genus Pterorytis soon!

Acantholabia sp., APAC Quarry, Sarasota, FL

Two Acantholabia specimens from APAC Quarry, Sarasota, FL, that bear a strong resemblance to Acantholabia floridana

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References:

Olsson, A. A. and Harbison, A. (1953). Pliocene Mollusca of Southern Florida with Special Reference to Those from North Saint Petersburg, ANSP Monograph No. 8, 1990 Reprint by the Shell Museum and Educational Foundation, Inc., Sanibel Island, FL.

Petuch, E. J. (1994). Atlas of Florida Fossil Shells (Pliocene and Pleistocene Marine Gastropods), Chicago Spectrum Press.

Vokes, E. H. (1992). “Cenozoic Muricidae of the Western Atlantic Region, Part IX,”  Tulane Studies in Geology and Paleontology, Vol. 25(1-3), pp. 89-92, Plate 20.

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