Tag Archives: florida

Miocene fossils from Florida

Auffenberg et al. (2015) just released a new paper on fossils from the Miocene in Florida. The land shells fossils have hitherto been considered as Odontostomidae, which as extant species occur in the southern part of South America. Consequently, some ‘mental flexibility’ was needed to explain the biogeography of these fossils.

“Orthalicoid terrestrial snails recorded from the lower Miocene portion of the upper Oligocene to lower Miocene Tampa Member of the Arcadia Formation (Hawthorn Group) of southern Florida and the lower Miocene St. Marks Formation of northern Florida are reviewed. These taxa, previously allocated to the genus Hyperaulax Pilsbry, 1897 (Odontostomidae), are reassigned to Tocobaga new genus (Bulimulidae) on the basis of a distinctive suite of morphological characters, particularly those of the peristome and the embryonic whorl sculpture. Examination of all type material of the fossil taxa historically assigned to Hyperaulax reveals that only three species are separable (Partula americana Heilprin, 1886; Bulimulus americanus wakullae Mansfield, 1937; and Bulimus floridanus Conrad, 1846). The varietal names Bulimulus americanus var. partulinus and B. americanus var. laxus, both Dall, 1890, are indistinguishable from the nominate form in any important morphological character. Bulimulus heilprinianus, Bulimulus stearnsii, both Dall, 1890, and Bulimulus ballistae, Bulimulus remolina, Bulimulus tampae, and Bulimulus tortilla, all Dall, 1915, are synonyms of B. floridanus Conrad, 1846. The status of B. a. wakullae from northern Florida is problematic. Although clearly not conspecific with P. americana, it is tentatively assigned to Tocobaga new genus and is herein elevated to species level. The biogeography of Tocobaga new genus is tentatively discussed. Fossiliferous deposits in North America and South America have not yielded taxa with the combination of shell characters found in the new genus and relationships with other bulimulid genera are unknown. However, it is probable that the new genus, like other non-marine mollusks from the Tampa Member of the Arcadia Formation, dispersed to Florida after contact between the Caribbean Plate and the Bahama Platform (circa 38 Ma)”.

Auffenbach et al 2015

Reference:
Auffenberg, K., Slapcinsky, J. & Portell, R.W., 2015. A revision of the fossil taxa assigned to Hyperaulax (Gastropoda: Odontostomidae), with the description of a new genus (Gastropoda: Bulimulidae). – The Nautilus 129: 54–62.

Digital field work: the next step?

Bill Frank has already been doing some very clever detective work in and around Jacksonville, Florida on the occurrence of Bulimulus aff. sporadicus (e.g., here and here). Today his next message read: “Was using Google Street View this afternoon on my computer to “drive” or maybe I should say “mouse” around Jacksonville looking for Bulimulus sporadicus. Much to my surprise I found a location where it appeared that Bulimulus were present but the Google imagery wasn’t high enough in resolution to be absolutely sure plus the imagery was dated April, 2013.

Capture

Although in the past I have used Street View to view snails after I had first visited the location and confirmed their presence, today’s find, if confirmed by an on site visit, would be the first time that snails would were found solely based upon street view. So I jumped in the car and drove downtown to the location in question which is on Deer Street underneath the US-1 overpass. Upon arrival I found Bulimulus in the exact location as depicted in Street View on the concrete wall in somewhat modest numbers. However on the other side of the road live specimens were present in large numbers on another concrete wall. After looking around for a bit I changed my estimation from hundreds to probably tens of thousands of snails being present. The ground was just white with empty shells and represents the most specimens I have ever seen at a single location which is really saying something. This location within the past couple of  years has undergone a complete transformation due to road/overpass construction which makes the find all that more impressive (i.e. the snails had accomplished this in a relatively short period of time)”.

Detailed photos of the locality can be found in this document: Deer Street

So one might ask, will malacological field work turn into a digital exercise? Perhaps the saying of football coach Johan Cruijff may be apt in this context… “Je ziet het pas als je het doorhebt” [you see it when you get it]. Bill’s previous experience undoubtedly helped him a lot, but still: Chapeau for this digitally savvy malacological detective!

Color-full and catching the eye

Under this ttitle an iconographic study of Liguus shells from the 17th-beginning of 20th century just has been published. The first book in which a Neotropical snail, L. virgineus (L., 1758), was illustrated we are aware of was Philippo Buonanni’s Recreatio mentis et oculi. This appeared in 1684.

Buonanni1681

The illustration of species from this genus is followed through time, with comments on their (current) classification, until the first full-colour photographs in Simpson’s 1920 book “In lower Florida wilds”.

Unfortunately there are some glitches in the text, and the table appears to be in very small print in the hardcopy (but should be more legible in the PDF); the bold print intended for some text in the table has not survived the editorial process. The correct file is given below (link).

IcongrLiguusT1_*

Reference:
Breure, A.S.H., Álvarez-Lajonchère, L. & González Guillén, A., 2014. Color-full and eye-catching: an iconography of Liguus land shells (Gastropoda: Orthalicidae). – Archiv für Molluskenkunde 143: 1–19.

Photo of the day (156): Drymaeus

The previous post evidently led to some excitement in Florida… Bill Frank sent the the following message and photos:

“These are the two that I got out of the palm tree yesterday in Twelve Mile Swamp. They are the largest and nicest specimens that I’ve ever found.  I guess that it was worth it to have figured out how to retrieve them from 12-15 feet above ground. Obviously since I’m less than six feet tall and my rake is less than that, I had to do some jumping……….“

Keep jumping Bill, these are lovely creatures 🙂

P6070002 (2)jjP6070019 (2)jjP6070007 (2)jjP6070043jjj

Photo of the day (155): Drymaeus

This time the “Photo of the day” is another video link. Bill Frank caught these specimens of Drymaeus dormani (W.G. Binney, 1857) crawling around. Or perhaps better: in a race to the bottom…

Ddormani1

https://www.youtube.com/watch?v=8HmSbUYbS9o

And another one:

Ddormani2

https://www.youtube.com/watch?v=lyZ77JiF4Ns

Many thanks Bill for sharing these! And perhaps I should consider to rename this series…

Cerion revisited

Some months ago Jerry Harasewych published a new paper on Cerion (Harasewych, 2012), in which he described a new fossil species and presented a hypothesis about the phylogeography of the family.

Cerion petuchi, new species, the first record of the genus from the Pleistocene of Florida, is described from Loxahatchee, Florida, from deposits of the Loxahatchee Member of the Bermont Formation (Aftonian Pleistocene). This new species is more similar to Cerion agassizii from the Pleistocene of the
Great Bahamas Bank, and to the Recent Cerion incanum saccharimeta, from the Florida Keys, than to either of the species from the Late Oligocene—Early Miocene Ballast Point Silex Beds of Tampa, Florida. Data on the geographic distribution and geological age of all known cerionids is compiled and, together with models of the geologic and tectonic history of the Caribbean region, used to construct a hypothesis of the origins, ages, and relationships among the various lineages within the family since the Upper Cretaceous. The early distribution of the family was governed primarily by overland dispersal and vicariance. It is suggested that the significant proliferation of diversity that began during the Pleistocene is due to the increased prevalence of stochastic dispersal of small propagules (either by rafting or hurricane-born) among the islands of the Cuban and Bahamian archipelagos. Sea level changes caused by Pleistocene glaciations amplified diversity by repeatedly and sequentially recombining / hybridizing and isolating neighboring
populations. Amplification of diversity would have been greatest on the Great Bahama Bank, as it had the highest number of islands that were isolated during interglacial periods and conjoined during glaciations.

This hypothesis may be interesting to work with in families or groups that show a similar distribution in Florida, the Caribbean and Central America, and (northern) South America. However, it must be noted that this model draws heavily on the work of Iturralde-Vinent, and among geologists there is still debate about the different geological hypotheses of the Caribbean region.

Recently, he presented also research on populations of Cerionids in the Florida Keys (Harasewych & Shrestha, 2013). This work is partially underpinning the paper mentioned above, and was used to determine the spatial scale and patterns of genetic diversity across the entire range of Cerion incanum, and to correlate these patterns to the geology and origin of the Florida Keys.

References:
Harasewich, M.G., 2012. The fossil record and phylogeography of the family Cerionidae (Gastropoda: Pulmonata), with the description of a new species from the Pleistocene of Florida. – The Nautilus 126: 119–126.
Harasewich, M.G. & Shrestha, Y., 2013. Patterns of genetic relatedness among populations of the genus Cerion (Cerionidae: Gastropoda: Mollusca) in the Florida Keys. In: Frias Martins, A. de et al. (eds.) World Congress of Malacology 2013. Book of Abstracts: 83.