Like Haustellum (Vokesimurex) gilli, I often see collectors misidentifying specimens of Chicoreus (Siratus) from the early Miocene Chipola Formation of Florida. Species of Chicoreus (Siratus) are in fact found in all three formations of the Alum Bluff Group, so perhaps by figuring specimens from all three formations, I can help to clear things up a bit. If nothing else, I can provide literature references for you to look up for further information.
First, I often see specimens of C. (S.) juliagardnerae misidentified as C. (S.) chipolanus. If one only has access to Julia Gardner’s work on the Alum Bluff Group (specifically USGS Professional Paper 142-H from 1947), one might be forgiven for this. Gardner mistakenly figured a specimen of what was actually an as-yet undescribed species as “Murex (Murex) chipolanus Dall, 1890.” The fact that Dall never actually figured that species didn’t help, and his description wasn’t the most helpful either. The figure below shows Dall’s original description (note also that “M. messorius” is not in fact found as a fossil in south Florida), as well as Gardner’s specimen, which she referred to as a lectotype of “Murex chipolanus.” (You can also view an electronic copy of Dall’s work in Google Books (scroll to page 139); Gardner’s figure and discussion is available electronically on the USGS Publications website (scroll to pages 29 and 154).
Dall's description of C. (S.) chipolanus (left) with Gardner's incorrect figure (right; public domain image courtesy of the U. S. Geological Survey)
In 1963, Emily Vokes argued that Gardner’s specimens were not of Dall, and named the species figured by Gardner as Murex (s.s.) gardnerae. However, advances in generic assignments over the years indicated that “Murex gardnerae” actually belonged in the subgenus Murex (Siratus), introducing the problem that there was already a species named Murex (Phyllonotus) gardnerae Dall, 1915 (a synonym for what is now classified as Chicoreus (Phyllonotus) trophoniformis). So the name of the Chipola species needed to change. In 1970, Vokes renamed the species Chicoreus (Siratus) juliagardnerae. Her holotype for the species is figured in Tulane Studies in G&P, Vol. 23(1-3), Plate 6.
All was not yet well in Chipola Siratus land, however. Back in 1947, Gardner had also described another species from the younger (middle Miocene) Shoal River Formation as Murex (s.s.) nicholsi. This species was later placed in the genus Chicoreus (Siratus) by Vokes. Given the rarity of the species in the Shoal River Formation, and the poor preservation of Shoal River shells in general, Gardner’s holotype was not the best. In the early 1960s, the Tulane University researchers likewise lacked good specimens. Thus, when a handful of specimens of a similar species popped up in the basal beds of the Chipola Formation, Dr.Vokes referred them to C. (S.) nicholsi. This assignment in itself was not that unusual; there are a number of species that are in fact found in more than one formation of the Alum Bluff Group. You can view Gardner’s holotype of “Murex nicholsi” on page 154 of the electronic file for USGS Professional Paper 142-H, on the USGS Publications website. Vokes’ original figured specimens from both Shoal River and Chipola can be found in Tulane Studies in G&P, Vol. 1(3), Plate 3.
As often happens, years passed, more collections were made, and Tulane University ended up with “hundreds” of specimens of the Chipola species formerly referred to C. (S.) nicholsi. Differences between the Shoal River and Chipola specimens emerged, and Dr. Vokes named the Chipola species C. (S.) sextoni in 1990. Specifically, the differences between the two species are as follows: C. S. (sextoni) has “only very short varical spines, which normally merge into a flange,” whereas C. (S.) nicholsi has “coarser spiral ornamentation and the tendency to three stronger spiral cords that give rise to short spines where they cross the varices” (p.42). Figures from Dr. Vokes’ 1990 discussion of the subgenus can be found in Tulane Studies in Geology and Paleontology, Vol. 23(1-3), Plate 6. C. (S.) chipolanus is shown in Figures 5 and 6; C. (S.) juliagardnerae in Figure 7, C. (S.) sextoni in Figures 8-11, and C. (S.) nicholsi in Figure 12.
To summarize and help with specimen identification, I have figured below several specimens from each of the 4 species of Chicoreus (Siratus) found in the Alum Bluff Group, including a specimen tentatively referred to C. (S.) sextoni from the Oak Grove Sand.
Chicoreus (Siratus) chipolanus (click to enlarge)
Chicoreus (Siratus) juliagardnerae (click to enlarge)
Chicoreus (Siratus) sextoni (click to enlarge)
Chicoreus (Siratus) nicholsi (click to enlarge)
Side by side comparison (sextoni, nicholsi, chipolanus, juliagardnerae)
Chicoreus (Siratus) sp. cf. sextoni - Oak Grove Sand
Specimen of C. (S.) nicholsi now in the FLMNH collection
In closing, I would like to briefly touch on a problem I have faced several times over the years in dealing with other amateur collectors with far less experience collecting in the various formations of the Alum Bluff Group than myself. Often, I will look over a private collector’s specimens from the Chipola Formation and see that they have misidentified either C. (S.) juliagardnerae, C. (S.) sextoni, or both. One might think that this is due to their only having access to Julia Gardner’s USGS publications. But that isn’t always the case. Many times, these collectors get defensive and even arrogant when I point out Dr. Vokes’ recent work on these species, and make some statement to the effect that “Vokes is always changing her mind; her work can’t be trusted.” I’d like to point out just a couple of things here. First, scientific knowledge does advance over the years. It has been over 40 years since Tulane University first collected in the Alum Bluff Group. Many highly respected scientists once thought our world was flat, and we all know how that worked out. Criticizing a scientist for recognizing previous errors or misinterpretations and working to advance knowledge in their field over time is wrong. Second, Dr. Vokes has a PhD in the field; these amateur scientists (like me) do not (I do have a PhD but it’s in MIS, not geology/paleontology). Most of these amateur collectors revere a particular invertebrate paleontologist from south Florida who will go nameless here. They view this scientist as being infallible, while criticizing everyone else. That is wrong. I know many people (both professionals and amateurs) who have already forgotten more about the Alum Bluff Group than this other scientist will probably ever know. The goal isn’t to fight over who is intellectually superior, who has named the most species (legitimate or not), or who has had the most species named after them (a highly overrated measuring stick these days), but to humbly advance science through honest, diligent, selfless effort.
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References:
Dall, W. H. “Contribution to the Tertiary Fauna of Florida,” Wagner Free Inst. Sci. Trans., Volume 3, part 1, p.139.
Gardner, J. “The Molluscan Fauna of the Alum Bluff Group of Florida,” USGS Prof. Paper 142-H, pp.517-520, Plate LIII.
Vokes, E. H. (1963). “Cenozoic Muricidae of the Western Atlantic Region, Part I,” Tulane Studies in Geology and Paleontology, Vol. 1(3), pp. 99-100, 105-106, Plates I, III.
Vokes, E. H. (1970). “Chicoreus (Siratus) juliagardnerae, New Name for Murex gardnerae Vokes NON Dall, With Observations on the Species,” Tulane Studies in Geology and Paleontology, vol. 8(1), pp. 51-52.
Vokes, E. H. (1990). “Cenozoic Muricidae of the Western Atlantic Region, Part VIII,” Tulane Studies in Geology and Paleontology, Vol. 23(1-3), pp. 40-44, Plate 6.
