Posted: Dec 15 2009
Chicoreus florifer (Reeve, 1846)
The following discusison occured on Conch-L regarding differences between C. florifer and C. dilectus:
John Wolffe offered:
"Quoting Emily Vokes in Tulane Studies 3:(4)194 (1965):
'C. florifer, although similar to C. dilectus, may be distinguished from that species by its larger average size and heavier shell. It also has one longer spine at the shoulder and generally more imbricated spines. There is only one intervarical node which is much stronger than that of C. dilectus and the shell is proportionally wider at the periphery, giving it a triangular aspect. The shell is darker in color, ranging from a pale yellow body with dark brown fronds as shown by Reeve, to a completely dark brown shell such as the one figured by Kiener, as Murex rufus'
C. florifer is discussed further in Tulane Studies 23:(1-3) p.32 (1990)
Whether or not to use subspecies in nomenclature is a separate issue. At the risk of misquoting her, Emily felt that the requirements for naming a subspecies - describable and consistent differences plus a non-overlapping range (bathymetric or geographical), made little difference from the definition of a species and you might as well call it that."
Andrew Grebneff focused in on John's comment regarding Vokes' comments about using subspecies:
"That's right. If there are consistent differences, then there is no reason not to differentiate them as species. If the differences are not consistent, and intergrades occur, then there is either only one species (the norm) or hybridization is going on.
Distribution isn't necessary to take into account; distinct but similar forms can be sympatric (living together in the same environment) or allopatric (distributions not overlapping; allopatry can be either geographic or environmental; in the latter two species can live within meters of one another, but not actually be found together... except where the boundaries of their environments are in contact)."
Steve Rosenthal, upon reviewing the photos wrote:
"Hi Marlo, saw the first installment of your latest great feature. Did you get any BIG Murex in Eleuthera, ie in the 3 inch range? I think the big Bahamas florifer with longer spines and triangular shape indeed make it easier to see the differences alluded to in the Vokes description. I believe all your Eluethera pics are small "true" florifer, and the rest (all from FLA) will be "dilectus" (whether form or subspecies or distinct species).
Marlo's note: I've never collected this shell myself. Jim Cordy provided some large florifer from the Bahamas for examination.
So, using Vokes' characters, C. florifer differs by:
1. Larger average size and heavier shell.
2. One longer spine at the shoulder
3. Generally more imbricated spines
4. Only one intervarical node which is much stronger than that of C. dilectus
5. Proportionally wider at the periphery, giving it a triangular aspect
6. Darker in color, ranging from a pale yellow body with dark brown fronds as shown by Reeve, to a completely dark brown shell
And, using John's interpretation of Vokes' comments on speciation as concurred upon by Andrew, if the above six characters "are consistent differences," esp. if the two are sympatric (sharing the same territory), then we can assert that separate species are involved. However, the two do not appear to share the same territory and absent a DNA analysis, I don't beleive we can yet assert that these two shells are indeed sparate species. One may well be a geographically separated variation of the same species.
12/15/09 Tom Wattters posted:
There was, and perhaps still is, a population of
melanistic dilectus on the seawall by the lighthouse at
Key Biscayne. The specimens are very dark brown, at
least as dark as florifer. Emily was kind enough to verify
the ID many years ago. So we might want to footnote
the difference in color between florifer and dilectus.
(Note the SINGLE intervarical node on both. The white
specimen is a Yocius specimen from off St. Augustine.)
I assume you mean a specimen collected from deep water via dredge by Ted Yocius?
I think I covered the possibility of all dark brown C. dilectus by indicating that the dark brown overlay can completely dominate. The specimen presented from Stock Island, Key West, illustrates (see presentation of C. dilectus).
I've never been one to buy into the idea of subspecies, preferring to consider differing "subspecies characters" to be no more than a persistent (generally genetically dominant) variation within a species, or where what is a "subspecies" may be a "separating cline" in development (potentially an allopatric, parapatric or simultaneously both speciation mechanisms in progress). C. dilectus may well fit this model. Both the Bahamas and southern Florida have been populated with animals originating from the Greater Antilles. It may well be that C. florifer arrived at both destinations, bred true in the Bahamas, but the Florida populations represent a persistent, dominant, within species variation that is evolving away from the mother line (or maybe not, but the character differences persist). And, it would not be surprising if this mechanism continues to deposit C. florifer in southern Florida where interbreeding may occur with C. dilectus repeatedly "absorbing" and dominating these new arrivals. Discussing C. dilectus in his recent Marine Shells of Northeast Florida, Harry Lee notes that "The ranges of the temperate subspecies tend to meet the tropical one in S.E. Florida."
I guess what it all comes down to is that I really can't accept C. dilectus as a separate species from C. florifer until DNA analysis addresses the issue.