Conus praecipuus (Hoerle, 1976)

 

 

Diagnosis (1):

 

Shell slender, spire high, shoulder rounded; nucleus unknown, nine teleoconch whorls remaining. Spire whorls flat to concave, ornamented with three or four spiral threads; shoulders heavily tuberculate, tubercles absent on final turn; sutures closely adpressed, undulating with the tubercles; anal fasciole narrow and concave; anal notch deep; outer lip arched forward. Sculpture of last whorl consisting of narrow spiral cords, nearly obsolete adapically, stronger abapically.

 

Dimensions of holotype: height 38.0 mm, diameter 18.7 mm.

Holotype: USNM 220119.

Type locality: TU 546, Ten Mile Creek, about 1 ½  miles west of Chipola River (NW ~ Sec. 12, T1N, R10W), Calhoun County, Florida (?=USGS 2212, "one mile west of Bailey's Ferry").

Occurrence: Chipola Formation, Florida; late lower Miocene.

 

Figured specimen: USNM 220119 (holotype ).

 

Other occurrences: TU locality nos. 459, 951.

 

Discussion: C. praecipuus, an exceedingly rare species, is known from only three specimens, the holotype, a badly eroded paratype measuring 49.0 mm (incomplete) in the writer's collection, and one juvenile paratype, 28.8 mm in height, in the collection of Paul Drez, Chapel Hill, North Carolina. The latter specimen is in somewhat better condition than the other two, but the spiral sculpture on the final whorl is barely discernible. Whether this ornamentation increases with the maturity of the shell or is but a variable feature cannot be stated with any degree of certainty at this time. Additional specimens are needed to clarify this detail. Morphological characteristics such as the heavy tubercles, narrow, concave fasciole, deeply arcuate growth lines and prosocyrt labrum, are common to the three specimens examined.

C. praecipuus possibly is ancestral to C. consobrinus Sowerby, commonly found in ( ?) Miocene localities of Santo Domingo , Panama, Mexico, and Jamaica, as there is a marked resemblance in the two species. C. consobrinus is not known from southeastern United States. The high spire with heavy tubercles on the whorls, low rounded shoulder, attenuated and strongly sculptured final whorl all tend to make C. consobrinus a distinctive species. C. praecipuus is not as elongate, nor is the final volution as strongly ornamented; how ever, the similarity between the two species is apparent. No species similar to C. consobrinus has been reported from beds earlier than ( ?) upper Miocene. Because of the age differentiation and minor diagnostic features, the writer deems it more judicious at this time to give full taxonomic recognition to the Chipola form.

 

 

 

 

Conus praecipuus

Holotype 220119

mm. 38,0 x 18,7

 

Conus praecipuus

 

 

 

 

 

 

 

Bibliografia Consultata

 

·         (1) - Hoerle, S. E., 1976. The Genus Conus (Mollusca: Gastropoda) from the Alum Bluff Group of Northwestern Florida. Tulane Studies in Geology and Paleontology, 12 (1 )