Conus alleni   (Hendricks & Portell, 2008)

 

 

 

Diagnosis (1):

Shoulder undulate; subsutural flexure diagonal; last whorl with raised spiral cords on anterior half.

 

Description (1):

Shell medium-sized (up to about 36 mm in length). Last whorl conical; outline straight to slightly sigmoidal (convex near shoulder). Shell widest at shoulder. Shoulder angulate and with large tubercles resulting from weak undulations. Spire of moderate height; outline straight to slightly concave. Larval shell unknown. Early postnuclear whorls tuberculate. Subsutural flexure diagonal, depth about 1.5x width. Teleoconch sutural ramps concave with several raised spiral cords. Aperture opening about as wide at base as at shoulder. Last whorl with pronounced raised spiral cords on anterior hall, sometimes extending weakly as threads to shoulder.

 

Type Series (1):

Holotype, UF 119920 (Figures 31, 32).

The three paratypes consist of external molds and include UF 119977 (Figure 33), UF 119919 (Figure 34), and UF 119976 (Figure 35). See Table 2 for measurements of these specimens.

 

Type Locality and Occurrence (1):

The holotype (UF 119920. Figures 31, 32) was collected by J. E. Allen from the Jacksonian Moodys Branch Formation at Montgomery Landing (UF localitv ZL004), Grant Parish, Louisiana.

The paratvpes are all from the Ocala Limestone of Florida, including two specimens from Lafayette County (UF 119976, Uf119977. UF locality LF002, Mill Creek Quarry) and one specimen from Suwannee County (UF 119919, UF locality SU014, Suwannee American Cement).

 

Etymology (1):

This species is named in honor ol James E. Allen (1914-1997) of Alexandria, Louisiana, who was an enthusiastic collector and scholar of Gulf Coast Eocene mollusks.

 

Discussion (1):

Conus alleni co-occurs in the Eocene at Louisiana with C. sauridens and in the Ocala Limestone of Florida with C. palmerae new species and C. sauridens.

Conus alleni can be readily differentiated from both species by its undulate shoulder and spiral cords on the anterior half of the last whorl (raised spiral threads on the last whorl may also be present on small shells of C. palmerae, but if so are much weaker).

 

Conus alleni shares some resemblance with a moldic Oligocene fossil (USNM 166720) from Decatur County, Georgia that Dall (1916) described as C. vaughani. Dall's (1916: pi. 86, fig. 1) figure of the cast shows a specimen (partially observed by matrix) with an obtuse spire angle, undulate shoulder, and raised spiral threads on the sutural ramps that are similar to the teleoconch morphology of C. alleni. The presence of rows of spiral beads on the last whorl, the fact that the shell is widest below the shoulder (rather than at the shoulder, as in C. alleni), and the fact that the anterior end of the shell appears completely obscured by matrix prevents us, however, from considering these two forms equivalent.

 

The only known shell material of Conus alleni is the holotype (from Grant Parish, Louisiana); the other three specimens are from Florida and all consist of external molds. This taxon was apparently rare, especiallv outside of Florida. We recognized this new form from the moldic Floridian material before we—by chance—discovered the similar shell from Louisiana in the FLMNH collections.

We chose to designate the shell as the holotype, lather than one of the paratype external molds, because of its greater number of characters available for observation.

 

 

 

 

Louisiana

 

 

Florida

 

 

Conus alleni

 

Holotype UF 119920

mm. 36,2 x 20,7

 

Moodys Branch Formation, UF locality ZL004

(Montgomeiv Landing), Grant Parish, Louisiana

Late Eocene

Conus alleni

 

33. Paratype (UF 119977) of C. alleni, preserved shell length 35.1 mm, Ocala Limestone, UF locality LF002 (Mill Creek Quarry), Lafayette County, Florida.

 

34. Paratype (UF 119919) of C alleni, presened shell length 33,2 mm, Ocala Limestone, UF locality SU014 (Suwannee American Cement), Suwannee County, Florida.

 

35. Paratype (UF 119976) of C. alleni, preserved shell length 34.5 mm, UF locality LF002 (Mill Creek Quarry), Lafayette County, Florida.

 

Late Eocene

 

 


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