Conus aemulator (Brown & Pilsbry, 1911)

Conus aemulator manzanillaensis (Mansfield, 1925)

Conus aemulator michoacanensis (Perrilliat, 1992)

 

 

 

Descrizione e caratteristiche:

 

Occurrence (4).

Conus aemulator was described from excavations for the Gatun locks, which Woodring (1970, p. 351) characterized as middle Gatun Formation. Woodring (1970) reported the species as spanning the Gatun Formation. Additional records presented by Woodring (1970) for C. aemulator come from Neogene localities throughout tropical America, including the Darién and Bocas del Toro areas of Panama, Ecuador, the Dominican Republic, Haiti, the Grenadine Islands, and Colombia; these all require confirmation (4).

Very recently, Landau et al. (2016) reported the species from the lower–middle Miocene Cantaure Formation of Venezuela (4).

 

Description (4).

—Maximum shell size: medium. Largest observed specimen (UF 270973) has SL 43.7 mm. Typical shell size of specimens from UF locality YN020: medium (32.3 mm; N=29). Last whorl.—Shape conical to broadly conical (RD 0.64–0.73, x= 0:68; PMD 0.86–0.91, x= 0:88; N=17); outline convex on posterior half, nearly straight on anterior half, resulting in a slightly convex profile. Shoulder carinate and forming a posteriorpointing ridge. Widest part of shell below shoulder. Aperture slightly wider at base than shoulder. Siphonal notch absent. Slightly wavy spiral threads or cords present, usually restricted to the anterior half, but in rare cases extend past the midline or are absent altogether. Some specimens (e.g., UF 259739, UF 270980) show evidence of weakly beaded spiral threads. Spire whorls.—Spire low to moderate (RSH 0.05–0.19, x= 0:11; N=17); outline concave to slightly sigmoidal. Early spire whorls stepped. Protoconch unknown. Ornamentation of early postnuclear whorls unknown. Sutural ramp slightly convex

to flat on early whorls, concave or sigmoidal in later whorls, with 3–6 (typically four) spiral grooves that separate threads. Subsutural flexure asymmetrical to strongly asymmetrical (ASSF 0.2–0.7, x =0:4, N= 4), depth typically slightly greater than width (DWSSF 0.9–1.7, x=1:3, N=4) (Fig. 6.6) (4).

 

Coloration pattern (4).

—One pattern present. Pattern usually consists of three rows of discontinuous spiral bands. The elements within the bands are complex, including sub-rectangular blotches (e.g., Fig. 6.7), diagonal streaks (e.g., Fig. 6.8), subtriangular markings (e.g., Fig. 6.11, 6.13), irregular blotches (Fig. 6.14), or closely spaced axial streaks (Fig. 6.15); in one observed specimen (Fig. 6.16), the spiral elements form nearly continuous bands. Sutural ramp with occasional blotches (4).

 

Materials (4).

—ANSP 1691 (holotype, Fig. 6.1–6.3); USNM 645744 (one specimen, figured by Woodring, 1970; Fig. 6.4, 6.5); 56 additional observed specimens, all from UF locality YN020, which are listed in Supplementary Data Set 1 (4).

 

Remarks (4).

—This species was described from the Gatun Formation on the basis of a single calcitic cast (holotype, ANSP 1691; Fig. 6.1–6.3). This poorly preserved specimen has a conical last whorl (RD 0.66, PMD 0.86) and a moderately high spire (RSH 0.14); there is evidence of several spiral threads on the sutural ramp and on the anterior half of the last whorl. Despite the poor preservation of the holotype, the characteristics preserved allow it to be recognized as a valid taxon. Shells of Conus aemulator are very similar to those of C. molis and the possibility that specimens of C. aemulator are in fact juvenile C. molis was carefully considered. Both taxa have shells that are similar in overall shape, are widest below the shoulder, have raised spiral ornamentation on the anterior half of the last whorl, and possess spiral ornamentation (4).



Distribuzione temporale:     Oligocene Superiore – Miocene Medio

Distribuzione geografica:     Colombia, Venezuela, Ecuador, Panama, Lesser Antilles, Grenadine Island

 


 

 

 

 

Conus aemulator (1) - ( Brown & Pilsbry, 1911 )

mm. 22,5 x 12,8

Panama

 

Conus cf. aemulator (3) - ( Brown & Pilsbry, 1911 )

mm. 45,1 x 26,4

Carriacou Island

 

Conus aemulator manzanillaensis (Mansfield, 1925)

Trinidad

 

 

Conus aemulator (1) - ( Brown & Pilsbry, 1911 )

mm. 45 x 28

Panama

 

Conus aemulator (3)

mm. 22,7 x 12,8

 

 

 

Conus aemulator

Conus aemulator

Conus aemulator michoacanensis (Perrilliat, 1992)

Messico

 

 

 






Panama

Conus aemulator - ( Brown & Pilsbry, 1911 )

mm 39,1 x 24,6 – Miocene - Gatun Fm.

[AZFC N. 507-01]

 

Coll: ALESSANDRO ZANZI

 

Conus sp.

39.2 mm - Panama

*Collect on 70´s. in Gatún. The place dissapeared by construction of a road

 

Ex Coll: María Vidal Sigler - 2238461

 

 

 

 

Conus cf. aemulator (3)

mm. 45,1 x 26,4

Carriacou Island

Conus aemulator (1) (4)

USNM 645744

Woodring (1970, pl. 56, figs. 4, 8)

mm. 45,2 x 28,7

Panama

Conus aemulator

mm. 39,1 x 24,6

Miocene - Gatun Fm.

[AZFC N. 507-01]

Conus aemulator (3)

mm. 22,7 x 12,8

Conus aemulator (1)

mm. 22,5 x 12,8

Panama

 

 

 



Bibliografia Consultata

 

·        (1) - A.P. Brown and H.A. Pilsbry (1911) “Fauna Of The Gatun Formation, Isthmus Of Panama”, Proceedings Of The Academy of Natural Science of Philadelphia Vol. LXIII, Part II

·        (2) - Peter Jung - Fossil Mollusk from Carriacou, West Indies

·        (3) - Woodring – Geology and Paleontology of Canal Zone and Adjoining Parts of Panama

·        (4) - Hendricks (2017) “Diversity and preserved shell coloration patterns of Miocene Conidae (Neogastropoda) from an exposure of the Gatun Formation, Colón Province, Panama