Conus acolus (Woodring, 1970)

Descrizione e caratteristiche:

Shell, broad-shouldered, edge of shoulder angulated. Spire of moderate height,  profile evenly conical or almost evenly conical. Protoconch missing. Earliest post-protoconch whorls worn, shoulder angulation exposed on later whorls.

Anal fasciole concave, marked only by growth lines. Lower part of body whorl sculptured with widely spaced spiral grooves ⁽¹⁾.

Type locality : 136a ( Stanford University 2011 , figured specimen ) . Transisthmian Highway , lat 9 ° 21 ' N. plus 1,100 feet ( 335 meters ); long 79 ° 49 ' W., Panamá ; same as USGS 16912 ),lower part of Gatun formation  ⁽¹⁾.

Conus acolus is a small species based on  nine specimens in three collections from the lower part of the Gatun formation . It may be distinguished from immature shells of C. bravoi, with which it is associated, by its more evenly conical spire, more concave anal fasciole and stronger spiral sculpture on the lower part of body whorl ⁽¹⁾.

C. cercadensis Maury ( 1917 , p . 43 , pl . 7 , fig . 4; Cercado formation, Dominican Republic) has a more rounded shoulder; its late whorls overlap to the edge of the shoulder of the preceding whorl, and its spiral sculpture covers a larger part of the body whorl, although in reduced form ⁽¹⁾.

In outline Conus acolus suggest a  small version of Conus bermudensis, a living western Atlantic species from Bermuda and the east coast of Florida⁽¹⁾.

Occurrence:  Lower part of Gatun Formation, Middle Miocene, loc. 136, 136a, 138c. Middle Miocene deposits, Chiriquì area (USGS 7955, identification dubtfull), Panama ⁽¹⁾.

Conus acolus also occurs in the late Miocene Angostura Formation at Punta Verde, Esmeraldas Province, Ecuador, and has a close ally in the Recent Tropical East Pacific in C. perplexus Sowerby, 1857 ⁽²⁾.

Bibliografia Consultata

• (1) - Woodring, W. P., 1970. Geology and Paleontology of Canal Zone and Adjoining Parts of Panama. U.S. Geological Survey Professional Paper, 306-D pag. 346-349 = 459-462

• (2) - W.D. Pitt, L.J. Pitt (1993) “ULTRA-VIOLET LIGHT AS A USEFUL TOOL FOR IDENTIFYING FOSSIL MOLLUSKS, WITH EXAMPLES FROM THE GATUN FORMATION, PANAMA”

• (3) - Aguilar, Acevedo, Ulloa (2010) “PALEONTOLOGY OF A SECTION OF THE CORREDORES RIVER, CURRE’ FORMATION, MIOCENE, COSTA RICA”

• (4) - Hendricks (2018) “Diversity and preserved shell coloration patterns of Miocene Conidae (Neogastropoda) from an exposure of the Gatun Formation, Colón Province, Panama” May 2018, Journal of Paleontology 92(5):1-34