Conus aristos (Jung, 1965)

Descrizione e caratteristiche ⁽¹⁾:

Conchiglia di dimensioni da piccole a medie e slanciata; la spira è elevata, Il profilo della spira è rettilineo o leggermente concavo. L’ultimo giro è talvolta compresso verso la base. La protoconchiglia è formata da tre giri lisci e relativamente alti. I successivi giri sono otto o nove; i primi due o tre di questi giri hanno una ornamentazione che inizia con tubercoli assiali che dopo mezzi giro si evolvono in nodi sovrapposti alla carena che inizia nella stessa zona: questa ornamentazione può comunque essere poco evidenziata. I giri seguenti sono piatti o leggermente concavi; sono lisci ma mostrano linee di crescita. La sutura è posta ad una certa distanza sotto la spalla, quasi sempre piuttosto carenata. Le linee di crescita poste sull’ultimo giro sono poco evidenziate. La parte inferiore dell’ultimo giro è ornata con circa una dozzina di linee incise, che generalmente diventano più grandi  verso la base ⁽¹⁾. 

Descrizione e caratteristiche ⁽²⁾:

Kohniconus aristos is characterized by its small, slender shell; its pupoid protoconch composed of ca. 3.5 smooth whorls, with a small nucleus; its high scalariform spire, with the early teleoconch whorls bearing sculpture of axial ribs (Pl 46, Fig. 3d); its shallow subsutural flexure and slender last whorl, which is sharply carinate at the shoulder, slightly constricted at the base; and relatively long siphonal canal, slightly bent to the right. Spiral sculpture is restricted to the base and consists of ca. 12 narrow grooves. A color pattern is seen under ultraviolet light consisting of square blotches on the spire and just below the carina on the last whorl, below which lie horizontal rows of small dots.

J. K. Tucker and Tenorio (2009: 145) placed this species in the genus Jaspidiconus. However, according to J. K. Tucker and Tenorio (2009: 145), Jaspidiconus species do not have nodulose early whorls, the anal sinus is deep, the siphonal canal is short, and the protoconch is paucispiral. Therefore, the species description given above is far removed from these generic characters. It more likely that the Cantaure species is more closely allied to the present-day Panamic-Pacific Conus arcuatus Broderip & G. B. Sowerby I, 1829, which also has nodules on the early teleoconch whorls, a slight constriction at the base, and a longer siphonal canal. This species was placed in the genus Kohniconus by J. K. Tucker and Tenorio, 2009. Kohniconus arcuatus is also high spired, but has a broader shell than K. aristos. Having placed this species in the genus Kohniconus, none of the fossil tropical American species listed by J. K. Tucker and Tenorio (2009) or the present-day species are particularly similar to the Cantaure specimens. Almost all are much lower-spired.

Jung (1965) compared his species to Jaspidiconus sophus (Olsson, 1932), from the lower Miocene Zorritos Formation of Peru, but the Peruvian specimens are lower spired, with a wider last whorl. One of the paratypes of J. sophus (PRI 2279) has the protoconch and early whorls well preserved; the protoconch is tall and multispiral, similar to that of K. Aristos, but there is no axial sculpture on the early teleoconch whorls.

Jung (1965) also compared his species to the Plio/Pleistocene Floridian Conus waccamawensis B. Smith, 1930, which was synonymized with Ximeniconus oniscus (Woodring, 1928) by

Hendricks (2008: 34), but this species also lacks axial sculpture on the early teleoconch whorls.

Distribuzione: Lower–middle Miocene: Cantaure Formation, Venezuela (Jung, 1965).

 Conus aristos 24,0 x 9,0 mm. ⁽¹⁾

Bibliografia Consultata

·        (1)  - Jung (1965), “Miocene Mollusca from the Paraguana Peninsula, Venezuela”, Bulletins of American Paleontology vol. XLIX  (1965) N. 223, pp.577

·        (2) – Landau, Da Silva, Heitz (2016) “ Systematics of the Gastropods of the Lower– Middle Miocene Cantaure Formation, Paraguaná Formation, Paraguaná Peninsula,  Venezuela“

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