Conus olssoni (Maury, 1917)

Description

Shell of medium size, very elongate, the length considerably more than twice the width; spire one-twelfth of the total length. Whorls eleven, the first two forming the protoconch rise abruptably above the following whorls, on which they rest like a minute but striking pinnacle visible to the unaided eye. The three whorls following the protoconch are flattened and discoidal, the subsequent six slope more rapidly towards the shoulder angle of the body whorl, they are convexly rounded between the deeply impressed suture lines, and marked with slightly arcuate, oblique growth-lines. The specimen described shows only very faint, nearly obsolete striae on the spire. Body whorl roundly angulated at the shoulder, thence tapering evenly and gradually to the base, smooth except for a few irregular, more or less obsolete basal striae ⁽¹⁾.

Length 38, width 16 mm.

This species is named in honor of Mr. Axel Olsson, by whom it was collected.

Locality. — (Exp'd '16) Zone D, Rio Gurabo at Los Que- mados.

Holotype: PRI 28612.

Other specimens: PRI 66157, PRI 67198–67206 (TU station 1422); PRI66137, PRI 67592–67604 (TU station 1215); PRI 66180, PRI 67242, PRI 67244–67251 (TU station 1354).

Coloration pattern

One pattern present. Pattern consists of slightly wavy to nearly straight, sometimes branching axial streaks that often extend from the base to the shoulder; these become finer in width as shell size increases. In some specimens, pigmented blotches occur at the shoulder; it is not clear how these relate to the principle pattern. The last whorl pattern extends over the shoulder onto the sutural ramp ⁽²⁾.

Remarks

Conus olssoni has a distinctive shell shape that is not easily confused with co-occurring species. It does, however, bear some similarity in shell form to Conus granulatus Linnaeus, 1758, an extant western Atlantic species recently characterized by Kohn. In particular, both species have similarly shaped last whorls and stepped spire whorls. While some specimens of C. granulatus have faint axial streaks on the last whorl (e.g., [8], pl. 2, Figs. 10–11), these are much more pronounced in C. olssoni. Additionally, C. granulatus possesses spiral rows of ribs and pigmented dots on the last whorl; these were not observed in C. olssoni. Tucker and Tenorio placed C. olssoni in the genus Dauciconus Cotton, 1945. Given the similarities in shell shape that it shares with C. granulatus, however, it is instead tentatively placed in the subgenus Atlanticonus Petuch and Sargent, 2012, following the designation for C. granulatus by Puillandre et al. It is worth mentioning that none of the four extant species assigned to the subgenus Atlanticonus by Puillandre et al. have been subjected to phylogenetic analysis; thus, this clade still requires verification ⁽²⁾.

Conus olssoni

Plate 7 – Fig. 3

mm. 38 x 16

A-I: Conus olssoni ⁽²⁾

(A) PRI 67198, TU 1422, SL 46.4 mm;

(B) PRI 67203, TU 1422, SL 22.4 mm;

(D) PRI 66137, TU 1215, SL 36.8 mm;

(E) PRI 67204, TU 1422, SL 25.4 mm;

(F-G) PRI 67200, TU 1422, SL 27.4 mm;

(H) PRI 67245, TU 1354, SL 36.7 mm;

(I) PRI 67598, TU 1215, SL 21.1 mm;

J: Conus graulatus ⁽²⁾

Isla Payardi, Bahia las Minas, Panama

(J) UF 329263–1,SL 35.0 mm

Bibliografia Consultata

· (1) - Maury, C. J., 1917. Santo Domingo Type Sections and Fossils. Bulletins of American Paleontology, 5 (29 )

· (2) - Hendricks (2015) “Glowing Seashells: Diversity of Fossilized Coloration Patterns on Coral Reef-Associated Cone Snail (Gastropoda: Conidae) Shells from the Neogene of the Dominican Republic”