Conus angosturis

Conus angosturis (Olsson, 1964)

The shell is small or medium-sized, slender, except during the more youthful stages. The mature shell is slender, about three times as high as its width at the shoulder, the conic spire composed of 10 plus whorls on the type specimen. The nucleus is a high, cylindrical coil of three smooth whorls, the second one large with bulging sides, the whole forming a pronounced nipple to the apex of the shell. Subsequent whorls are carinate, the sutures coiled a little below the sharp shoulder angle. On the last or body whorl, the shoulder carries a small, cordlike keel which accentuates its sharpness. Upper surface of whorls between the shoulder and the suture, or the subsutural fasciole is wide, smooth, except for the even concave curve of the growth line, the stronger ones with a tendency to be spaced at fairly regular intervals, and an obscure striation produced by minute spiral lines. The body whorl on the type is a long, slender, inverted cone, its widest part placed a little below the shoulder, its side with a modest convex curve above, then sloping inward below into a mildly contracted zone about the lower third and then more narrowed and attenuated towards the end. Younger and smaller shells found with the type are short and stubby but are considered to belong to the same species. On the type, there is a wide, plain or smooth band around the upper one-sixth; below this zone, the surface is marked with about 21 spiral bands set between engraved lines or grooves, the grooves becoming deeper and wider, the spiral bands progressively narrower and higher anteriorly. The upper bands are smooth but become weakly pustulated below, the pustules set along their upper margin. The smaller shells have pustulated bands over the whole surface below the shoulder. There is apparently no differentiated siphonal canal notch and no siphonal fasciole.

Length 33.7 mm., diameter 11.7 mm. Cueva de Angostura, Rio Santiago. Holotype, USNM 643928;

Length 17.6 mm., diameter 8.5 mm., an other length 21 mm., diameter 9.1 mm., specimen with nucleus. Cueva de Angostura, Rio Santiago. Paratype, USNM 643929.

Angostura formation: Cueva de Angostura, Rio Santiago.

Conus angosturis alegris, new subspecies

The shell is small, stout, like an immature C. angosturis but stubbier, the anterior end not noticeably contracted, and the sculpture is stronger. Shape of spire and the subsutural fasciole is similar to that of C. angosturis marked mainly by the curved inflexion of the lines of growth. The shoulder is sharply carinate. Body whorl is marked with strong, narrow, spiral cords for its whole length below the shoulder, and on the type specimen numbers about 20. These spirals form narrow, equal-size cords set between deep, grooved interspaces of the same width and are finely cross-threaded. The spiral cords carry small evenly spaced beads throughout.

Length 20.9 mm., diameter 9.6 mm. Holotype, USNM 643930.

A single specimen from the higher Picaderos beds along the Rio Santiago. It is possibly a fully distinct species, differing from C. angosturis, as described above, by its stubbier form and stronger sculpture.

Borbon formation: Selva Alegre, Rio Santiago.


Conus angosturis ⁽¹⁾ Plate 13 fig. 3 Holotype USNM 643928 mm. 33,7 x 11,7 Angostura fm., Cueva de Angostura Rio Santiago, Ecuador	Conus angosturis ⁽¹⁾ Plate 13 fig. 3b Paratype USNM 643929 mm. 21,0 x 9,1 Angostura fm., Cueva de Angostura Rio Santiago, Ecuador	Conus angosturis ⁽¹⁾ Plate 13 fig. 3b Paratype USNM 643929 mm. 17,6 x 8,5 Angostura fm., Cueva de Angostura Rio Santiago, Ecuador	Conus cf. angosturis IGL:IGM: 3239 Hypotype Miocene Medio – Frm. Ferrotepec Mkichoacan – Messico

Conus angosturis alegris ⁽¹⁾ Plate 13 fig. 4 Holotype USNM 643930 mm. 20,9 x 9,6 Borbon fm., Selva Alegre Rio Santiago, Ecuador