Conus lyelli (Hendricks, 2015)

Description ⁽¹⁾

Shell size. Shell moderately small (largest observed complete specimen, PRI 66156, is 23.7 mm; a fragment of a larger specimen, PRI 66192, with MD 22.8 mm is also known, suggesting a complete shell size of about 35 mm).

Last whorl. Broadly conical (RD 0.70–0.75, μ = 0.73; PMD 0.89–0.93, μ = 0.91; n = 3); outline slightly sigmoidal. Shoulder subangulate, with undulations. Widest point of shell at shoulder. Aperture uniform in width from base to shoulder. Siphonal notch absent. Spiral threads on anterior half, diminishing towards shoulder.

Spire whorls. Spire height low to moderate (RSH 0.09–0.17, μ = 0.15; n = 3), with later whorls depressed beneath shoulder in some specimens; outline concave. Protoconch with 2.2 whorls, diameter 0.8 mm (based on PRI 66189). Tubercles present on first several postnuclear whorls, becoming posterior-pointing shoulder undulations in later whorls. Sutural ramp slightly concave to flat, with 3–6 fine spiral threads. Subsutural flexure symmetrical, depth about 0.6–0.8x width.

Coloration pattern. One pattern present. Pattern consists of slightly jagged to saw-toothed, non-branching thin axial streaks that in many cases extend from the base to the shoulder. There is no evidence of a coloration pattern on the spire whorls ⁽¹⁾.

Etymology ⁽¹⁾

Named for the great geologist Charles Lyell (1797–1875), who popularized the concepts of uniformitarianism and the antiquity of the earth.

Remarks ⁽¹⁾

Conus lyelli is most similar in shell shape to Conus xenicus Pilsbry and Johnson, 1917 (Fig. 11M,N), which is also known from the Neogene of the Dominican Republic. An important difference is that C. lyelli possesses tubercles or shoulder undulations on all postnuclear whorls, while these features are absent in the holotype of C. xenicus (ANSP 2575). Additionally, the shoulder in C. xenicus is angulate and this species also has much more prominent spiral threads on its sutural ramp. As detailed locality information is not available for C. xenicus, it is not known whether it was contemporaneous with C. lyelli.

Conus ornatus of Maury, 1917 (not of Röding, which in turn is a junior synonym of C. generalis Linnaeus, 1767; see Röckel et al.) and C. williamgabbi Maury, 1917 are also somewhat similar to C. lyelli, both having broad shells with low spires. Like C. xenicus, C. ornatus differs from the new species in its lack of tuberculate postnuclear whorls. Conus williamgabbi has an asymmetrical, deep subsutural flexure and is much larger than the new species. Conus lyelli is not similar to any known extant species, suggesting that it, along with C. xenicus, may be members of an extinct clade of cone snails.

Material examined ⁽¹⁾

Holotype:

PRI 66156 (TU station 1422).

Paratypes: PRI 66189–66192 (TU station 1422); PRI 66184 and 67165 (TU station 1354); PRI 66115 (TU station 1278).

Type locality and horizon ⁽¹⁾

TU 1422: Arroyo Bellaco, Dominican Republic; upper Miocene Cercado Formation.

Other localities and horizons ⁽¹⁾

TU 1354: Cañada de Zamba, Dominican Republic; lower Pliocene Gurabo Formation. TU 1278: Río Gurabo, Dominican Republic; lower Pliocene Gurabo Formation.

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Conus lyelli ^(1) (A-C) PRI 66156 (holotype), TU 1422, SL 23.7 mm; (D-F) PRI 67165 (paratype), TU 1354, SL 21.2 mm; (G-I) PRI 66189 (paratype), TU 1422, SL 20.3 mm; (J) PRI 66184 (paratype), TU 1354, SL 22.3 mm; Miocene
Conus lyelli ^(1) (K-L) PRI 66115 (paratype), TU 1278 SL 29.4 mm (estimated from digital image)
Conus xenicus ^(1) S. Domingo (M-N) ANSP 2575 (holotype) SL 28.3 mm (estimated from digital image) Oligocene	Conus xenicus (Pilsbry & Johnson, 1917) S. Domingo Plate XX Fig. 11= mm. 28,5 - ANSP 2575 (holotype) Gig. 11a= mm. 27,0 Oligocene

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Conus xenicus (Pilsbry & Johnson,1917

The shell is broad above, the diameter about two-thirds of the length; spire low, its outline strongly concave, rising to an acute apex; periphery carinate, the slopes below it nearly straight. The early whorls have a smooth keel, projecting above the suture, but the last five are flat, with very weak traces of spiral striae, and separated by a plain, narrowly impressed suture. The last whorl has coarse, well separated spiral cords on the anterior end, but under suitabty oblique light very faint spirals may be seen throughout. The faint growth-strise retract rather strongly near the shoulder. The aperture is very narrow.

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Bibliografia Consultata

· (1) - 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”

· (2) - Pilsbry, H. A., and Johnson, 1917. Oligocene Fossils from the Neighborhood of Cartegena, Columbia, with Notes on Some Haitian Species. Proceedings of the Academy of Natural Sciences of Philadelphia, 69

· (2a) - Pilsbry, H. A., and Johnson, 1917. Oligocene Fossils from the Neighborhood of Cartegena, Columbia, with Notes on Some Haitian Species. Proceedings of the Academy of Natural Sciences of Philadelphia, 69