Conus bellacoensis (Hendricks, 2015)

Description

Shell size. Shell moderately large (largest observed specimen, PRI 67252, is 76.0 mm). Last whorl. Conical (RD 0.53–0.66, μ = 0.57; PMD 0.88–0.93, μ = 0.91; n = 3); outline slightly convex. Shoulder angulate; smooth in mature specimens. Widest part of shell at shoulder in juvenile specimens, below shoulder in mature specimens. Aperture slightly wider at base than near shoulder. Siphonal notch absent. Weakly beaded spiral threads on anterior half.

Spire whorls. Spire height high (RSH 0.25–0.31, μ = 0.28; n = 3); outline straight, whorls stepped. Protoconch unknown. Most spire whorls tuberculate (information unavailable on earliest post nuclear whorls; 5 tuberculate whorls preserved on PRI 67252, 7 on PRI 66158), though later whorls are not. Sutural ramp concave, unornamented. Subsutural flexure symmetrical, depth about 3x width.

Coloration pattern. Two interacting patterns (one complex, one simple) present; it is not clear which pattern is primary. The more complex pattern consists of an irregular spiral band on the anterior end of the last whorl and a complex posterior pigmentation region composed of diamond-shaped blotches that are linked along their edges or corners to form axial or oblique-axial streaks. The simpler pattern consists of about 20 rows of spiral dots; spaces between dots sometimes appear to be unpigmented. The spiral dots are more closely spaced in regions where they intersect the complex pattern. The two patterns differ in the color of emitted light. Axial streaks on the last whorl sometimes extend onto the sutural ramp ⁽¹⁾.

Localities. — TU 1422: Arroyo Bellaco, Dominican Republic; upper Miocene Cercado Formation ⁽¹⁾.

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

Etymology

Named for the type locality, Arroyo Bellaco.

Remarks ⁽¹⁾

Conus bellacoensis is similar in shell form—and especially in its complex coloration pattern—to members of the “Conus cedonulli Species Group”, which includes the western Atlantic species C. cedonulli Linnaeus, 1767, C. pseudaurantius Vink and von Cosel, 1985, C. aurantius Hwass in Bruguière, 1792, C. mappa [Lightfoot, 1786], and C. curassaviensis Bruguière, 1792. The phylogenetic analysis of Puillandre et al. also recognized the eastern Pacific species C. archon as closely related to three of these species: (C. archon(C. cedunolli(C. curassaviensis,C. mappa))). Puillandre et al. assigned these extant species to the subgenus Stephanoconus, a designation that is followed here for C. bellacoensis, based on the hypothesis that it is also a member of this group. A key difference that separates the new species from extant members of this group is its narrower last whorl: the two known adult shells (PRI 66158 and PRI 67252) have relative diameters of 0.53, while other species in the group all have wider last whorls (mean values range from 0.60 to 0.66; [8]). Among Neogene fossils from the Dominican Republic, C. bellacoensis is most similar to C. sewalli, a species that is also hypothesized to be a member of the Stephanoconus clade.

Conus bellacoensis can be differentiated from C. sewalli by its narrower last whorl and higher spire.

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Fig 16. Conus (Stephanoconus) bellacoensis Hendricks sp. nov. (A-H)

(A-E) PRI 66158 (holotype), TU 1422, SL 59.7 mm;

(F) PRI 67252 (paratype), TU 1354, SL 76.0 mm;

(G-H) PRI 67186 (paratype), TU 1422, SL 12.4 mm

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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”