Hendricks—Miocene Conidae from the Gatun Formation of Panama
consistently show the presence of two non-interacting patterns. UV light reveals a very different pattern on the dorsal surface of USNM 645757: three rows of nearly circular blotches, with no secondary pattern (Fig. 5.2). If this different pattern were found to be consistent in the older, Gatunian specimens of C. symmetricus, it could be reasonably argued that the speci- mens from the Gatun Formation constitute a different species. A single poorly preserved specimen (UF 271037, Fig. 5.3)
found at UF locality YN020 is questionably assigned here toC. symmetricus. Unfortunately, it does not show any evidence of a preserved coloration pattern under UV light, so does not provide any clarification with respect to this question. Pending discovery of additional specimens bearing preserved coloration patterns, C. symmetricus is tentatively accepted as occurring in the Gatun Formation. See discussion in Hendricks (2015) for the reasons why C. symmetricus cannot currently be assigned to a subclade within Conus.
Conus aemulator Brown and Pilsbry, 1911 Figures 6.1–6.16, 7.1–7.5
1911 Conus aemulator Brown and Pilsbry, p. 342, pl. 23, fig. 9.
1922 Conus veatchi Olsson, p. 44, pl. 2, figs. 5, 8.
1970 Conus aemulator aemulator; Woodring, p. 351, pl. 55, figs. 5, 6, pl. 56, figs. 4, 8.
1993 Not Conus aemulator aemulator; Pitt and Pitt, p. 10, pl. 3, fig. 6.
2009 Dauciconus aemulator (Brown and Pilsbry); Tucker and Tenorio, p. 88.
2016 Dauciconus aemulator (Brown and Pilsbry); Landau
et al., p. 204, pl. 44, fig. 5, pl. 45, figs. 1, 2, pl. 46, fig. 8, pl. 47, fig. 8.
Holotype.—ANSP 1691, “excavations for the locks at Gatun” (Brown and Pilsbry, 1911, p. 336), Panama Canal Zone.
Occurrence.—Conus aemulator was described from excava- tions for the Gatun locks, which Woodring (1970, p. 351) characterized as middle Gatun Formation. Woodring (1970) reported the species as spanning the Gatun Formation. Additional records presented by Woodring (1970) for C. aemulator come from Neogene localities throughout tropical America, including the Darién and Bocas del Toro areas of Panama, Ecuador, the Dominican Republic, Haiti, the Grenadine Islands, and Colombia; these all require confirma- tion. Very recently, Landau et al. (2016) reported the species from the lower–middle Miocene Cantaure Formation of Venezuela.
Description.—Maximum shell size: medium. Largest observed specimen (UF 270973) has SL 43.7mm. Typical shell size of specimens from UF locality YN020: medium (32.3mm; N=29). Last whorl.—Shape conical to broadly conical (RD 0.64–
0.73, x=0:68; PMD0.86–0.91, x=0:88;N=17); outline convex on posterior half, nearly straight on anterior half, resulting in a slightly convex profile. Shoulder carinate and forming a posterior- pointing ridge. Widest part of shell below shoulder. Aperture
Materials.—ANSP 1691 (holotype, Fig. 6.1–6.3); USNM 645744 (one specimen, figured by Woodring, 1970; Fig. 6.4, 6.5); 56 additional observed specimens, all from UF locality YN020, which are listed in Supplementary Data Set 1.
Remarks.—This species was described from the Gatun Forma- tion on the basis of a single calcitic cast (holotype, ANSP 1691; Fig. 6.1–6.3). This poorly preserved specimen has a conical last whorl (RD 0.66, PMD 0.86) and a moderately high spire (RSH 0.14); there is evidence of several spiral threads on the sutural ramp and on the anterior half of the last whorl. Despite the poor preservation of the holotype, the characteristics preserved allow it to be recognized as a valid taxon. Shells of Conus aemulator are very similar to those of
C. molis and the possibility that specimens of C. aemulator are in fact juvenile C. molis (see below) was carefully considered. Both taxa have shells that are similar in overall shape, are widest below the shoulder, have raised spiral ornamentation on the anterior half of the last whorl, and possess spiral ornamentation on the sutural ramp. One key difference is that mature specimens of C. molis are much larger than mature C. aemulator, but this does not assist with differentiating immatureC. molis from matureC. aemulator. The very different coloration patterns (revealed by UV light) of the two species, however, do help to resolve this problem: C. aemulator has only one layer of pigmentation (three discontinuous spiral bands), while C. molis has two layers that vary in the color of emitted light (two or three regions of axial streaks covered by two or three nearly continuous spiral bands). Two features provide some additional assistance for differentiating the two species. The sutural ramp of C. aemulator features three to six (but usually four) grooves that separate spiral threads, while more such grooves (often five or more) are commonly present on the ramps of specimens of C. molis. Finally, relative to C. molis, the subsutural flexure of C. aemulator is much more
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slightly wider at base than shoulder. Siphonal notch absent. Slightly wavy spiral threads or cords present, usually restricted to the anterior half, but in rare cases extend past the midline or are absent altogether. Some specimens (e.g.,UF 259739,UF 270980) show evidence of weakly beaded spiral threads. Spire whorls.—Spire low to moderate (RSH 0.05–0.19,
x=0:11; N=17); outline concave to slightly sigmoidal. Early spire whorls stepped. Protoconch unknown. Ornamentation of early postnuclear whorls unknown. Sutural ramp slightly con- vex to flat on early whorls, concave or sigmoidal in later whorls, with 3–6 (typically four) spiral grooves that separate threads. Subsutural flexure asymmetrical to strongly asymmetrical (ASSF 0.2–0.7, x=0:4, N=4), depth typically slightly greater than width (DWSSF 0.9–1.7, x=1:3, N=4) (Fig. 6.6). Coloration pattern.—One pattern present. Pattern usually
consists of three rows of discontinuous spiral bands. The ele- ments within the bands are complex, including sub-rectangular blotches (e.g., Fig. 6.7), diagonal streaks (e.g., Fig. 6.8), sub- triangular markings (e.g., Fig. 6.11, 6.13), irregular blotches (Fig. 6.14), or closely spaced axial streaks (Fig. 6.15); in one observed specimen (Fig. 6.16), the spiral elements form nearly continuous bands. Sutural ramp with occasional blotches.
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