Early Pliocene to Late Pliocene; Extinct.
Southern Florida to northern Florida.
Original Description (from Mansfield, 1932, p. 48-49):
"In the report by Cooke and Mossom I referred this form to Encope macrophora Ravenel, but I now believe, after more study, that it represents a new subspecies of E. macrophora.
E. macrophora tamiamiensis appears to be an intermediate form between E. macrophora and E. grandis (L. Agassiz). It differs from E. macrophora in having a proportionately wider and thinner test, a concave instead of convex posterior margin, and a much smaller interambulacral lunule. It differs from E. grandis, a Recent species reported by A. Agassiz to occur in the Gulf of California, in having in general a shallower anterior marginal notch and less incised lateral marginal notches. The posterior margin on both forms is very similar in the degree of convexity, indicating a close relationship.
The test of the new subspecies is usually wider than long, rather thin, but not having sharp edges. The region directly in front of the lunule is the thickest part of the test. The lunule is elliptical and is surrounded on its upper surface by a raised border.
Dimensions: Holotype (catalogue No. 371328, U. S. Nat. Mus.), length, 84 millimeters; width, 87 millimeters; height, 11 millimeters; thickness of margins, about 6 millimeters.
Type locality: Station 1/1177, Tamiami Trail, 5 miles east of Carnestown and about 7 miles northeast of Everglades, Collier County.
Occurrence: Pliocene. Type locality (abundant), station 1/1180 (abundant), station 1/1178 (rare?). Small specimens that have been referred to Encope macrophora, from the Pliocene Caloosahatchee marl at Alligator Creek, Monroe County, Fla., appear to be more closely related to the new subspecies than to E. macrophora."
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