Eopecten johnsoni Szente, 1996
SZENTE, I. 1996. Bivalve ecology in the Pliensbachian (Lower Jurassic) of the Bakony Mts. (Hungary). Description of a new species of Eopecten. Fragmenta Mineralogica et Palaeontologica, 18: 19-29, figs. 1-3, pl. 1. [p. 25, pl. 1, figs. 9, 19]
1996 Eopecten johnsoni Szente, 1996
I. Szente, 1996, plate 1.
|
«Holotype: a left valve housed in the Department of Palaeontology, Loránd Eötvös University, Budapest (EUŐT 9611)
Name: After Andrew L. A. JOHNSON, researcher of Mesozoic scallops. Type strata: Red fissure-filling limestone of the Margaritatus Zone (Upper Pliensbachian). Type locality: Eplény, former manganese-ore mine. Material: Five left valves íiom the Hierlatz limestone of the Kericser Hill, seven left valves and a right one flom the former manganese-ore mine at Eplény. Diagnosis: Medium-sized Eopecten with yery numerous fine, radial costae. Measurements (mm):
Description: Left valve (Pl. I: 9): higher than long, subaequilateral, moderately inflated. Dorsal margin straight. Umbones placed at about the three fifth of the length. Outline relatively regular. Anterior wing large, indistinctly demarcated. Some specimens bearing coarse comarginal plicae confined to the umbonal region. Valves omamented with numerous fine radial costae, whose number is increasing toward the disc margin by intercalation of new costae gaining rapidly the size of original ones. - Right valve: Only an incomplete specimen is available (Pl. I: 10), which is almost flat and bears fine radial costae.
Remarks: The remarkable variability observable within Eopecten has resulted in a plethora of specific names available for European Jurassic representatives of this genus. JOHNSON (1984) found, however, that they can be assigned to three species. Among them only left valves of E. spondyloides (Roemer, 1836) are ornamented with original costae of equal size and with intercalatory costae rapidly gaining the height of originals. The standardized numbers of costae of E. spondyloides (at H: 10 between 22 and 32, and at H: 20 between 30 and 48) (JOHNSON 1984) are, however, much smaller than those of E. johnsoni (at H: 10 about 70 and at H: 20 about 100). Assignement of the Bakony specimens to a new species seems to be therefore well justified. Range and occurrence: Eopecten johnsoni sp. n. is known from the Pliensbachian (Jamesoni to Margaritatus zones) of the Bakony Mts., Hungary.» ISTVÁN SZENTE, 1996
|