Neithella Hayami, 1965
HAYAMI, I. 1965. Lower Cretaceous marine pelecypods of Japan, part I. Memoirs of the Faculty of Sience, Kyushu University, [Serie D - Geology], 15 (2): 221-349, pls. 27-52. [p. 291]
«Subgenus Neithella nov.
Type-species.— Janira wrightii SHUMARD, 1860, Upper Albian, Gulf Coast.
Diagnosis.— Shell small, scarcely exceeding 40 mm. in height, comparatively narrow; right valve provided with four, five or six roundly plicated and broad ribs; secondary riblets absent; a number of fine radial striae marked on the bottom of each interspace and the slopes of the primaries; left valve also plicated, with digitated ventral margin; auricles unequal; anterior auricle usually pointed in front, much larger than posterior one.
List of species.--
Pecten atavus RÖMER, 1839, p. 29, pI. 18, fig. 21 (WOODS, 1902, p. 197, pI. 39, figs. 1-5) (non D'ORBIGNY, 1847, p. 627, pI. 442, figs. 1-3, 5; non PICTET and CAMPICHE, 1870, p. 237, pI. 180; non GILLET, 1924 b, p. 51, text-figs. 27-29; non ALENCASTER, 1956, p. 12, pI. 2, figs. 5-7) upper Neocomian-Aptian, Western Europe and (?) Japan. Janira cometa D'ORBIGNY, 1847, p. 640, pI. 445, figs. 15-20 (WOODS, 1902, p. 200, pI. 39, figs.6-10) Cenomanian, Western Europe. Janira johannisboehmi TIESSEN, 1895, p.473, pI. 17, figs.5 (? = J. cometa) Pecten (Neithea) hourcqi COLLIGNON, 1939, p. 13, pI. 1, figs. 16, 17, Cenomanian, Madagascar. Janira longicauda D'ORBIGNY, 1847, p. 639, pI. 445, figs.9-14 (GEINITZ, 1872, p. 202, pI. 45, figs. 16, 17) Turonian, Western Europe. Janira matheroniana DE LORIOL, 1866, p.65, pI. 2, fig. 9 (? = P. atavus, as interpreted by WOODS, 1902). Janira neocomiensis D'ORBIGNY, 1847, p. 629, pI. 442, figs. 4, 6-9 (DE LORIOL, 1861, p. 105, pI. 14, figs. 2, 3) (= P. atavus). Pecten notabilis MÜNSTER, in GOLDFUSS, 1836,p. 56, pI. 93, fig. 3 (GEINITZ, 1872, p. 202, pI. 45, figs. 10-12) "Greensand", Germany. Pecten (Neithea) ornithopus KEEPING, 1870, p. 107, pI. 4, fig. 5 (= P. atavus, as interpreted by WOODS, 1902). Janira valanginiensis PICTET and CAMPICHE, 1870, p. 242, pI. 181, figs. 1-3, Neocomian, Switzerland. Janira wrightii SHUMARD, 1860, p. 607 (CRAGIN, 1893, p. 217, pI. 32, figs. 2, 3; WHITNEY, 1911, p. 13, pI. 1, fig. 4; KNIKER, 1919, p. 23, pI. 4, figs. 1-3; ADKINS and WINTON, 1920, p. 69, pI. 11, figs. 8-11; WINTON, 1925, p. 53, pI. 10, fig. 6; ADKINS, 1928, p. 125, pI. 17, fig. 6; SRANTON, 1947, p. 46, pI. 21, figs. 6, 7) Albian, Gulf Coast. Remarks.— The unequal auricles have not been observed in all the above-listed species, because of the inadequate state of preservation, but this subgenus is well characterized by the small size of the shell, the broadly plicated primary ribs, and the weak secondary ornament. Many species of this group have six primary ribs as those of Neithea (s. str.). According to WOODS (1902), Neithea cometa (D'ORBIGNY, 1847) has only five primary ribs on the right valve, and Neithea wrightii (SHUMARD, 1860), the type-species of this subgenus, is characterized by only four primaries. In all the species of this subgenus with six primaries, however, the 1st and 6th ribs are much weaker than other ribs, and, therefore, the number of primaries may not be a very important character for the classification of this subgenus.
Judging from the stratigraphic occurrences, this subgenus may have constitute a distinct evolutionary stem ranging from Neocomian to Turonian. Species with decreased primaries appeared mainly in the Albian and later,. and they were probably derived from six-ribbed species which were common already in the Neocomian.» ITARU HAYAMI, 1965
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Neithea wrighti (Shumard); H. T. Kniker, 1919, Comanchean and Cretaceous Pectinidae of Texas, plate 4, figures 1-3.
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Neithea (Neithella) notabilis (Muenster in Goldfuss); A. V. Dhondt, 1973, Systematic revision of the subfamily Neitheinae (Pectinidae, Bivavia, Mollusca) of the European Cretaceus, plate 4, figure 2.
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«The division of the genus Neithea as proposed by I. HAYAMI, 1965, must be revised, because he relies on the work of NORTH which, as stated above, is based upon an erroneous interpretation of the rules of zoological nomenclature:
— Aequineithea HAYAMI (1965, p. 292) is an objective synonym of Neithea s. s. as designed by CHENU: both taxa have Pecten aequicostatus LAMARK as type-species.
— Neithea s. s. HAYAMI (1965, p. 292) [type-species Neithea quinquecostata (SOWERBY)] is a taxonomic synonym of Neitheops because both taxa have the same content.
— Neithella I. HAYAMI (1965, p. 29I) [type-species Janira wrighti SHUMARD, 1860 (O.D.)] has been created for species with 4-6 asymmetrical ribs and very unequal auricles. The ribs of the left valve are the reflection, and not the negative impression, of those on the right valve. This subgenus must be maintained.»
DHONDT, A. V. 1973. Systematic revision of the subfamily Neitheinae (Pectinidae, Bivavia, Mollusca) of the European Cretaceus. Mémoires du Institute Royal des Sciences Naturelles de Belgique, 176: 1-101, pls. 1-5. [p. 8]
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