Argopecten invalidus (Hanna, 1924)
HANNA, G. D. 1924. Rectifications of nomenclature. Proceedings of the California Academy of Sciences [4th Series], 13 (10): 151-186. [p. 177]
1906 Pecten (Plagioctenium) cooperi Arnold, 1906
1924 Pecten invalidus Hanna, 1924 [nomen novum pro Pecten cooperi Arnold, 1906]
1925 Pecten (Plagioctenium) subdolus Hertlein, 1925
1929 Pecten (Plagiotecnium) callidus Hertlein, 1925
1924 Pecten invalidus Hanna, 1924 [nomen novum pro Pecten cooperi Arnold, 1906]
1925 Pecten (Plagioctenium) subdolus Hertlein, 1925
1929 Pecten (Plagiotecnium) callidus Hertlein, 1925
Chlamys (Argopecten) invalida Hanna; L. G. Hertlein & U. S. Grant IV, 1972, The Geology and Paleontology of the marine
Pliocene of San Diego, plate 33, figures 1, 3, 8
|
«63. Pecten invalidus Hanna, new name
Pecten (Plagioctenium) cooperi ARNOLD, Prof. Paper 47, U. S. Geol. Surv. 1906, p. 124, pl. 49, figs. 2-4, Pliocene, Pacific Beach, San Diego County, California. Not Pecten cooperi, E. A. SMITH, Fauna and Geography of Maldive and Laccadive Archipelagos, Vol. 2, 1903, p. 621.» GEORGE DALLAS HANNA, 1924
|
«EMENDED DESCRIPTION. Shell medium size, up to height 117 mm; specimens commonly approximately height 45-55 mm. Valves slightly longer than high on most specimens; smaller specimens tend to be slightly longer than high, larger specimens tend to be slightly higher than long. Left valve more convex than right valve on most specimens; valves nearly equally convex on few specimens. Hinge line approximately half of disk length. Umbonal (apical angle) 100°–105°. Ribs 20-22 in number on both valves, with lamellae in interspaces. Ribs become obsolete on anteriormost and posteriormost parts of valves and tend to flatten out and become more convex in the later stages of growth. Auricles with prominent radial riblets on both valves; riblets stronger on anterior auricles of both valves. Left valve: ribs narrower than on right valve; interspaces wider than ribs and wider than those on right valve; anterior auricle with very small notch; posterior auricle slightly truncated; anterior and posterior auricles, both auricles with seven to nine riblets. Right valve: ribs wider than on left valve; interspaces narrower than ribs and narrower than those on left valve; anterior auricle with small notch; five to seven flattish riblets, strongest one coincident with notch area and variable in width and elevation; posterior auricle slightly truncate; six to seven (rarely more) radial riblets.
COMPARISON. Argopecten invalidus, A. callidus, and A. subdolus are conspecific based on a comparative study of actual specimens of each ‘‘species’’ that shows they lack consistent, reliable morphologic differences separating them from one another. Their reported differences (see Hertlein, 1925; Hertlein and Grant, 1972) were based on whether or not the ribs are flattopped, rounded, and on the depth of the interspaces. These differences, however, are attributable to how much weathering the specimens have experienced. In the study area, for example, specimens of A. invalidus at any one locality show variation in the shape and depth of the ribs, with the variation clearly attributable to the degree of weathering. In addition to A. invalidus, A. callidus, and A. subdolus, Grant and Gale (1931: see pages 210, 211, 212, 214) reported three other argopectinid species in the study area beds: A. percarus (Hertlein, 1925), A. mendenhalli (Arnold, 1906), and A. imposter (Hanna, 1924). Argopecten percarus differs from A. invalidus by having 24-25 ribs on the left valve and an umbonal angle of 118°. Argopecten mendenhalli differs from A. invalidus by having a much longer hinge line, weak sculpture on the rightvalve anterior auricle, obsolete sculpture on the left-valve anterior auricle. Argopecten imposter differs from A. invalidus by having weak grooves along the sides of the major ribs and a left valve with narrower interspaces. Argopecten invalidus is similar to A. deserti (Conrad, 1855) and the extant A. ventricosus (G.B. Sowerby II, 1842). Argopecten invalidus differs from A. deserti by having larger size, right-valve interspaces narrower than the ribs, left-valve ribs narrower than those on the right valve, left-valve interspaces wider than the ribs, more ribs on the right-valve anterior auricle, and a shorter hinge line. Argopecten invalidus differs from A. ventricosus by having a larger maximum height (95 mm), less-inflated right valve, as well as narrower and generally more ribs on the right-valve anterior auricle. In the comparision of the above-mentioned argopectinids, only the ribs that extend continuously from the beak to the venter were counted. Specimens with one or two weak, noncontinuous ribs that are present on both the anteriormost and posteriormost sides of the specimens were not included. The largest specimen of A. invalidus in the study area is 70 mm in height. TYPE MATERIAL. Holotype of Pecten (Plagioctenium) cooperi Arnold, 1906: CAS 61855.01 [ex CAS/SU 8]; holotype of Pecten (Plagioctenium) subdolus Hertlein, 1925: CAS 61881.01 [ex CAS/SU 51]; holotype of Pecten (Plagioctenium) callidus Hertlein, 1925: CAS 61882.01 [ex CAS/SU 53]. TYPE LOCALITY. Of Pecten (Plagioctenium) cooperi: Pacific Beach, San Diego, San Diego County, California; San Diego Formation, Pliocene. Of Pecten (Plagioctenium) subdolus: CAS loc. 61881 [ex SU loc. 115], San Diego County, California; San Diego Formation, Pliocene. Of Pecten (Plagioctenium) callidus, CAS loc. 61882 [ex SU loc. 116], Cedros Island, Baja California, Mexico, Almejas Formation, Pliocene. GEOLOGIC AGE. Early to late Pliocene. STRATIGRAPHIC DISTRIBUTION. LOWER PLIOCENE: Almejas Formation, eastern Cedros Island and Tortugas Bay, Baja California Sur, Mexico (Hertlein, 1925; Jordan and Hertlein, 1926; Minch et al., 1976); Tirabuzon Formation [formerly Gloria Formation], Baja California Sur, Mexico (Wilson, 1955). UPPER PLIOCENE: Pico Formation, Holser Canyon area, Los Angeles County, (Grant and Gale, 1931); Pico Formation, northern Simi Valley (especially Las Llajas Canyon), Ventura and Los Angeles counties, California (new information); and Valencia and Newhall areas, northern Los Angeles County, California (Grant and Gale, 1931; Squires et al., 2006; present report); Niguel Formation, San Juan Capistrano, Orange County, California (Vedder, 1960); San Diego Formation, lower member, San Diego County, California (Hertlein and Grant, 1972; Deméré, 1983); and Infierno Formation (Wilson, 1955), Baja Californa Sur, Mexico. REMARKS. Argopecten invalidus is one of the most common megafossils in the study area, and its preservation is excellent. Specimens range from 3 mm to 67.6 mm in height. Although they can be weathered, they are unabraded, many have their fragile auricles intact, and many specimens are paired valves (i.e., Table 1).» SQUIRES, R. L. 2012. Late Pliocene Megafossils of the Pico Formation, Newhall area, Los Angeles County, Southern California. Contributions in Science, 520: 73-93, figs. 1-108. [p. 81, 83]
|
Argopecten invalidus (Hanna, 1924); R. L. Squires, 2012, Late Pliocene Megafossils of the Pico Formation, Newhall area, Los Angeles County, Southern California, figures 16-19.
|
«TYPE MATERIAL. Holotype (of Pecten (Plagioctenium) cooperi Arnold, 1906) CAS 61855.01 (ex CAS 8).
TYPE LOCALITY. Pacific Beach, San Diego, San Diego County, California; San Diego Formation, Pliocene. GEOLOGIC AGE. Pliocene. STRATIGRAPHIC DISTRIBUTION. LOWER PLIOCENE: Almejas Formation, eastern Cedros Island and Tortugas Bay, Baja California Sur, Mexico (Jordan and Hertlein, 1926; Minch et al., 1976). UPPER PLIOCENE: Pico Formation, Valencia area, northern Los Angeles County, California (new information); Niguel Formation, San Juan Capistrano, Orange County, California (Vedder, 1960); San Diego Formation, lower member, San Diego County, California (Hertlein and Grant, 1972; Deme´re´, 1983). PLIOCENE UNDIFFERENTIATED: Pico Formation, northern Los Angeles County, California (Grant and Gale, 1931); formation undesignated, Pacific Beach, San Diego County, California (Arnold, 1906; Grant and Gale, 1931). REMARKS. Argopecten invalidus is one of the most common megafossils in the Valencia area, and its preservation is generally excellent. Specimens range from 3 mm to 50 mm in height. They appear to be unabraded, and many have their fragile auricles intact. The species is especially abundant at LACMIP locality 17778, where a total of 40 specimens were collected, four of which have paired valves. Upsection at LACMIP locality 17779, 10 specimens were collected (three with paired valves); at LACMIP locality 15719, 23 specimens were collected (three with paired valves). This species is characterized by having, on both valves, 18 to 20 flat-topped, squarish ribs, separated by U-shaped interspaces. The ribs tend to flatten out and become more convex in the later stages of growth. The shells of this species are slightly longer than high and moderately convex. Arnold (1906: 125) reported that his species occurs only in the Pliocene San Diego Formation. He also listed it in a table of taxa from the Pliocene Purisima and Merced formations, but he used the occurrence in a chronostratigraphic sense, not a lithostratigraphic sense, which has led to many species being misrepresented (C.L. Powell, II, personal communication). Hertlein and Grant (1972) restricted A. invalidus to the Pliocene of Southern California and Baja California. The occurrence of A. invalidus in the Pico Formation in the Valencia area represents the northernmost known limit of this species.» SQUIRES, R. L., L. T. GROVES & J. T. SMITH. 2006. Information on Molluscan Paleontology and depositional environments of the Upper Pliocene Pico Formation, Valencia Area, Los Angeles County, Southern California. Contributions in Science, 511: 1-24. [p. 13]
|
Argopecten invalidus (Hanna, 1924); R. L. Squires, L. T. Groves & J. T. Smith, 2006, Information on Molluscan Paleontology and depositional environments of the Upper Pliocene Pico Formation, figures 15, 16
|
«Comparison.— "The smaller shell, more rounded outline, fewer ribs which become broader and more rounded toward the ventral margin, occasional concentric zones of interrupted growth, and smaller umbonal angle are features which serve to separate this, species from Chlamys callida.
"The generally smaller more orbicular shell and fewer ribs which become decidedly broader and more convex but not obsolete near the margin are characteristics which serve to separate C. invalida from 'Aequipecten' antonitaensis Durham. "Chlamys (Argopecten) coopericellus Ferreira * * * described from strata of early Miocene age in Brazil, was compared by its author with 'C. (A.) cooperi (Arnold, 1906)' [= Pecten invalidus Hanna]. A small riblet is present in the interspaces between the ribs of the Brazilian species and in this and in other details it is quite distinct from C. invalida." (Hertlein and Grant, 1972, p.201) Comments.—The holotype is a right valve with square to subrounded ribs separated by U-shaped interspaces half as wide as the ribs. The interspaces have imbricated, concentric lamellae; near the ventral margin, looped concentric lamellae also cross the ribs. Geographic range.— Southern California to Baja Califolnia Norte. Geologic range.— Miocene to Pleistocene. Occurrence in the Californias.— Miocene and Pliocene: Purisima Formation (Arnold, 1906); Pliocene: Almejas (Minch and others, 1976), Niguel (Vedder, 1972), and. San Diego (Hertlein and Grant, 1972) Formations; Pliocene and Pleistocene: Fernando (J. D. Mount, written commun., 1971), Merced (Arnold, 1906), and Pico (Grant and Gale, 1931) Formations.» MOORE, E. J. 1984. Tertiary Marine Pelecypods of California: Propeamussidae and Pectinidae. United States Geological Survey Professional Paper, 1228-B: iv + B1-B112, figs. 1-2, pls. 1-42. [p. B37]
|
Argopecten invalidus (G D. Hanna); E. J. Moore, 1984, Tertiary Marine Pelecypods of California: Propeamussidae and Pectinidae, plate 10, figure 5.
|