Lyropecten catalinae (Arnold, 1906)
ARNOLD, R. 1906. The Tertiary and Quaternary pectens of California. United States Geological Survey Professional Paper, 47: 1-264, pls. 1-53. [p. 76, pl. 20, figs. 3, 3a, 4]
1906 Pecten (Lyropecten) estrellanus var. catalinae Arnold, 1906
1926 Pecten (Lyropecten) gallegosi Jordan & Hertlein, 1926
1926 Pecten (Lyropecten) gallegosi Jordan & Hertlein, 1926
R. Arnold, 1906, plate 20.
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«Description.— Shell averaging about 65 millimeters in altitude, considerably longer than high, equivalve, equilateral, of medium thickness, only slightly ventricose, and with margins more or less serrate; base evenly rounded; sides only slightly concave above. Right valve with 19 or 20 square, flat-topped ribs, all of which are sculptured by incremental lines and the 3 or 4 outer ribs on each side by more or less prominent radial lines; interspaces narrower than ribs and ornamented by a prominent squarish riblet; hinge line over one-half length of disk; anterior ear arcuate in front, with rather small byssal notch, and ornamented by concentric lines and 5 or 6 rather prominent radiating ridges; posterior ear with concave end and ornamented by numerous fine radiating ridges and incremental lines. Left valve similar to right except that the ears are both like the posterior one of the right valve, and the interspaces are relatively a little wider.
Dimensions.— Alt. 62 mm.; long. 72 mm.; hinge line 40 mm.; diameter 12 mm. This species is similar in general characteristics to the typical P. estrellanus, but differs from it in being much flatter, having a relatively much longer hinge, and, on the average, more ribs. The characteristic constriction of P. estrellanus is also lacking- in this variety, so far as known. P. var. catalinae ranges from the upper Miocene to the Pliocene. On Santa Catalina Island it is associated with the typical P. estrellanus, in beds which are probably upper Miocene, while at Temescal Canyon, near Santa Monica, it is associated with the well-known Pliocene species P. stearnsii, P. cerrosensis, and Laqueus californicus [or jeffreysi). The type, which is figured and is now in the collection of Delos Arnold, was found in a limy matrix near the isthmus, Santa Catalina Island, Los Angeles County, by Mr. F. H. Thurston. RANGE
Pliocene (lower). Temescal Canyon, Santa Monica Mountains, Los Angeles County (Watts).
Miocene (upper). Isthmus, Santa Catalina Island, Los Angeles County (Thurston, Mrs. Trask); San Ardo and vicinity, Monterey County (Hamlin, Anderson).» RALPH ARNOLD, 1906
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«REMARKS. This pectinid [Lyropecten catalinae (Arnold, 1906)] is common in the Valencia area. Fourteen specimens were collected: two paired valves, 10 left valves, and two right valves. Most of the specimens are very fragile and break easily when attempts are made to extract them from the outcrop. Complete specimens were found at LACMIP locality 17774 and especially at locality 17778.
Smith (1991:23) reported that L. catalinae is closely related to, or possibly conspecific with, L. gallegosi. Our observations indicate that they are conspecific. Smith (1991) provided detailed morphologic descriptions and illustrations of both L. catalinae and L. gallegosi. Both have flat-topped rectangular ribs, straight-sided auricles with costae, and adult right valves with 17 to 20 ribs and one midriblet per interspace. The rectangular right auricle has coarse costae crossed by growth lines. Adult left valves have 16 to 20 ribs and one midriblet per interspace. Left-valve raised ribs are separated by three regular ribs in a scheme described as R 3r Rc 3r R (see Smith, 1991: fig. 15). Vedder et al. (1979:249) reported the geologic age of L. catalinae found at its type locality on Santa Catalina Island as possibly late middle Miocene to late Miocene, but in their faunal list (table 5) they indicate that the specimens are of late Miocene in age. Smith (1991) restricted L. catalinae to Southern California and to the late middle Miocene to late Miocene, but these reports were made before it was recognized that L. catalinae and L. gallegosi are the same species. Smith (1991), furthermore, reported that the geologic age of L. gallegosi at its type locality on eastern Cedros Island was late Miocene, but she stated that these beds are correlative with the Almejas Formation, now known to range in age from late Miocene to early Pliocene (Carreño and Smith, in press). More work is needed to establish which mollusks come from which part of the Almejas Formation because there is a distinct possibility that float material from several horizons was collected by early workers. Smith (1991:49) reported L. catalinae from the Modelo Formation in the Ventura Basin, but the unit was mapped by Dibblee (1996) as the upper Miocene Castaic Formation. Winterer and Durham (1962) reported L. cerrosensis from the Pico Formation. However, their specimens were never given museum catalog numbers; thus, their identification cannot be verified. We restudied Groves’s (1991a) lower Saugus specimen of ‘‘Lyropecten cerrosensis,’’ which is deposited in the LACMIP collection (LACMIP locality 12599), and determined that it is L. catalinae. This report is the first confirmed report of L. catalinae from the Pico Formation of the eastern Ventura Basin, and this occurrence 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. 15]
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Lyropecten catalinae (Arnold, 1906); R. L. Squires, L. T. Groves & J. T. Smith, 2006, Information on Molluscan Paleontology and depositional environments of the Upper Pliocene Pico Formation, figures 17-19.
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