JACK D. MOUNT
University of California, Riverside 92502
Living members of the gastropod genus Fulgoraria, well known to collectors and amateurs because
of the size and beauty of their shells, are restricted to Japan and adjacent seas. The lesser known fossil species occur along both the
eastern and western margins of the northern Pacific Ocean. The published age range of Fulgoraria has been given as Eocene to
Recent (Grant and Gale, 1931; Wenz, 1943). Shikama (1967), in the most thorough study to date of the fossil forms of Fulgoraria,
has shown that the oldest known occurrence previously consisted of at least one species from the lower portion of the Nishisonogian
Stage (middle Oligocene) of Japan. It is with particular interest, therefore, that I present the description of a new species of
Fulgoraria from the Paleocene "Martinez Provincial Molluscan Stage" of southern California. This new record constitutes a
significant extension for the known time range of the genus. Most of the specimens used in this study were collected by me during
geologic mapping of eastern Simi Valley, Ventura County, in the Summer of 1968. William J. Zinsmeister, University of California,
Riverside, currently studying the Paleocene invertebrate fauna of this region, has obtained additional specimens.
The genus Fulgoraria is not common in the Tertiary strata of the Pacific margin of North America with only four species having been previously described:
The five species of Fulgoraria now known in the west American fauna are potentially useful in age determination and correlation of the shallow water marine Tertiary of this region and apparently represent a phylogenetic lineage.
Family VOLUTIDAE Rafinesque, 1815
Genus FULGORARIA Shumacher, 1817
Type (by original designation).--Fulgoraria chinensis Shumacher, 1817 (= Voluta rupestris Gmelin, 1791); Recent, Japan.
Type (by monotypy).-Voluta concinna Broderip, 1836; Recent, Japan. The placement of Psephaea as a subgenus of Fulgoraria follows the more conservative classification of the fulgorarids set forth by Weaver and duPont (1970). In some recent studies of west American Tertiary Mollusca (Moore, 1963; Addicott, 1970) Psephaea is treated as a separate genus, being distinguished from Fulgoraria by characteristics of the columella, aperture and protoconch. These are highly variable features within Fulgoraria. Some specimens of the same species may have differing numbers of columellar folds. Miopleiona Dail, 1907, is a synonym.
Diagnosis.--The new species is distinguished from other species of Psephaea by having
the following features: whorls slightly inflated, with 11 to 12 axial ribs and about 44 very fine spiral ribs on the penultimate whorl;
the columella has 4 folds, the outer two subdued.
Description.--Shell medium in size for the genus, moderately thick, long, slender, fusiform, spire greatly elevated. Whorls 10, slightly inflated, evenly convex, abutting. Nucleus unknown. Axial sculpture of about 11 to 12 prominent, wide, rounded ribs; ribs become nearly obsolete and slightly deflected near posterior suture; interspaces are usually as wide or wider than ribs. Spiral sculpture consists of numerous very fine ribs which become faint on body whorl, approximately 44 on penultimate whorl. Aperture large, elongate, narrow; inner lip with a wide thin callus deposit. Columella straight and tapering, with 4 slightly oblique folds, the outer two folds subdued.
The measurements of the type specimens are listed in Table 1. All specimens are broken off at the apex and base.
Holotype.--Department of Earth Sciences, University of California, Riverside (UCR) 6602/1 (Pl. 1, figs. 1, 2).
Paratypes.--UCR 6602/2 (Pl. 1, figs. 3, 4) and 6602/3 (Pl. 1, fig. 5), UCR locality 6602. UCR 6825/1, UCR locality 6825. UCR 6885/11, UCR locality 6885.
|TABLE 1.--Measurements (in mm) of the type specimens|
of Fulgoraria (Psephaea) zinsmeisteri n. sp.
Type Locality.--UCR 6602; at elevation of 375 m on top of ridge between Runkle and Meier
Canyons, on north slope of the Simi Hills, Ventura County, California; 216 m east and 150 m south of the southwest corner of sec. 13, T.
2 N., R. 17 W., Calabasas 71/2 minute quadrangle (1967 edition).
Distribution.--UCR localities 6602, 6825 and 6885; north slope of the Simi Hills, Ventura County, California.
Stratigraphic Position.--The localities noted above occur in the "Martinez marine member" of Nelson (1925). The type locality is in a prominently exposed bed of indurated, dark gray sandstone 479 m above the lower contact with the Simi Conglomerate of Nelson (1925).
Age.--At the type locality the new species is associated with the following: Anthozoa: Flabellum remondianum Gabb; Brachiopoda: Kingena simiensis Waring; Gastropoda: Acrilla (Undiscala?) n. sp., Amaurellina martinezensis (Dickerson); Bivalvia: Macrocallista cf. M. furlongi Nelson, Pholadomya n. sp.; Scaphopoda: Dentalium cf. D. cooperi Gabb.
In California these species are restricted in stratigraphic occurrence to the "Martinez Provincial Stage." On the basis of prevailing Paleogene megafaunal and microfaunal correlations the "Martinez Stage" is Paleocene in age. Mallory (1959) has shown that the "Martinez Stage" is apparently equivalent to his Ynezian Foraminiferal Stage. From planktonic foraminiferal evidence the Ynezian Stage appears to be early Paleocene to late Paleocene in age (Gibson, 1973).
Remarks.--Fulgoraria (Psephaea) zinsmeisteri n. sp. is nearest to F. (P.) weaveri (Tegland) but differs principally in the general shell profile and form of the sculpture; the latter species has a narrower spire with more inflation of the whorls, greater number of axial ribs, and coarser spiral ribbing.
The new species is named for Mr. William J. Zinsmeister, in recognition of his contributions to molluscan paleontology.
Addicott, W. 0. 1970. Miocene gastropods and biostratigraphy of the Kern River area, California. U. S. Geol. Surv. Prof. Paper 642, 174 p., 21 Pls.
Conrad, T. A. 1849. Fossils from northwestern America, in Dana, J. D., U. S. Exploring Exped., 1838-1842, under the command of Charles Wilkes, Geology 10: app., 723-728; atlas, Pls. 17-21.
Dall, W. H. 1907. Notes on some Upper Cretaceous Volutidae with descriptions of new species and a revision of the groups to which they belong. Smithsonian Misc. Colln. 50(1) :1-23, 13 figs.
Durham, J. W. 1944. Megafaunal zones of the Oligocene of northwestern Washington. Univ. Calif. Dept. Geol. Sci. Bull. 27(5) :101-211, Pls. 13-18.
Gibson, J. M. 1973. Foraminiferal and nannoplankton biostratigraphy, paleoccology, and basinal reconstruction, Anita Formation, western Santa Ynez Mountains, California. Amer. Assoc. Pet. Geol. Bull. 57:781. (Abstr.)
Grant, U. S., IV, and H. R. Gale. 1931. Catalogue of the marine Pliocene and Pleistocene Mollusca of California and adjacent regions. San Diego Soc. Nat. Hist. Mem. 1:1-1036, Pls. 1-32.
Mallory, V. S. 1959. Lower Tertiary Biostratigraphy of the California Coast Ranges. Amer. Assoc. Pet. Geol., Tulsa, Oklahoma, 416 p., 42 Pls.
Moore, F. J. 1963. Miocene mollusks from the Astoria Formation, Oregon. U. S. Geol. Surv, Prof. Paper 419, 109 p., 32 Pls.
Nelson, R. N. 1925, A contribution to the paleontology of the Martinez Eocene of California. Univ. Calif. Dept. Geol. Sci. Bull. 15(11) :397-466, Pls. 49-61.
Shikama, T. 1967. System and evolution of Japanese fulgorarid gastropods. Sci. Repts. Yokohama National Univ. 2(13) :23-132, Pls. 1-17.
Tegland, M. N. 1933. The fauna of the type Blakeley upper Oligocene of Washington. Univ. Calif. Dept. Geol. Sci. Bull. 23(3) :81-174, Pls. 2-15.
Weaver, C. S., and J. E. duPont. 1970. Living volutes. Delaware Mus. Nat. Hist. Mon. Ser. 1, 375 p., 79 Pls.
Wenz, W. 1938-1944. Gastropoda. Handbuch der Paläeozoologie 6(1) :1-1639, 4211 figs.
MANUSCRIPT RECEIVED MARCH 13, 1974
REVISED MANUSCRIPT RECEIVED NOVEMBER 11, 1974
EXPLANATION OF PLATE 1
Fulgoraria (Psephaea) zinsmeisteri n. sp. Primary types from the Paleocene "Martinez Provincial Stage," UCR locality 6602, Simi Hills, Ventura County, California.
Figs. 1, 2--Holotype, UCR 6602/1. 1, side view, X1.5; 2, apertural view showing four columellar folds, X2.5.
3, 4--Paratype, UCR 6602/2. 3, side view; 4, apertural view; X1.5; specimen slightly crushed.
5--Side view of latex cast of Paratype mold, UCR 6602/3, X1.5.
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