Tulane Studies in Geology and Paleontology
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TULANE STUDIES IN GEOLOGY AND PALEONTOLOGY Volume 11, Number 2 July 31, 1974 NOTES ON CHICO REUS (MOLLUSCA:GASTROPODA) FROM THE CENOZOIC OF THE WESTERN ATLANTIC REGION, WITH THE DESCRIPTION OF NEW SPECIES EMILY H. VOKES TULANE UNIVERSITY CONTENTS Page [. ABSTRACT ....... 81 II. INTRODUCTION .... 8I Ill. ACKNOWLEDGMENTS 82 IV. SYSTEMATIC DESCRIPTIONS 82 v. LOCALITY DATA . 94 VI. LITERATURE CITED 95 ILLUSTRATIONS PLATE 1 85 PLATE 2 89 PLATE 3 93 !. ABSTRACT occurrence of C. brevifrons is noted in the middle Miocene ( ?) Encanto Formation of Three new species of fossil Chico reus and Mexico. Chicoreus argo is shown to be a two new Recent species are described from synonym of C. spectrum, a Caribbean Recent the western Atlantic region. The fossil species. species are: C. elusivus, from the late lower Miocene Chipola Formation of northwestern II. INTRODUCTION Florida; c: xestos, from the middle Pliocene Pinecrest beds of southwestern Florida; and In an earlier monograph of the gastropod C. prolixus from the Pleistocene Mom genus Chicoreus s.s. in the western Atlantic Formation of Costa Rica. The Recent species region (Vokes, 1965) it was noted that there are C. mergus and C. bullisi. In addition, a are but few species of Chico reus in this area, form that occurs in the Recent fauna of the in contrast to the many species found in the Gulf of Mexico, here identified as C. dilectus Indo-Pacific. At that time there was a total variety, becohles the first record of the genus of 12 known species, both fossil and Recent, in the early Pliocene Agueguexquite in the entire western Atlantic Cenozoic. Formation of Veracruz, Mexico. The earliest Since then extensive collecting has EDITORIAL COMMITTEE FOR THIS PAPER: HARVEY R. BULLIS, JR., National Fisheries Service, Miami, Florida. A. MYRA KEEN, Department of Geology, Stanford University, Stanford, California. DRUID WILSON, United States Geological Survey, Washington, D.C. 8I 82 Tulane Studies in Geology and Paleontology Vol.ll continued in the fossil beds of the area, and Diagnosis: Proto<:onch small, of SY2 smooth, much additional collecting of the Recent conical whorls ending at a small varix, with spiral fauna has been done, primarily by the U.S. and axial ornamentation immediately well-developed. Probably eight post-nuclear whorls Bureau of Commercial Fisheries, under in a full-grown adult, seven maximum in type Harvey R. Bullis, Jr., until recently Base material. Spiral ornamentation beginnings on first Director of the Pascagoula Laboratory. post-nuclear whorl with three smooth cords, Several new species are among this material continuing to third whorl where smaller spiral threads arc intercaJated, one between each two and in this paper three fossil and two Recent major cords; on fourth whorl another set of species of Chicoreus are described. However, tertiary threadlets appearing until by fifth and two of the formerly accepted names, C. succeeding whorls the entire surface of the shell is spectrum (Reeve) and C. argo (Clench and covered with spiral lines of varying siz.es, superimposed on spiral ridges developed from the Perez Farfante ), are herein placed in original three spiral cords. On the body whorl five or synonymy, so that the net gain is four. six of these ridges, plus an additional two on the Another fossil species was subsequently extended siphonal canal. Axial ornamentation on removed to Chicoreus (Phyllorwtus) (Vokes, first post-nuclear whorl of about 12 axial lines, 1967, p.143). Thus we may now say there forming sharp nodes where they cross the spiral cords; continuing to about the third whorl where arc nine fossil and six Recent species, of every third axial line is strengthened to form a small which two are also represented in the fossil varix, leaving the others as intervarical nodes, two record, or a total of 15 species of Chicoreus between each varical pair. By the fourth and s.s. in the Cenozoic of the western Atlantic. succeeding whorls three wcl\-dcvelopcd varices present on each whorl; where "the spiral ridges cross In addition to new forms discovered, the varices long, open, foliated spines produced, other new data on occurrences and with smaller spinelets where the smaller threadlets extensions of both stratigraphical and cross. On the median whorls two or three spines per geographical range arc documented. A few varix, and on the body-whorl five or six, corresponding to the major spiral ridges, plus errors from the 1965 paper arc rectified. another two on the siphonal canal. Two varical spines at the shoulder with the posterior one th e Ill. ACKNOWLEDGMENTS larger, then two median smaller spines, one often almost lost, and finally the two anterior-most spines nearly as large as the second shoulder spine. Two long spines on the siphonal canal, in addition to t11e The writer wishes to express her gratitude long, recurvcd distal end of each succeeding canal, to those persons who contributed material which gives rise to a strongly diverging spur. that made this new study possible. They are: Aperture ovaJ; outer lip crenulated into the open J. Wyatt Durham and Joseph H. Peck, Jr., spines of the terminal varix, with several paired University of California, Berkeley ; Harvey R. lirations on the inner side. Inner lip smooth, wilh a narrow, free-standing rim that crosses over the Bullis, Jr., National Fisheries Service; entrance of the siphonal canal, almost closing it. William G. Lyons, Florida Department of Canal covered by a thin plate extending from th e Natural Resources; Mr. and Mrs. Robert C. columellar wall but open b y a narrow slit along t11 e Haerle, West Palm Beach, Florida; Mrs. varical side. Bonnie McCash, Casey, Illinois; and John Dimensions of holotype: height 44.6 mm, Phillips, Santa Barbara, California. She diameter (excluding spines) 21.0 mm. would also like to thank the members of the Holotype: USNM 647110. Type locality: TU 547, west bank of Chipola Editorial Committee for their time and River, about 2000 feet above Four Mile Creek (SW assistance in improving the manuscript. 'A Sec. 29, TIN, R9W), Calhoun County, Florida. Paratypc A: USNM 647!1!; height 29 mm, IV. SYSTEMATIC DESCRIPTIONS diameter (excluding spines) 14.5 mm; locality TU 825. Paratype B: USNM 647 112; h eight 34.5 mm, CHICOREUS (Oi!COREUS) ELUSIVUS diameter 19.0 mm; locality TU 655. Para type C: USNM 647113 (a fragment to show E. H. Vokes, n. sp. potentia] size); height 26.9 mm, width 43.5 mm; Plate 1, figs. 1 -4 locality TU 950. Occurrence: Chipola Formation, Flor ida; late Chicoreus (Chicoreus) cornurectus (Guppy). E. H. lower Miocene. VOKES, 1965, Tulane Stud. Geol. , v. 3, no. 4, p. Figured specimens: Fig. 1, USNM 647110 186 (in part, Chipola references only). (holotype). Fig. 2, USNM 64 7111 (paratypc A). No.2 Chico reus from Cenozoic of Western Atlantic 83 Fig. 3, USNM 647112 (paratypc B). Fig. 4, USNM species in th e varical fronds: C. spectrum has 647113 (paratype C). Other occurrences: TU a single large spine at the shoulder, with locality nos. 70, 196, 458, 459, 546, 555, 709, 817, 820, 830, 951, 998. three smaller spines anteriorly; C. elusiv"us has one long spine at the shoulder also, but Discussion: During the more than 15 the second spine, immediately anterior to years that the writer and associates have that one is almost as large as the first, then been collecting fossils from the Chipola there are two smaller spines, and the two Formation of northwestern Florida, anteriormost spines are almost as large as the nwnerous fragments of a new, markedly shoulder spine. distinct, species of Chico reus have appeared. C. elusivus is smaller than either of these Prior to the recent finding of the holotype by Recent species but it is larger than any other Mrs. Bonnie McCash the collections consisted Chipola Chicoreus. The fragment here of 31 juvenile or broken adults specimens and figured as para type C suggests a total height 117 identifiable fragments. The next best of at least twice that of the holotype, or shells previously taken were the one figured as some 90 mm. The largest specimens of C. para type A, from TU 825, and the somewhat lepidotus (Vokes, 1963) or C. dujardinoides atypical paratype B, from TU 655. In (Vokes, 1963 ), the other Chipola species of addition, th ere was one complete adult fr om Chicoreus, are both under 60 mm. C. TU 546, which has, however, a very elongate cornurectus alone is of a comparable size, siphonal canal much like that of C. spectrum with the lectotype being 89.2 mm. The shell (Reeve). The name of this species, an arbitrary is relatively thin, much like some of the combination of letters with the connotation Indo-Pacific species. Presumably it is this of being elusive, was originally bestowed upon thinness that causes the shells of larger the form during the long search for a specimens to be broken too easily to be well-preserved type specimen. preserved, leaving only juveniles and When the writer treated Chicoreus s.s. in fragments as representatives in the fossil 196 5, she had in her possession only th e record. para type Band three tiny juvenile specimens From the occurrence list it can be seen from localities TU 70 and 196. that the species was widespread in the Unfortunately the TU 655 specimen is not a Chipola Formation; however, only at TU normal example of the form or the writer 546 and 830 does it approach anything but would never have confused it with C. extreme rarity. At TU 546 there have been cornurectus (Guppy) as sh e did ten more-or-less entire specimens and 43 (1965,p.187).