A NEW SPECIES OF TRICHOTROPIS (:MESOGASTROPODAI FROM THE ESMERALDAS BEDS, ONZOLE FORMATION, NORTHWESTERN ECUADOR

WI LLIAM D. PITT',' and LOIS J. PITT'

ABSTRACT the Esmeraldas Formation was never Only one species of Trichotropis. T . properly defined by Olsson, and, as lhe pacifica (Dall, 1908b), is known to occur in name Onzole Formation has been widely the Recent fauna of the Panamic-Galapa­ used in Ecuador and accepted through gan fauna! province of the Tropical East common usage, it is best to retain the name Pacific. A new species, Trichotropis vok­ Onzole Formation over Esmeraldas For­ esae, described here in from the Pliocene mation. Vokes (1988, p. 41 finds it difficult Esmeraldas beds, Onzole Formation, of to accept the name Onzole Formation for northwestern Ecuador, is the fi rst species the mollusk-rich shallow-water grav1ly­ of Trichotropis from the fossil record in the flows of the upper part of the Onzole For­ Tropical East Pacific. mation and proposed usage of the term "Esmeraldas beds" for these deposits in INTRODUCTION northwestern Eucador. In this usage the Esmeraldas beds are equal lo the upper In the Tropical East P acific, the family Onzole Formation. Trichotropidae is represented by one ex­ Whittaker (1988, p. 11) cited the age of tant species, Trichotropis pacifica (Dall, the Onzole Formation in Esmeraldas Pro· 1908b), a deep-water spe cies from P anama vince (Borb6n Basin) as between late Bay, Panama. Trichotropis vokesae, n. sp., Miocene (N 16) and late Pliocene (N 211, from the Plioce ne Esmera ldas beds, On­ however, he Ip. 12) cites lhe upper Onzole zole Formation, near the village of Cama­ as being wholly of Pliocene age. Haman rones, Esmeraldas P rovince, Ecuador. is and Kohl ( 1986, p. 181) dated the "Esmeral· the first member of the ge nus Trichotropis das beds" at Camaroncs as earlv Pliocene to be reported from the fo ssil record of the (N 18-191, which has been ac~epted by area. Vokes (1988, p. 4) and DuShane (1988, p. In discussing the formational name to be 51). used for the fossiliferous deposits at Queb­ In discussing the deposition of the Es· rada Camarones, Vokes (1988, p. 3) notes meraldas Formation, Olsson (1964, p. 71 that the name Esme raldas F ormation was stated that the fauna of the "Esmeraldas proposed by Olsson (1942 , p. 260) for lhe beds" has many species closely allied lo "highly foraminiferal, tuffaceous shales so Caribbean taxa because the Isthmus of extensively exposed along the coast of Es­ Panama was open, at least part of the time, meraldas and along the Esmeraldas river during the deposition of the Esmeraldas itself." Bristow and H offstetter (1977) con­ beds. Olsson added that most of lhe firmed the name "Esmeraldas Formation" species with· deep-water characteristics of Olsson, 1942, but stated: "Olsson thought were well preserved while the shallow· that the Esmeraldas F aci es was equivalent water forms showed signs of transport. He to the Borbon Formation, differing only by further observed (1964, p. 171: ··The the depositional zone, But in reali ty the Es­ bathymetric range of most deep-sea mol· meraldas Formation is the Onzole Forma­ lusks is still poorly understood, and their tion" (1977, p. 142, translated). The name distribution at varying depths may be as "Onzole Formation" w as fi rst published by much dependent upon water temperature Stainforth (1948, p. 143) followi ng an un­ as on any other single factor." published work of the I.E.P.C. by Smith In his systematic treatment of species, (1946) (fide Bristow and Hoffstette r, 1977, Olsson (1964, p. 1121, noted lhal A.foria p. 217). Bristow (1976, p. 193) claims lhat ecuadoriana Olsson, 1964, is n.•markably similar to the Pleistocene to Recent A. Cl r cinata (Dall, 187:ll, which is found in lhe 1Field Associate, Depl. of Geology, California •·Bering Sea; Alaska and Japan" !Abbott, Academy of Sciences, San F rancisco, Califor­ 1974. p. 2651. Vokes (1988, p. 91 111cluded nia three muricid specil~s in her Table 1 2Home address: 2444 38th Ave., Sacramento, California, 95822 Group III, California· Northl•rn Pacific· 131 132 Tulane Studies in Geology and Paleontology Vol. 22

Ceratostoma notiale Vokes, 1988; Pteropur­ Discussion: This new species is named pura marksi Olsson, 1964; and Pteropur­ for Emily Vokes of Tulane University. pura ecuadoria (Olsson, 1964). These three Emily and her husband Harold Vokes species from the Esmeraldas beds are have assisted on collecting trips to Ecuador either living in the more northern waters and have given us much encouragement to or have close allies there. In view of these work on these unique fossil deposits of species that either occur in deep-water or northwestern Ecuador. have northern cold-water allies it is not Trichotropis vokesae is remarkably close surprising to see occurring at Quebrada to the Pliocene to Recent Trichotropis Camarones, Trichotropis vokesae, n. sp., a bicarinata (Sowerby, 1825), a boreal member of a which seems to be rep­ species ranging from the Queen Charlotte resented only in more northern or colder Islands, British Columbia, Canada, cir­ waters today. cumpolar lo Newfoundland, Canada. Trichotropis vokesae d iffers from T. SYSTEMATIC PALEONTOLOGY bicarinata in that the whorls taper inward rather than being perpendicular and the Class GASTROPODA faces of the whorls are flat-sided rather Order MESOGASTROPODA than slightly concave. Also the distance be­ Superfamily CREPIDULOIDEA tween the carinae is greater in proportion Family TR!CHOTROPIDAE Gray, 1850 to shell height and the columella is more Genus TRICHOTROPIS arcuate and much narrower. The aperture Broderip and Sowerby, 1829 also is shorter in proportion to shell height. Trichotropis BRODERIP and SOWERBY, 1829. Specimens of T. bicarinata examined at Zool. Jour., London. v. 4, p. 373. LACM, CAS and USGS(MP) have five Type species: Turbo bicarinara Sowerby. whorls plus the protoconch, whereas 1825, by subsequent design., Herrmannsen. specimens of T. vokesae have four plus the 1849. protoconch; however, there is a difference in shell height among specimens of the two TRICHOTROPIS VOKESAE Pitt and Pitt, n. sp. species examined. Broderip and Sowerby Pl. I, figs. 1, 2a, 2b (1829, p. 374), in discussing T. bicarinata, noted that it has four or five whorls, which Description: Shell thin; four whorls, plus a leaves the difference in the number of protoconch of about one and one-half smooth. post-nuclear whorls of little importance. rounded whorls with a blunt ending. Whorls straight-sided, slightly tapering inward, suture Specimens of T. bicarinata from Punuk Is­ distinct. Spiral sculpture of two sharp carinae, land, Bering Sea, Alaska (LACM 37-1) one at the periphery and one near the base; have axials on one or two post-nuclear basal carina adjacent to posterior side of suture. whorls, otherwise all other specimens of T. Axial sculpture of seven to nine irregular ribs bicarinata examined have no axials. The extending from suture to suture. crossing the paratype of T. vokesae is smaller than the spiral carinae, and decreasing in number on holotype and has axials on all whor ls, the later whorls, disappearing on last two whorls; holotype does not have axials on the last otherwise only retractive growth lines. Apertw·e two whorls. Triclwtropis pacifica (Dall, wide, somewhat triangular, truncated below basal carina. Body whorl slightly shorter than 1908b), the only recorded member of the spire. Columella arcuate, narrow, ending with a genus Trichotropis from the Tropical East small anterior notch. Umbilicus nanowly open, Pacific, differs from T. vokesae is being with a narrow groove to tip of columella. tall, slender, cancellate w ith aperture nar­ Holotype: CASG 66058.01; height 24.0 mm, di­ row and about one-third of shell height; ameter 18.9 mm (pl. 1, fig. 1). specimens of T. vokesae are short, robust, Paratype: CASG 66058.02; height 13.9 mm, di­ have two carinae, the aperture is large and ameter 10.0 mm (pl. I, figs. 2a, 2b). about one-half of shell height. Type locality: TU 13!)7, ·'Esmeraldas beds"; Vokes (1988, p. 8) noted that the average Quebrada Camarones, cut-bank on east side of canyon, east of the village of Camarones, 20 km living depth for· the mollusks in the de­ (by road) east of bridge over Rio Esmera!das, posits at Quebrada Camarones was about Esmeraldas Prov., Ecuador. 75 m but, as a result of gravity flows, the Occurrence: Esmeraldas beds, Onzole Forma­ sediments at this locality were redeposited tion, Esmeraldas Prov., Ecuador. in perhaps 1,000 m of water. The depth No. 4 New Trichotropis.from Ecuador 133

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P LATE! Figures 1-2. Trichotropis vokesae Pitt a nd P itt, n. sp. I . CASG 66058.01 (holoty pe); he ight 24.0 mm, diameter 18.9 mm (X21. 2. CASG 66058.02 (pa ra ty pe); heig ht 13.9 mm, diameter 10.0 mm (X41. Locality of both: TU 1397, Esmeraldas beds, Ecuador: Pliocene. 3-4. Trichotropis bicarinata (Sowerby). 3. LACM 37-1; he ig ht 39.3 mm, diameter 36.0 mm (X21. Locality: Punuk Island, Alaska; Recent. 4. USNM 443585 (hypotype); he ight 26.6 mm, diameter 2:l.6 mm (X21. Locality: Ocean Point, Coleville River, North Slope, Alaska; Pliocene. 134 Tulane Studies in Geology and Paleontology Vol. 22 range of the ge nus Trichotropis is from 1 to bicari nata are found between Ecuador about 2,300 m. and the Queen Charlotte Islands may be There are 18 listed spe cies in the genus due to either a paucity of fossil deposits on Trichotropis occurring in the eastern the Pacific coast of Central and South Pacific and Caribbean, Recent and fossil, America, an artifact of collecting, or a lack which are distributed in time and space as of deep-water collecting of the Recent shown in Table I. faunas. It is also possible that these two The two Cretaceous species are in­ forms may have evolved separately and cluded here only because they are similar may not be closely related. and possibly represent ancestral forms. Trichotropis obstricta (White) is only simi­ ACRONYMS lar in general outline. Trichotropis missis­ CAS California Academy of Sci­ sippiensis Sohl is very close in outline and ences does have two sharp carinae but the rest of I.E.P.C. International Ecuadorian the sculpture is quite different from T. vok­ Petroleum Company esae. LACM Los Angeles County Muse­ The ge nus Trichotropis is usually found um of Natural History in either cold or deep water. Its presence TU Tulane University together with the many warm-water ele­ USGS(MP) Unite d States Geological ments of the Quebrada Camarones fauna Survey, Menlo Park is presumed lo be due to mixing of the faunas by gravity flows. Trichotropis vok­ ACKNOWLEDGMENTS esae possibly represents a divergence from Our thanks go to Emily and Harold T . bicarinata and possibly originated in Vokes of Tulane University for making colde r or more northern waters. The fact their collections available and furnishing that forms of neither T. vokesae or T. the specimens for this paper; to James Mc-

TABLE 1

T. mississippiensis Sohl, 1960 Cretace ous Mississippi T . obstricta (White , 1889) Cretaceous California T . alienensis Effinger , 1938 Oligocene Oregon, Washington T. unicarinata Sowe rby, 1866 Miocene Oregon, Washington T . tricarinata Addicott, 1970 Pliocene Kern County, California T. coronatu Gould, 1860 Miocene­ Oregon, Washington Recent Arctic Ocean, Bering Sea T. cancellata (Hinds, 1843) Pliocene­ Southern California Recent Bering Sea to Oregon T. migruns Da ll , 1881 Recent Cuba T. nuda Dall, 1927 Recent Florida and Gulf of Mexico T. turrita Dall, 1927 Recent Florida and Gulf of Mexico T. bicarinata (Sowerby, 1825) Recent British Columba; Arctic Seas to Newfoundland T. borealis Brod. and Sow., 1829 Recent Europe, Arctic Seas to Bering Sea, Alaska, Japan T. circumcinata (Da ll , 1873) Rece nt Arctic Ocean, Bering Sea T. insignis Midde ndorff, 1849 Rece nt Bering Sea, Alaska, Japan T. kelseyi Dall , 1908a Recent San Diego, California; Baja California, Mexico T. kroyeri (P hilippi, 1849 ) Rece nt Arctic Ocean, Bering Sea T. lomana Da ll , 191 8 Recent San Diego, California; Baja California, Mexico T. pacifica (Dall, 1908b) Recent Panama Bay, Panama

Table 1. Distribution of species of Trichotropis. No. 4 New Trichotropisfrom Ecuador 135

Lean and Gale Sphon, Los Angeles DALL. W. H., l908b, Reports on the dredging County Museum of Natural History, for operations off the west coast of Central ma king their collections available and for America to the Galapagos, to the west coast assistance at the museum; to Lou Ella of Mexico, and in the Gulf of California . Saul, Los Angeles County Museum of Nat­ XIV. The and Brachiopoda: Bull. u ral History, fo r furnishing information on Mus. Comp. Zoo!., Harvard Univ .. v . ..J3, no. Cretaceous species of Trichotropis; J ohn 6, p. 205-487. pis. 1-22. Whittaker, British Museum (Natural His­ DALL, W. H., 1918, Description of new species tory), for making museum collections and of shells, chiefly from Magdelena Bav. Lower California: Biol. Soc. Washingto~, his collecting and research data available: Proc.. v. 31, p. 5-8. lo R oger Bristow, British Geological Sur­ DALL, W. H., 1920, Pliocene and Pleistocene vey, Exeter, England, for making his re­ fossils from the Arctic Coast of Alaska and search and collecting data available; to auriferous beaches of Nome, Norton Sound, P eter Rodda of the California Academy of Alaska: U. S. Geo!. Surv., Prof. Paper 125, Sciences and Charles Powell, United p. 23-37. pis. 5-6. Stales Geological Survey, Menlo Park, for DALL, W. IL, 1921, Summary of the marine criticizing the manuscript; and Allan shell bearing mollusks of the northwest coast McMakin for photography of the type of America, from San Diego, California, lo specimens. the Polar Sea: U.S. Natl. Mus .. Bull 112. 217 p .. 22 pis. DALL, W. H., 1927, Small shells from dredgings BIBLIOGRAPHY off the southeast coast of the United States ABBOTT, R. T., 1974, American Sea Shells, by the United States Fisheries Steamer "Al­ Second Edition. New York, Van Nostrand batross" in 1885 and 1886: U. S. Natl. !'viw , Reinhold, 663 p., 24 pis., 6,405 figs. Proc., v. 70, art. 18, no. 2667. p. 1-134. ADDICOTT, W. 0., 1970, Miocene Gastropods DUSHANE, HELEN, 1988, Pliocene Epitoni­ and Biostratigraphy of the Kern River area, idae of the Esmeraldas beds, northwestern California: U. S. Geo!. Surv., Prof. Paper Ecuador: Tulane Stud. Geo!. Paleonl.. v 21 642, p. i-iv, 1-174, pis. 1-21, text-figs. 1-11. p. 51-58. 12 figs. BRISTOW, C. R. , 1976, The Daule Group, EB'FINGER, W. L., 1938, The Gries Ranch Ecuador (middle Miocene-Pliocene): News!. Fauna !Oligocene) of western Washington: Stratigr., v. 5, nos. 2/3, p. 190-200, 2text-figs. Jour Paleontology, v 12. p. 355-:~90, pis. ..J5 BRISTOW, C.R., and ROBERT HOFFSTET­ 47. TER, 1977, Ecuador: Lexique Stratig­ GOULD, A. A.. 1860, Descriptions of shells col· raphique International, Second Edition, v. 5, lected in the North Pacific Exploring Expedi­ Amerique Latine, Fasc. 5A2, 410 p. tion under Captains Ringgold and Rodgers: BRODERIP, W. J., and G. B. SOWERBY, 1829, Boston Soc. Nat. Hist, Proc, v. 7 p. 32:{-3:-w. Observa tions on new and interesting Mol­ HAMAN, DREW, and BARRY KOHL. 1986. lusca contained, for the most part, in the Early Pliocene Montfort(:'lla IForaminift>ndal Museum of the Zoological Society: Zoo!. fro~ Ecuador: Tulane Stud. Geo!. Paleont Jour., London, v. 4, p. 359-379. pl. 9. v 19, p. 181-183, 1 pl. DALL, W. H., 1873, Preliminary descriptions of' HINDS, R. B., 1843, On new species of shell~. new species of Mollusca from the coast of collected by Sir Edward Belcher, C. B: Zool. Alaska with notes on some rare forms: Calif. Soc. Lond~n. Proc., v. 11, p. 17-19. Acad. Sci., Proc., v. 5, p. 57-62, pl. 2. MACPHERSON, ELIZABETH, 1971, The DAL L, W. H., 1881 , Reports on the results of Marine Molluscs of Arctic Canada. \Prosob· dredging, under the supervision of Alexan­ ranch Gastropods, Chitons and Scapho der Agassiz, in the Gulf of Mexico, and in the pods), Natl. Mus. Nat. Sci., Pub!. in Biology Caribbean Sea, 1877-79, by the United States Oceanography; Oceanogrnphy No. 3: Natl. Coast Guard Steamer "Blake".. XV. Pre· Mus. Canada, Ottawa, vi-viii, l·t-1 p., 7 pl~. 5·t liminary report on the Mollusca: Bull. Mus. maps,:~ figs. Comp. Zoo!., Harvard Univ., v. 9, no. 2, p. MIDDENDORFF. A. T. VON. 18-19. BPitrage zu 33-144. einer Malacozoo!ogia Rossica. St Peters­ DALL, W. H ., 1908a, Descriptions of new burg, Pt. 2, 187 p.; Pt. 3, 99 p., 21 pis. species of mollusks from the Pacific coast of OLSSON, A. A., 1942, Tertiary deposits .>f the United States, with notes on other mol­ northwestern South America and Panama lusks from the same region: U.S. Natl. Mus., Eighth American Sci. Cong.. Proc, v . ..J. p. Proc., v. 34, no. 1610, p. 245-257. 231 287 l36 Tulane Studies in Geology and Paleontology Vol. 22

OLSSON, A. A., 1964, Neogene Mollusks from chyliorum, or monographs of genera of northwestern Ecuador. Paleontological Re­ shells, edited by G. B. Sowerby, Jr. London, search Institution, Ithaca, New York, 256 p., v. 3, pts. 24, 25, p. 272-331, pis. 266-290. 38 pis. STAINFORTH, R M., 1948, Applied micro­ PHILIPPI, R. A., 1849, Centuria tertia tes­ paleontology in coastal Ecuador: Jour. taceorum novorum: Zeit. Malak., Jahrg. , v. Paleontology, v. 22, p. 113-151. 5, no. 11, p. 161-176. VOKES, E. H., 1988, Muricidae (Mollusca:Gas­ SMITH, J. A., 1946, Informes geo!6gicos y trnpoda) of the Esmeraldas beds, northwest­ geofisicos de la International Ecuadorian Pe­ ern Ecuador: Tulane Stud. Geol. Paleonl., v. troleum Co.: Dir. Min. Petrol., Minist. Econ., 21, p. 1-50, 6 pis., 14 text-figs. Quito (Unpublished report). WEA VER, C. E., 1942, Paleontology of the SOHL, N. F., 1960, Archeogastropoda, Meso­ marine Tertiary formations of Oregon and gastropoda and stratigraphy of the Ripley, Washington: Univ. Washington lSeattle], Owl Creek, and Prairie Bluff formations: U. Pub!. Geo!., v. 5, pts. 1-3, 789 p., 104 pis. S. Geo!. Surv., Prof. Paper 331-A, p. 1-151, WHITE, C. A., 1889 , On invertebrate fossils 18 pis., 11 text-figs. from the Pacific coast: U. S. Geol. Surv., SOWERBY, G. B., 1825, A catalogue of the Bull.51, 102p., 14pls. shells contained in the collection of the late WHITTAKER, J. E., 1988, Benthic Cenozoic Earl of Tankerville. London, i-vii, 1-92, app. Foraminifera from Ecuador. British Museum p. i-xxxiv, 9 pis. (Natural History), London, xi + 194 p., 25 SOWERBY, G. B., JR, 1866, Thesaurus Con- pls., 16 text-figs.

December 28, 1989