NASSARIUS (MOLLUSCA:NEOGASTROPODA) FROM THE NEOGE~I<~ OF NORTHWESTERN ECUADOR
1 WILLIAM D. PITT i AND LOIS J. PITT l ABSTRACT East Pacific, as well as the Caribbean Recent and fossil faunas. NassarlUs mas The nassarid fauna from the Neogene tus Olsson, 1964, was descnbed froT!l the formations of northwestern Ecuador con Picaderos Formation, and occurs in both sists of five species, none of which are the Angostura and Onzole formations. known from either the Recent or fossil fau Other species include: N. thielei Olsson, nas of the Caribbean or Pacific. There is 1964, from the Esmeraldas beds, with one species with affinities to the western affinities to an Indo-Pacific species: N. Pacific Recent fauna, one with affinities to hylus Olsson, 1964, known only from the Recent species in both the Caribbean and the Esmeraldas beds; and one species N. eastern Pacific faunas, the remaining repetiti Olsson, 1964, known on:y from •rp three species are known only from the Onzole FormatiOn. Ecuadorian Neogene, one of which, The Angostura Forme t!on of Late Nassarius mcmahini, n. sp., is confined to Miocene age (planktic for tminifpral zom• the Angostura Formation. N. 16) is the oldest formation di~cus~ed .n this paper. The name was first publi~hEd INTRODUCTION by Stainforth (1948, pp. 142, 143, 146 fol lowing an unpublished report of the It is generally accepted that there was International Ecuadorian Petroleum free passage of water between the Company ({lde Bristow and Hoff:!:e!:ter, Caribbean Sea and the Pacific Ocean, 1977' p. 32). through the Isthmus of Panama, for much The name "Esmeralda::: Formation \V<. of the Tertiary Period, allowing exchange proposed by Olsson ( 1942, p. 26Ul for tr1e of molluscan species. It has been suggest highly foraminiferal tuffaceous .,hale-, ed that the closure took place about 3.5 exposed along the coa,.:;t of E.'mt ra:da~ MA (Saito,1976). Jones and Hasson (1985) Province and the Esmeratdas Rivt r. accepted this date as the most likely time Bristow and Hoffstetter ( 1977, p. 141 rec when migration of species ended, with ognized the name Esmeraldas Formation final emergence of the Isthmus at about 3 but considered it to be part of the On.wle MA or later. Formation. Vokes (1988, p. 4) found .t
135 136 Tulane Studies in Geology and Paleontology Vol. 29
Picaderos species as occurring along the Class GASTROPODA Cuvier, 1797 Rio Onzole and considerd some Picaderos Subclass PROSOBRANCHIA species as being from the Borbon Milne-Edwards, 1848 Formation. Superorder CAENOGASTROPODA Bristow and Hoffstetter (1977, p. 219, Cox, 1959 232) state that the name Picaderos Order NEOGASTROPODA Thiele, 1925 Formation is in disuse and consider it to Superfamily MURICOIDEA be equal to the Onzole Formation. The Rafinesque, 1815 Servicio N acional de Geologia y Minera Family NASSARIIDAE Iredale, 1916 (Cuadro no. 83) also considers the Subfamily NASSARIINAE Picaderos Formation to be equal to the Onzole Formation; however, it places Genus NASSARIUS Dumeril, 1806 Olsson's Playa de Tigre locality at the border of the Onzole and Angostura forma Nassarius DUMERIL, 1806, Zool. Anal., p. 166. tions and within the Angostura Formation. Type species: Buccinum arcularia Linn., 1758, Olsson's collecting data is not precise by monotypy. enough to know exactly how close to Playa de Tigre he made his collections, thus it is Subgenus NASSARIUS s.s. difficult to know in which formation this NASSARIUS (NASSARIUS) REPETITI locality should be placed. Olsson, in the Olsson text, also listed some species as occurring Plate 1, figure 4 at Picaderos; Borbon Formation. It is pos Nassarius repetiti OLSSON, 1964, Neogene sible that some of his collecting data is in Moll. Northwest. Ecuador, p. 146, pl. 24, figs. 6, error and we may never know where some 6a. of his specimens were really collected. Description: "The shell is small, subovate, with an elevated sharp spire of about seven ABBREVIATIONS FOR whorls, including that of the small nucleus con REPOSITORY INSTITUTIONS sisting of one turn. The sculpture of the spire whorls consists of three rows of sharply beaded CASG - California Academy of Sciences, spiral cords which stand high above the adja San Francisco, California. cent sutural zones, which thus appear as if USNM- United States National Museum deeply excavated, the fine suture itself lying of Natural History, Washington D.C. away in the bottom as if hidden. The spirals on PRI - Paleontological Research Institution, the apertural side of the body whorl number Ithaca, New York. about seven with an additional eight or nine, much smaller ones, partly smooth lying along ACKNOWLEDGMENTS the basal sulcus and over the short beak in front. The .spiral cords are neatly beaded by We want to thank Elt:lily Vokes for mak small axials which faintly undulate the spiral ing Tulane University collections avail interspaces. On mature specimens, the sculp able and for help with the manuscript. We ture is obsolete on the back of the body whorl, also want to thank the following persons replaced there by a large smooth patch. The for making museum collections available: aperture is broadly subovate with a short longi Thomas Waller, United States National tudinal posterior canal at its junction with the Museum of Natural History; Gary parietal wall. The outer lip is thickened by a rib Rosenberg, Academy of Natural Sciences, on the back, and bears on its inner side four or Philadelphia; and Warren Allmon, more small denticles. There is a thin spread of Paleontological Research Institution. callus over the inner lip through which the Thanks also to Allan McMakin of Astoria, underlying spiral cords still show through; the Oregon, for the photography. parietal callus extends downward over the pil lar is a small shelflike feature [sic], bearing four small denticles a long it. The siphonal canal SYSTEMATIC PALEONTOLOGY notch is deep, its sides a little elevated, its fasci ole marked with small smooth spirals but has Phylum MOLLUSCA Cuvier, 1797 no bordering keel." (Olsson, 1964) No.4 N eogene Nassarius 137
Holotype: USNM 643999; height 14.6 mm, Pacific species N . iodes (Dall, l919 J, N. diameter 7.8 mm. moestus (Hinds, 1844), and !v. tiarula Type locality: Onzole Formation, Telembi, (Kiener, 1841), which occurs as far north Esmeraldas Prov., Ecuador. as San Francisco, Califorma 1 &'"> N. tegula Occurrence: Onzole Formation, Ecuador. (Reeve, 1853), see Skoglund, 1992, p. 85]. Nassarius iodes differs from N. mcmalani Discussion: Nassarius repetiti is similar in having three or four weak l1rations on toN. complanatus (Powys, 1835) from the the inner side of the outer lip and one Tropical East Pacific but differs in being much larger one posterior to the other:- at larger, more slender with the spire whorls about the center of the apertu.re The body slightly convex rather than straight sided. whorl of N. iodes has ten axml ribs, fc
about four, are shouldered around the upper genera of Recent Mollusca, v. 1, p. 120. third, the angle of which carries a strong cord. Type species: Buccinum miga Bruguiere, The body whorl is large and forms about a half 1789, by subsequent designation, Cossmann, the whole shell, quadrate in shape, widest about 1901. the middle, the base strongly contracted. The NASSARIUS (UZITA) HYLUS sculpture is formed by about eight axial riblets Olsson which are noded by the shoulder cord and by Plate 1, figure 2 flat closeset spiral threads which cover the sur Nassarius (Uzita) hylus OLSSON, 1964, face between the shoulder angle and the beak. Neogene Moll. Northwest. Ecuador, p. 145, pl. The space above the shoulder angle is essential 37, figs. 10, 11 . ly smooth, except for small spirals. Aperture subovate, with a calloused shelf on the parietal Description: "Shell small, subovate, stout, the wall, the outer lip thin, smooth within. There is spire about twice the aperture and composed of a short, nassoid beak formed by the contraction about six whorls. The nuclear whorls are large, around the base. End of columellar pillar with a with a turbinate coil of two and one-half to sharp keel which margins the siphonal canal three rapidly enlarging smooth turas develop notch. Siphonal fasciole strong, bordered by a ing a small keel and a few axials near the end. nassoid keel." (Olsson, 1964) The sculpture consists of low, narrow, axial Holotype: USNM 644190; height 14.1 mm, rib lets ( 12 to 14) crossed by alternating spiral diameter 7.2 mm. threads producing a coarse cancellation. The Type locality: Esmeraldas beds, Punta Gorda, aperture is subovate, rimmed with a narrow, Esmeraldas Prov., Ecuador. nearly continuous, calloused peristome, finely Occurrence: Esmeraldas beds, Ecuador. denticulated on both lips. Beak short, encircled by a fasciolar fold ." (Olsson, 1964) Discussion: In comparing our specimens Holotype: USNM 644000; height 10.5 mm, of N. thielei to specimens from Olsson, diameter 5.8 mm. 1964, we find N. thielei to be a quite vari Type locality: Esmeraldas beds, Quebrada able species. Our specimens from Punta Camarones, Esmeraldas Prov., Ecuador. Gorda (fig. 6), mostly incomplete and Occurrence : Esmeraldas beds, Ecuador. worn, have the shoulder angle from almost turreted to moderately angled, the shoul Discussion: Nassarius exsarsus (Dall, der cord is almost non-existant in some 1908), a deep water species from the specimens. The axial ribs vary from verti Galapagos Islands, is similar in outline; cal in the figured specimen to protractive. however, the spire whorls are turreted, the The spiral threads are weak in our speci axial and spiral sculpture is closer togeth mens, although this appears to be due to er and more subdued. wear. The whorls on the figured specimen are straight sided, although on some of the NASSARIUS (UZITA) MASTUS fragmentary specimens they are more Olsson rounded. If we had more specimens this Plate 1, figure 3 could possibly prove to be an undescribed Nassarius (Uzita) mastus OLSSON, 1964, spec1es. Neogene Moll. Northwest. Ecuador, p. 146, pl. This common species, as noted by 38, fig. 7. Olsson, is similar toN. babylonica Watson, 1882, from the Philippine Islands but has Description: "The shell is small, stout, pupoid, a single cord at the shoulder rather than a its protoconch unusually large for its size, the double cord and the protoconch whorls are nuclear stage followed by a single, sculptured not carinate. Nassarius babylonica occurs turn (that of the body whorl). The large proto in the Recent western Pacific and Indian conch is composed of four, smooth convex Oceans. whorls, the first small, the others enlarging rapidly to form a turbinate coil. The nuclear Subgenus UZITA H. Adams stage is followed by the sculptured body whorl. and A. Adams, 1853 Assumption of the adult sculpture is gradual with the appearance of a few widely spaced Uzita H . ADAMS and A. ADAMS, 1853, The axial lines intersected by two or three spiral • 0. 4
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J>LXI E 1 Figc1res 1. assarius ( ras:wriusJ mcmakini Pitt and P1tt . n . :-; p CASG 67H:32.01 !holot. pe>l; hPight ' .0 mm. c!J ::lllwiPJ'5. 1 nlln t> ·, Locality: P -103, Ango.·lura Formntion 2. ossarws tL'zllaJ hvlus 01:-ison. 1~)(14 . . C'AS(~ 67 :3:3.0 1: he;ght 11.1 mm. dinnwt<•r G ~J mrn (;\ 1 .i1 Locality: P-100. Onzol> Fonn;Jtion, Ett~ador :3. assarius rUzitoJ mas/us Ol~son. 19f1J ..... C 'NM 64419 ( hololype 1; af'ter OJ....:-;on. pl.;).'), fig 7 '· heigl t ~ ~~ 1 Pll dwmeter 1. mm ! Xl~ . l l. Localil ·: Onzole Formntion. Ecuadt>r. ·L Nossarius r 'assanusJ repl'liti Olsson. 1 ~lf1 • ! L\ ·. 1 645:27 ( pnratyp '. al"tcr ( b .. on. pl. :21. fi ~. f) J; h!•Jgh • J.L~, mn diam •ter 6.4 mm
February 26, 1997