Cainozoic Research, 6(1-2), pp. 61-70, March 2009

The Gastropod in the Neogene of

Tropical America

³ Geerat+J. Melissa+A. ² & Bernard+M. Landau Vermeij ¹, Frey

'Department of Geology, University ofCalifornia at Davis, One Shields Avenue, Davis, CA 95616, United States;

e-mail: [email protected]

2 Center for PopulationBiology, University of California at Davis, One Shields Avenue. Davis, CA 95616, United States;

e-mail: [email protected]

3 InternationalHealth Centers, Av. Infante D. Henrique, Areias Sdo Jodo, 8200 Albufuera, Portugal;

e-mail: [email protected]

Received 8 November2007; revised version accepted 14 January 2008.

The Nerita is in the Cantaure neritid neritaemorph gastropod genus Linnaeus, 1758, representedby two new Formation (Early

Nerita the known member Nerita clade Miocene: Burdigalian)of Venezuela. (Nerita) rugulosa n. sp. is earliest of s.s., a of tropical

American species that also includes the Recent West Indian N. peloronta Linnaeus, 1758,and N. versicolor Gmelin, 1791, and the east- differs from ern Pacific N. scabricosta Lamarck, 1822. Nerita rugulosa these species by having fewer, more prominent spiral ribs and a

is related Atlantic conspicuously ridged, pustulose septum. Nerita (Theliostyla)paucigranosa n. sp. to the Recent western N. fulgurans

Gmelin, 1791, and the eastern Pacific N. funiculata Menke, 1850, but differs from these species by its larger size and by having fewer,

moreprominent septal pustules. We report N. (T.) exuvioides Trechmann, 1935, previously known from the Point Hilaire beds of Carri-

acou and the Gatun Formation of Panama,from the Baitoa Formation (early Middle Miocene) ofthe Dominican Republic. Nerita oli-

gopleuraDali & Ochsner, 1928, from the Pliocene ofthe GalapagosIslands, is here tentatively assigned to the subgenusIlynerita von

Martens, 1887. Members of the Nerita ascensionis Gmelin, 1791,complex in the southwest Atlantic are removed from Theliostyla

Mörch, 1852, and recognized as related to N. magdalenaeGmelin, 1791.from the southwestern Indian Ocean. Nerita magdalenaeCol-

lignon & Cottreau, 1927,from the Miocene ofMadagascar, is renamed N. valdespinosa. We assign Nerita chilensis Philippi, 1887, from

the Navidad Formation of Chile,to the subgenusLisanerita Krijnen, 2002; and we more tentatively assign Nerita joaquinensisAddicott,

of California 1970,from the Round Mountain Silt (Middle Miocene) to the same subgenus.

KEY WORDS:: Nerita, systematics, new species.

informative Introduction n. sp., a phylogenetically taxon in Nerita S.S.,

an exclusively tropical American clade. To place these taxa

Gastropods characteristic of the rocky intertidal zone are in a broader context, we review other known Recent and

infrequently encountered in the fossil record, but the ex- Neogene fossil species ofNerita in tropical America and

tremely rich faunaofthe Cantaure Formation (Early Mio- comment on the taxonomic assignments and nomenclature

cene: Burdigalian) ofVenezuela contains a diverse assem- of several other species.

blage ofwell preserved, hard-bottom, intertidalto shallow-

subtidal species of notably modern aspect. These include

species of Thais, Acanthais (as Stramonita in Vermeij, Materials and Methods

2001), Stramonita, Plicopurpura, Neorapana, Microrhytis,

various of the fossil examined is in Ocinebrina, , Hesperisternia, and limpets, Most material we the Landau

among others (Jung, 1965; Gibson-Smith et al., 1997; collection, but we have also examined specimens at CAS

Vermeij & Yokes, 1997; Vermeij, 2001, 2006). An addi- (California Academy of Sciences, San Francisco) and

tional rocky-shore genus in the faunais Nerita. Jung (1965) UCMP (MuseumofPaleontology, University ofCalifornia, identifiedthe single species he encounteredin the Cantaure Berkeley). All Recent material discussed is in the Vermeij

Formation as N.fulgurans Gmelin, 1791, a Recent West collection.

this form Indianspecies. Here we describe as the new spe-

cies Nerita (Theliostyla) paucigranosa n. sp., and name a Shell dimensions measured are as follows: major diameter

second, hitherto unknown form as N. (Nerita) rugulosa D, more or less perpendicular to the shell’s axis ofcoiling; -62-

minordiameterD more or less to the axis of coil- s.s. to be The 2 parallel monotypic (Vermeij, 1984; Krijnen, 2002). ing; and height H, distance from dorsal surface to base. West Indian N. versicolor Gmelin, 1791, has generally

12 Relative was calculated as R = x D been the taxon height H(D| 2) . assigned to subgenus Ritena Gray, 1858, a

based on the Recent Indo-WestPacificN. plicata Linnaeus,

1758 (see Krijnen, 2002); whereas the eastern Pacific N.

Shell Morphology scabricosta Lamarck, 1822, has been placed in either

Ritena (Keen, 1971) or Cymostyla von Martens, 1887,

In describing shells of the genus Nerita, we employ a whose Indo-West Pacific type species ( Lin-

different from that slightly terminology used by previous naeus, 1758) has recently been clarified (Krijnen, 2002; authors. In the is in the form of loose nerites, outer a Krijnen et al., 2006). spiral, whose growing end is atthe adapical end ofthe shell ventral to the apex. In the abapical direction, the spiral ex- Molecularphylogenetic analyses now show, however, that tends around to the abapical end of the aperture and then Recent high-spired forms of Nerita in tropical America continues less distinct This which form clade as a more or ridge. ridge, a strongly supported monophyletic comprising we call the abapertural ridge, marks the abapertural limitof N. peloronta, N. versicolor, and N. scabricosta. Within this the septum and peters out on the adapical side of the sep- clade, the West IndianN. peloronta appears as a sister spe- tum. We use the term septum for the convex, flat, or con- cies to the West Indian N. versicolor, together, these spe-

surface the the ventral surface cies sister the Pacific scabricosta cave adjacent to aperture on are to eastern N. (M. of the shell. Other authors have referred the in All members ofthe clade inhabitthe to septum as Frey, preparation). the parietal shield or columellararea. The abapertural ridge upperrocky shore. They have two medianteeth as well as a is indistinct of absent or extremely in species the subgenera square adapical toothon the septal edge. The septal surface

and Amphinerita von Martens, 1887, Linnerita Vermeij, is typically sculptured with irregular ridges, although in N.

1984. In fact, in Nerita umlaasiana Krauss, 1848 (type peloronta it is more or less smooth. The denticlesinside the species ofAmphinerita) and related Recent Indo-West Pa- outer lip are always present in adults. In N. versicolor and cific species, the septum is covered with an extensive, N. rugulosa n. sp. (see below), the adapical-most tooth on glossy-smooth callus that extends onto the dorsal side of the outer lip is enlarged and ventrally protruding; in the the last whorl the This of other the tooth is opposite aperture. case partial species, enlarged protruding abapical to a shell envelopment was overlooked by Vermeij (2005) in small tooth. his of survey enveloped molluscs.

Morphologically, shells ofNerita s.s. veryclosely resemble

In adults of many species ofNerita s.l., the septal surface is those of Cymostyla. The only consistent differencebetween sculptured with ridges thatrun from the septal edge ofthe these two groups is that the abapical-most outer-lip toothin aperture to the abapertural ridge. These are here called sep- Nerita s.s. is somewhat enlarged (though not as much as the tal ridges. In most cases, these ridges are expressed only on adapical-most tooth), whereas in species of Cymostyla the the abapical half to two-thirds of the septal surface. In abapical-most tooth is not enlarged. Nerita s.s. resembles many groups, the ridges bear granules or pustules. The ap- Ritena in many characters as well, including the heavily ertural edge of the septum often bears denticles, but these ridged septum, numberand prominence ofteeth on the sep- do not bear a relationship to the septal ridges. In juvenile tal margin, and enlargement of the abapical and adapical

and denticles specimens, septal ridges, septal denticles, on teeth. Nerita s.s., however, has more numerous outer-lip the inner thickened of the outer often absent. teeth and ribs. edge lip are spiral converges in aper-

tural characteristics on N. (R.) plicata, but its apertural

teeth are more numerous and smaller, and the teeth on the

Systematic Paleontology abapical and adapical end of the outer lip protrude much

less than in N. (R.) plicata. The new species N. rugulosa

Genus Nerita Linnaeus, 1758 describedbelow has the high spire, septal ridges, andaper-

turalteeth ofRecent members ofNerita s.s., and therefore

— Nerita fall within the clade defined Type species peloronta Linnaeus, 1758, Recent, appears to Nerita s.s. as by

West Indies (see Abbott, 1958). molecularcriteria. It represents either a direct ancestor or a

sister species to the Recent members ofNerita s.s.

Subgenus Nerita Linnaeus, 1758

of the ofN. the Regardless exact placement rugulosa n. sp.,

Remarks — The taxon Nerita is based onthe Recent West new fossil species yields additional insights into the bio-

Indian “bleeding tooth”. Nerita peloronta, a species living geographic history of high-spired Nerita in tropical Amer-

high in the intertidal zone on rocky shores in the West In- ica. Contemporary geographic ranges ofN. peloronta and

is characterized dies. This species uniquely by two strong, N. versicolor extend across the tropical western Atlantic

denticles; smooth from Bermuda and the ofFlorida protruding septal a concave, nearly sep- east coast throughout the tum; and anoperculum whose outer surface is marked by a West Indies to the mainland coast ofnorthern South Amer-

Nerita the smooth central depression surrounded by a smooth spiral ica (Russell, 1941). scabricosta ranges in eastern

thickening. Most modern authors have considered Nerita Pacific fromthe west coast ofBaja California and through- -63-

out the Gulfof California to northern Peru Most similar N. is (Keen, 1971). among living species to rugulosa N. ver- Whilesister species from the Atlanticand Pacific coasts of sicolor. In contrast to N. peloronta andN. scabricosta, both

America oftenreflect tropical divergence resulting from the N. versicolor and N. rugulosa have the adapical-most den-

ofthe Isthmus of Panama the ticle the inner side of the uplift during Pliocene, large on outer lip strongest and most distances the Recent of genetic among species Nerita s.s. protruding. In the other species, the strongest denticle is the indicate that the between split the N. scabricosta and V. second from the adapical end of the lip. Nerita rugulosa

is much ancient has 12 13 denticles peloronta/versicolor groups more (M. to on the outer lip, whereas N. versi-

Frey, in preparation). Indeed, fossil specimens ofA. scab- color has fewer (usually ten to 11, sometimes 12). The

ricosta have been reported from the Latrania Formation numberof spiral ribs in N. rugulosa (17 to 18) falls within

(Late Miocene) of southern California (Demere & Rugh, the wide range oj N. versicolor (13 to 23). Some specimens

the of that well before of N. versicolor its have 2006), indicating presence species throughout range a nearly or com-

the formation of a continuous Panamanian land bridge. pletely smoothlast whorl, with ribs (ifpresent) confined to

Nerita which is closer the rugulosa, morphologically to N. adapical sector. This condition is not known in N. rugu-

versicolor than the other in the Ameri- losa. Available of'N. to species tropical specimens rugulosa are much smaller

can clade, the first — pushes appearance of the clade and (maximum major diameter22.5 mm) than N. versicolor

the N. perhaps divergence between peloronta and N. versi- (maximum 30.5 mm, west coast of Aruba, Netherlands

color — back to at least the Early Miocene. Antilles).

& Macsotay Campos Villaroel (2001) describedtheirnew

Nerita Nerita from shells (Nerita) rugulosa, n. sp. species amplisulcata empty dredged at a

1-3 of nine Figures depth meters from near Isla Margarita, Venezuela.

This is characterized taxon by having 13 strong cords and

— A Nerita with 16 18 six teeth Diagnosis small, globose to to seven large on the outer lip. We have not seen

strongly spiral ribs, and illustrations the authors expressed well-developed septal ridges, specimens, given by are poor, and two strongly expressed pustules on abapical septal but it is possible that N. amplisulcata is a distinct species,

extinct differs ridges. possibly an one. It from other Atlantic spe-

cies ofNerita, including.N. rugulosa. by having fewer teeth

Description — Shell small for clade, maximum major di- inside the outer lip.

ameter 22.5 mm, globose (relative height 0.69 to 0.76,

last whorl mean 0.725); convex, evenly rounded, bearing In the eastern Pacific, shells ofthe A. scabricosta complex

17 to 18 ribs; outer thickened within, bear- differ from N. sharp spiral lip rugulosa by having more numerous spiral 12 to 13 denticles; denticle ing adapical-most largest,, pro- ribs (23 to 33 in the typical scabricosta form from Mexico;

denticle also somewhat 25 28 in truding ventrally; abapical-most to the subspecies N. s. ornata Sowerby, 1823, with tooth and enlarged; septal edge square adapical two from Panama; 23 to 29 in the form from the Galapagos,

prominent medialteeth; surface flat to con- the septal slightly perhaps belonging to subspecies ornata) and more nu-

vex, bearing seven to nine prominent the ridges, abapical merous denticles inside the outer lip (16 to 18 in popula-

five of which bear two well-expressed pustules each; tions from Mexico to Panama, 15 to 20 in the Galapagos). rounded, abapertural ridge indistinct; spire protruding. Typical N. scabricosta from Mexico (Pacific coast ofBaja

California Sur, GulfofCalifornia, Nayarit, and Jalisco) and

Holotype — NHMW 2007z0169/0001: Major diameter specimens from Guanacaste Province in northwestern 21.1 minor diameter mm, 16.6 mm, height 13.8 mm. Costa Rica are somewhat less convex (relative height re-

spectively 0.68 ± 0.028, n = 12; and 0.66 ± 0.024, n = 5) Paratype — Major diameter22.5 mm, minordiameter 18.9 than shells of are N. s. ornata from Panama(0.725 ± 0.026, mm, height 14.2 mm. = and the n 13) Galapagos (0.72 ± 0.036, n = 7). The

southern ornata populations are thus of about the same Type locality — Casa Cantaure, east of San Jose, Falcon globosity as those of N. rugulosa. Like the fossil A. State, Paraguana Peninsula, Venezuela. rugu- losa, A. s. ornata has a septal surface sculpture ofstrongly

pustulose ridges. Molecular studies show that Panamanian Distribution — Cantaure Formation (Early Miocene: N. scabricosta differ about0.5% from Mexican but Burdigalian), Venezuela. by ones

the two populations do not formreciprocally monophyletic

Etymology — Latin; roughened, referring to the external groups (Hurtado et al., 2007). Nerita scabricosta is one of the sculpture and the well expressed septal ridges. largest known nerites (maximum major diameter50.0

mm, Isla Santa Cruz, Galapagos).

Remarks — Nerita rugulosa n. sp. is a distinctive member

ofthe American clade ofNerita characterized tropical s.s., Nerita rugulosa co-occurs in the Cantaure Formationwith

by strong septal ridges distinct and 17 bearing pustules by N. (Theliostyla) paucigranosa n. sp. It can be immediately 18 ribs. No of to strong spiral species Nerita s.s. has spiral distinguished from N.paucigranosa by its globose, higher- ribs that well are as developed as does N. rugulosa. spired shell, and by the outer lip dentition. -64-

Figure 1-8. -65 -

1-3.NHMW Nerita Cantaure Venezuela. Figures 2007z0169/0001 rugulosan. sp., holotype. Miocene, Formation, Paraguana Peninsula,

Scale bar 5 mm; (1) frontal view, (2) rear view, (3) side view.

NHMW Nerita Cantaure Vene- Figures 4-6. 2007z0168/0002 paucigranosan. sp., holotype. Miocene, Formation, ParaguanaPeninsula,

zuela. 5 frontal side view. Scale bar mm; (4) view, (5) rear view, (6)

7-8. BML Nerita exuvioides. Baitoa Rio del bar 5 Figures n.n. Miocene, Formation, Yaque Norte, DominicanRepublic. Scale mm; (7)

frontal view, (8) top view.

In N. rugulosa, the adapical-most and to a lesser extent the 12 prominent, slightly overhanging spiral ribs and a finely

abapical-most tooth are enlarged and protruding; in N. denticulated outer lip (see also Jung, 1971). Nerita (T.)

from paucigranosa, the adapical two teeth are enlarged. The fortidentata Vermeij &Collins, 1988,known only the

is smaller that of Formation of is aperture ofN. rugulosa relatively than N. Cayo Agua (Early Pliocene) Panama,

paucigranosa, and the more convex septum bears strong smaller(21.3 mm) and has 21 strong, slightly overhanging ridges with two pustules, whereas the septum ofN. pauci- spiral ribs and very strongly expressed outer-lip teeth.

granosa is flat to concave and has ridges with three promi- Other fossils were questionably referred to N. fulgurans by

of is much Careful examination of nent pustules. The abapertural ridge N. rugulosa Jung (1965, 1969). numerous

less distinct than that in N. paucigranosa. specimens from the Cantaure Formation of Venezuela,

however, persuades us that these represent a previously

unrecognized species, which we here name Nerita (Thelio-

1852 also Subgenus Theliostyla Morch, styla) paucigranosa n. sp. We reporta new occurrence

of N. exuvioides.

Type species — Linnaeus, 1758, Recent,

Indo-West Pacific. Another fossil member of the clade to which the American

species of Theliostyla belong is the MediterraneanEarly

Remarks — Three Recent tropical American species and Pliocene Nerita emiliana Mayer, 1872 (for a thorough re-

the Recent eastern Atlantic Nerita senegalensis Gmelin, view see Landau et al., 2004). This species is extremely

1791,form a distinct clade (M. Frey, in preparation) whose close to, or perhaps even identical with, the living N. sene-

members have generally been assigned to the subgenus galensis. It shares with N. senegalensis and the American

Theliostyla, a taxon based on the Recent Indo-WestPacific forms the two prominent adapical teeth on the outer lip.

Nerita albicilla. The West Indian N. fulgurans Gmelin, Like N. senegalensis, the Pliocene N. emiliana varies from

1791, and N. tessellata Gmelin, 1791, the Eastern Pacific being almost wholly smooth to very weakly ribbed.

N. funiculata Menke, 1850, and the West African N. sene-

all characterized flat galensis are by a to concave septum, Vermeij (1970) tentatively assigned Nerita ascensionis

pustules on the adapical septal ridges, prominent abaper- Gmelin, 1791, and its subspecies N. a. chlorostoma I .a-

tural ridge, and denticles inside the outer lip of which the marck, 1816 (as N. a. deturpensis and N. a. trindadeensis.

two adapical-most teeth are enlarged and protruding. The both ofVermeij, 1970) from the western South Atlantic to

two small central teeth. is of their septal margin bears The spire Theliostyla because very weakly pustulose septum

either slightly protruding or flat. All American species have and granulose operculum. This complex offorms, however,

spiral ribs that often bifurcate, whereas N. senegalensis is differs strikingly from Theliostyla in having only one

either entirely smooth or, in populations from Sierra Leone strong adapical tooth inside the outer lip, in having a

to Cameroon, very weakly ribbed. glossy-smooth, flat septal surface boundedabaperturally by

an indistinct rounded ridge, and a flat instead of convex

The widespread Indo-West Pacific N. albicilla. type spe- operculum. Shell characters indicatethat N. ascensionis IS

cies of Theliostyla, resembles the species in the American closely related to N. magdalenae Gmelin, 1791, a Recent

clade differs in most respects. It slightly by having the sec- species from Mauritius and Reunion in the southwestern

ond tooth from the adapical end of the outer lip enlarged, Indian Ocean.

whereas the first tooth, though present, remains small. The

septal margin bears two to three small denticles. Nerita We note in passing a primary homonymy ofNerita magda-

albicilla tends to have weakly expressed, distant, rounded lenae Collignon & Cottreau, 1927. The latter, and Early

ribs, and in large adults has the edge of the outer lip pol- Miocene (Aquitanian) species with strongly expressed

ished. In the Atlantic and eastern Pacific species men- spines from Marofototra, Madagascar, is here renamed

tioned, the lip edge is always sharp and, where spiral rib- Nerita (s.l) valdespinosa.

bing is well developed, is distinctly crenulated.

Two previously described fossil species from tropical Nerita (Theliostyla) exuvioides Trechmann, 1935

America also belong to Theliostyla. Nerita exuvioides Figures 7-8

Trechmann, 1935, from the Point Hilaire beds (Middle

of Carriacou and the Gatun Nerita exuvioides 30. Miocene) (Trechmann, 1935) Trechmann, 1935: p. 551, pi. 20, fig.

Nerita exuvioides Trechmann: Formation(Late Miocene) ofPanama (Vokes, 1983)has a (Nerita) Jung, 1971, p. 175,

figs 1-2. large shell (maximum major diameter 33.0 mm) with 11 to pi. 6, -66-

Nerita (Theliostyla) exuvioides Trechmann: Yokes, 1983, p. from the IndianOcean, which, however, has fewer, almost

b. 133, pi. 1, fig. la, tuberculate ribs.

Remarks — Trcchrnann (1935)described Neritaexuvioides

Nerita from an incomplete specimen from the Point Hilaire beds (Theliostyla) paucigranosa, n. sp.

4-6 on the island of Carriacou in the Grenadines. Jung (1971) Figures further discussed this species from Carriacou and inferred

Nerita Gmelin: 1965: its age to be early Middle Miocene. Yokes (1983) de- (Nerita) fulgurans Jung, 479, pi. 62, fig. 14. scribed a well preserved specimen of N. exuvioides from the Gatun Formation (Late Miocene) of Panama.

— with 19 21 Diagnosis Large Theliostyla to strong spiral

One of us (BML) has collected an additional worn speci- ribs, 11 to 13 teeth inside the outer lip of which the two men of this uncommon species at Rio Yaque del Norte, adapical-most ones are largest and often protruding, and a

surface with three Lopez section (location equivalent to NMB 17281) in the strongly ridged concave septal large pus-

Baitoa Formation (Early Miocene) of the Dominican Re- tules per ridge. public. The specimen is small (major diameter 15.7 mm,

— Shell for minordiameter 13.5 mm, height 9.8 mm) and has 12 very Description large subgenus, maximum major

diameter 32.2 shell 0.68 strong ribs separated by deep interspaces. Its septum is mm; globose (relative height ±

0.032, n = 20); flat sculptured by abapical ridges each bearing three pustules, spire or very slightly protruding, bounded by a distinct abapertural ridge. The septal edge eroded; last whorl with 19 to 21 strong spiral ribs; outer lip bears one small medial tooth. The spire is flat, and the crenulated at edge, bearing 11 to 13 prominent denticles on

its inner denticles the outer lip bears ten prominent teeth on its inner surface, of side; two adapical (especially second which the adapical-most toothis protruding. This specimen from the adapical end) larger than others, protruding ven- is considerably smaller than other known specimens trally; septum distinctly set off by abapertural ridge, con-

(Vokes’s shell from the GatunFormationbeing 33.0 mm in cave, bearing seven to ten septal ridges each bearing up to

three with medial major diameterand 28.3 mm in minor diameter). The num- large pustules; septal edge two prominent ber ofribs (12) is the same as in the Carriacou material but teeth. one more than in Vokes’s specimen.

Holotype - NHMW 2007z0168/0002: Major diameter

21.2 minor diameter 16.4 The small size, together with characters of the apertural mm, mm, height 12.5 mm. dentition, indicates that the specimen from the BaitoaFor- mation is subadult. Vokes’s specimen (USNM collections) Paratype - NHMW 2007z0168/0001 and NHMW of exuvioides has two the 2007zO diameter 25.4 minor diameter N. very strong adapical teeth on 160/0180: major mm, 19.6 15.3 outer lip (as in other American species of Theliostyla) and mm, height mm. two strong teeth on the central sector ofthe septal margin.

Baitoa — Casa of San Falcon The specimen has just one adapical tooth enlarged Type locality Cantaure, east Jose,

small Peninsula, Venezuela. and bears a single medialtoothon the septal margin. State, Paraguana

Nerita exuvioides differs from N. fortidentata Vermeij & Distribution — Cantaure Formation (Early Miocene,

Collins, 1988, from the Cayo Agua Formation(Early Plio- Burdigalian), Venezuela. cene) of Panama by having 11 or 12 instead of 21 promi- nent spiral ribs and by having the strongest abapical tooth Etymology — Latin, few-grained, referring to the small in the most abapical position insteadof in the third position number of pustules (or granules) on the septum. from the abapical end.

Remarks — This large neriteis so similar to the Pliocene to

and Yokes drew attention to Trechmann (1935) (1983) the Recent western Atlantic N. fulgurans Gmelin, 1791, that

close between N. exuvioides and the Recent very similarity Jung (1965) considered it to belong to the latter taxon, al- western Pacific N. exuvia Linnaeus, 1758. Examination of though he did observe some differences.Recent specimens Recent ofN. exuvia from the specimens Philippines, Papua of N.fulgurans reach a somewhat smaller maximum size;

New and Indonesia reveals that this Guinea, species the neotype, from Cartagena (Colombia), has a major di- reaches maximum size diameter 35.7 ameter a (major mm, Moti, of 29.1 mm, whereas the largest specimen in the that of exuvioides. As Maluku, Indonesia) comparable to N. Vermeij collection (Jupiter, Florida) is 28.7 mm. Nerita noted Yokes N. exuvia differs by (1983), by having some- fulgurans has less prominent and more numerous pustules what ribs to 14 to 11 to the six three in more numerous (13 as compared on septum (four to as compared to N. pau-

to 12) and outer-lip teeth (15 as compared 10). The two cigranosa) and usually has more numerous, much less adapical-most teeth in N. exuvia are enlarged, not just one prominent spiral ribs (16 to 35 in N. fulgurans, 19 to 21 in in as N. exuvioides. The septum has two medial teeth at its N. paucigranosa). The ribs in N. fulgurans tend to bifur- edge, and ridges bearing eight pustules each on its surface. cate toward the outer lip, whereas in N. paucigranosa they

Nerita exuvioides has three the do The in the number teeth the in only pustules on septal not. range of on outer lip

Another similar is N. textilis N. that in N. ridges. species Roding, 1798, fulgurans (10 to 16) encompasses pauci- -67-

A fossil granosa (11 to 13). specimen of N. fulgurans is Ilynerita bears some resemblance to the monotypic Recent

known from the MaoFormation of the Domini- Adenerita based (Pliocene) genus or subgenus Dekker, 2000, on

can Republic (Costa et ai, 2001). Nerita adenensis Mienis, 1978,from the southern Red Sea

Another similar is extremely species N. funiculata Menke, and Arabian Gulf.Like Ilynerita, Adenerita has anentirely

1850, from the eastern Pacific. This species, which is also smooth but Adenerita differs operculum, by having very known from the Latrania Formation (Late Miocene) of weak ribs spiral and a very small, concave, finely granu-

southern California (Demere & is lated Adenerita Rugh, 2006), relatively septum. has two small denticlesonthe me-

small (maximum diameter22.0 Isla Pa- dial major mm, Perico, sector of the septal edge, and lacks denticles on the

nama), but with in numberof overlaps broadly iN.fulgurans outer lip.

ribs (15 to 38) and number of outer-lip denticles (nine to

14). It has more on the surface is in the pustules septal (six to eight Although Ilynerita represented Recent faunaby a than either N. N. per septal ridge) fulgurans (four to six) or single Indo-West Pacific species, the taxon appears to have

Nerita is less had much broader paucigranosc (three). funiculata slightly glo- a distributionin the past. Nerita listrota bose shell (relative height 0.655 ± 0.030, n = 7) than either Woodring, 1973, fromthe GatuncilloFormation (Late Eo-

N. (0.67 ± 0.020, = fulgurans n 8) or N. paucigranosa cene) ofPanama, appears to belong to Ilynerita (Vermeij &

(0.68 ± 0.032, n = 20). Collins, 1988). It has a pustulose septum whose edge bears

five one abapical tooth, medial teeth, and an adapical tooth

& Collins that the here situated the end of Vermeij (1988) suggested species at an adapical septal fold. There is an

as N. shouldbe included in N. flat distinguished paucigranosa angulation demarcating a nearly adapical shell face We this fortidentata. reject suggestion. The two species are from the rest of the shell, as in N. planospira. The lip ofA.

indeed similarin the number of listrota is described very septal pustules, spiral as “finely striate” (Woodring, 1973). and ribs, outer-lip teeth; but N. paucigranosa has much less Our examinationofthe holotype (USNM 646646) indicates ribs prominent, narrower separated by shallower inter- that dentitionon the innerside of the outer lip is obsolete, excavated spaces, a more steeply septum, and different and that, as in living N. planospira, the abapertural ridge is

abapical teeth on the outer lip. In N. fortidentata, the indistinct.

abapical-most tooth is small, and it is the third tooth from

the end that is whereas in N. Shells of similar form abapical most enlarged; pau- occur in Europe. These include the tooth is the cigranosa, enlarged at most abapical posi- Nerita plutonis Basterot, 1825,from the Late Oligocene to

tion on the outer lip. Middle Miocene of France; and the Middle Miocene N.

1837, 1837,and asperata Dujardin, N. N. funata Dujardin,

Subgenus Ilynerita von Martens, 1887 proserpinae Mayer, 1895, all from the Touraine basin of

France. the Although sculpture varies among and within

— Nerita Anton, 1838, Recent, these there is Type species planospira species, always an angulation separating a Indo-West Pacific. nearly flat adapical shell face from therest ofthe shell. The

outer lip in these species is thickenedand smooth (not den- Remarks The and type only Recent species ofIlynerita, ticulate) within. The septum is pustulose, its edge typically

Nerita planospira Anton, 1838, resembles Theliostyla in bearing two weak central denticles. Gilbert (1949, 1962) shell characters but is immediately distinguished from assigned these species to Theliostyla, presumably because its smooth instead of Theliostyla by entirely externally ofthe pustulose septum. We tentatively assign these Euro- Nerita has flat granulated operculum. planospira a to im- pean fossils to Ilynerita because of the presence of the

mersed spire; its spiral sculpture consists of 14 to 15 angulation and the absence ofouter-lip denticles. The dis-

prominent ribs, ofwhich the fourthor fifth from the adapi- covery of opercula would settle the matter. cal end is somewhat form enlarged to a weak angulation.

The face of the shell is therefore adapical more or less flat- Dali & Ochsner(1928) described a peculiar neritefrom the

tened. The adult outer is thickened within and bears lip 25 upper (Pliocene) horizons of Seymour (= Santa Cruz) is-

extremely weak denticles, none of which is The land in the enlarged. Galapagos. Examination of the heavily worn broad is flat septum to concave and bears distinct ridges, holotype (CAS 2937) indicates that the spiral sculpture each with four to five which like the consists of four the prominent pustules, angulations, abapical-most one being ridges are largely confined to the abapical sector of the distant from the other three. The adapical-most angulation

surface. The bears is the most septal septal edge uniquely a prominent prominent, and sets off a more or less flat

tooth, and a number shell face from the of the shell. The abapical variably developed (usually adapical rest septum sometimes two, four) numberof medial teeth, as well as a appears to be pustulose and bears two central denticles. broad tooth. In from The have adapical specimens eastern Papua outer lip appears to one small denticleat both the

New Guinea, there is a prominent adapical fold on both the adapical and abapical end, but is otherwise smooth within.

outer and the lip septum. This fold is weak or absent in This species differs strikingly fromall Neogene to Recent

fromOkinawa, the Indone- American specimens Philippines, eastern tropical nerites, as already noted by Dali & sia, and The have has Singapore. largest specimen we seen Ochsner (1928). It does, however, bear a closeresemblance

a major diameterof 32.5 mm M. at Na- to the (collected by Frey European species discussed in the preceding para-

gaji-Jima, Okinawa). graph. We therefore tentatively assign N. oligopleura to the -68 -

subgenus Ilynerita. We tentatively assign two additional fossil species from

North America to the subgenus Lisanerita. One is Nerita

joaquinensis Addicott, 1970,from the lower Round Moun-

Subgenus Lisanerita Krijnen, 2002 tain Silt (Middle Miocene) of the Kent River area ofCali-

fornia.The holotype (USNM 650051) is a small (13.9 mm)

Type species — Nerita lirellata Rehder, 1980, Recent, shell with an immersed spire, a thickened denticulate outer

Island. Easter lip, two median denticles on the septal margin, and three

the of the surface. granules on preserved part septal Sculp-

ture ofthe last whorl consists of fine incremental lines Remarks — Krijnen (2002) proposed his subgenus Lisan- only The is well erita for several subtropical and warm-temperate species (Addicott, 1970). abapertural ridge developed. from Easter Island, New Zealand, and Australia (for de- Squires & Saul (2002) placed this species in the subgenus

Theliostyla, presumably because of its granulose tailedtreatment ofRecent species see Spencer etal.,2007). septum. Its shell characters fit better with those ofLisanerita. Ifthis Species in the group are chararacterized by strongly re-

allocation is correct, Lisanerita would have been ducedspiral sculpture, a flat to concave, smooth to weakly repre-

with smooth with sented in the northern hemisphere. pustulose septum a edge or up to two

weak medial teeth, an outer lip with thickened, finely den-

This interpretation is strengthened by our tentative assign- ticulateinner side, and a smooth to weakly granulose oper-

ment ofNerita Dali, 1892, from the Silex beds culum. The septum is broad and not distinctly set off by an tampaensis ofthe Limestone earliest Mio- abapertural ridge. Tampa (latest Oligocene or cene) of Florida, to the subgenus Lisanerita. Its holotype

(USNM 112663, illustratedby Mansfield, 1937) is strongly In the Navidad FormationofcentralChile, Nerita chilensis eroded, but it shows two central denticles on the septal Philippi, 1887,occurs as one of several warm-water littoral margin, at least two granules on the septal surface, and ob- molluscs. According to Finger et al. (2007), the shallow- solete spiral elements on the shell exterior. The inner side water molluscs of the Navidad Formation are older (Late ofthe outer lip is not thickened and lacks denticles, perhaps Oligocene to Early Miocene) than are the deep-water, indicating that the specimen is not an adult. No similar cooler-climatemicrofossils and molluscs in that formation. spe-

cies is known from the Miocene to Recent on the Atlantic These latter elements are of Late Miocene to Early Plio- coast of the Americas. to cene age. According Finger etal. (2007), shallow-water species would have been carried in reworked condition

from shallow-water sediments laid down during the early Literature Cited Neogene and redeposited at bathyal depths later.

Abbott, R. T. 1958. The marine mollusks of Grand Cayman Is- Nielsen et al. (2004) assigned Nerita chilensis to the sub- land, British West Indies. Monographs of the Academy of genus Hemineritavon Martens, 1887, on the grounds that Natural Sciences ofPhiladelphia 11, 1-138. N. chilensis resembles N. lirellata. In his strongly original Addicott, W. O. 1970. Miocene gastropods and biostratigraphy of of the latter Rehder N. description species, (1980) placed the Kem River area, California. United States Geological

lirellata from Easter Island in Heminerita, an assignment Survey Professional Paper 642, 1-174.

affirmedby Nielsen et al. (2004). Neritajaponica Dunker, Anton, H. E, 1838. Verzeichniss der Conchylien welche sich in

der Herrmann Eduard Anton 110 1860, the type (and, in our view, the only) species of Sammlung von befinden, Halle. characterized pp. Heminerita, is a Japanese species by a glo- Basterot, B. de 1825. Description geologiquedu bassin Tertiaire shell with raised, blunt in- bose, smooth a apex, steeply de sud-ouest de la France. Premiere Partie, comprenant les clined smooth septum distinctly set off by an abapertural observations generates sur les mollusques fossiles, et la de- ridge, smooth or very weakly denticulate septal edge, and scription particuliere de ceux qu'onrencontre dans ce bassin. internally thickened smooth outer lip. By contrast, N. Memoires de la Societe d’Histoire Naturelle de Paris 2, 1- chilensis has 38 to 45 flattened spiral ribs. Rehder (1980) 100, pis. 1-7.

andNielsen et al. Heminerita to (2004) interpreted broadly Collignon, M. & J. Cottreau 1927, Paleontologie de Madagascar.

include that would to other species we assign subgenera XIV.—Fossiles du Miocene marin. Annales de Paleontologie

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phinerita and Lisanerita (Frey, in preparation). Given its paleontology in the northern Dominican Republic 22. The family (: ). Bulletins ofAmeri- morphological similarity to N. lirellata, the type species of

can Paleontology 359,47-71. Lisanerita, we assign N. chilensis to the latter subgenus. Dali, W. H. 1892. Contributions to the Tertiary fauna of Florida, Miocene South Biogeographically, a subtropical Early with especial reference to the Miocene Silex-beds ofTampa American occurrence of an otherwise Indo-West Pacific

and the Pliocene beds ofthe Caloosahatchee River area. Part and Australasian clade of nerites has parallels in at least II. Streptodont and other gastropods, concluded. Transac- two other gastropod families, the Trochidae (DeVries and tions of the WagnerFree Institute ofScience ofPhiladelphia Hess, 2004) and Turritellidae (DeVries, 2007), and perhaps 3, 202-458.

the The also (DeVries, 2006). nerite, trochid, Dali, W. H. & W. H. Ochsner 1928. Tertiary and Pleistocene

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