Two new species of Mitrella (Gastropoda: Neogastropoda: Columbellidae) from the Lower Miocene Chipola Formation of northwestern Florida

2008·1.6 MB·English

THE NAUTILUS 122(3):151-154, 2008 Page 151
Two new species oi Mitrella (Gastropoda: Neogastropoda:
Columbellidae) from the lower Miocene Chipola Formation of
northwestern Florida
Richard Duen-
Post Office Box 1055
Okeechobee. FL 34973 USA
pdiegel@gHiailcom
ABSTRACT stitutional aL)bre\iatiuns are: UF: Florida Museum of
Natural Histoiy (FLMNH for locality records), Univer-
Two new species oi Mitrella from the lower Vliocene Chipola sity of Florida, Gainesville; PRI: Paleontological Re-
aCFhonnidipioMalitatiroFenolrloamfatpalirueo/nldleeissxacperoisbnueredew.sMasilptoernceiglelFsaarahlraeeiyjCcfsrooeunenikdmipnnreniomwratrshipwleeycsitei-sn sraelarScchieInncsetsi,tutPihoinl,adIethlapchai;a;ANASMPN:HT:heAmAecraidceamnyMofusNaetuum-
ern Florida. USA. Placement ofthe new species in die genus of Natural Histon', New York.
Mitrella is tentati\e.
Additional Keywords: Neogene, ultraviolet light, gastropod. SYSTEMATICS
Astyiis
Superfamily Buccinoidea Raiinesque, 1815
Family Columbellidae Swainson, 1940
INTRODUCTION Genus Mitrella Risso, 1826
Diagnosis: Small to veiy small, smooth, fusiform
Species assignedto the genus Mitrella arewadelydistrib-
uted in tlie warm and shallowwaters ofthe Recent seas shells. Sculpture, if present, ofincised spiral hues. Spiral
oftlie world (Gardner, 1947. 1948). The exact origin of sculpture is generally restricted to tlie anterior end near
Mtaittirx'eelloafistlnieotgcelneuars, fbruotmsotmhee sofoutthheeaesatrelirenstporretpiroenseno-f atbhseenbtas.e:Thaexiaolutsecrullpitpurisedies,ntwaittehifnewadeuxlctepstpieocnism,eennsti(rDeil-y
agnosis according to Campbell [1993] and Keen [1971]).
North America appeared in the Eocene (MacNeil and
Dockeiy III, 1984; Palmer, 1937). Maury- (1910) de- ?Mitrella hayesomm new species
scribed diree Mitrella (asAstijris) from the Chipola For-
(Figures 1-3, 10)
marion. These were originally deposited in the Cornell
Uni\ersit\- collection at Ithaca, New York, and now de- Description: Shell fusiform, narrow. Height ut liolo-
posited at PRI. With more specimens than Mauryhad at type 19.8mm. Protoconch mammillated, with about t\vo
her disposal, Gardner (1947) described 13 species and smooth, rounded whorls, the second expanded, with no
t\vo subspecies ofMitrella from the Chipola Formation. perceptible protoconch/teleoconch transition. Teleo-
Mitrella have been found in all exposed facies ofthe conch with ten slightlv convex, shiny whorls with micro-
ChipolaFormation on die Chipola River, Tenmile Creek scopic irregular spiral grooves, a.xial sculpture lacking.
and Farlev Creek, in tlie Chipola River drainage in Cal- Spire elevatedwith somewhat concave sides. Suture dis-
houn Countw Florida. Thev are also present in the tinct. Aperture elongated, less than halfthe length ofthe
Chipola Formation e.x|iosed in the lower bed at Alum entire shell. Outer lip sinuous, varicose externally, mar-
Bluff in Libertv Count\-, Florida. The two new species gin thin and sharp. Basal lip extending slightly beyond
describedherein have been collected onlyin the Chipola pillar. Posteriorcanalproducedandthickenedexternally.
Formation exposures in the Chipola Ri\'er drainage, pri- Denticles present on innersurface ofouterlip, ten to 12
niarilv at Farlev Creek. \'okes (1989) stated the Chipola in number, weak on anterior third, strongest on central
facies along FarleyCreek\\4iere the two new species are third, frequently absent on posterior third. Parietal wall
most prevalent is a bi\alve-ricli niihohd Hme-sand with with two axial lidges, outer lidge weakwith small raised
manv calcareous algae and coral heads, and assumed it beads reflecting underlying sculptiu'e on pillar. Inner
was a shallow back-reefenvironment. ridge prominent with median notch, adapical half of
Some specimens were photographed under ultraviolet ridge strong, abapical half tapering and completelv chs-
Hght (Ur\") to facihtate visuahzation ofcolor patterns. In- appearing abapically. Base of pillar with about nine
Pag-e 152 THE NAUTILUS, \'ol. 122, No. 3
R. Duerr, 200S Paee 153
oblique groo\'es with a idiiikK'iI siiiiiinit lu'tween species. Seven spt'ciiiu'us ol the most common Mitrella
groines. Darkbandaboutone thirdwidth ol pcnnltiniate in the Chipola Formation, Mitrella iselvia Gardner,
whtirl appears below suture on last threi' whorls ol ho- 1947, a more robust species than M. Iiai/e.soniin, were
lot\pe. Band has irregular narrow, obli(|ne, lighl colored examined under UV light and revealed fine filamentous
lines, some forming u- or \-ligni'es. lines covering all teleoconch whorls. Three specimens of
Type Material: llolotxpe: UF 119655, height hMiatirjeelsloaruams.einexahiGbairtsd,neurn,de19r47U,Valsihgohrt,tenrasrpreocwiesaxtiahlanbaMr.s
sIpQe.cSiinmme,n;wiAdMthNH5.-6Fnuln:43P3a1r2a,t'vpoense: sApNeScPi-meInP;8P1R32I4,83o8n2e, nmning from suture to suture, offset in alignment from
prexious whorls, willi lour perwhorl on most teleoconch
one specimen; Diegel-Duerr collection, one specimen.
whorls.
All from t^pe localit\'. , •-.,,.
T>pe Locality: FLMNH locality Farlex' Creek 07 r'Mitrella plu/lli.sae new species
(CA022), FarleV Creek east ofSR 275, Calhoun County, (Figures 7-9, 11)
Florida (to protect privacy rights oflandowners, specific Description: Shell small, hisilornr Height 7 mm,
localit\- information is available onlv to qualified re- width 2.2 irmi. Protoconch with two smooth whorls, sec-
searchers upon written request to the author or the In- ond whorl enlarged. Teleoconch witli five smooth, con-
vertebrate Paleoutolog\' Dixision of the FLMNH), vex whorls, without axial stulpture. Spire sides shghtly
Chipola Formation. concave. Suture impressed. Apeiiure less than half the
length ofentire shell. Outer lip with slight vaixx, margin
Distribution: Chipola Formation along Teumile and
thin andshaq:), usuallydentate witliin. Thin parietalwash
Farle\- Creeks and the Chipola River, Calhoun County,
present. About seven impressed olilicjue grooves cross
Florida.
base ofpillar, separated by narrow liands with rounded
Etymology': Named to honor the forestn'-oriented summits. Faint round spots, eight on last whorl ofholo-
Ha\es faniih- who ha\-e graciously granted the author, type, appear on last three whorls. Spots about one-
and others, permission to collect on tluir piDpeit)'. quarter the height ofpenultimate whoil in diameter rest
just above median line of the whf)rls.
Remarks: The species currently placed in MitrcUa
comprise acomplexgroupandmayhavebeen diiterently Tyjie Material: Holot)q3e, UF 119656, height 7.(.) nun,
assignedtodiegeneraA?;rt, Asti/ri.s, Nitidelh bydifferent width 2.2 nun; ParatyjDes, ANSP-IP SI325, one speci-
authors (Keen, 1971). The taxonomie position of M. men; AMNH-FI 43313, one specimen; PRI 8383, one
haijcsonim is questionable and its current assignment to specimen; Diegel-Duerr collection, one specimen. All
Mitrella is tentative. Mitrella hai/csoruin has unique from t)rpe locality.
characters, such as the bulbous second whorl ofthe pro- Type Locality: FLMNH locality Farley Creek 07
toconch, extended slightlyconcave spire andwide sipho- (CA()22), Fai-lev- Creek east ofSR 275, Calhoun Count)',
nal canal extending below the pillai", and cannot be con- Florida, (to protect privacy rights of landowners, specific
fusedwith any other knowii Mitrella. Althougli no speci-
locality information is a\ailable only to qualified re-
mens oiMitrella dalli (Maun-, 1910), the species in the searchers upon written reijnest to the author or the In-
Chipola Formation closest in form to MM. hai/csonim, vertebrate Paleontolog\' Dixision of the FLMNH),
were a\ai]able forstudv, Maun's figure ot chilli (1910: Chipola Formation.
pi. 6, fig. 2) indicates a smaller shell (12 mm), a shorter,
stouter spire, and a narrower anterior canal than M. Distribution: Chipola Foinuilion along Tenrnile and
hai/esomm. The nearest European fossilcongenerof Mi- Farley Creeks and the Chipohi Hixer, Calhoun Count)',
trella haijesorum is MitrcUa (MacnireUa) nasspicles Florida.
(Grateloup, 1827) (Figures 4—6) from the earlv Pliocene Etymology: Named for Plnllis Diegel, the author's
ofItalw which is larger, wider at the midbody, and has a companion and a knowledgeable conchologist and pale-
narrow anterior canal. The maximum height ofall speci-
ontologist.
mens of Mitrella haijesonim examined is 19.93 mm,
minimum height is 18.17 mm. Exposure of M. haije- Remarks: As witli Mitrella hai/esonim, the assignment
sonim to ultra\iolet light (Figure 10) reveals a fluores- ofi\/. plnjllisae to Mitrella is tentatix'e. A cursoiy inspec-
centpattern ofaxial flammules in addition to the narrow tion would indicate Mitrella phijllisae to be a dwarf M.
band belowthe suture on the anteriorwhorls ofthe new haijesonim. Closer examin;ition reveals that M. phijllisae
—
Figures 1-11. Mitrella species. 1-3. Apertural, lateral, andabaperturalviexvs ofthe holotyjDe oi'Mitrella luiijesoniin newspecies,
UF 1196.5.5,height 19.8mm,width5.6mm, Burdigalian Miocene. 4-6.Apertural, lateral, andabaperturalxiexx'sofMitrella nassoides
(Grateloup. 1827) UF 119657,height25.5mm,xxidth 8.6mm.Zaiiclean Pliocene,fromLiguriaComity,Ceriale, Italy,forcomparison
xxitli M. haijesonim. 7-9. Apertural. lateral, and abapertural xiews ofthe holotspe oi Milnllu yilujlhsae new species, UF 119656,
height7.0 mm.width2.2rnm, Burdigalian Miocene. 10, 11. Mitrella exposedto U\'light. 10. Ilolotxpeoi'Mitrella haijesonim (same
specimen as Figure .3) showing U\' exposed pattern. 11. Holotxpe of Mitrella phi/lhsae (same specimen as Figure 9) shoxving UV
exposed pattern.
Page 154 THE NAUTILUS, Vol. 122, No. 3
differs from the much larger M. hayesorum by the debted to two anonymous reviewers whose comments
shorter spire, the shghtly more impressed suture, and and suggestions improved the manuscript.
fewer oblique incised lines on the base of the shell. A
series ofdots about 1 mm in diameter are visible on M. LITERATURE CITED
phijUisac encircling all teleoconch whorls, one-third the Campbell, L. D. 1993. Pliocene molliKsks from die York-town
length of the whorl below the suture, eight on the last and Cliowen River Formation in Virginia. Virginia Divi-
UV
whorl. E.\-posure to light reveals (Figure 11), in ad- sion ofMineral Resources, Pulilication 127: vii + 173 pp.,
dition to the larger dots, a field of minute dots covering 43 pis..
the entire teleoconch, somewhat reminiscent ofthe pat- Gardner, 1947. The molluscan fauna of the Alum Bluff
J.
tern on the RecentMitrclln ocellata (Gmehn, 1791) from Group ofFlorida. Fait VIII. Ctenobranchia (remainder),
the western Atlantic. Also, the anterior portion of the Aspidobranchia and Scaphopoda. United States Geologi-
outer lip ofM. plujUisac is less developed than that ofA'/. cal Survey. Professional Paper 142-H: i-ii + 493-638, pis.
52-62.
hayesontm, wliich iswiderandextends bevontl thepillar.
Gardner, 194S. Mollusca from the Miocene and Lower
Tvahreiesheliegsshtthoafnal1l.0smpemc,imfernosmoafmMa.xiphmiujlmlisoafe7e.4xammimnetdo SPlciaopchJeo.npeodaofaVnidrgGiansitaroapondda.NoUrntithedCaSrtoaltiesna.GeoPlaorgtica2l.
a minimum of 6.S mm. Sun-ey. Professional Paper 199-B: i-iii +179-279, pis. 24-
38.
Keen,A. M. 1971. SeaShellsofTropiciJWestAmerica. Marine
ACKNOWLEDGMENTS
mollusks from Baja California to Peru. Second Edition.
Stanford Universitv Press, Stanford, California: .xiv + 1064
The author extends his appn-ciation to Roger Poitell, pp., 22 pis.
FLMNH, forpnnidingthe plates andconnnentingon an Mac Neil. F. S. and D. T. Docken- III. 19S4. LowerOligocene
earlier draft ofthe manuscript. Digital images were pre- Gastropoda, Scaphopoda, and C^ephalopoda ofthe Vicks-
pared by Sean Roberts, FLMNH. Thanks also to Marc Imru; Group in Mississippi. Mississippi BureauofGeology.
Gnarsisgoiisc,leBse.ltgoiuDmr,. fBoerrndaorntaltiLoanndoafu,a sPopretcuigmale,nfoofrMeintcroeuUra- MaunFB,luolrlCie.dtai.n[.B12u14l9:l1e0t4.1i.n5sNpeopfw.,AO7ml2eirpgiiosc.caennePa(lMeionotcoelnoeg)y s4h(e2l1l)s: f1r1o9m-
ageinent and advice, and to Burke and Brooks Hayes 164, pis.18-26.
and also Archie and Vicki Whittington for permission to Vokes, E. H. 1989. An oveniew ol the Chipola Fonnation,
collect on their respective properties in North Florida. northwestern Florida. Tulane Studies in Geolog)' and Pa-
Pamela McBride provided secretarial assistance. I am in- leontolotrv 22: 13-24.