Bulacanites obtusiplicatus gen. et sp. nov., a large lucinid bivalve (Mollusca) from the Pliocene of central Luzon, Philippines

2007·1.9 MB·

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N.llv'NFrv l(j4s4u ),2,0061P3E28N
Mern.Natn,Sci,Mus,,Ibkyo,(44M)a,rch 28,2006

Bulacanites Gen. Nov, Large LucinidBivalve
obtusiplicatus et a
(Molluscfrao)mthePlioceneSpC,entralLuzon, Philippines
of
[Ibmoki Kasei and Yblanda Maac Aguilaff
i Department ofGeologyl National Science Museum, 1[bkyo ,3-23-1 Hyakunin-cho,
Shiajuku-kuI,bkyo,169-O073Japan

E-mail:[email protected]

2Petrolal], Mines and Geoscience Bsureau ,North Aye. ,Diliman ,Quezo CnitM ?hilippines
E-inail :[email protected]
'of
Abstract . Bulacanite osbtttsiplicatus is describe das a new genus and species the bivalv efam-
ily Lucinida eba,sed on the valves collected fror nthe upper Lower Pliocen eTartar oFormation in
Bulacan province e,entral Luzon, Philippine Tsh.is new genus has very larg eshells and edentulous
hinge plates a,nd is close to Anodontia and Mbganodontia, but diffb risn having very thick shells,
anteriorly more incline udmbones, and unique radially divergen rtibs in the shell surface. The sedi-
mentary facie sand associated fossi lrseveal that B. obrnsiplicatus sp, nov live din shallow marine,
intertid taol subtidal envirerrrnents,
Key werds: Bulacanit eosbtusipiicatus, new genus, new species, Lucinidae, Philippin ePsl,iocene,
[[lartaFroormation.

unpublished report by Melendres and Versoza
Introduction
(1960 a)l,ong the Madlum River in the vicinity of
In an effbrt to strengthen paleontoleg irce- barrio sTartaro and Sibul ,about 10km ENE of
search in the Mines and Geoscience sBureau, San Miguel municipality In the typ elocali ttyhle
Philippin e(sMGB) ,the Nationa lScienc eMuse- fbrmatio nunconfbrmably overlies marine sedi-
um (NSM) ,Tokyo, Japan , and the MGB ments of the Miocene Madlum Formatio nin the
Iaunched in 2003 ajoint research program on east, and to it swest it is unconfbrTnably overlain
fbssi lcollection bui]din gand natural history by the non-marine Pleistoce nAelat Conglomer-
studies in the Philippine sTh.e program aims to ate Member of the Guadalupe Formation (Gon-
establish staiidard fossi rleference material in the zales et al., 1971) .Based on it ssedimentary fea-
Philippine sg,eared tewards understanding the tures and fbssi lcontent, the Tartar oFormation
origin of high biodiversi tiyn the tropica lIndo- represents an interti daandl subtidal, shallow ma-
Western Pacifi cS,ince then, the authors have rine setting. It is slightly over 200m thick .The
been undertaking fossi lcollection surveys in fbrmatio nconslsts of very gentl ydippin gbeds of
Luzon, Cebu, Mindanao, Leyte, and Panay is- clayey sandstone and sandy siltstone that are
lands ,and explored a number of younger Ceno- strongly bioturbate odr in place sthinly bedded,
zoic fbssi llocalit iyeest unstudied previously It is highly fossilifer othursoughout the succes-
One of the targete dareas in this projec tis Bu- sion and contains abundant mollusks and corals,
lacan provinc ein central Luzon, where the Benthic fbraminifer sare also abundant in the
younger Cenozoic [fartar oFormation crops out matrix, and patchy coral mounds are also present
along the east-central 1imb of the Luzon Central mostly in the middle section of the Madlurn
Vhlley Basin ,about 100 km north of Manila River succession. Specimens collected from the
(Fi g1,) .The best exposures ofthe fartar ocan be Madlum River are not only abundant but also
observed at the type sectien, designated in an highly diverse and exquisitely preserve d.Many
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176 Tomoki Kase and "folanda M. Aguilar
luscan fbssil sH.owever, these age determinations
becausebenthicfbraminifers
are not reliable and
fossi mlollusks are not good age indicato rVsi,l-
lanuev aet al. (1995 f)bund namiofossils indica-
tive of lat eMiocene to early Pliocen efrom the
middle part of the formatio nalong the Madlum
River, Recent preliminary nannofbssil analyses
by Kameo (per sco.mm., 2005) showed tha tthe
Thrtar oFormation along the Madlum River is
within the lat eEarly Pliocene, which is defined
by the las toccurrences ofE)?henolithus abies and
ReticulojZinestprsaeudoumbilica3,.6to 3.75Ma

(Sait1o9,99).

Kanno et aL (1982 r)eported 55 species of
mollusks from the Tartaro Formation. In the cur-
rent projec tw,e have been collecting fossi lmol-
lusks extensively throughout the fbrrnati oatn the
type locali tanyd in other newly discovere adreas.
As a result, more divers efbssi lmollusks have
been recognized, which tota lup to 200 species.
We her einitia rlelpoyrt a remarkably 1arg enew
lucini sdpecies from the Tartar oFormation.
Fig, 1. Map showing the collecting localit ioefs
Bulacanites obtusiplicatus sp. nov in Bulaean Fossi lLocalities
province, central Luzon ofthe Philippines.
The specimens of the new lucini dspecies de-
inthis fromlocality
scribed paper were collected
still retain thei rpristin eoriginal eolor matkings. AGT. 2 (14057.11 41'2N1e,02.999'E )a, riverbed
Because of the almost fla tgeomorphology ofBu- of the Bayabas River in baranga yBanaban,
lacan province e,xposures of the [lartar oForma- Angat municipalityL Bulacan provinc e(Fi g1,).
tion are limite adnd widely separated. The forma- An additional fragmentar yspecimen was also
tion also exposes jn the south of the type area collected at TTR20, a rivert}ed of the Madlum
along the Magasawang Mangga Creek, a tribu- River in barri oTartaro of the same province T,he
tary of the Salapunga nRiver about 10km SSE beds exposed at locali tAyGT. 2 belong to the
of San Ildefonso municipality, and along the lower part of [fartar oFormation, about 15m
Bayabas River, about fbur km NE of Angat mu- thick, very gentl ydipping, highly fbssiliferous,
nicipality. Here too, abundant and divers emol- and consists mainly of strongly bioturbate dfid-
lusca nfbssi losccasionally admixed with coral able, fine-graine dsand and silty sandstone. The
fragment shave also been found. specimens were obtained from two beds in the
The detaile gdeologic age of the Tartar oFor- middle and upper part sof the succession. The
mation has not been well understood. Gonza!es lower bed consists of ill-sort efdine-grained
et aL (1971 d)ated it as Pliocen eto Pleistocenesandstone, is not highly fossiliferou san,d bears
based on the benthi csmaller foraminife rsI.n many small calcareous concretions. IIWo speci-
contrast, Kanno et al. (1982 d)ated a fbssil-bear-mens collected from this bed are articulated
ing horizo nofthe middle part of the formatio nin and likel yto be autochthonous in origin. Other
the type area as lat eMiocene on the basi sofmol- common mollusks identifi iend thi sbed are large
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A new Pliocen leucini gdenus and species from Philippines 177
gastropod ssuch as A(felongen agigas (Martin,plicatus sp. nov can be classified under the sub-
1883) and SZrombus maximus Martin, 1882, and famil yMilthinae Chavan, 1959. Among modern
many articulated valves ofPtaeuna (llphmpium)lucinid st,he newly introdnce dgenus matches
(Retziu1s7,8g) identifiebdy AnodbntiaLink,1807 Megunodon-
guadriangularis well with and
Kanno et ai. (1982 )[[.Wo disarticula tvaeldves tia Bouchet and von Cosel ,2004 in terms of the
are from a highl yfbssilifer ofuisne-grain esadnd- shell size and the edentulous nature ofthe hinge
stone bed jus atbove an autochthonous finger- plate ,However, species categorized under tliese
coral bea and associated with diver smeollusks two genera are characterized by having much
such as Cerithiu mj'onker iMartin ,1884, C. be- thinne rshells, a circular shell outline, without
benkiria.n uMma,rtin ,1884, Strombus varinginen- any distin icntterrupti ionn the ventral shell mar-
sis Martin ,1899, Pbtema ]'unghuhni (Martin,gin due to the absence of radial sulci that define
1895) ,Pblema sp., several species of Conus, the escutcheon and lunule M,oreover ,Anodontia
Circe sp., and Dosinia (Bonartem istsab)itis and Meganodontia have a narrower hinge plate
Iredal e1,929. Another common species in this and a shorter but wider anterior adductor scar
bed is Smaragdia pauluccian aGasseies ,1870, than in Bulacanites.
an interti dtaol subtidal species known in sea- Among known fbssi llucinid so,nly Lucina
grass beds in the modern tropica lPacifi eB.ased magameris Dall ,1901 from the upper Eocene of
on the assQciated mollusk species and corals, Bu- Jamaica was describe das having an edentulous
lacanite sobtusiplicatus sp. noy thrive din an in- hinge and the maximum shell lengt habout twice
tertidal to subtidal shallow marine environment. greater than our [farta rspoecimens. Comparison
of Dall' s(1901 asp)ec'imens with the 1fartaro
Systematics specimens is diMcult because they are represent-
Fami]y Lucinidae Fleming ed by intern amlolds that only show the presiennnceer
SubfamilyMilthinaeChavan ofalong anterior adductor scar and smooth
Genus Bul acanite gs en. nov vmeanrtkraablly sh el1la rmagr egi(n.al mCoo xts h(tre1e 9t4im1 eds)e sgcrreiabte e dart hraen-
[fype species. Bulacanites obtusiplicatus sp, the holotyp eof B, obtusiplicatus sp. nov,) and
nav well preserve dspecimen of L, magameris also
Diagnosis .Shel lvery large v,ery thick, mod- from the Eocene of Jamaica in the collections
erately inflate qequivalve, quite inequilateraolf, the Natural History Museum, London. This
and subcircular in outline. Umbones small, situ- specimen clearly shows a resemblance to B,
ated well in fron tof vertical midline, markedly obtusiplicatus sp, nov, based on the presenc eof
hooked forwarq not protruded beyond ventral escutcheon that is depresse dfrom the main sur-
margin of shell. Shallow but sharp posterior face .Although information regardmg the shell
sulcus presen ton both valves, forrnin gshallow thickness and detai losf hinge and ligamen tareas
notch adjunct to ventral margin. Lunule absent, are still poorly known, it can be presumed that L,
but depresse dand extended anterior area fbrming ntegameris is closely related to Buftzcanit eDsal.l
pseudolunul eS.culptur eof commarginal rugae, (190l bpl)aced L. megameris under the subgenus
with thick divergin gradial ribs .Hinge edentu- Ryeudomiltha ,subsequently fbllowe dby Cox
lous ,archect with moderately wide and fia ptlate. (194 1)and Wbodring (1982 )w,hile Bretsky
Ligament area long ,arched and deeply inse tinto (197 62:90) suggested that it be referred to the
valve, Anterior adductor muscle long ,slender, subgenus EDmiltha .These assignments are, how-
and eurved almost in accordance with pallial ever, untenable because the hinge is edentulous
line I.nner valve margin smooth. in L. megameris.
Discussion .Based on the thick shell and the Genus OMptolucina Saul 'et al,, 1996 is also a
long anterior adductor scar, Bulaeanites obtusi- larg eand edentulous lucini dthat originally in-
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178 Ibmoki Kase and Y)landa M. Aguilar
Cr)Lptolucina Saul
cluded megadyseides et aL, Bulacanites obtusiplicatus sp. noM
1996 and C. elassoclyseidles Saul et aL, 1996 (Fig2s-3)
from the Eocene cold-seep assemblages of west-
ern Washington, USA, Cmptolucina megadysei- T>rpe material. Holotype :reg. no. MGB
des attains a shell length of about 180 mm, so fat MFOOO2, complete lef tvalve, lengt h105.3 mm,
the second larges tlucinid ever known. This heigh t106.9mm, thickness 31.5 mm, housed in
is by theMines GeosciencesBureau(MGB),Que-
species represented peorly preserved and and
distort esdhells, but ,like B. obtusiplicatus sp. zon Cityl Philippines ,collected from N]G. 2,
nov, the shells are thicke r(bu tthinner tha nthose riverbed of Bayal)as River in barangay Banaban,
ofB. obtusiplicatus sp. noy), and have a deeply Angat municipalityi 14057.114'N, 121e02.999'E.
grooved ligamen tarea that is covered by the ex- TXvo paratype sin the National Science Museum,
tended shell of the postero-dorsa lmargin. How- [[bkyo :reg, no, NSM PM14862, fragmentary
ever, this species seerns to haye a shell fbrm conioined valves, length 120.5mrn, thicknes isn
quit ediffere nftrom B. obtusiplicatus sp. nov, in coajoined valves 57.2mm; reg. no. NSM
that the shells are wide, the umbones are more PM14861, complete lef tvalve, lengt h95.8mm,
protmded from the dorsa lmargin and not so heigh t98.8mm, thickness in single valve 30.5
strongly prosogyrate ,and the well define des- mm. One paratype: reg. no. MGB MFOO03, ftag-
cutcheon and pseudolunule are absent. Cp:Jtptolu-mentary coajoined valves, heigh t98.0 mm, thick-
cina elassodyseides is smaller and longer than a ness in both valves 53.5 mm, in the collection of
thePresence MGB, fromthetypelocality,
magaclyseides and shows ofan elon- all
gate anterior addnctor scar ef lucini tdype w,hich Diagnosis .Sameasgenus.
otherwise does not extend so long toward the Description Shel lvery larg efbr familM up
yertical midline lik eB. obtusiplicatus sp. novL to 120,5 mm long ,slightly higher than wide, very
Saxolucina (Mbgaxim usma)tsushitai Mat- thick and solia subcircular in outline, inequilat-
sumoto, 1971 from the lower Miocene forearc eral and equivalve, moderately inflate dwith
basin deposit osfcentral Japan is also a 1arg eand thicknessAength ratio of ahout O,3 .Umbones
edentulous lucini tdhat can be referred to Cizp- small, locate dwell anterior of vertical midline,
toiucina. The larges tspecimen (Matsumotoma,rkedly hooked anteriorlM enly slightly pro-
1971, pl .2, fig 1,) has an equivalent shell size to truding beyond dorsa lmatgin, Shel lexterior sur-
C megadyseides, and this species is a constituent face with dense, irregularl sypaced, rugose cQm-
of a chemosynthetic cold-seep community (Maji-marginal growth 1ines ,and with thick, round-
ma et at,, 2005), The type series ofS (IL tmaCt-) toppect somewhat irregularl ydivergin gradial
sushitai appears to be an admixture of at least ribs of variable prominence ,numbering les sthan
two species, which will necessitate futur etaxo- 20 at ventral margin. Ventral to antero-ventral
nomic revision based on additional material. The margin broadl yrounded; anterior margin slightly
holotyp e(Matsumo t1o97,1, pl .1, fig .1) shows rostrate and set offby weakly curved radial ridge,
an almost complete subquadraiigular shell out- demarcate dby pseudolunule, Posteri ormargin
lin echai:acteristic of Cr zptolucina ,which is defi- with relatively larg eand depresse descutcheon
differenftromB, from discby distinct
nitely obtusiplicatus sp. noy separated main posterior
EtymologyL The new genus is named after sulcus, juncti woitnh ventral margin forming a
Bulacan ,the name of province where the bi- notch of varial)le prominence .Greates tdorso-
valve-bearing formatio nis distribut edg;ender ventral gxtens idoentermine dby rounded pos-
mascu]ine. tumbonal dorsa lmargin,
Hinge plate wide fbr lucinid sed,entulous; an-
terior part broade rthan posterio arl,most fla ta,nd
constrictedjust anterior of umbones due to inser-
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A new Pliocene 1ucini gdenus and speeies fromPhilippines 179
Fig.2 . Holetyp eof Bulacanit eosbtusiplieatzLs sp. noy, MGB MFOO02, from a riverbed of Bayabas nver,same
barangay Banaban, Angat municipality in Bulacan province. A, ExteTior of lef tvalve; B, interi oofr the
valve. Scale bar :20 mm.
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180 Tbmoki Kase and Yblanda M. Aguilar
Fig. 3. Paratypes ofBulacanites obtusiplicatus sp. nev from the same locali tofythe holotyp eA, & B, Exterior
and interi oofrleft va]ve, respectively, NSM PM14861; C, anterior view ofcoajoined yalves, NSM PM14862,
Scal ebar :20 mrn.
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A new Plioeen leucini gdenus and species from Philippines 181
tion of sinus; posterior part arched and variably specimen from Solo because their depositories
Ligamental long However,
concave medially area and are unlenown. an almost complete artic-
arched sunken steeply and deepl yint oshell, with ulated specimen (RGM6996 )from the Junghuhn's
deep slit on it sdorsa lside; ligameta larea com- locali tOy housed in the Nationa lMuseum of
pletel ycovered by extension of postero-dorsalNatural History Naturali sL,eiden, and two other
margin of escutcheon when both valves con- vety larg especimens (th meaximum shell diame-
joined, ter is 213mm) from the middle Miecene of
lmer ventral shell margin almost smoeth and Nyalindung ,west Java, illustra taendd identified
varial]ly uneven, but occasionally with irregularb,y Dharma (200 5p,. 282) as Anodonn'a sp.,
crest-topped radial crenulations. Inner shell sur- seemingly match the descriptio ngsiven to L.
face uneven, with manM -random]y distributedmaxima. If this identificat iiso cnorrect, L. mcLxi-
pit sof unknown functio nA,nterio radductor scar ma can be referable to Anodontia ,which evident-
very long ,slender, pointed at dista elnct and ex- ly diffe rfsrom B. obtusiplicatus sp. nov
tending close to vertical midline, with weak, ir- When compared with L, megameris, B. obtusi-
regular radial striae. Posteri oarddn ¢tor scar an- piicatus sp. noy is smaller and more infiate aqnd
gularl yelliptical. Palli allin ebroad and radially has many obsolete radial ribbing son the shell
striated. surface, in contrast to the smooth surface of the
Etymology The species narne refers to the Jamaican species.
obtuse ribbin gon the shell surface. Lucinid bivalve hsave attracted much attention
Remarks. Bulacanites obtusiplicatus sp. since many species investigat heodst endosymbi-
nov is quit edistin cantd carmot be confused with otic, sulphur-oxidizing bacteri aa,nd sometimes
any other modern lucinid sin the tropica lIndo- constitute members in modern and fossi lcold-
Western Pacific .Among the livin gforms ,only seep communities (e.g ,Ta,ylor and Glover ,1997,
Cbdokia tigerin a(Linna e1u75s8,) and degan- 2000; Sara & Wbodside, 2002; Kitazaki & Maji-
odontia acetabulum Bouchet and von Cosel, ma, 2003; Majima et aL, 2003, 2005) .A unique
2004 attain a shell size the same as or larger shell featur aessociated with cold-seep commimi-
than B, obtusipgicatus sp. noy, but other distinctties is the acquisition of larg esize (e. gS,au,l et
shell feature sseparate them from our new aL, 1996; Bouchet & ven Cosel ,2004; Majima et
specles. al., 2005), and fossi lexamples show aggregated
When compared with other fossi slpecies from occurrences of such species in calcareous con-
the Indo-Wester nPacifi cL,ucina mexima Martin, cretions (e, gM.a,jima et al., 2005). Bulacanites
1883 is comparably 1arge rthan B. obtusiplieatus obtusiplicatus sp. n(rvi is unusually large in shell
sp. nom The holotyp eand single specimen de- size arnong lucinid fsrom the tropical Indo-Wdst-
scribed by Martin (1883 w)as collected from the ern Pacific .However, judgi fnrgom the sedimen-
upper Miocene at Junghulmi glocalit yO (south-tary facies and other associated mollusks and
western part of the Bandong high ,Rongga dis- corals, it is evidently an interti daorl subtidal
trict G,unung Sera or Cilanan gGap in the Nang- shallow marine dwelle crhiring Pliocene time.
gulan area, Java ;see Hoek Ostende et aL, 2002),
It is an intern amlold of the right valve that does Acknuwledgements

not show any shell characteristics except for
the circular and strongly inflat esdhell ouSline. We would lik eto thank M, A, Zepeda, E,
Martin (1919 i)llustra taend additional better- Mula, R. Ancog, E. Azurin ,W Mago (MGB) and
preserve dspecimen of this species from Solo R. Wani (NSM) for their assistance in our field
(=Surakar ctenatr)al, Java, but the shell seems to work and N. Mateer for 1inguisti ccorrection, We
be thin according to his illustrat iTohne. authors aeknowledge the time, help ,and access to Mart-
were unable to examine the holotyp eand the inl sIndonesia nCenozoic molluscan collections
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182 Tomoki Kase and Yblanda M. Aguilar
kindly given to us by E P Wesselingh ofNational outer-shelf cold-seep assemblage in forearc basin fill,
Museum of Natura lHistor yNaturali sL,eiden, Pliocene [al[anab eForrnation ,Kyushu Island ,Japan.
lhleontologicalResearch,7:297-3l1,
This study was financial sluypported by the Na-
tiona lScienc eMuseum, Tokyo, and by a Grant- M afjbismsai , lRch.em, oZsy ntNheotbicuhar a &as sTem bKliagteasza ki in2 ,0J0ap5a. nR. elvhileawe oef-
In-AidfbrScientifiRcesearchfrom the Japan
geogmplijl RTIaeolimatolqgy ,lhlaeoecology, 227i 86-
Societ yfor the Promotion of Scienc e(JSPS ()no. l23,Martin,
15253008) and by a grant for scientific exehange K., 1883. Nachtrage zu den "Tbrtidrschichten auf
from JSPS and the Netherland sOrganizati ofnor Javaj 'Erster Nachtrag: Mollusken. Skimmulungen des
ScientifiRcesearch. Geolagischen Reichs-Adeiseum sin Leiden, 1st series, 1:
I94265, 9-13.
pls
Martin, K., 1919. Unsere Palaeozoologische Kenntni svon
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sion of Cenozoic Mellusca), National Museum of chemosymbiosis and evolution of Lucinidae .in: Harp-
Natura lHister yLleiden ,NIVM fechnica Blulleti n5,: er, E. M,, et aL (ed sT)he evo]utionary biolog yof Bi-
1-130, 3 pls. valvia. Speci Paulbticati oonf the Geolagica Slbeiet oyf
Kanne, S., S. O'Hara & N L. Caagusan, 1982. Molluscan London, 77: 207-225,
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central Luzon, Philippines .Geolqgy and flaleontolctg y Paleontologi canadl paleoenvironmen tsatludies of the
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NII-Electronic Library Service
NNaatitoinaolnal　 sSocieineoence　 MMuusesuemum
A　new 　Pliocene　lucini　gdenus　and 　species 　from　Philippines 183
Woodring，　W 　P．，1982．　Geo］ogy　and　paleontology　Qf States　Gθ010g ∫cαJ　Survey　J）rofession αl　Paper．，（306−F）：
　CanaユZone　and　a（ljoini　npagrts　of　Panama ．　United 541−759，pls　83−124．
・
フ ィ リピン ル ソン 島中部の鮮新世タル タロ 層産ツ キガイ科大型二枚貝の
　　　　　　　新属新種B”lacanit　eobstusiplicatus 　gen．　et　sp．　nov ．
・ ・ ー ・ ー
加瀬友喜 ヨ ラン ダ マ ク アギラ
・
　フ ィ リピン ルソン島中部のブラカン地方に分布する前期鮮新世後期の タル タロ層から得られた
ツキガイ科二枚貝の新属新種Bulacanite　sobtusiplicatus 　gen．　et　sp ．　n。v．を記載した．　Bulacanitesは大型
でこ う歯を欠く点ではAnodontia属とMeganodontia 属に似るが，殻が厚く，殻頂部が より前方に傾
き，さらに殻表面に特徴的な分岐をする放射肋をもつ 点で容易に区別される．産出 した地層の堆積
相と随伴する他の貝化石の解析か ら，この二枚貝は熱帯の潮間帯あるい は潮下帯に生息 して いた と
考えられる．
一
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