A new subspecies of Cupuladria cavernosa Cadйe from the Pliocene of Western Emilia (N. Italy) (Bryozoa Gymnolaemata Cheilostomatida Cupuladriidae)

2006·0.99 MB·

by  C. Pizzaferri

Quoderno di Studi e Norizie di Srorio woru*ÈìàlloRor*grro
QuadS. tudNi at.R omagna,22:39-5g1iu, gno2 006 tssN1 i2s_6787
Claudio Pizzaferri
A NEW SUBSPECIESO F CUPULADMA CAVERNOSA CADEE
FROM THE PLIOCENE OF WESTERN EMILIA (N. ITALY)
(Bryo zoa GymnolaemataC heil ostomatidaC upuladriidae)
Riassunto
fUna nuova sottospecied i Cupuladria cavernosaC adée (Bryozoa, Cheilostomatida)n el
Pliocened ell'Emilia occidentale( tatia)l
In tre affroramentpi liocenicid ell'Emilia occidentales onos tatet rovaten umerosec olonied i
Cupuladria cavernosaC adéec he si discostanop er alcuni caratterid alla forma tipica della
specieL' e differenzep iù evidenti,c he le colonied i questetr e popolazionei sibisconori spet-
to ai caratterit ipici di C. cavernosa,s ono la presenzac ostanten ella parte medianao medio-
distaled ell'opesiod i duel unghid entelli,p rodottid al criptocisti,e unad istribuzionep iù irre-
golare delle cameree dei settori nella regione centraled el disco basale.N on essendom ai
statas egnalatala presenzad ei due lunghi dentelli del criptocisti in C cayernosaede ssendo
questod iversom orfotipo presentec on numerosi zoari,s i è ritenuto necessarios eparareq ue-
ste colonie da C. cavernosae d istituire per loro la nuova sottospecieC upuladria cavernosa
placentina. Questep opolazionid i Cupuladria cavernosap lacentina n. subsp.s ono statet ro-
vate nei sedimentid el Piacenzianoa ffioranti nella cava di Camporea SalsomaggioreT erme
(PR) ed in quelli delle sezionid i Monte padovae Monte Falcóned il Castell,Aryuato(p C).
Nelle popolazioni plioceniche di Cupuladria cavernosa Cadée pi molte altre località
dell'Emilias i possonotr ovarec oloniec on zooecic he mostranoi af Aentettdi el criptocisti,
ma questiq uandop resentis onom inimamentee stesie d applicati iry'pochiz ooeci.L a presen-
za in questep opolazionir invenibili in Emilia di C. caveriò.sad eifue dentelli, anches ep oco
frequentie di dimensionim inori, non consented i separarea livúlo specifico questod iverso
morfotipo dalla forma tipica, ma permettep erò di suppoffec he probabilmenten el pliocene
si stavac ompiendou n tentativod i speciazionef,o rsen on riuscito completamentec, he propo-
neva' con Ì'accentuazioned i alcuni carallerid ella speciem adre,u no ruiluppo zooecialeq uasi
omeomorfoa quello di Cupuladria bugei Galopimde Carvalho.
Abstract
Many colonieso f Cupuladriac avernosaC adée,w hich are different from the typical morpho-
speciesin somec haractersh, aveb eenf ound in threeP lioceneo utcropso f the WestemE milia
area'T he differences,w hich divide the colonieso fthese populationsf rom C. cavernosa,a re
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the constantp resenceo ftwo long denticlesi n the centralr egion ofthe opesia,w hich are pro-
ducedb y the cryptocyst,a nd a more irregular distribution of the chambersa nd sectorsi n the
centralr egion ofthe zoarialb asald isk. For the two long cryptocystald enticlest hat have not
beeno bservedt o be presenti n C. cavernosa,i t is necessaryto separateth esec oloniesf rom
C. cayernosa and to define a new subspeciesw ith the name Cupuladria cavernosap lacenti-
na.The colonieso f C. cavernosap lacenlina n. subsp.h aveb eenf ound in the sedimentsc rop-
ping out in the Camporeq uarry near SalsomaggioreT erme( ParmaP rovince)a nd in thoseo f
the Monte Padovaa nd Monte Falcones ectionst o Castell'Arquato( PiacenzaP rovince);s edi-
mentso fthese three outcropsa re Piacenziani n age.
Key words: Bryozoa, CheilostomatidaC, upuladria cavernosap lacentina n. subsp.,
Pliocene,E milia.
Introduction
CaoBs (1979) consideredh is Cupuladria canariensis cavernosat o contain many
Europeana nd Mediterraneanf ossils ascribedb y previous authors to Cupuladria
canariensis (Busk) and Cupuladria biporosa Canu & Bassler.T his subspecieso f
Cadéeh as been given a speciesr ange by Coor & CHrvtoNrors( 1994) and was
furthermore regarded as a senior synonym of Cupuladria vindobonensisB alntk
& Radwanski (Coor & CrmrroNIrES,1 994). Cadée marked offhis C. canarien-
sis cavernosa from his two other subspeciesC .c. canariensis and C.c. surina-
mensisd ue to the fact that it < Differs from the foregoing subspeciesb y the pre-
senceo f more than one layer of basal kenozooeciar esulting in a thicker layer of
basal calcification of the zoaÍirrÍÍr,b y its finely granular basal surface, its more
developeda nd more gently descendingc ryptocyst. The averagen umber of basal
poresp er sector( 4.5-8.1) is somewhatl ower than in C. tens$ canarrcns$.
but some populations have a relatively high number of (Fécamp,P alluau).
Variation observed in number of pores is large: 1-28. basal kenozooecial
poresa re relatively small. Vicariousv ibraculan ot obse >. In practice he
consideredi t as a geographical-temporals ubspecieso f Cupul,
occuffing in the Mio-Pliocene of Europe and the
Subsequently,C oor & CnnUoNIDES(1 994) described Cupuladria cavernosa
Cadée as ( Colonies medium sized, diameter up to 12 mm. Autozooidal
cryptocyst slightly curved to straight laterally; lateral septulae not visible.
Zooidal avicularia monomorphic, vicarious avicularia present,b ut rare, in some
populations only; gymnocyst long, opesia auriform to rounded. Basal sectors
very variable, with 4-10 (usual$ a-8) chambersp er sector,c hambersu p to 6 in
a vertical series. >. The remarks of CADEE( 1979) and CooK & CsnuoNnps
(1994) suggestt hat C. cavernosa is a polytypical speciess howing a great mor-
phological variability.
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Castell'
Arquato
2 ;
.4 -: Ct
salsomaggrcre_72
H 0 1 2 3 4Km
E Plioceneo utcrops #
Fig. 1 - Location ofthe outcrops containing Cupuladria cavernosa placentìna new subsp. in the Westem
Emilia region: I - Monte Padova section; 2 - Monte Falcone section; 3 - Campore quarry.
The Neogene sediments,c ropping out in the Western Emilia area, often contain
faunas in which C. cavernosd is present,b ut always with moderatep resence.I n
these faunas,t he characterso ccurring in the colonies ofthis speciesa re usually
constant but, in a few of these assemblages,C . cavernosa is also present witry
many colonies in which the zooecia have the opesium partially occupied by/a
long laminar denticle on both sides, which is produced by the cryptocyst/Ihe
abundanceo f these colonies, which also differ from the typical specimeglof C.
cavernosai n cryptocyst width and in the sectorso f the central basal dis$ allows
us to recognizethe existenceo f a speciation attempt in the populationsrbf the Po
Basin during the Pliocene. These colonies, separablef rom the typical ones,h ave
to be regarded as belonging to a subspecieso f C. cavernosa because,w ith the
actual knowledge on their distribution and frequency, we have to regard that they
presumably did not reach a complete reproductive isolation to attain the critical
level of speciation.
Taxonomic account
Cupuladria cavernosap lacentina n. subsp.
Locus typicus: Monte Padova section cropping out near Castell'Arquato
(Piacenza Province), Piacenzian (planktic foraminifera zone MPl5a) in age
(mid-Pliocene).
Derivatio nominis: From its presencein the hills of PiacenzaP rovince,I taly.
Type material
Holotype and paratypes come from a thick siltstone layer interbeddedb etween
"M.
strata that correspondt o the lst and2nd Giogo Biocalcarenite" in the stra-
tigraphic column proposedb y RaEEre t al. (1989, frg.2), cropping out in the
Monte Padova section. The type-material has been deposited in the Museo
Geologico "G. Cortesi" of Castell'Arquato, Piacenza Province, Italy (sample
numberM G1123).
\
Diagnosis \
cupuladria with two broad denticlesp roduced by the crlpQcyst, emerging from
the cryptocystal margins at mid-distance. Central area of thè zoaial basal disk
with inegular sectors.
Description
Zoarium cupuliform or conical-cupuliform, from flattened to moderately high.
Perimetric edge of the basal disk suborbicular, denticulate due to projection of
the peripheral zooecia. Zooecia in altemating radial series,e ach with a avicula-
rium (vibraculum) at the distal vertex. Basal surface variably concave, with
radial and transversalg rooves determining radially elongated,r ectangularo r tra-
pezoidal sectors,e ach sector usually containing 5 to t2 suborbicular chambers
which are normally affanged in two rows; tubercular protuberancesm ay be pre-
sent. Basal calcification gradually closest he chambersa nd a new one is succes-
sively formed which communicatesw ith the preceding one by a small subcen-
Fig. 2 - Cupuladria cavernosap lacentina new subsp.: A - Frontal view of zooecia; B - Sectors and cham-
bers in zoarial basal surface; C,D,E-Zoanal outlines.
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Fig. 3 - Cupuladria cavernosap lacentína new subsp.: Holotype (MGl123), Monte Padova section.
tral pore.S ectorsin the centralp art ofthe basald isk are ofirregular shapea nd
contain only one or very few pore chambers;i n this region large subglobular
thickeningsa re sometimesp roduced,p enetratedb y pores of various size.
Surfaceo fsectorsf inely granulateb, eingc oarserin the centralr egion,a ndo ften
with more or lessr aisedt ubercles.S ectorsin itially separatedb y deepd istinct
groovesb, ecomings hallowera nd lessd istinctw ith increasings econdaryc alci-
fication.
Zooecias ubrhombicV. ertical walls raiseda nd finely granulatedp, enetratedb y a
linears erieso f small interzooeciapl ores,t he perimetricarl egiono f basalw alls
is perforatedb y a linear serieso f communicationp ores.V estibulara rc (sensu
Coor, 1965a:1 54; CloÉa,1977: 444)w ith a raisede dge,o ften acute,s ometi-
mest hickeneda ndc rescentica, ndw ith non-convergensti des.C ryptocystg ranu-
lated,v ery steepo r almostv ertical in the proximal region,g ently descending
distally and,o n both sideso f opesia,f orming a broad,s ubtriangulaor r curvili-
near,l aminard enticle,w ith a gtanulart o finely saw-toothedri m, situatedju st
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Fig. 4 - Qupuladria cavernosa placentina rrew subsp.: zooecia of central region in holotype.
Fig. 5 - Cupuladria cavernosa placentina new subsp.: peripheral zooecia in holotype
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Fig. 6 - Cupuladria cavernosa placentina new subsp.: general aspect ofzooecia and avicula-
ria (vibracula) in a colony from the Monte Padova section.
Fig. 7 - Cupuladria cavernosa placentina new subsp.: single zooecium of the same colony as
in Fie. 6.
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Fig. 8 - Cupuladria cavernosa placentína new subsp.: new zoarium produced by regenera-
tion of a zoarial fragment (Monte Padova section).
Fio Q - Cupuladria cavernosap lacentina new subsp.: basal surface of the same zoarium as
in Fig 8.
Fig. 10 - Cupuladria cavernosa placentina new subsp.: young colony (Monte Padova sec-
tion).
Fig. 1l - Cupuladria cavernosa placentina new subsp.: zoarial basal surface in a fragment of
colony from the Monte Padova section.
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Fig. 12 - Cupuladria cavernosa placentina new subsp.: fragment of a colony from the
Campore quarry.
distal to mid-distance of opesia,u sually occupying half of opesia length. When
large and projecting the two denticles produce a bifoliate opesia.E arly astogeny
with zooecialp roliferationa s that proposedb y Lacaau (1963: 183,t ext fig. 10)
in Cupuladria canariensls (Busk), and Coor (1965a: 155, text fig. 18) for
Cupuladriidae. Ancestrula surrounded by seven zooecia and one avicularium.
Astogenetic change reflected by an increase in autozooid and avicularium
dimensions. During astogenyt he first three zooecia and many of the periance-
strular zooecia become partially obstructedb y granular secondaryc alcification,
which is added to the cryptocyst and to the interior of vertical walls; this calci-
fication produces a funnel-shapedd epressioni n the zooeciaw ith a fissure at its
lower apex. Avicularium (vibraculum) with auriform opesia, palate subtriangu-
lar and with a raised, arched,s ubtriangulard enticle on the convex side of its rim.
Vicarious avicularia (vibracula) were not observed.O ccasionally, greatly enlar-
ged avicularia are present in colonies emanating from regeneratedz oarial frag-
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