On the occurrence of Spirolaxis lamellifer (Rehder, 1935) in the Mediterranean Sea (Gastropoda, Prosobranchia, Architectonicidae)

5 Pages·2002·1 MB·English

by  Smriglio, Carlo

BASTERIA, 66:183-188,2002
On theoccurrence ofSpirolaxis lamellifer(Rehder, 1935) inthe MediterraneanSea
(Gastropoda, Prosobranchia, Architectonicidae)
CarloSmriglio
Via diValle Aurelia 134,100167Rome,Italy; [email protected]
& PaoloMariottini
DipartimentodiBiologia,University "RomaTre",Viale Marconi 446,100146 Roma,Italy;
[email protected][corresponding author]
Spirolaxis lamellifer (Rehder, 1935), first record from the Mediterranean Sea: central
TyrrhenianSea,coast ofLatium,Italy.
Keywords: Gastropoda, ArchitectonicidaeS,pirolaxis lamellifer, Mediterranean Sea,Italy.
INTRODUCTION
ThegenusSpirolaxis Monterosato, 1913, was untilnowthought toberepresented inthe
MediterraneanSeaonly by Spirolaxis clenchiJaume & Borro, 1946,whichmediterranean
occurrence and systematic position hasbeendiscussedby Smriglio & Mariottini(1990).
Inthispaperforthefirsttimeanotherinterestingspecies ofArchitectonicidaeJ.E. Gray,
1840,isreported from the Mediterraneanbasin, viz.Spirolaxis lamellifer (Rehder, 1935),
originally describedfromFlorida.As forthe systematic position ofthisspecies, wefollo-
wed Bieler(1993).
MATERIAL
Thematerialexaminedconcernedthreearchitectonicidspecies ofthegenusSpirolaxis;
all shells were identifiedafter conchological comparison with original descriptions and
illustrations.Two specimens ofSpirolaxis lamellifer(Rehder, 1935), bothlacking softparts,
were collectedfrom the central Tyrrhenian Sea. Specimen A, off the south-coast of
Latium[San FeliceCirceo (LT)], dredged atadepth of80-100m,ona seabottomhost-
ing thebiocoenosis C (sensu Peres &Picard, 1964),4.8mm in width(CR). Specimen B,
offshorePonzaIsland(LT), dredged ata depth of 160 m,4.0mm in width(CS-PM).
Two specimens ofSpirolaxis centrifugus Monterosato, 1890,offshoreLanzarote Island
(Canary Islands, Spain), dredged atadepthof50m, collectionCS-PM.
Fifty-six specimens ofSpirolaxis clenchiJaume & Borro, 1946, central Tyrrhenian Sea,
offthe coastofLatium(41°51'N 11°28'E),dredged at a depthof450-600m(CS-PM).
Abbreviationsusedforcollections:CR, CarloRebecchini(Rome, Italy); CS-PM,Carlo
Smriglio andPaoloMariottini(Rome, Italy).
184 BASTERIA, Vol. 66,No. 4-6,2002
Figs 1-7.Spirolaxislamellifer(Rehder,1935). 1, originalfigureby Rehder 1935 (pl. 7 figs8-10);2-5,specimen
A, central Tyrrhenian Sea,offthe southcoast ofLatium,80-100m; 6-7, specimenB, central Tyrrhenian
Sea,offshorePonzaIsland,160m.2, 6,apicalviews;5, 7,basal views.
SYSTEMATICS
FamilyArchitectonicidaeJ.E.Gray, 1840
GenusSpirolaxis Monterosato,1913
Spirolaxislamellifer(Rehder, 1935) (figs 1-13)
Pseudomalaxis lamelliferaRehder,1935: 128,pi.7 figs8-10(USNM426235/holotype,"FloridaStraitsin205
fathoms").
Original description (Rehder, 1935: 128). — "Shell small, discoidal, flattenedon the
uppersurface, broadly umbilicatebelow, theearlywhorlsslightlyexsertedabovethesur-
Smriglio &Mariottini: Spirolaxis lamelliferin theMediterraneanSea 185
face of the lastwhorl. Colorgrayish white,the periostracum yellowish brown. Nuclear
whorlssmoothish,inverted(thenucleus hasbeenbroken offsincethese characterswere
noted). Postnuclearwhorls,ofwhichthereare aboutthree, haveveryfaintaxial riblets,
whichgradually increaseinstrength, as doesthe subsuturalcord, whichappearsinthe
early whorls. The lastwhorl is almost quadrangular, the right angles whichbound the
peripherical surfacemarkedby cordlikecarinae;the uppersurfacesomewhatdepressed
atthe suture,thelowersurfaceroundedatthe edge of theumbilicus.Thewholesurface
is sculptured withprominent, rather closelyset, retractively curvedribs; they are more
prominent, almostnodulose, where they cross the carinae,and they are symmetrically
arcuate onthe peripherical surface, between the carinae; near the mouththe ribs are
more closely andirregularly set,their prominence being largely due to the folding of
periostracum. The mouthhasbeen broken away, but the broken aperture is rounded,
while the carinae give the outer edge an angular appearance. The unique holotype
(U.S.N.M. no. 426235) was dredged in theFlorida Straitsin 205 fathoms,andmeasures
3 mm. in widthand 1 mm. inheight."
DISCUSSION
The geographical distributionof S. lamellifer was previously discussed by Talavera
Casanas(1982), Bieler(1983, 1984),and Fernades & Rolan (1994), allauthorsindicating
that this architectonicidis amphi-atlantic, ranging from the centralwestern (Bahamas,
Florida, Northern Brazil) to the central eastern (Spain, Morocco) Atlantic Ocean.
Surprisingly, two specimens of S. lamellifer (figs 1-7)have beensortedoutanalyzing sed-
imentsamples collectedfrom two spots closetogether inthe centralTyrrhenian Seaoff
the south-coastof Latium.Theshellof S. lamellifer atfirst glanceis easy distinguishable
fromtheonesofS. clenchiandthealliedAtlanticS. centrifugus Monterosato, 1890(the sys-
tematicposition ofthesetwo species hasbeendiscussedbySmriglio & Mariottini, 1990).
In fact, the body whorlsof S. lamelliferare always jointed during shelldevelopment, so
theteleoconchdoesnotshow thetypical half-moonshaped opening, createdby thesep-
arationof the initialwhorls, typical featureof the other two species mentionedabove.
Furthermore,S. lamellifer shows two strong diagnostic charactersthat are missing in S.
clenchiand S.centrifugus: 1) the teleoconchsculpture consists ofmany "curvedribs" (the
specific namerefers to thisfeature!);2)the suture is deeply marked (figs 8-13).
BothmediterraneanshellsofS. lamelliferlookvery fresh;specimen Astillretains the
periostracum (figs 2-5). This strongly suggests that this species can be added to the
Recent malacofaunaof the MediterraneanSea. The family Architectonicidaeincludes
species invariably feeding upon cnidarians, according to Bieler (1993: 24) "Data and
habitsandhabitatsare available forseveralarchitectonicidspecies. Allmembersof the
familyfeed oncoelenterates,andtheirradulae(frequentlyptenoglossate-like asin other
coelenteratefeeders such as Epitoniidae) and alimentary system (with cuticularization)
show several specializations". We like to recall the mediterraneanrecord ofanother
interesting architectonicid,Solatisonaxallerii (Sequenza G., 1876), found feeding on a
scleractiniancoralbyMifsud(1997),asanotherwelldocumentedcaseofassociation (pre-
dation/parasitism) between anarchitectonicidandcnidarians.Carophyllia smithy (Stock-
Brod.) formclavus (fig. 14) canbe tentatively assigned as apotential host Madreporaria
forS. lamellifer, sinceits commonpresencein the dredgedsedimentfromwhichthespec-
imenB (figs 6-7, 8-13) hasbeen obtained.
186 BASTERIA, Vol. 66,No.4-6, 2002
Figs 8-13.Spirolaxislamellifer(Rehder,1935). 8-13,specimenA,centralTyrrhenianSea,offthesouth-coastof
Latium,80-100 m,details ofthe sculpture.Fig 14.Carophylliasmithy(Stock-Brod.) form clavus
Smriglio &Mariottini: Spirolaxis lamellifer intheMediterraneanSea 187
ACKNOWLEDGEMENTS
Theauthorswishtothank Mr.CarloRebecchini(Rome,Italy) forpermittingto exam-
ineS. lamellifer specimen Aand Mr. CesareBogi (Rome, Italy), whomadeavailablefos-
sil materialfor comparison. We are grateful to Dr. JerryHarasewych (Department of
InvertebrateZoology, NMNH, SmithsonianInstitution, Washington, USA) forvaluable
advice and discussionand to Dr. Harry G. Lee (Jacksonville, Florida, USA) for useful
informationand bibliographic help. Dr. Andrea Di Giulio (Department of Biology,
Universita"RomaTre") isacknowledged forSEM photographs.
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