Indo-Pacific migrants into the Mediterranean. 3. Atys angustatus Smith, 1872 (Gastropoda, Opisthobranchia)

2006·0.64 MB·English

by  Van Aartsen, J J

BASTERIA, 70:29-31,2006
Indo-Pacificmigrants intotheMediterranean.3.
Atys angustatus Smith, 1872(Gastropoda, Opisthobranchia)
J.J. vanAartsen& J.Goud
National MuseumofNaturalHistoryNaturalis,P.O.Box9517, NL 2300RALeiden,TheNetherlands;
[email protected] /[email protected]
The RedSea speciesoftheopisthobranchgenusAtysarerevisedinordertounraveltheiden-
tityofanAtys speciesthathas settledintheMediterranean. The speciesinquestionturnedout
tobeAtys angustatus.
Keywords: Gastropoda,Opisthobranchia,Haminoeidae,Atys, taxonomy,Red Sea,Mediterra-
nean,migrantspecies.
Figs 1-3. Atys spec. 1,Atys angustatus Smith, 1872, lectotypeBMNH 196972,Suez; 2,Atys angustatus
Smith, 1872,specimenfromHaifa Bay, Israel;3,Atys cylindricus (Helbling, 1779),juvenilefrom Azaiba,
Gulf ofOman.All onthesamescale.
')No. 2:Basteria70: 1-6,2006.
30 BASTERIA, Vol. 70,No. 1-3,2006
Among several Indo-Pacificmolluscanspecies foundin theMediterranean,but not
yetrecordedas such, isasmallopisthobranch ofthegenusAtysMontfort, 1810.Although
already known forthirtyyears,itsidentificationproved difficult.Acriticalrevisionofthe
known species ofAtys fromtheRedSeais necessary.
Issel (1869: 168)mentions: Atys solidaBruguiere, 1792, usually consideredaformof
Atys cylindricus (Helbling, 1779)afterPilsbry (1895: 265);Alicula cylindrica ”L.”, probably
referringto thespecies of thatnamefirst describedby Helbling (1779: 122);Aliculabacil-
lus Ehrenberg, 1831, considered to be aCylichna by Pilsbry (1895: 311); Alicula succisa
Ehrenberg, 1831,a youngA. cylindricus, afterPilsbry (1895: 268); and described as new
(1869:281) Alicula ehrenbergi Issel, 1869.
NotethatAliculaEhrenberg, 1831, nonEichwald, 1830(=AliculastrumPilsbry, 1896)is
presently consideredaseparategenusora subgenus ofAtys Montfort, 1810.
M'Andrew(1870: 445) addsAtys naucum (L.,1758)aswell asAtys (Dinia) dentifera(A.
Adams,1850),whichiscurrently placedin Diniatys Iredale,1936,probably belonging also
tothe Haminoeidae.Healso recorded"twospecies, undetermined".Thesespecies were
describedby Smith(1872: 346,347) asAtys angustata and Atysmiranda,bothfromtheGulf
ofSuez.
Cooke (1886: 131,132) revised thematerialrecordedby bothM'AndrewandSmith
andconcludedthat Atys cylindricus (Helbling, 1779)=A.succisa=A.alicula.Cooke (1886:
131,132)also consideredA.ehrenbergi (Issel, 1869)tobeajuvenile Atys semistriatus Pease,
1860, aHawaiianspecies. AboutA.angustatushecommented:"Types in theBrit.Mus.In
my opinion nothing more thanthe very young formof [Atys] cylindrica.”. This opinion
was repeated by Pilsbry (1895:265)andis probably thereasonwhyDekker & Orlin(2000:
34)only mentionA.cylindricus, A.ehrenbergi, andA. naucum, as wellas Diniatys dentifera.
We obtainedthetype-lot (BMNH 196972:five specimens) ofAtys angustata Smith,
1872from the British Museum for comparison. It became immediately clear that these
specimens andtheonesfromtheMediterraneanbelong tooneandthesamespecies. They
alsocorrespond exactly withtheoriginal description bySmith(1872: 346) : "A[tys]testa
parva,alba,semipellucida, nitida,elongata-ovata, superius basique aliquanto attenuataet
fortiter striata, mediolaevi; apertura angusta, basimversus vix dilatata; labrumtenue,
verticismediojunctum etibivaldeincrassatum etsinuatum;columellacurta,recta, leviter
reflexa.Long. 5 mill., diam.2.66. thesuperior andinferiorstriaeareeachabouttwelve
..
innumber."
Smithapparently describedthe largest ofthe fivesyntypes and we hereby designate
thisspecimen,withdimensions5.0x2.6mm,as thelectotypeofAtysangustata Smith, 1872.
Afigureofthislectotypeis given(fig. 1)andaspecimen fromHaifabay (Israel)isalso
figured (fig.2).
AlthoughthedifferencesbetweenA.angustatusand juveniles ofA.cylindricus are few,
twoof theseareconstant enough to separatethetwotaxa.Inthefirstplace thenumberof
spiral incisionsaroundtheapexisaboutequal tothenumberof spirals atthebase(both
about 12) in A. angustatus whereasinA. cylindricus there are only five to seven spirals
aroundtheapexand doublethatnumberaroundthebase.Secondly thecolumellaofjuve-
nileA. cylindricus is always oblique whereasin A.angustatus itis nearly vertical.Aspeci-
menof A.cylindricus is figured hereforcomparison (fig.3).
Although theLevantinecoastsof theMediterraneanwere thoroughly explored dur-
ing thelastthirty years,noonehasevermentionedthepresenceof(semi) adultspecimens
of Atys cylindricus. We take this as anadditionalargumentthatA. angustatus is not the
juvenile ofA. cylindricus as suggested by Cooke(1886:132).
Atys angustatusSmith, 1872,is apparently presentin theMediterraneanfromatleast
1974(Haifa bay, 3shells). Itwas foundin theMersin-area (Turkey) in 1986 andsince then
VanAartsen &Goud: Atys angustatus Smith 31
regularlyupto thepresent. Noneofthespecimens studiedwere larger than5.0 mm.
ACKNOWLEDGEMENT
We thankMrsKathyWay [British Museum(Natural History),London] forkindly letting
usstudy thesyntypes ofAtysangustataSmith, 1872.
REFERENCES
COOKE, A.H., 1886. Report on the testaceous Mollusca...by Robert MacAndrew.-Republished,with
additions andcorrections.- Annals and MagazineofNaturalHistory (5) 17:128-142.
DEKKER,H.,&Z.ORLIN,2000. Check-list ofRed SeaMollusca. - Spirula47.Supplement:1-46.
HELBLING,G.S., 1779.BeytragezurKenntnifineuerund seltenerKonchylien.AuseinigenWienerischen
Sammlungen.-AbhandlungeneinerPrivatgesellschaftinBohmen,zurAufnahme derMathematik,
dervaterlandischen Geschichte,undderNaturgeschichte4:102-131.
ISSEL,A., 1869.Malacologiadel MarRosso:i-xi, 1-388.Pisa.
M'ANDREW,R., 1870.Report onthe testaceousMollusca obtained duringadredging-excursioninthe
Gulf ofSuezinthemonths ofFebruaryand March1869.- Annalsand MagazineofNaturalHistory
(4)6:429-450.
PILSBRY, H.A., 1893-1895. Manual of Conchology; .. 15: 1-64 [1893], 65-180 [1894], 181-436 [1895]
Philadelphia.
SMITH,E.A., 1872.Remarks onseveral species ofBullidae,with descriptions ofsomehitherto unde-
scribedforms,and ofanewspeciesofPlanaxis.- Annals andMagazineofNaturalHistory(4)9:344-
355.