M.-7. Gomoiu,M. Skotka- A new gastropod- Opistobranchat the RomanianBlack Sea

A NEW GASTROPOD- OPISTHOBRANCH AT THE ROMANIANBLACK SEA COAST

Marian-TraianGoMorul, Marius Srorre2

' NationalInstitute of MarineGeology and Geo-Ecology, ConstantaBranch, 304 MamaiaBvd., Constanta 8700. Romania '"Ovidius" University,Natural Sciences Faculty, 124MamaiaStr., Constanta 8700, Romania

Abstract. A new speciesrecorded at the RomanianBlack Sea Coast- Doidella obscuraVenill 1870 (GastropodaOpisthobranchiata: Corambidae)- is presentedin this paper.This is a North-Atlanticform accidentallyintroduced into the BlackSea in the '80s, probably attachedto the hullof ocean-goingships. The authorsalso present the illustrationsofthe new invertebrate,as well as some obseryations concerningits behaviorin the newhabitat. Key Words: Gastropoda,Nudibranchiata, Black Sea, Dondella.

INTRODUCTION Ord. Nudibranehiata Doridella obscura Verrill 1870, a little Sord.Doridacea OpisthobranchGastropod, was mentionedfor the Fam.Corambidae first time in the Black Sea by Roginskayaand Gen.Doridella Verrill 1870 Grintsov (1990) in the North-Westernpart of the (Syn.Corambe Bergh 1869 ?) sea, in 1986,and later,in 1989,on the Southern coast of Crimea on a mussel collector Doridella obscura Verrill 1870 (Roginskaya,Grintsov 1990). With this mollusk, The general aspect of the adult was drawn the number of Ophistobranchspecies in the Black using the living individual. For the young Sea reaches16 (Golikovet al., 1972, Gomoiu, specimensand for some details, fixed materials 1961,1966). werealso used (Fig.1). In November199G, 17 youngspecimens of an Morphology.The bodyof the molluskis oval, unidentifiedgastropod without shell were collected stiff; the notum curved is smooth. Young in two samples from Mamaia Bay, on rocky specimenswere 2-4 mm long (Fig.1b) and the bottom.In August1997, an adultspecimen of the adultis 6-7 mm long,3-3.5 mm broadand 2.5 mm same specieswas collectedon a mussel colony, high (Fig1a).The color of the molluskis olive- on a jetty nearMamaia, at 0.5 m depth.This living green,the cromatophoresbeing most abundanton specimenwas maintainedin laboratoryconditions the central part of the notum. The rhinophores - a microcosm aquarium - for 18 days. The (Fig.1.a, c), white, thin and elongated, with observationof the behaviorof Doridellaobscura in roundedtops, are protectedby short and cylindric captivity recoded that it finally acceptedas food sheaths,On the rhinophores,some longitudinal the BryozoanConopeum seuratiCanu. pointed combs are present. The head (Fig.1b), In October 1997,another two specimenswere mostlycovered by the anteriorpart of the notum, collectedon a large colonyof C.seurati,at 0.1 m presentstwo short lateral tentacles. The eyes are depth. Near these specimens, about 20 flat situatedon the tentacles,subterminal. The foot, spiraled egg masses were also present on the covered entirely by notum, is bilobate proximal Bryozoan colony, each of them containing and rounded distal. The gills (Fig.1b, c), approximately2000 egs. lamellated, are situated median and distal, betweenthe notum and the foot. on both sides of ln order to identifythe new immigrant,more anus. Among the four gills, the two inferiorones than 100 paperswritten by the famous specialists are small, with 2-3 pairs of lamellae and the K. Baba, l. Hamatani,Evelin and E. Marcus,etc superior ones present 7-B pairs of lamellae. and some key-books(Thiele 1932, Prouvot-Fol Radula(Fig.1c), resembling those of the genera 1954,etc.) were consulted, Corambe Bergh and Corambel/a Belch (l-hiele, SYSTEMATICAL STATE 1931; Prouvot-Fol,1954) is characterizedby the - - - - Gastropoda lackofthe mediantoothand a 5 (6) 1 0 1 (6) 5 formula. The two ante-median teeth are (Opisthobranch Euthyneura iata) massive,claw-like, sharped and dentated lateral.

GEO-ECO-M AR|NA, 2/1 997 Nationallnstitute of Maine Geologyand Geo-ecologyof Romania Proc. lntern. Workshopon'Fluvial-Marine lnteractions" in Mafnas,Romania, Oct.1-7, 1996 M.-7.Gomoiu, M. Skolka- A.newgastropocl - at the RomanlanB/ack Sea

The rest of the teeth are smaller and sharp the RomanianCoast is an Atlantic pointed. Widely distributedon the North-American This Opistobranchwhich was not mentionedat Doridellaobscura is quotedfrom the

Ventral mouthrhinophores

lmm Anterior

Ventral

foot head

^Md"' tu Gills(detailes)

Fig.l. - Doridellaobscura Venill 1870; a. adultspecimen, b. youngspecimens, c. details.Original

202 GEO-ECo-.MARINA.2/1997 NationalInstitute of MarineGeology and Geo-ecologyof Romania Proc.lntem. Workshop on'FluvialMaine lntEnctions" in Malnas,Romania, Oct.l-7, 1996 M.-7. Gomoiu,M. Skolka - A new gastropod- Opistobranchat the RamanianBlack Sea ligrant. part of the UnitedStates to the Gulf of Mexicoand communityof the ships as adultsor as egg- the CaribbeanSea. On the American immigrant capsules.The other theory, according to whichthis shore, - iastern opisthobranchand the Bryozoan in the same Opisthobranchgastropod was transported as benthalassociation. larvaein the ballastwater, appears to be less ln our samples, Doridella abscura was in probable, association with other species like Mytilus ln the Black Sea, Doridellaobscura conquers I galloprovincialis,Actinia equina, Obelia longissima, an emptyecological niche and developsstable I Leptopl ana tremell aris, Hedi ste diversicolor,Nereis populationswell adapted to the newenvironment, I zonata, Balanus improvisus, ldothea baltica, Beinga predatorwith no competitors(in the Black Sphaeroma pulchellum, Sphaeroma serratum, Sea there are no predatorsspecialized on Stenothoe monoculiodes, Rhithropanopaeus Bryozoansexclusively), this molluskhas unlimited I hanisii tridentatus, etc, the red algae Ceramium foodresources. In its Pontichabitat the Bryozoans rubrum and Ceramiumelegans, and the Bryozoans like Electra, Membranipora and Conopeum Conopeum seurati, Lepralia pallasiana, species - its preferred prey - are largely Membranipora membranacea, Membranipora distributed,covering mussels and rockybottoms aurita and Bowerbankia gracilis. From these betweenthe suface and 10-15 m depth. species of Bryozoans,the most common in the In the future,we expectthat this specieswill area is C. seurati. becomecommon on the rocky bottomsin the In the same association,in August-September biocoenosiswith Mytilus galloprovincialison the 1997,we find also a numberof youngspecimens RomanianCoast. The presenceof morethan 10 of another interestingspecies - the little sea youngspecimens in a singlesample is a signthat anemone Aiptasiamorpha luciae Verrill thisspecies is nota rareone. (Coelenterata,Anthozoa). This sea anemonewas Acknowledgements mentionedin 1960-1970(Bacescu et all. 1971), This paper was presented the but since then, no data on this speciesat the at national Symposium "25 years of activity at the Constanta RomanianCoast have been available. Dolphinarium- 4 - 5 sept. 1997". We are gratefulto The penetrationof this new immigrantin the GEOECOMARINAfor publishing this paper with Black Sea took place probablyearly in the 1980- priority.Also, we are indebtedto Dr. lrina Roginskaya 1985s, approximatelyin the same period with for havingsent us via fax the first article,in Russian, another North-Atlanticspecies, the comb-jelly announcingthe presence of Doridella obscara in the Mnemiopsis leidyi Agassiz. Low salinity of the Black Sea. Just beforethe impressionof the present Black Sea and the temperaturesrecorded in this article, we received an envelope containing other informationon the Black Sea Doridella area are not an obstaclein the spreadingof this iRoginskaya, Grintsov, 1995; 1997) for which we would like to gastropod. On the Americancoast it is mentioned expressour thanksagain. both in brackishand seawater(2-23 "/ss). Related to the immigration, Doridella obscura was most probablebrought into the Black Sea in the fouling

REFERENCES Rocrrusxnyn,1.S., Gnrrursov,V.A., 1990, Nudibranch gastropod Doridella obscura Verrill first record for BAcEscU,M., MULLER,G.I., GoMoIU,M.-T., 1971, the Black Sea. Okeanologyia/Oceanology30(5), Ecologie marind Vol. lV, Ed Acad. R.S.R., 855-857,Moscova (in Russ.) "l Bucuresti,357 (in Rom.). RoGTNSKAYA,1.S", GRrNrsov, V.A., 1995, On the GoLrKov,A., Scnnmro, O.A., SrenoBoGATov,J., 1972, reproductionand dispersionof the new immigtant I Opredelitel'fauniCernogo iAzovskovo morei, 1, 60- Doridella obscura (Gastropoda, Opisthobranchia, l 250, lsdatelistvo"Naukova Dumka" Kiev (in Russ.) j Corambidae)in the Black Sea.Zool.2h.74, 7, 28- GoMoru, M.-T., 1961, Contributii la cunoasterea 31(lnRuss. ). (Gastropoda molustelor nudibranchiate RocrNSKAyA,1.S., GRrrursov,V.A., 1997, Range partea Opisthobranchiata)din vesticda MdriiNegre. Expansionof an alien Invader - the Nudibranch (in Com.Acad. RPR11(10), e55-857 Rom.) Mollusk Doridella obscuraiVenill 1870 GoMoru,M.-T., 1966, Speciile de opisthobranchia-tedin (Opisthobranchia,Corambidae) in the Black Sea. I Marea Neag16.Hidrobiologia 7, 141-147(in Rom ) The Veliger40(2), 160-164. PRouvot-Fol, Altce, 1954, Mollusques Opistho- Tnrels, J., 'l931, Handbuch der systematischen branches. In Faune de France 58, 460, Paul Weichtierkunde,1,vi + 778,Gustav Fischer, Jena. I Lechevalier.Paris.

GEO-ECO-MARINA, 2/1 997 203 Nationallnstitute of Maine Geologyand Geo-ecologyof Ramania 'Fluvial-Maine Proc. lntern. Workshopon lnteractions"in Malnas,Romania, Oct,1-7, 1996