Cryptostylochus hullensis sp. nov. (Polycladida, Acotylea, Platyhelminthes): A possible case of transoceanic dispersal on a ship’s hull

Helgol~nder Meeresunters. 50, 533-537 (1996)

Cryptostylochus hullensis sp. nov. ( P o l y c l a d i d a , A c o t y l e a , P l a t y h e l m i n t h e s ) : a p o s s i b l e case of t r a n s o c e a n i c d i s p e r s a l o n a ship's hull A. F a u b e l 1" & S. G o l l a s c h 2 IInstitut ffir Hydrobiologie und Fischereiwissenschaft, Universit~t Hamburg; Zeiseweg 9, D-22765 Hamburg, Germany 2Zoologisches Institut und Museum, Universit~t Hamburg, N[artin-Luther-King-Platz 3, D-20146 Hamburg, Germany

ABSTRACT: In July 1993, the car carrier "Faust" entered Bremerhaven after a voyage from the North-American Atlantic coast to Europe. In a dockyard, five living specimens of the order Polycladida were collected from the hull of the ship. This could be a possible case of trans-atlantic dispersal of plathelminths living as fouling organisms of ships. The specimens found represent a new species of the genus CryptostylochusFaubel, 1983, Cryptostflochus hullensis sp~ nov.

INTRODUCTION O b s e r v a t i o n s on the dispersal of benthic macro- and m e i o f a u n a w e r e a l r e a d y m a d e a long time ago (for r e f e r e n c e s see Young & Young, 1976; Gerlach, 1977). Most macrob en t h i c species d e v e l o p planktonic larvae (known also from species of the order Polycladida) that drift in w a t e r currents a n d can settle in n e w areas. In contrast, m e i o f a u n a l organisms as a n i l e lack planktonic larvae; colonization of n e w areas is b r o u g h t about by other m e c h a n i s m s (Palmer, 1988). Dispersal m e c h a n i s m s are, for example, aerial transport by birds an d wind, floating on ice (Steinbbck, 1931) a n d driftwood (fouling), transport in the ballast of sailing ships (cf. Young & Young, 1976; Gerlach, 1977), plate tectonics (Sterrer, 1973), w a t e r - c o l u m n p a t h w a y s (Butman, 1986; Palmer, 1988), a n d transport of n o n - i n d i g e n o u s species for a q u a c u l t u r e (Hedgpeth, 1980; Reise, 1993). Records of turbellarians i n t r o d u c e d to a n e w habitat by h u m a n impact w e r e published by M a u r i n & Le D a n t e c (1979), Carlton (1985), an d Lipton et al. (1992). T h e r e are no records of turbellarians living on the hulls of ships. In 1993 the co-author collected aufw u c h s from a ship's hull d o c k e d in B r e m e r h a v e n , Germany. Th e s p e c i m e n s p r o v i d e evid e n c e that individuals m a y be dispersed by ships, in this case possibly e v e n on transo cean i c seaways. T h e s p e c i m e n s b e l o n g to a n e w species d e s c r i b e d below.

* Adressee for all correspondence 9 Biologische Anstalt Helgoland, Hamburg

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Five s p e c i m e n s w e r e collected from the hull of the vessel "Faust", a car carrier, on J u l y 23rd 1993, after docking. The ship left Jacksonville, Florida, USAi at t h e b e g i n n i n g of July. Before crossing the Atlantic, the ship s t o p p e d at Charleston, South Carolina, Baltimore, M a r y l a n d , a n d N e w York, respectively. The E u r o p e a n ports e n t e r e d successively w e r e S o u t h a m p t o n (Great Britain), Le H a v r e (France), A n t w e r p (Belgium) a n d Bremerh a v e n (Germany). T h e ship was d o c k e d at B r e m e r h a v e n h a r b o u r at t h e e n d of July. During the ship's v o y a g e the o r g a n i s m s on the ship's hull w e r e e x p o s e d to c h a n g i n g e n v i r o n m e n t a l conditions. Salinity d e c r e a s e d from 35.10 PSU in the Atlantic p e l a g i a l to 11.10 PSU in the W e s e r river e s t u a r y at Bremerhaven. The w a t e r t e m p e r a t u r e at Brem e r h a v e n w a s 18.7 ~ After docking, the fouling c o m m u n i t y was e x p o s e d to 15.3 ~ air t e m p e r a t u r e (direct radiation of sunlight for a b o u t 1 hour). The o r g a n i s m s w e r e collected at 1.00 p. m. a n d a f t e r w a r d s t r a n s p o r t e d to the laboratory, w h e r e t h e y w e r e transferred to s e a w a t e r of 33 PSU. Next d a y t h e y w e r e fixed in 70 % ethanol. For histological observation, s p e c i m e n s w e r e e m b e d d e d in P a r a p l a s t plus, cut sagittally at 6.5 pm, a n d s t a i n e d with h a e m o t o x i l i n - e o s i n a c c o r d i n g to M a y e r (Romeis, 1968). DESCRIPTION S u p e r f a m i l y S t y l o c h o i d e a Poche, 1926 Family P s e u d o s t y l o c h i d a e Faubel, 1983 G a t t u n g CryptostFlochus Faubel, 1983 Cryptostylochus hullensis sp. nov. (Fig. 1) L o c a 1 i t y : Hull of the c a r carrier "Faust" d o c k e d in the h a r b o u r of B r e m e r h a v e n , 5 specimens, J u l y 23rd 1993. The f a u n a l fouling association, consisting of turbellarians, p o l y c h a e t e s , a m p h i p o d s , d e c a p o d s , cnidarians a n d cirripedes, c o v e r e d n e a r l y 10 % of the ship's hull. The p o l y c l a d s were found inside e m p t y shells of cirripedes. M a t e r i a 1 e x a m i n e d : Sagittally s e c t i o n e d specimen, 6.5 p m sections m o u n t e d on 44 slides, d e p o s i t e d in the Zoological M u s e u m , University of H a m b u r g , Germany, V 13213 [holotype]~ 3 w h o l e mounts, V 13214 [paratypes]. Living s p e c i m e n s of CrFptostylochus hullensis 1.1 cm long by 0.6 cm wide. In fixed s p e c i m e n s b o d y s h a p e more or less r o u n d of firm consistency (Fig. 1A) w i t h s m o o t h dorsal surface. Basic colour whitish in i n c i d e n t light; diffuse, light b r o w n dots s p e c k l e d t h r o u g h the dorsal b o d y wall. Tentacular, frontal, a n d m a r g i n a l e y e spots present. Tentacular ones a r r a n g e d at b a s e of tentacles (Fig. 1B) a n d in distal p a r t s of both n e r v e tracts a s c e n d i n g from the v e n t r a l b r a i n to the tentacles. F e w frontal e y e s s c a t t e r e d b e t w e e n b r a i n a n d a n t e r i o r margin. M a r g i n a l e y e s small, confined to a single i r r e g u l a r anterior row. Epidermis, 13.0 p m high, with i n t r a e p i t h e l i a l nuclei, rhabdites, a n d m u c u s glands, c o v e r e d with 14.8 p m long cilia; m u c u s g l a n d s dorsal m o r e n u m e r o u s t h a n ventral. Pigm e n t cells are l o c a t e d b e t w e e n b a s e m e n t m e m b r a n e a n d muscle wall of body. Dorsal a n d v e n t r a l muscle walls of b o d y different. Dorsal wall with w e a k a n d s m o o t h layers consisting of outer circular a n d i n n e r l o n g i t u d i n a l m u s c l e fibres; v e n t r a l w a l l w i t h strong lay-

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Fig. 1. Cryptostylochus huflensis sp. nov. A: Dorsal view (bar = 0.5 cm). B: D i a g r a m m a t i c sagittal reconstruction (bar = 200 pro). C: Sagittal reconstruction of the m a l e a n d female copulatory a p p a r a t u s (bar = 100 pm). b, brain; bm, b a s e m e n t m e m b r a n e ; bw, b o d y m u s c l e wall; c, circular m u s c l e fibres; e, eyes; ex, extravesicular glands; dr, d o r s o v e n t r a l m u s c l e fibres; g, m u c u s gland; i, intestine; 1, longitudinal muscle fibres; m, mouth; ma, m a l e atrium., n, nucleus; o, ovary; ov, oviduct; p, p e n i s papilla; ph, p h a r y n x plicatus; pi, p i g m e n t ; pv, prostatic vesicle; s, sperm; sv, seminal vesicle; t, testes; te, tentacle; u, uterine vesicles; v, vagina; vd, vas deferens; d, m a l e gonopore; i , f e m a l e g o n o p o r e

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ers of circular, a n d l o n g i t u d i n a l fibres, two layers d i a g o n a l l y crossing e a c h other, a n d a layer of l o n g i t u d i n a l fibres in i n w a r d succession. Dorso-ventral muscle fibres present. P h a r y n x plicatus well ruffled with m a n y m u c h - c o i l e d folds l o c a t e d s o m e w h a t anterior to centre of body. Mouth o p e n i n g at the centre of the p h a r y n g e a l cavity. M a i n intestine arises directly a b o v e the m o u t h opening, e x t e n d i n g dorsally forwards to t h e level of the b r a i n a n d b a c k w a r d s to the prostatic vesicle of the m a l e g e n i t a l complex. R e p r o d u c t i v e system (Fig. 1B, C). Testes a n d ovaries d i s p e r s e d t h r o u g h o u t w h o l e b o d y p a r e n c h y m a ; testes ventrally l o c a t e d a n d ovaries dorsally. Male a n d f e m a l e genital c o m p l e x l o c a t e d in posterior half of body, well b e h i n d t h e p h a r y n g e a l cavity. G e n i t a l pores v e r y close to e a c h other, but distinctly s e p a r a t e d . M a l e c o m p l e x directed b a c k w a r d s (Fig. 1C). Vasa deferentia t e r m i n a t e b y j o i n i n g the s e m i n a l vesicle. The copulatory o r g a n consists of a voluminous s e m i n a l vesicle, a free prostatic vesicle t u b u l a r l y c h a m b e r e d , a n d a distal u n a r m e d penis p a p i l l a h o u s e d in a male atrium. Prostatic a n d e j a c u l a t o r y ducts u n i t e h a l f w a y b e t w e e n o p e n i n g of penis papilla a n d b a s e of papilla. S e m i n a l a n d prostatic vesicles i n v e s t e d b y thick monol a y e r e d m u s c u l a r housings. Prostatic g l a n d s extravesicular. Their g r a n u l a r secretion ducts p e n e t r a t e the m u s c u l a r housing. The f e m a l e complex lies close b e h i n d m a l e one (Fig. 1C). Lang's vesicle lacking. Proximal oviducts w i d e n e d a n d filled with oocytes. Distal oviducts ciliated, j o i n i n g the vagina dorso-caudally. Proximal part of the v a g i n a ciliated, d i r e c t e d frontad. Distal v a g i n a r u n n i n g dorso-ventrad, without cilia in t h e s e parts s u r r o u n d e d by m a s s e s of eosinophilous m u c o u s glands. R e m a r k s : C r y p t o s t y l o c h u s h u l l e n s i s is the s e c o n d species of the g e n u s d e s c r i b e d . Diagnostic distinctions are a r r a n g e m e n t of eyes, a small p h a r y n g e a l c a v i t y with central mouth o p e n i n g a n d the non-ciliated lining of the distal vagina. E t y m o 1 o g y : The specific e p i t h e t refers to the locality w h e r e s p e c i e s w a s found, i.e. a ship's hull. DISCUSSION A c c o r d i n g to F a u b e l (1983), the family P s e u d o s t y l o c h i d a e Faubel, 1983 is c h a r a c t e rized by a c o m b i n a t i o n of the following features: m a l e copulatory a p p a r a t u s d i r e c t e d b a c k w a r d s a n d free prostatic vesicle with t u b u l a r l y c h a m b e r e d interior lining. At p r e s e n t 7 g e n e r a of the family are known, d i s t i n g u i s h e d m a i n l y on the basis of t h e f e m a l e a p p a ratus. The g e n e r i c feature of the g e n u s C r y p t o s t y l o c b u s Faubel, 1983 is the l a c k of Lang's vesicle. C r y p t o s t y l o c h u s h u t l e n s i s sp. nov. differs m a r k e d l y from the only k n o w n r e p r e sentative of the genus, C r y p t o s t y l o c h u s c o s e i r e n s i s (Bock, 1925), in the a r r a n g e m e n t of frontal a n d m a r g i n a l eyes, in the p h a r y n g e a l s y s t e m a n d the ciliated l i n i n g of the proxim a l vagina. C. h u l l e n s i s r e p r e s e n t s a n e w species, b u t w e h a v e no information o n its environm e n t a l p r e f e r e n c e s a n d w h e r e t h e s p e c i e s c o m e s from. Nevertheless, w e a r e c o n v i n c e d that C r y p t o s t y l o c h u s h u l l e n s i s is from s u b t r o p i c a l or w a r m t e m p e r a t e w a t e r s of the w e s t e r n N o r t h Atlantic. The r e a s o n for this a s s u m p t i o n is that the p o l y c l a d f a u n a of the w e s t e r n N o r t h Atlantic a n d the C a r i b b e a n S e a is not well k n o w n d e s p i t e t h e w o r k of Hym a n (1940, 1955), in contrast to t h e e x t e n s i v e k n o w l e d g e of the p o l y c l a d s of t e m p e r a t e E u r o p e a n Seas.

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T h e r e a r e f e w r e p o r t s o n t h e r e c r u i t m e n t of p l a t h e l m i n t h s . M a u r i n & Le D a n t e c (1979) a n d L i p t o n e t al. (1992) d o c u m e n t e d t h e i n t r o d u c t i o n of Komostylochus ostreophagus ( H y m a n , 1955) b y i m p o r t i n g J a p a n e s e o y s t e r s to F r a n c e a n d B r i t i s h C o l u m b i a ( C a n a d a ) , r e s p e c t i v e l y . C a r l t o n (1985) c o l l e c t e d a s p e c i e s of t h e o r d e r A c o e l a in b a l l a s t w a t e r t a k e n in W i l l m i n g t o n , D e l a w a r e , U S A . E v i d e n c e t h a t n e w i m m i g r a n t s h a v e e s t a b l i s h e d n e w p o p u l a t i o n s w a s p r o v i d e d b y H a u e r (1950) for Euplanaria tigrina i n G e r m a n y a n d b y Ball (1969) for Dugesia polychroa i n t h e G r e a t L a k e s , U S A . A s m e a n s of d i s p e r s a l t h e s e a u t h o r s a s s u m e t r a n s p o r t i n b a l l a s t w a t e r of s h i p s .

Acknowledgements. We t h a n k the s h i p p i n g c o m p a n y a n d the dockyard for their cooperation. The study w a s financed by the Federal E n v i r o n m e n t a l Agency, Berlin ("Invasion of n o n - i n d i g e n o u s marine species into the North a n d Baltic Sea via ship's ballast water: investigations on the ecological threat"). Prof. Rahde kindly checked the English. This article is based in part on a doctoral s t u d y by S. Gollasch in the Faculty of Biology, University of H a m b u r g .

LITERATURE CITED Ball, I. R., 1969. Dugesia lugubris (Tricladida, Paludicola), a European immigrant into North American freshwaters. - J. Fish. Res. Bd. Can. 26, 221-228. Bock, S., 1925. Papers from Dr. Th. M o r t e n s e n ' s expedition 1914-16. XXVII. Planarians. IV. New Stylochids. - V[densk. Meddr. dansk, naturh. Foren. 79, 97-184. Butman, C. A., 1986. Larval settlement of s o f t - s e d i m e n t invertebrates: some predictions b a s e d on an analysis of nearbottom profiles. In: Marine interfaces ecohydrodynamics. Ed. by J. C. d. Nihoul. Elsevier, A m s t e r d a m , 487-513. Carlton, J. T., 1985. Transoceanic a n d interoceanic dispersal of coastal marine organisms: T h e biology of ballast water. - Oceanogr. mar. Biol. 23, 313-374. Faubel, A., 1983. T h e Polycladida, Turbellaria. Proposal a n d e s t a b l i s h m e n t of a n e w system. Part. I. T h e Acotylea. - Mitt. hamb. zool. Mus. Inst. 80, 17-121. Gerlach, S. A., 1977. M e a n s of m e i o f a u n a dispersal. - Mikrofauna M e e r e s b o d e n 6I, 89-103. Hauer, d., 1950. Der n o r d a m e r i k a n i s c h e S t r u d e l w u r m Euplanaria tigrina (Girard) a m Oberrhein. Beitr. naturk. Forsch. Sfdw. Dtl. 9, 70-75. H e d g p e t h , J. W., 1980. The problem of introduced species in m a n a g e m e n t and mitigation. - Helgol6nder M e e r e s u n t e r s . 33, 662-673. H y m a n , L. H., 1940. The polyclad flatworms of the Atlantic coast of the United States a n d C a n a da. - Proc. U.S. natn. Mus. 89, 449-495. H y m a n , L. H., 1955. Some polyclad flatworms from the West Indies a n d Florida. - Proc. U.S. natn. Mus. 104, 115-150. Lipton, D. W., Lavan, E. F. & Strand, I. E., 1992. Economics of m o l l u s c a n introduction a n d transfers: T h e C h e s a p e a k e Bay dilemma. - d . Shellfish Res. 1 I, 511-519. Maurin, C. & Le Dantec, L., 1979. The culture of Crassostrea gigas in France. In: Exotic species in mariculture. Ed. by R. Mann. MIT Press, Cambridge, Mass. 106-120. Palmer, M. A., 1988. Dispersal of m a r i n e meiofauna: A review active conceptual model explaining passive transport a n d active e m e r g e n c e with implications for recruitment. - Mar. Ecol. Prog. Ser. 48, 81-91. Reise, K., 1993. A u s l 6 n d e r durch A u s t e r n im Wattenmeer. - W a t t e n m e e r int. 3, 16-17. Romeis, B., 1968. Mikroskopische Technik. Oldenbourg, M i i n c h e n 757 pp. Steinb6ck, O., 1931. Freshwater Turbellana. In: T h e zoology of the Faroes. Vol. I, Part 1. Ed. by A. S. J e n s e n , W. Lundbeck, T. M o r t e n s e n & R. Sparck. Host, C o p e n h a g e n 9, 1-32. Sterrer, W., 1973. Plate tectonics as a m e c h a n i s m for dispersal a n d speciation in interstitial s a n d fauna. - Neth. J. Sea Res. 7, 200-222. Young, J. O. & Young, B. M., 1976. First records of eight species a n d n e w records of four species of freshwater Microturbellaria from East Africa, with c o m m e n t s on m o d e s of dispersal of the group. - Zool. Anz. 196, 93-108.