New records on sea anemones (Anthozoa: Actiniaria) from hydrothermal vents and cold seeps

New eco ds on sea anemones (An hozoa: Ac inia ia) om hyd o he mal en s and cold seeps P.J. López-González, E. Rod íguez, J.-M. Gili & M. Segonzac López-González, P.J., E. Rod íguez, J.-M. Gili & M. Segonzac. New eco ds on sea anemones (An ho- zoa: Ac inia ia) om hyd o he mal en s and cold seeps. Zool. Ve h. Leiden 345, 31.x.2003: 215-243, igs 1-16.— ISSN 0024-1652/ISBN 90-73239-89-3. Pablo J. López-González, Depa amen o de Fisiología y Zoología, Facul ad de Biología, Uni e sidad de Se illa, Reina Me cedes 6, 41012 - Se illa, Spain (e-mail: [email p o ec ed]). Es e anía Rod íguez, Depa amen o de Fisiología y Zoología, Facul ad de Biología, Uni e sidad de Se illa, Reina Me cedes 6, 41012 – Se illa, Spain / Depa amen o de Biología Ma ina y Oceanog a ía, Ins i u o de Ciencias del Ma , CMIMA (CSIC), Paseo Ma í imo de la Ba celone a, 37-49, 08003 Ba celona, Spain (e-mail: [email p o ec ed]). Josep-Ma ia Gili, Depa amen o de Biología Ma ina y Oceanog a ía, Ins i u o de Ciencias del Ma , CMIMA (CSIC), Paseo Ma í imo de la Ba celone a, 37-49, 08003 Ba celona, Spain (e-mail: gili@cmima. csic.es). Michel Segonzac, I eme , Cen e de B es , DRO-EP/Cen ob, BP 70, 29280 Plouzané, F ance (e-mail: [email p o ec ed]). Key wo ds: Cnida ia; An hozoa; Ac inos olidae; Pa an hosac is denha ogi gen. e spec. no .; Hadalan hus a . knudseni; Ma ac is imica i o a; hyd o he mal en s; cold seeps. Du ing se e al c uises ca ied ou by he I eme (Ins i u ançais de eche che pou l’exploi a ion de la me ) wi h he subme sile “Nau ile” a di e en hyd o he mal si es and cold seeps, an impo an col- lec ion o an hozoans - mainly ac inia ians - was sampled. Addi ional ma e ial was collec ed by an Ame ican c uise wi h he subme sile “Al in”. The goal o he p esen con ibu ion is o desc ibe pa o his ac inia ian auna inhabi ing h ee chemoau o ophic si es, one o hem in he Mid-A lan ic Rise and he o he wo in he Eas e n Paci ic. A new genus and species o ac inos olids is p oposed a e he s udy o specimens collec ed a hyd o he mal en s in he Guaymas Basin (Eas Paci ic Rise, Gul o Cali o nia, 27º00’N-111º24’W, 2020 m). Fu he mo e, some specimens collec ed in cold seeps along he MAT (Middle Ame ica T ench, o Mexico, 18º21’-20°01’N 104º21’-106º17’W, 3354-3795 m) a e epo ed as Hadalan hus a . knudseni. This ma e ial is discussed and compa ed wi h he exis ing ype ma e ial o H. knudseni Ca lg en, 1956, and Tealidium junge seni Ca lg en, 1921. In addi ion, some specimens o Ma ac is imica i o a Fau in & Ba be , 1999, we e collec ed a hyd o he mal en s o he Mid A lan ic Ridge Snake Pi (23º22.9’N-44º55.8’W, 3490 m) si e. This species is collec ed o he i s ime a e i s o iginal desc ip ion a T ans-A lan ic Geo a e se (TAG, 26º08’N 44º49.6’W, 3650 m). Some ecological ema ks a e gi en om in si u and ideo obse a ions. In oduc ion Hyd o he mal en s and cold seeps a e cha ac e ized by low di e si y - bu high- biomass - communi ies. Tube wo ms (polychae es and es imen i e a), la ge bi al es, gas opods, di e en ypes o c us aceans (copepods, amphipods, sh imps, b achyu- ans), and ishes a e ep esen a i e aunis ic elemen s o hyd o he mal en and cold seep si es. Li le is known abou hyd o he mal and cold seep sea anemones (see e iew by Van Do e , 2000 o en s and Sibue & Olu, 1998 o seeps), al hough hey ha e some imes been obse ed o be abundan enough o play an impo an ole in he deep sea en i onmen s and in he hyd o he mal en ood web (see Doumenc & Van P aë , 1988; Gage & Tyle , 1991; Van Do e , 2000, o addi ional e e ences). They López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003)216 we e o en epo ed a seeps, a ached on bi al e shells o on o he subs a es (e.g. Junipe & Sibue , 1987; Ba y e al., 1996; Olu e al., 1997). In spi e o he p esence o locally dense beds, an endo- o episymbio ic ela ionship wi h chemoau o ophic bac- e ia has no been empi ically de e mined. Sea anemones a e p esumed o be suspen- sion eede s cap u ing a wide ange o p ey including la ge p ey i ems (e.g. Shick, 1991; Van Do e e al., 1997; Fau in & Ba be , 1999; Van Do e , 2000). No hing is known abou specia ion, e olu ion o biogeog aphic p ocesses in sea anemones inhabi ing hese chemoau o ophic en i onmen s. A high le el o endemism is expec ed and may co obo a e he idea o educed gene low be ween loca ions. The e alua ion o he po en ially es ic ed gene low is pa icula ly impo an wi h espec o specia ion. The Indo-Paci ic shows a complex ec onic his o y in compa ison wi h he Mid-A lan ic Ridge, including ou o he six biogeog aphic p o inces (Van Do e , 2000; Van Do e e al., 2001, 2002). In his scena io, mos o he sea anemone species epo ed om hyd o he mal en s a e cu en ly known om Indo-Paci ic si es, while only wo species a e known inhabi ing A lan ic hyd o he mal en s. Se en species o sea anemones ha e been documen ed om hyd o he mal en s. Fi e species a e membe s o he amily Ac inos olidae and wo species we e Ho - ma hiidae, hey all belong o he wo iches amilies o deep-sea ac inia ians (Des- b uyè es & Segonzac, 1997; Fau in & Ba be , 1999). The A lan ic ac inos olids associa - ed wi h hyd o he mal en s only include wo species, namely, Pa asicyonis ingol i Ca lg en, 1942 and Ma ac is imica i o a Fau in & Ba be , 1999 (see Segonzac, 1992; Fau in & Ba be , 1999). P. ingol i was collec ed a Snake Pi (23º22.94’N-44º56.09’W, 3480 m), while M. imica i o a was ound a a no he n loca ion, T ans-A lan ic Geo - a e se (TAG, 26º08’N 44º49.6’W, 3650 m). F om he Paci ic, h ee o he ac inos olid species ha e been epo ed (one o hem iden i ied only a gene ic le el): Ac inos ola sp., Cyanan hea hyd o he mala Doumenc & Van-P aë , 1988, and Ma ianac is by hios Fau in & Hessle , 1989 (see Doumenc & Van-P aë , 1988, Fau in & Hessle , 1989). The Fig. 1. Loca o map indica ing he hyd o he mal en s o cold seep whe e he species desc ibed in his pape a e p esen . 217López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003) wo o me species we e collec ed a 12º48’-49’N-103º56’ (2630-2635 m), while M. by hios was ound a Ma iana back-a c basin 18º10.9’-12.6’N 144º42.4’-43.2’E (3660 m). The ho ma hid species epo ed om hyd o he mal en s, one o hem only iden i ied a gene ic le el, we e collec ed a 12º48’-49’N-103º56’ (2630-2635 m) in he Eas e n Paci ic Rise (EPR): Chond ophellia co ona a (Ve ill, 1883) and Phelliac is sp. (see Doumenc & Van-P aë , 1988). Th ee species o sea anemones ha e been epo ed om cold seep si es, he Ho ma h- idae Monac is es i a (G a ie , 1918), om deep Ba bados p ism mud olcanoes, 4980 m (Olu e al., 1997) and wo Ac inos olidae om he Mon e ey Bay seeps, bo h only iden i- ied a gene ic le el, S omphia sp. and Pa ac inos ola sp., 1000 m (Ba y e al., 1996). In his pape , we desc ibe a new genus and species o ac inos olid om hyd o he - mal en s a Guaymas Basin collec ed du ing he GUAYNAUT c uise (Eas e n Paci ic, No -Dec 1991). Fu he mo e, we desc ibe as Hadalan hus a . knudseni some specimens a ibu able o he mono ypic genus Hadalan hus Ca lg en, 1956, collec ed om cold seeps a Middle Ame ica T ench o Mexico (18°-19°N; Me cie de Lépinay, 1997) du - ing he NAUTIMATE c uise (Eas e n Paci ic Rise, Jan-Feb 1994). Finally, we gi e desc ip ions o he ou specimens o Ma ac is imica i o a collec ed om he hyd o he - mal en s a Snake Pi du ing he ecen Ame ican c uise DIVERSExpedi ion (Mid- A lan ic Ridge, Jul 2001). Ma e ial and Me hods This pape is based in pa on he ma e ial collec ed in h ee chemoau o ophic en i onmen s, wo o hem we e hyd o he mal si es [Guaymas Basin, 2020 m (Eas e n Paci ic Rise, EPR) and Snake Pi , 3500 m (Mid-A lan ic Ridge, MAR)] and he las one a cold seep sys em, 3354-3795 m (Middle Ame ican T ench) ( ig. 1). The GUAYNAUT c uise was suppo ed by he I eme , B es , and he Uni e sidad Au ónoma de México (UNAM), and was conduc ed by A-M. Alayse, (I eme , Cen e de B es ), on boa d he R/V “Nadi ” and he R/V “El Puma”, he o me equipped wi h he subme sible “Nau ile”, om 8 No embe o 7 Decembe 1991. The main goal o his c uise was he s udy o he ecology o he Guaymas Basin hyd o he mal en sys em, mainly om he poin o iew o i s bac e ian communi ies and he chemis y o he luids and he sedimen s (Ma chand e al., 1994; Guézennec e al., 1996), bu also he dis ibu ion o he mega- and meio auna. The NAUTIMATE c uise was suppo ed by he Uni e si é UPMC, Pa is, I eme , UNAM (México) and Texas A&M Uni e si y, and was conduc ed by B. Me cie de Lépinay (Uni e si é de Nice-Sophia-An ipolis) and F. Michaud (Labo a oi e de Géo- dynamique sous-ma ine, Ville anche-su -me ), on boa d he R/V “Nadi ” equipped wi h he subme sible “Nau ile”, om 16 Janua y o 9 Feb ua y 1994. The main goal o his c uise was he s udy o some geodynamic aspec s o he neogene subsidence along he Middle Ame ica T ench o Mexico (18°-19°N). In addi ion some biological obse a ions and samples we e collec ed om his cold seep. The Ame ican c uise DIVERSExpedi ion was conduc ed by C. Van Do e (College o William & Ma y, Williamsbu g, USA), wi h he pa icipa ion o Ame ican, Po - uguese and F ench ins i u ions (e.g. College o William & Ma y, WHOI, Uni e si- dade dos Aço es and I eme ), on boa d he R/V “A lan is” equipped wi h he sub- López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003)218 AB CD EF 219López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003) me sible “Al in”, om 26 June o 29 July 2001. The main goal o his c uise was o p ospec and compa e he in e eb a e composi ion and biomass associa ed wi h beds o he bi al es Ba hymodiolus spp. a di e en hyd o he mal si es in MAR (Loga che , Snake Pi , Lucky S ike, B oken Spu ). The sea anemones collec ed in he be o e men ioned c uises we e ixed in 10% sea- wa e o malin, and hen p ese ed in 70% e hanol. F agmen s om selec ed specimens we e dehyd a ed in bu hanol (Johansen, 1940), and embedded in pa a in. His ological sec ions 7-8 µm hick we e s ained wi h Ramón y Cajal’s T iple S ain (Gabe, 1968). Cnidae measu emen s we e aken om p ese ed ma e ial in squash p epa a ions a 1000x magni ica ion wi h Noma ski di e en ial in e e ence con as op ics. F e- quencies gi en a e subjec i e imp essions based on squash p epa a ions. Fo pu poses o compa ison, he ollowing ype ma e ial was examined: - Tealidium junge seni Ca lg en, 1921. 1 syn ype (SMNH- ype-5568), Ingol -Expedi ion, s n 11, Danma k S ai , 64º34’N-31º12’W, 1300 ms, 21 May 1895; 2 specimens (ZMUC), Ingol Expedi ion, s n 11, Danma k S ai , 64º34’N-31º12’W, 1300 ms, 21 May 1895; 1 specimen (ZMUC), Ingol Expedi ion, s n 38, Da is S ai , 59º12’N- 51º05’W, 1870 ms, 30 Jul 1895. - Hadalan hus knudseni Ca lg en, 1956. 2 pa a ypes (ZMUC), Gala hea Expedi ion, s n 658, 35º51’S-178º31’W, SW Paci ic, 6660-6720 m. Rema ks: F om hese agmen - ed specimens only a ew cnidae measu emen s we e ob ained. Tenaculi a e p esen as desc ibed in he o iginal desc ip ion by Ca lg en (1956). The ma e ial s udied in his a icle is deposi ed in he Muséum na ional d’His oi e na u elle in Pa is (MNHN), he Zoological Museum in Copenhagen (ZMUC), he Swedish Museum o Na u al His o y in S ockholm (SMNH), and in he Zoology Sec ion o he Facul y o Biology a he Uni e si y o Se ille in Spain (SZ). Resul s Family Ac inos olidae Ca lg en, 1932 Pa an hosac is gen. no . Diagnosis.— Ac inos olidae wi h well de eloped pedal disc. Column smoo h (dome- shaped o cylind ical in p ese ed ma e ial), no di isible in o scapus and scapulus. Fig. 2. Pho og aphs aken in si u a he di e en chemoau o ophic en i onmen s p ospec ed. A) speci- mens o Pa an hosac is denha ogi gen. no . spec. no . wi h he es imen i e an Ri ia pachyp ila (one li ing specimen and wo dead ones) on ac i e hyd o he mal edi ice a he Guaymas Basin a 2020 m dep h. Copy igh : “Pho og aph I eme /Guaynau -1991”; B) de ail o Pa an hosac is denha ogi gen. no . spec. no . close o some li ing specimens o Ri ia pachyp ila. Copy igh : “Pho og aph I eme /Guaynau -1991”; C) specimens o Hadalan hus a . knudseni Ca lg en, 1956 (b ownish en acles) on dead and li ing bi al e shells o Calyp ogena sp., and he gala heid c ab Munidopsis subsquamosa a cold seeps, 3795 m dep h, in he Middle Ame ican T ench. Copy igh : “Pho og aph I eme /Nau ima e-1994”; D) o al iew o some speci- mens o H. a . knudseni li ing nex o cold seeps. Copy igh : “Pho og aph I eme /Nau ima e-1994”; E) gene al iew o Snake Pi -Elan hyd o he mal si e a Mid-A lan ic Ridge, 3500 m dep h, showing some ac inia ians, he my ilid Ba hymodiolus pu ose pen is, he ophiu id Ophioc enella acies and he ish Pachyca a he mophilum. Copy igh : “WHOI/DIVERSExpedi ion-2001”; F) De ail o he sea anemone Ma ac is imi- ca i o a Fau in & Ba be , 1999 a Snake Pi -Elan, 3500 m. Copy igh : “WHOI/DIVERSExpedi ion-2001”.  López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003)220 Sphinc e dis inc ly ma ked on he su ace o he column as a p ominen ci cum e en- ial ma ginal ing; mode a ely s ong, mesogloeal. Ten acles o uni o m hickness along en i e leng h (no comple ely hidden in p ese ed e ac ed ma e ial). Inne en- acles longe han ou e ; no nume ous (abou 70). Longi udinal en acle and o al disc ci cula muscula u e ec ode mal; ha o en acles equally well de eloped on all sides. Mesen e ies no a ayed acco ding o Ac inos ola ule; i s cycle o mesen e ies pe - ec ; all s onge ones e ile, including he di ec i es. Two well de eloped siphono- glyphs and wo pai s o di ec i es. Re ac o muscles di use; pa ie obasila muscles no di e en ia ed; basila muscula u e di e en ia ed. Mesogloea ela i ely hin. Same numbe o mesen e ies dis ally and p oximally. Cnidom: spi ocys s, basi ichs, mic obasic b-mas igopho s(?), mic obasic p-mas igopho s. Type species.— Pa an hosac is denha ogi spec. no . E ymology and gende .— The gene ic name e e s o he mo phological simili ude o he new axon o he genus An hosac is Danielssen, 1890. The gende is eminine. Fig. 3. Pa an hosac is denha ogi gen. e spec. no . P ese ed specimens. A) holo ype, MNHN; B) SZ (ANT-2138); C) SZ (ANT-2138); D) MNHN, de ail o he dis al pa o he column and en acles. Abb e ia ions: co, column; m , ma ginal ing; e, en acles. Scale ba s: A-C, 10 mm; D, 4 mm. AB CD 221López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003) Pa an hosac is denha ogi spec. no . ( igs 2A-B, 3-7, able 1) Ma e ial.— MNHN, holo ype, one specimen, GUAYNAUT c uise, Gul o Cali o nia, Guaymas Basin, PL 16, 27º00.94’N-111º24.66’W, 2025 m dep h, 28.xi.1991; MNHN, pa a ypes, 2 specimens, wi h he same sampling da a as he holo ype; MNHN, 2 specimens, GUAYNAUT c uise, Gul o Cali o nia, Guaymas Basin, PL 07, 27º00.45’N-111º24.53’W, 2020 m dep h, 16.xi.1991; SZ (ANT-2137), 2 specimens, GUAYNAUT c uise, Gul o Cali o nia, Guaymas Basin, PL 07, 27º00.45’N-111º24.53’W, 2020 m dep h, 16.xi.1991; SZ (ANT-2138), 2 specimens, GUAYNAUT c uise, Gul o Cali o nia, Guaymas Basin, PL 16, 27º00.94’N-111º24.66’W, 2025 m dep h, 28.xi.1991. Desc ip ion.— Ex e nal ana omy ( ig. 3): Column smoo h, much b oade p oxi- mally han dis ally; o 16 mm diame e and 15 mm heigh in p ese ed and pa ially e ac ed specimens. Pedal disc well de eloped and enla ged, o 35 mm a maximum axis; some specimens wi h o eign sulphide pa icles adhe ed o i . Column smoo h, wi h a ma ginal p ominen ing co esponding o he muscula sphinc e ( ig. 3B, D). O al disc no obse ed in p ese ed ma e ial. Ten acles abou 70 in numbe , ou e en acles sho e han inne ones, up o 8 mm and no comple ely wi hd awn in p e- Table 1. Size anges o he cnidae o Pa an hosac is denha ogi gen. e spec. no . X: a e age. SD: s anda d de ia ion. Samples: he a io indica es he numbe o polyps in which each cnidae was ound ou and he numbe o polyps o each species examined. N: indica es he o al numbe o capsules measu ed. F: F equency: +++ = e y common, ++ = common, + = a he common, --- = spo adic. Abb e ia ion: Mc, Mic obasic. Ca ego ies Range o leng h and X±SD Sample N F wid h o capsules in µm Pedal disc Basi ichs (B,C) (17.2-20.2) 3.0 18.6± 1.2 3.0±0.0* 1/1 17 +/++ Column Basi ichs (B,C) (15.1-21.2) (3.0-4.0) 18.3±1.4 3.6±0.5 4/4 67 ++ Ten acles apex Spi ocys s (A) (17.2-56.6) (3.0-9.1) 31.2±8.0 5.0±0.2 6/6 80 +++ Basi ichs (B,C) (19.2-30.3) (2.0-4.0) 25.4±2.9 3.2±0.4 6/6 77 ++/+++ Mc. b-mas igopho es(?) 1 (D) (24.2-27.3) 4.0 25.6±1.5 4.0±0.0* 2/6 3 --- Mc. p-mas igopho es 1 (F) (16.2-19.2) (4.0-5.0) 18.2±1.1 4.5±0.5* 5/6 7 --- Ten acles base Spi ocys s (A) (11.1-50.5) (4.0-9.1) 27.3±7.5 5.3±1.3 6/6 80 ++/+++ Basi ichs (B,C) (17.2-25.2) (2.0-4.0) 21.1±1.65 3.0±0.3 6/6 47 ++/+++ Ac inopha ynx Basi ichs (B,C) (15.1-33.3) (2.0-4.0) 26.8±3.8 3.1±0.4 4/4 46 +/++ Mc. p-mas igopho es 2 (G) (30.3-43.4) (4.0-6.1) 34.7±2.3 4.6±0.5 4/4 80 ++/+++ Mc. p-mas igopho es 3 (H) (31.3-42.4) (4.0-6.1) 38.2±3.4 5.2±0.6* 3/4 21 + Mc. b-mas igopho es(?) 2 (E) (39.4-45.4) (4.0-5.0) 42.4±3.03 4.7±0.6* 1/4 3 --- Filamen s Basi ichs (B,C) (12.1-21.2) (2.0-4.0) 15.5±2.0 2.8±0.5* 4/4 31 ---/+ Mc. p-mas igopho es 2 (G) (24.2-40.4) (4.0-6.1) 34.7±2.7 4.7±0.6 4/4 70 ++/+++ Mc. p-mas igopho es 3 (H) 37.4 (5.0-6.1) 37.4±0.0 5.6±0.7* 1/4 2 + * A e age based on less han 40 measu ed capsules. The measu emen o a leas 40 capsules is usually conside ed enough o ha e signi icance. López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003)222 Fig. 4. Pa an hosac is denha ogi gen. e spec. no . (SZ (ANT-2138)) A) c oss sec ion a s omodaeum le el; B) di ec i es; C) basila muscula u e. Abb e ia ions: 1, pai o mesen e ies o he i s cycle; 2, pai o mesen e ies o he second cycle; 3, pai o mesen e ies o he hi d cycle; bm, basila muscle; di, di ec i es; ms, mesen e y; pd, pedal disc; ph, pha ynx; m, e ac o muscle. Scale ba s: A, 0.6 mm; B, 0.45 mm; C, 0.1 mm. A BC 223López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003) se ed specimens. No hickened a base, wi h longi udinal and ans e se u ows due o con ac ion. In e nal ana omy ( igs 4, 5, 6): Equal numbe o mesen e ies dis ally and p oximally. Mesen e ies hexame ously a anged in ou cycles, only he i s cycle pe ec . Th ee oldes cycles e ile, including di ec i es. Fou h cycle incomple e, poo ly de eloped and s e ile. Two pai s o di ec i es, connec ed wi h well-de eloped siphonoglyphs, mesogloea and gas ode mis o he siphonoglyphs sligh ly wide han he mesogloea and he gas ode mis o he ac inopha ynx. Re ac o muscula u e di use a s o- modaeum le el ( ig. 4A-B). Pa ie obasila muscula u e no de eloped. Basila muscu- la u e dis inc bu poo ly de eloped ( ig. 4C). Game ogenic issue well de eloped in specimens collec ed in No embe ; gonocho ic; de eloping oocy es ( o 0.13 mm in diame e on his ological sec ions). Sphinc e muscle mesogloeal, mode a ely s ong, and ela i ely sho ( ig. 5). O al disc and en acles wi h ec ode mal longi udinal mus- cula u e ( ig. 6). Muscula u e o en acles wi h simila de elopmen abo al and o al. Column wall o simila hickness en i e leng h. Epide mis 0.02-0.08 mm hick; mesogloea 0.05-0.08 mm hick, and gas ode mis 0.10-0.15 mm hick. Cnidom: Spi ocys s, basi ichs, mic obasic b-mas igopho es(?), and mic obasic p- mas igopho es. No ba e ies o mic obasic b-mas igopho es (o supposed mic obasic Fig. 5. Pa an hosac is denha ogi gen. e spec. no . (SZ (ANT-2138)) A) longi udinal sec ion a ma gin showing mesogloeal sphinc e , de ails showed in he igu es B, C, and D a e indica ed; B-D) de ails om A. Abb e ia ion: sph, sphinc e . Scale ba s: A, 0.5 mm; B-D, 0.06 mm. AB C D López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003)230 animals show a b ownish c own o en acles, while he column is di y whi e. Dis ibu ion and habi a .— A p esen , Hadalan hus a . knudseni is known om he Eas e n Paci ic in he Middle Ame ican T ench o Manzanillo (Mexico), be ween 3354 and 3795 m. This a ea is he sea o cold seeps coming om he ec onic pla e Ri e a subduc ion, on he le el o a aul sys em whose p incipal one is p olonged o he no h in o he basin o Guaymas. Colonies o bi al es esicomyid Calyp ogena sp. li e on he sedimen , o en co e ed by a bac e ial ma , a he exi o cold luids cha ged o educed compounds (CH4and SH2). The sea anemones a e ixed on hese bi al es ( ig. 2C-D), ali e, o mo e equen ly on he shells, which cons i u es he only ha d subs a e o hese sedimen a y a eas. The accompanying auna o hese communi ies is e y li le di e si ied. I consis s o a a e gala hea c ab Munidopsis subsquamosa ( ide E. Macphe - son), o zoa cid ish, and se pulid polychae es Neo e milia sp. ( ide H. Zib owius). Taxonomic ema ks.— Acco ding o Ca lg en’s diagnosis (1956) and Fau in & Hessle ’s key (1989), he p esen ma e ial can be included in he deep-sea genus Hadalan hus Ca lg en, 1956 by he ollowing se o ea u es: 1) e ili y o all s onge mesen e ies, 2) ec ode mal na u e o longi udinal en acles muscles, 3) six pai s o pe - ec mesen e ies, 4) absence o mic obasic b-mas igopho es in en acles, 5) p esence o mic obasic p-mas igopho es in en acles, 6) p esence o a column di ided in o scapus Table 3. Size anges o he cnidae o Hadalan hus a . knudseni Ca lg en, 1956. X: a e age. SD: s anda d de ia ion. Samples: he a io indica es he numbe o polyps in which each cnidae was ound ou and he numbe o polyps o each species examined. N: indica es he o al numbe o capsules measu ed. F: F equency: +++ = e y common, ++ = common, + = a he common, --- = spo adic. Abb e ia ion: Mc, Mic obasic. Ca ego ies Range o leng h and X±SD Sample N F wid h o capsules in µm Pedal disc Basi ichs (C) (20.2-25.2) (2.0-3.0) 23.1±1.4 2.8±0.4* 2/2 26 ---/++ Scapus Basi ichs (C) (18.2-24.2) (2.0-3.0) 21.2±1.3 2.5±0.5 3/3 60 +++ Mc. p-mas igopho es (D) (20.2-29.3) (3.0-6.1) 26.1±1.6 4.6±0.7 3/3 55 ++ Scapulus Basi ichs (C) (21.2-27.3) (3.0-4.0) 23.7±1.2 3.2±0.4 3/3 60 ++/+++ Mc. p-mas igopho es (D) (24.2-35.3) (4.0-6.1) 28.3±2.0 5.1±0.7 3/3 60 +++ Ten acles Spi ocys s (A) (18.2-50.5) (5.0-11.1) 30.1±7.2 7.2±1.6 5/5 75 ++/+++ Spi ocys s (B) (18.2-36.4) (4.0-10.1) 26.3±4.4 5.1±1.2* 3/5 33 +/++ Basi ichs (C) (14.1-35.3) (2.0-4.0) 21.9±4.6 2.8±0.5 5/5 100 ++ Mc. p-mas igopho es (D) (20.2-34.3) (4.0-7.1) 24.9±4.9 5.0±0.9 5/5 85 +/++ Holo ichs ? (E) (23.2-33.3) (6.1-8.1) 29.9±3.3 6.8±0.7* 4/5 8 --- Ac inopha ynx Basi ichs (B,C) (14.1-26.3) (2.0-4.0) 20.3±3.8 2.7±0.5 3/3 44 ++ Mc. p-mas igopho es (D) (22.2-38.4) (4.0-7.1) 31.5±3.8 5.3±0.9 3/3 43 ++/+++ Filamen s Basi ichs (B,C) (16.2-25.2) (2.0-3.0) 18.9±2.2 2.8±0.4 3/3 43 +/++ Mc. p-mas igopho es (D) (23.2-36.4) (4.0-6.1) 30.1±3.5 4.8±0.5 3/3 48 +/++ * A e age based on less han 40 measu ed capsules. The measu emen o a leas 40 capsules is usually conside ed enough o ha e signi icance. 231López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003) and scapulus, and 7) p esence o dis inc enaculi on low mesogloeal papillae. Ca lg en (1956: 13) poin ed ou he simila appea ance o he column o Hadalan- hus and Daon esia Ca lg en, 1942, aking in o accoun he absence o acon iae in he o me genus. Among he ac inos olid gene a, he p esence o mesogloeal papillae (e oded enaculi ?) in he genus Tealidium could be conside ed a common ea u e wi h Hadalan hus (see He wig, 1882, Ca lg en, 1921, 1949). Howe e , sensu Ca lg en (1949: 77) and Fau in & Hessle (1989: 817), he absence o ba e ies o nema ocys s in en a- cles is a dis inc i e cha ac e be ween bo h gene a. In he examined ype ma e ial o Tealidium junge seni, he e is no ace o cu icle o enaculi, al hough he mesogloeal papillae a e clea ly isible on he column. Howe e , in he examined ype ma e ial o Hadalan hus knudseni, he enaculi - isible a low magni ica ion - a e o med by a yellowish cu icle on small mesogloeal papillae. Despi e he examina ion o he ype ma e ial o Hadalan hus knudseni, i is di icul o decide whe he he ma e ial collec ed du ing he NAUTIMATE c uise should be desc ibed as a new species o included unde he name o he single species named in he genus Hadalan hus. The cu en s a e o he ype ma e ial o H. knudseni does no allow o ob ain mo e in o ma ion abou he s uc u e o he dis al enaculi (in ac mos o hem a e e oded), addi ional measu emen s o undischa ged cnidae in o de o ob ain a posi i e o nega i e signi icance based on s a is ic analyses (mos o hem a e exploded as indica ed in he able 4), and o he ana omical s uc u es commonly used o sol e speci ic ques ions. Thus, al hough ou NAUTIMATE specimens show da ke enaculi (yellowish in he ype ma e ial), la ened enaculi dis ally (can no be obse ed in he ype ma e ial due o he poo s a e o conse a ion) and some sligh di e ences in he cnidae ( hese can no be compa ed by he sca ce da a ob ained o m he issues o he ype ma e ial, see ables 3 and 4), we iden i y he NAUTIMATE Fig. 9. Hadalan hus a . knudseni Ca lg en, 1956. Tenaculi on scapus. No e he a iabili y in shape, la - ened dis ally (A) [MNHN, o ounded o poin ed a mid-column le el (B and C) [MNHN]. Scale ba s: A, 3 mm; B, 4 mm; C, 3.5 mm. AB C López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003)232 Table 4. Size anges o he cnidae o Hadalan hus knudseni Ca lg en, 1956 (Syn ypes ZMUC). X: a e age. SD: s anda d de ia ion. Samples: he a io indi- ca es he numbe o polyps in which each cnidae was ound ou and he numbe o polyps o each species examined. N: indica es he o al numbe o cap- sules measu ed. F: F equency, +++ = e y common, ++ = common, + = a he common, —- = spo adic. Abb e ia ion: Mc, Mic obasic Ca ego ies Range o leng h and X±SD Sample N F Da a om Ca lg en, 1956 wid h o capsules in µm Pedal disc Basi ichs (26.6-30.3)  3.0 29.0±1.9  3.0±0.0* 1/1 4 + no da a Scapus (1) Basi ichs (19.2-30.3)  3.0 24.4±2.5  3.1±0.3 2/2 55 ++ (24-32)  (2.8-3.5 Ten acles Spi ocys s (27.3-51.5)  (6.1-7.1) 40.0±0.5  5.6±0.8* 2/2 11 ++ 50  5.6 Basi ichs 1 (34.3-42.4)  3.0 38.9±3.0  3.0±0.0* 1/2 6 + (38-43)  (2.8-3.5) Basi ichs 2 no ound (48-53.6)  5 Basi hichs 3 (14.1-24.2)  (2.0-3.0) 19.0±2.3  3.0±0.3* 2/2 22 ++ no da a Mc. p-mas igopho es(2) (29.3-35.3)  (4.0-5.0) 33.1±2.6  4.8±0.4* 2/2 9 +/++ (39.0-50.8)  5 Ac inopha ynx Basi ichs (20.2-30.3)  (3.0-4.0) 24.6±2.8  3.1±0.3* 1/1 20 ++ no da a Mc. p-mas igopho es(3) (41.4-51.5)  (5.0-6) 45.3±3.7  5.2±0.4* 1/1 8 ++ no da a Filamen s Basi ichs (16.2-26.3)  (3.0-4.0) 21.0±2.4  3.1±0.2 2/2 83 ++ (19.7-24)  3 Mc. p-mas igopho es(4) (35.3-50.5)  (4.0-5.0) 41.4±4.6  4.8±0.4* 2/2 15 +++ (23-48)  4.5 * A e age based on less han 40 measu ed capsules. The measu emen o a leas 40 capsules is usually conside ed enough o ha e signi icance. (1) 4 exploded capsules (25.2-29.3)  5.0 ha e been also ound. (2) 8 exploded capsules (30.3-40.4)  (4.0-5.0) ha e been also ound. (3) nume ous exploded capsules (42.4-50.5  4.0-5.0) ha e been also ound; 5 exploded capsules (42.4-46.5)  (5.0-6.1) ha e been also ound. (4) nume ous exploded capsules (42.4-50.5  4.0-5.0) ha e been ound; 52 exploded capsules (23.2)(31.3-48.5)  (4.0-6.1) ha e been also ound. 233López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003) specimens as H. a . knudseni because o he simili ude in he o he compa able cha ac- e s. The a ailable di e en ia ing cha ac e s could be p oduc o he la ge size o he NAUTIMATE specimens (e.g. abou 140 en acles in he la ge indi idual, bu abou 70 in an indi idual o simila size as he ype ma e ial o H. knudseni). Genus Ma ac is Fau in & Ba be , 1999 Ma ac is imica i o a Fau in & Ba be , 1999 ( igs 2E, F, 14-16, able 5) Ma ac is imica i o a Fau in & Ba be , 1999: 625, igs. 1-4. Ma e ial.— MNHN, 2 specimens, DIVERSExpedi ion c uise, Snake Pi -Elan (Mid-A lan ic Ridge), di e 3674, 23º22.90’N-44º55.80’W, 3490 m dep h, 16. ii.2001; SZ (ANT-2141), 2 specimens, DIVERSExpedi- ion c uise, Snake Pi -Elan (Mid-A lan ic Ridge), di e 3674, 23º22.90’N-44º55.80’W, 3490 m dep h, 16. ii.2001. Fig. 10. Hadalan hus a . knudseni Ca lg en, 1956. (SZ (ANT-2139)). C oss sec ion a s omodaeum le el. Abb e ia ions: 1, pai o mesen e ies o he i s cycle; 2, pai o mesen e ies o he second cycle; 3, pai o mesen e ies o he hi d cycle; 4, pai o mesen e ies o he ou h cycle; di, di ec i es; si, siphono- glyph; Scale ba : 5 mm. López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003)234 Table 5. Size anges o he cnidae o Ma ac is imica i o a. X: a e age. SD: s anda d de ia ion. Samples: he a io indica es he numbe o polyps in which each cnidae was ound ou and he numbe o polyps o each species examined. N: indica es he o al numbe o capsules measu ed. F: F equency: +++ = e y common, ++ = common, + = a he common, —- = spo adic. Abb e ia ion: Mc, Mic obasic. P esen s udy Fau in & Ba be (1999) Snake Pi , 3500 m TAG, 3650 m. Ca ego ies Range o leng h and X±SD Sample N F Range o leng h and Sample N wid h o capsules in µm wid h o capsules in µm Pedal disc Basi ichs (B) (22.2-30.3)  (3.0-4.0) 24.4±2.2  3.1±0.3 4/4 58 +/++ ----- Column Basi ichs (B) (19.2-29.3)  (3.0-4.0) 23.7±1.9  3.1±0.3 4/4 80 ++/+++ (19.5-31.5)  (1.9-3.9) 5/5 71 Mc. p-mas igopho es 1 (D) (25.2-30.3)  (4.0-5.0) 27.4±1.9  4.3±0.5* 2/4 19 —-/++ (21.3-31.9)  (3.4-6.2) 4/5 54 Ten acles Spi ocys s (A) (27.3-81.8)  (4.0-7.1) 47.9±12.9  5.1±1.0 4/4 80 +++ (30.0-78.5)  (2.8-7.3) 5/5 91 Basi ichs (B) (19.2-45.4)  (3.0-4.0) 35.4±5.2  3.5±0.5 4/4 67 ++ (31.0-48.4)  (2.5-3.8) 5/5 50 (17.2-25.5)  (1.6-2.9) 5/5 54 (19.2-43.4)  (1.9-3.8) 5/5 74 Holo ichs (G) (35.3-48.5)  (5.0-8.1) 42.4±3.9  6.0±0.7* 3/4 22 ---/+ (30.4-53.9)  (4.5-6.4) 5/5 39 Ac inopha ynx Basi ichs (B,C) (16.2-36.4)  (3.0-4.0) 23.8±6.9  3.1±0.2* 2/4 17 ---/+ (23.4-34.9)  (2.3-3.2) 3/4 9 Mc. p-mas igopho es 1 (D, E) (29.3-41.4)  (3.0-5.0) 35.4±3.1  4.5±0.6 4/4 100 ++/+++ (28.6-42.1)  (4.1-5.2) 3/4 31 Mc. p-mas igopho es 2 (F) (1) (30.3-39.4)  (4.0-6.1) 34.1±2.7  4.4±0.6* 2/4 15 + Filamen s Basi ichs (C) (14.1-21.2)  (2.0-3.0) 17.3±1.7  2.9±0.3* 4/4 38 ---/++ (16.1-34.1)  (1.8-4.5) 5/5 61 Mc. p-mas igopho es 1 (D, E) (28.3-39.4)  (4.0-5.0) 34.6±2.6  4.7±0.5 4/4 100 ++/+++ (26.9-38.9)  (3.3-5.7) 5/5 61 Mc. p-mas igopho es 2 (F) (1) (30.3-37.4)  (4.0-6.1) 34.9±2.1  5.1±0.4* 2/4 15 ---/+ * A e age based on less han 40 measu ed capsules. The measu emen o a leas 40 capsules is usually conside ed enough o ha e signi icance. (1) Al hough his ca ego y could be included wi h he p eceden cnida by he o e lapping size ange, low equency and low cons ancy in he sampled specimens, we ha e p e e ed o main ain i sepa a ed om he o he mic obasic p-mas igopho e (D,E) by he sho V-shaped end and ela i e leng h o he sha . Examina ion o exploded capsules could gi e addi ional in o ma ion abou he s uc u e o he spines ows and sol e de ini i ely i hey should be conside ed as he same ca ego y o main ained hem sepa a ed. 235López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003) Desc ip ion.— Ex e nal ana omy ( ig. 14): Column wi h ough ex u e, much b oad- e p oximally han dis ally; o 28 mm diame e and 20 mm heigh in p ese ed speci- mens. Column wi h ans e sal u ows due o he con ac ion o he animals, some sul- phide pa icles adhe ed o hem. Pedal disc well de eloped and enla ged, o 41 mm along maximum axis, in some specimens wi h o eign sulphide pa icles adhe ed o i . O al disc no obse ed in p ese ed ma e ial. Ten acles abou 100, ou e en acles sho e han inne ones, up o 16 mm long, and no comple ely wi hd awn in p e- se ed specimens ( ig. 14). No hickening a base, wi h longi udinal and ans e se u ows due o he con ac ion. In e nal ana omy ( ig. 15): Equal numbe o mesen e ies dis ally and p oximally. Mesen e ies hexame ously a anged in ou cycles, only he i s cycle pe ec . All s onge mesen e ies e ile. Two pai s o e ile di ec i es, connec ed wi h s ong and well-de eloped siphonoglyphs. Mesogloea and gas ode mis o he siphonoglyphs sligh ly wide han he mesogloea and he gas ode mis o he ac inopha ynx. Re ac o muscula u e di use a s omodaeum le el ( ig. 15A). Pa ie obasila muscula u e only clea ly di e en iable in he s onge cycles. Basila muscula u e poo ly de eloped. Fig. 11. Hadalan hus a . knudseni Ca lg en, 1956. (SZ (ANT-2139)). A) longi udinal sec ion a ma gin showing mesogloeal sphinc e ; de ails showed in igu es B and C a e indica ed; B) de ail o meso- gloeal sphinc e ; C) c oss sec ion o a en acle, showing ec ode mal muscula u e; D) enaculi. A, 5 mm; B, 0.15 mm; C, 0.2 mm; D, 0.25 mm. AB C D López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003)236 Game ogenic issue well de eloped in specimens collec ed in July; gonocho ic; de eloping spe ma ic esicles ( o 0.25 mm in diame e in p ese ed specimens). Sphinc e muscle mesogloeal, s ong, ela i ely sho , occupying all mesogloea wi h he muscle bundles e icula ed ( ig. 15B). O al disc and en acles wi h ec ode mal lon- gi udinal muscula u e ( ig. 15C-D). Column wall o simila hickness along en i e leng h. Epide mis 0.04-0.12 mm hick; mesogloea 0.06-0.19 mm hick, and gas ode mis 0.02-0.12 mm hick. Fig. 12. Hadalan hus a . knudseni Ca lg en, 1956. (SZ (ANT-2139)). A) enaculi and i s mesogloeal papilla, longi udinal sec ion. Dis al po ion showed in B is indica ed; B) de ail o A. Abb e ia ions: ep, epide mis; me, mesogloea; mp, mesogloeal papilla; sc, s a i ied cu icle. Scale ba s: A, 0.25 mm; B, 0.05 mm. Fig. 13. Hadalan hus a . knudseni Ca lg en, 1956. Cnidae. A) spi ocys A; B) spi ocys B; C) basi ich D) mic obasic p-mas igopho e E) holo ich(?). See ex and able 3 o explana ion. Scale ba : 20 µm A ABC DE B 237López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003) Cnidom: Spi ocys s, basi ichs, holo ichs and mic obasic p-mas igopho es. A su - ey o he cnidae is p esen ed in able 5 and igu e 16. Colou : P ese ed ma e ial o a yellowish o whi ish colou . Acco ding o he pho- og aphs and ideo apes aken in si u ( ig. 2E-F) li ing animals a e whi ish in colou . Dis ibu ion and habi a .— A p esen Ma ac is imica i o a is known o li e in wo hyd o he mal si es a he Mid-A lan ic Ridge, TAG, 3650 m (Fau in & Ba be , 1999), and Snake Pi -Elan, 3490 m (Segonzac, 1992, and p esen accoun ). On hese wo si es, he sea anemones a e ixed on sulphide ocks. They a e inc easingly dense as one app oaches o he ac i e a ea (un il se e al ens o ind/m2), which makes he p esence o his g oup a good indica o o p esence o ac i e si es. Some specimens a e obse ed a he base o he black smoke s whe e he empe a u e o luids is ca 10°C. On he Elan si e, accompanying auna is composed by he ube-wo m polychae es Chae op e i- dae, gas opods Phymo hynchus, sh imps Rimica is exocula a and Cho oca is chacei, bi al es Ba hymodiolus pu eose pen is and zoa cid ish Pachyca a he mophilum. Sh imps R. exocula a can cons i u e p ey o sea anemones li ing close o he black smoke s (Van Do e e al., 1997), bu no o he majo i y o he popula ion ha li es a dis- ances he sh imps do no each. Taxonomic ema ks.— The ma e ial he e desc ibed and collec ed a Snake Pi a ea ag ees well in gene al aspec s wi h he o iginal desc ip ion o Ma ac is imica i o a (see Fau in & Ba be , 1999). Only a ela i ely sho e , s onge and e icula e mesogloeal sphinc e and he p esence - in some specimens - o a spo adic nema ocys ( ig. 16F) a e he appa en ly di e en ia ing ea u es be ween TAG and Snake Pi ma e ial. Fau in & Ba be (1999: 630) poin ed ou he p esence o a small sea anemone in TAG wi h a muscula sphinc e simila o ha obse ed in he p esen s udy; ha specimen was ini ially conside ed as a possible di e en species o M. imica i o a and P. ingol i. In he examined ma e ial o M. imica i o a om Snake Pi we ha e also obse ed sphinc e s o di e en sizes depending on he specimens [some examples o a io pedal disc diame e measu ed on he p ese ed specimens (in mm) / leng h o sphinc e measu ed on his ological sec ions (in mm) a e: 41/6.5, 30.4/ 3.5, and 21.5/3]. In gene al, he TAG ma e ial o M. imica i o a s udied by Fau in & Ba be (1999) eached la ge sizes han ha a ailable o his s udy om Snake Pi . Thus, in his case, he ela i e leng h o he muscula sphinc e could depend on he size o he specimen, and i s u ili y as di e en ia ing cha ac e should be aken wi h cau ion. Fig. 14. Ma ac is imica i o a Fau in & Ba be , 1989. P ese ed specimen (SZ (ANT-2141)). A) O al iew; B) la e al iew. Scale ba A-B: 15 mm. AB López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003)238 AB CD 239López-González e al. New eco ds on sea anemones. Zool. Ve h. Leiden 345 (2003) Wi h espec o he cnidae ypes, sizes and dis ibu ion, TAG and Snake Pi ma e ial ag ee in all ana omical pa s excep o he p esence (in Snake Pi specimens) o a a he - common/spo adic cnida p esen in he ac inopha ynx and mesen e ial ilamen s. Mo e- o e , his cnida (appa en ly a mic obasic p-mas igopho e in which he sha has a e y sho V-shaped end) has only been obse ed in wo o he ou examined specimens. In ou opinion he sligh mo phological di e ences be ween he ma e ial examined he e om Snake Pi and he o iginal desc ip ion based on specimens om TAG (Fau in & Ba be , 1999) does no jus i y a sepa a ion a speci ic le el. Concluding ema ks Wi h he p esen eco ds included, eigh sea anemone species ha e been epo ed om hyd o he mal en s, wo species in he A lan ic [Pa asicyonis ingol i (Snake Pi ) and Ma ac is imica i o a (TAG and Snake Pi -Elan)], and six species ha e been ound associa ed wi h Paci ic hyd o he mal si es - wo o hem iden i ied only a gene ic le el - [Ac inos ola sp., Chond ophellia co ona a, Phelliac is sp., Cyanan hea hyd o he mala (all ou species a 12º48’N-103º56’W, 2630-2635 m), Ma ianac is by hios (Ma iana back- a c Basin), and Pa an hosac is denha ogi (Guaymas Basin)]. Conside ing he ecen col- lec ions, ou sea anemone species a e now known om cold seeps - wo o hem iden i ied only a gene ic le el - [Monac is es i a (Ba bados p ism), S omphia sp. (Mon- e ey Bay), Pa ac inos ola sp. (Mon e ey Bay), and Hadalan hus a . knudseni (MAT)]. Doumenc & an P aë (1988) epo ed he s udied ma e ial collec ed du ing he F ench Biocya he m c uise om EPR, 11ºN, 2000 m dep h. Howe e , he o iginal iles o ha c uise place he sampled si es in EPR, 12º48’-49’N-103º56’, 2630-2635 m dep h. Taken in o accoun he possible mis ake, we ha e used in he p esen pape he o igi- nal sampling da a (Desb uyè es e al., 1982). Acco ding o he opinion o Doumenc & an P aë (1988), no all epo ed sea anemones could be s ic ly conside ed ela ed o hyd o he mal si es. This is also applicable o cold seeps. Those species p esen in he pe iphe y o he en s (such as Ac inos ola sp., Chond ophellia sp., and Phelliac is sp.) a e well known ep esen a i es o non- en deep sea auna (e.g. Doumenc, 1975). Howe e , o he ac inia ians local- ly o m dense beds, some imes placed di ec ly on he chimneys o on oxidized sul- phide a eas su ounding black smoke s (such as Cyanan hea hyd o he mala, Ma ianac- is by hios, and Ma ac is imica i o a). The knowledge o sea anemones in hyd o he mal si es and cold seeps is ecen , G assle (1986) epo ed ha sea anemones a e common in he icini y o hyd o he mal en s bu none has been desc ibed ye . Du ing he las 15 yea s, 12 species ha e been desc ibed ( ou o hem a gene ic le el) om chemoau o ophic en i onmen s (7 species om hyd o he mal en s and 5 species om cold seeps). E en wi h he eno - mous e o s o he deep sea c uises, he numbe o known species is low in spi e o Fig. 15. Ma ac is imica i o a Fau in & Ba be , 1989. A) c oss sec ion a s omodaeum le el; B) longi udi- nal sec ion o he ma ginal sphinc e ; C) c oss sec ion o a en acle; D) de ail o he ec ode mal longi u- dinal muscula u e o a en acle. Abb e ia ions: 1, pai o mesen e ies o he i s cycle; 2, pai o mesen e ies o he second cycle; 3, pai o mesen e ies o he hi d cycle; 4, pai o mesen e ies o he ou h cycle; em, ec ode mal longi udinal muscula u e; ep, epide mis; ga, gas ode mis; me, mesogloea; sph, sphinc e . Scale ba s: A, 0.5 mm; B, 2 mm; C, 0.4 mm; D, 0.2 mm. 