Biogeography of Antarctic sea anemones (Anthozoa, Actiniaria): What do they tell us about the origin of the Antarctic benthic fauna?

Estefanía  Rodríguez; Pablo López-gonzález

The present paper provides a complete zoogeographical analysis of the sea anemones (Actiniaria and Corallimorpharia) of continental Chile. The species described in the primary literature are listed, including depth and distribution records. Records and the taxonomic status of many eastern South Pacific species are doubtful and need revision and confirmation. Since 1994, we have collected more than 1200 specimens belonging to at least 41 species of Actiniaria and Corallimorpharia. We sampled more than 170 sites along the Chilean coast between Arica (18°30’S, 70°19’W) and the Straits of Magellan (53°36’S, 70°56’W) from the intertidal to 40 m depth. The results of three recent expeditions to the Guaitecas Islands (44°S) and the Central Patagonian Zone (48°-52°S) are included in this study. In the fjord Comau, an ROV was used to detect the bathymetrical distribution of sea anemones down to 255 m. A distribution map of the studied shallow water sea anemones is given. The northern part of the fjord region is inhabited by the most species (27). The results show the continuation of species characteristic for the exposed coast south of 42°S and the joining of typical fjord species at this latitude. This differs from the classical concept of an abrupt change in the faunal composition south of 42°S

Species of the genus Actinostola are known for high variability of features. Anatomy, histology and cnidae of type specimens of five species from South America and Antarctica originally described as members of Actinostola and one species of Stomphia were compared to specimens of Actinostola chilensis collected during this study. None of these traditionally used features clearly distinguish the examined Actinostola species. I therefore propose new distinctive taxonomic features, including in vivo and in situ data. I provide an emended diagnosis of the genus Actinostola and a revised list of its species. I accept the synonymy of A. excelsa, A. pergamentacea and A. intermedia with A. crassicornis, and reject the synonymy of A. chilensis with A. crassicornis and A. intermedia. I re-describe A. chilensis in detail, including in situ information. Specimens of A. chilensis inhabit exposed positions of rocky substrate from 22 m depth down in south Chilean fjords between Puerto Montt (41 35 ¢35 ¢¢S, 72 53 ¢W) and Puyuhuapi (44 31 ¢36 ¢¢S; 72 32 ¢6 ¢¢W); the most conspicuous features are its relatively large size, bright-orange colour, smooth, tough column and numerous and clearly entacmaeic tentacles.

ARTICLE IN PRESS Deep-Sea Research II 54 (2007) 1876–1904 www.elsevier.com/locate/dsr2 Biogeography of Antarctic sea anemones (Anthozoa, Actiniaria): What do they tell us about the origin of the Antarctic benthic fauna? E. Rodrı́gueza,, P.J. López-Gonzáleza, J.M. Gilib a Biodiversidad y Ecologı´a de Invertebrados Marinos, Departmento de Fisiologı´a y Zoologı´a, Facultad de Biologı´a, Universidad de Sevilla, Reina Mercedes 6, 41012 Sevilla, Spain b Departamento de Biologia Marina i Oceanografia, Institut de Ciències del Mar, CMIMA (CSIC), Passeig Marı´tim de la Barceloneta 37-49, 08003 Barcelona, Spain Accepted 6 July 2007 Available online 3 August 2007 Abstract The present study of the biogeography of the Antarctic sea anemone fauna is based on new records and redescriptions of material collected from the Weddell Sea and Peninsula Antarctica, and on an update of the bibliographic data of the Antarctic and sub-Antarctic regions. The faunal compositions at different levels, the geographic and bathymetric distributions of the sea anemone fauna, and the afﬁnities within the continent and with the sub-Antarctic fauna have been studied. Furthermore, the relationships of the sea anemone fauna, of the Southern Ocean, the Mediterranean Sea and Hawaii have been analysed. In this context, the origin of the Antarctic benthic fauna is discussed. r 2007 Elsevier Ltd. All rights reserved. Keywords: Biogeography; Sea anemones; Actiniaria; Corallimorpharia; Antarctica; Southern Ocean 1. Introduction General patterns of Antarctic benthic distribution have been described as essentially circumpolar (Arntz et al., 1994; and references therein). New studies have conﬁrmed these patterns and have reinforced the distinction between the western (including Bellingshausen Sea, Weddell Sea and Corresponding author. Current address: Department of Evolution, Ecology and Organismal Biology, Ohio State University, 1315 Kinnear Road, Columbus, OH 43212, USA. Tel.: +1 614 688 3974; fax: +1 614 292 7774. E-mail addresses: fani@us.es, rodriguez.292@osu.edu (E. Rodrı́guez). 0967-0645/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.dsr2.2007.07.013 the Antarctic Peninsula with the Scotia Arc and Bouvet islands) and eastern (from the Weddell Sea to the Ross Sea) Antarctic faunas (De Broyer and Jazdzewski, 1996; Barnes and DeGrave, 2000; Clarke and Johnston, 2003). Studies of some groups of polychaetes, isopods, and cumaceans, have shown faunal differences among these regions and have indicated that the Magellan fauna may resemble that of the Antarctic Peninsula fauna more than that of the Weddell Sea (Brandt et al., 1997, 1998; Montiel et al., 2005). In contrast, however, the caprellid fauna of the Southern Ocean shows different patterns of distribution although the limited records available make generalizations ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 difﬁcult in terms of biogeography (De Broyer et al., 2004). In sub-Antarctic waters, caprellids show 2 groups of species. One group is exclusively present in the sub-Antarctic islands of New Zealand and another group that is only present in the Magellan region (De Broyer et al., 2004). The polychaete fauna of the Magellan Province suggests a subdivision into a Paciﬁc and Atlantic sectors, with an overlap of only 10% of the species (Montiel et al., 2005). On the other hand, most Magellan nudibranch species are found in both Chilean and Argentinean coastal waters (Schrödl, 2003). The number of Magellan shelled gastropods and nudibranch species shared with the Antarctic region is low (Linse, 2000; Schrödl, 2003), although the number of Magellan bivalves species shared with waters south of the Polar Front is higher (Linse, 2000). One hundred and twenty-three nominal species of Antarctic and sub-Antarctic actiniarians and corallimorpharians (excluding the Chilean and Argentinean fauna) have been described since sampling began all around the continent (e.g., Hertwig, 1882a, b; McMurrich, 1893; Carlgren, 1927, 1928, among others). Based on her study of sea anemone material from the United States Antarctic Research Programme (USARP) collections, Fautin (1983 as Fautin Dunn, 1984) estimated the Antarctic and sub-Antarctic fauna of actiniarians and corallimorpharians to comprise 85 valid species. There have been only a few publications including remarks on the biogeography of Antarctic sea anemones (Pax, 1926; Carlgren, 1927, 1928; Dell, 1972) although several have been dealing with different areas of the sub-Antarctic region (Sebens and Paine, 1978, Häussermann and Försterra, 2005 for the Chilean coast; Riemann-Zürneck, 1986, Zamponi and Acuña, 1991 and Zamponi et al., 1998b for the South Atlantic coast). Carlgren (1927) reviewed the literature of Antarctic and sub-Antarctic regions summarizing the described species and the localities where they were found, but did not discuss the biogeography of the fauna, although he considered South Georgia as a transitional area between sub-Antarctic and ‘‘pure’’ Antarctic regions. Additionally, Carlgren (1927) criticized the taxonomic rigour of species descriptions by Pax, and cautioned that Pax’s (1926) biogeographic conclusions should be examined carefully. Carlgren (1928) listed 31 species from Antarctic waters (7 of them also present outside of the Antarctic region), but considered the Antarctic 1877 region more restricted than in the present work (e.g., he did not include South Georgia and Bouvet Island within this region). From those Antarctic species he listed, Carlgren (1928) considered 1 species cosmopolitan, 5 species with circumpolar distribution, 9 conﬁned to South Georgia, 2 species restricted to Bouvet Island, 22 species conﬁned to East Antarctica (absent from the Atlantic area of the Antarctic region), and 2 species conﬁned to West Antarctica. He listed 19 species present in the different sub-Antarctic islands (Carlgren, 1928); however, his interpretation of the limits of the sub-Antarctic region differs from those used by other authors. Furthermore, limited knowledge of the Magellan region made it difﬁcult to draw clear conclusions (Carlgren, 1928). The sampling effort in East and West Antarctica and in the Magellan region has improved considerably since that time. The recent results render Carlgren’s (1928) view of the distribution of the Antarctic sea anemone fauna dated, although it remains the most comprehensive work to date. Dell (1972) reviewed the knowledge on these benthic organisms, but this was basically a summary of Carlgren’s (1928) work, and it included some mistakes: Carlgren listed 22 species (not 19) present in East Antarctica (not West Antarctica). Fautin (1983 as Fautin Dunn, 1984) provided data on the distribution of the species she studied, but did not discuss other species, or make general conclusions. Riemann-Zürneck (1986) studied the distribution of 19 species of the sea anemone fauna of the Argentinean continental shelf and concluded that the actiniarian fauna located immediately near and beneath the Subtropical Front (35–381S) has a mixed sub-Antarctic/Antarctic character, with species typically permanent for the hydrographic fronts (Riemann-Zürneck, 1986). Zamponi and Acuña (1991) studied the sea anemone fauna of the Atlantic Magellan Province and concluded that the composition of the Magellan fauna differed from that of the northern Argentinean coasts, with little faunal overlap. The study of the South American Atlantic shallow sea anemone fauna suggested that the estuary of the Rio de la Plata represents a clear distributional barrier (Zamponi et al., 1998b). In their study on the distribution patterns of Chilean shallow-waters sea anemones, Häussermann and Försterra (2005) suggested that the Taitao Peninsula (47–481S) is a biogeographic barrier (at least for shallow water species), and they ARTICLE IN PRESS 1878 E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 recognized a division between the Paciﬁc and Atlantic section of the Magellan Province (with an overlap of 10–22%). Furthermore, they estimated the percentage overlap of the sea anemone fauna between the South East Paciﬁc and Antarctic region to be between 8% and 14% (Häussermann and Försterra, 2005). Several new species have been described and new records and some synonymies have been detected for many Antarctic sea anemones (Rodrı́guez and López-González, 2001, 2002, 2003, 2005). We update accounts of the Antarctic sea anemone fauna and analyse its distribution patterns. We review the sub-Antarctic sea anemone fauna and compare it with the Antarctic fauna. The distribution patterns found for Antarctic and sub-Antarctic sea anemones are compared with what is known for other benthic Antarctic taxa. 2. Material and methods 2.1. Data compilation The data compilation used in the present study is based upon a bibliography revision and new records and redescriptions of material collected from Ecology of Antarctic shelf ice zone (EASIZ) and Antarctic Benthic Deep-sea Biodiversity (ANDEEP) cruises. The Antarctic and sub-Antarctic actiniarian and corallimorpharian species considered is this work are listed in Table 1. We have excluded the following 9 species from the afﬁnity analysis since their status is uncertain: Actinernus elongatus sensu Fautin (1984): the material described as A. elongatus by Fautin (1984) does not correspond to the type material of A. elongatus described by Hertwig (1882a, b). In our opinion, Fautin’s (1984) material might include more than 1 species (and part of it might be a synonym of Actinernus sp. nov. 2). Actinothoe lobata (Carlgren, 1899): the taxonomic status of this species remains uncertain as the synonymizations and the presence of the species has not been conﬁrmed (Häussermann and Försterra, 2005). Actinostola intermedia (Carlgren, 1899): the taxonomic status of this species remains uncertain pending a detailed revision of the austral species of the genus. Actinostola clubbi (Carlgren, 1927): the only available specimen (the holotype) does not allow us establish whether the variability shown is constant enough to be considered as a distinct species; the taxonomic status of this species remains uncertain until new material recalling the original description is collected. Hormathia insignis (Stephenson, 1918): although the type material of the species has yet to be reexamined, this species is probably synonymous with Hormathia lacunifera (Stephenson, 1918). Bunodactis hermaphroditica (McMurrich, 1904), Bunodactis elongata (McMurrich, 1904) and Bunodactis eydouxii (Milne Edwards, 1857): after the redeﬁnitions of the genera Bunodactis and Aulactinia (England, 1987) followed in the present work it is necessary to review most of the species of the genus to know their validity and their correct generic placement. Bunodes maclovianus (Lesson, 1830): the use of the genus name Bunodes is currently not considered valid for the order Actiniaria (Neave, 1939; Dunn et al., 1980). The type material of this species has to be reexamined to ﬁnd out the validity and correct placement of the species. Distribution, bathymetry, and references of all the species considered in the present study are shown in Table 1. 2.2. Geographic scope In the present study, the Southern Ocean is considered to include all regions south of the Subtropical Front Zone to the coasts of the Antarctic continent (Deacon, 1982; De Broyer et al., 2004) (Fig. 1). Based on the benthic species distribution pattern, the Southern Ocean is classically divided in 2 main biogeographic regions (Hedgpeth, 1969, 1970; Dell, 1972; Knox and Lowry, 1977; De Broyer and Jazdzewski, 1993; De Broyer et al., 2004). We have accepted these for the present study. The Antarctic region comprises waters from the coast of the continent northwards to the Antarctic Polar Front (formerly the Antarctic Convergence). The subAntarctic region comprises waters northwards from the Polar Front (varying around 40–551S) to the Subtropical Front (varying around 301S). Around South America we have considered the northern limit of the sub-Antarctic region to be the northern boundary of the Magellan Province, because of the assumed biogeographic barriers (or at least a transitional change in faunistic composition) for benthic invertebrates (Häussermann and Försterra, 2005 and references therein). Different groups of Table 1 Distribution of the Southern Ocean actiniarian and corallimorpharian species by sectors Species Antiparactis lineolatus (Couthouy in Dana, 1846) Artemidactis victrix Stephenson, 1918 Aulactinia octoradiata (Carlgren, 1899) (d) Aulactinia patagoniensis (Carlgren, 1899) Aulactinia marplatenses (Zamponi, 1977) Aulactinia reyinaudi (Milne Edwards, 1857) Austroneophellia luciae Zamponi, 1978a, b Bathydactylus valdiviae Carlgren, 1928 Bathyphellia australis Dunn, 1983 Bolocera kerguelensis Studer, 1879 III II IV L-Ls-S L V VI S-S S VII S Ss L H H S S-Ss L Ss Ls Ss Ss* Ss S*-Ss S S Ss Ss-L-Ls Ss* S* Ss-L-LsL-Ls Ss-L-LLs Ss Ss Ss H S* H H H H Ss-S* S-Ss Ss* L-H A-SBA SBA ANT SBA ANT ANT A-SBA SBA SBA ANT SBA ANT SBA SBA-O SBA-O SBA SBA SBA-O 584–3001 100 2538 4732 123–2856 (1, 2, 56) (21) (3) (4) 606–3876 22–37 18–1220 250–567 9–88 – – 3797–3800 415–667 2852–2856 2852–2856 36 398–816 2912 2–216 (1, 5) (17, 21, 68) (1, 4, 6, 7, 8, 9, 11, 69) (8) (12) (7, 13) (14) (7, 8, 75) (21, 24) (1, 82) (4) (15, 4) 277–293 250–310 100 0 (69,78) Ss-Ss* A-S-O 2–327 Ss-Ss* Ss*-Ss SBA-O ANT A-S-O – 350–385 36–65 Ss-Ss* SBA-O 1–89 (1, 4, 5, 7, 8, 16, 17, 18, 19, 20, 21, 22, 23, 24) (7, 8, 72) (14) (17, 21, 24, 25, 26, 27, 28, 29) (1, 16) A-SBA 75–437 200–659 (8, 30, 31, 32) Ss A-SBA 1–1120 151–911 (2, 7, 8, 19, 21, 24, 31, 33) Ss SBA SBA SBA-O SBA ANT A-SBA A-SBA – – – – 4636 3200–4575 45–3642 200–3947 (7, 8) (64, 69, 75) (38, 64, 69,) (69,76) (12) (2) (1, 2, 4, 12, 21, 30, 34, 35) SBA-O – (64, 69) SBA – (17,72) S* L S-SsL-H References SBA L S-L-Ls-L OBS depth Ss H Ss*-Ls Depth VIII S L L S-L-L Ss S-Ss-S L-L Bio-cat S-L S-Ss-LLs-H Ss* Ss 1879 Boloceroides mcmurrichi (Kwietniewski, 1898) (*) Boloceropsis platei McMurrich, 1904 I Paciﬁc district ARTICLE IN PRESS Anthopleura hermaphroditica (Carlgren, 1899) Anthosactis epizoica (Pax, 1922) Anthothoe chilensis (Lesson, 1830) Indian district E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 Actinauge verrillii McMurrich, 1893 (a) Actinauge chilensis Carlgren,1959 Actinernus antarcticus (Carlgren, 1914) Actinernus elongatus Hertwig (1882) (b) Actinernus sp. nov. 1 Actinernus sp. nov. 2 Actinoscyphia plebeia (McMurrich, 1893) Actinostola chilensis McMurrich, 1904 Actinostola crassicornis (Hertwig, 1882a, b) Actinostola georgiana Carlgren, 1927 Actinostola kerguelensis Carlgren, 1928 Actinothoe georgiana (Carlgren, 1899) Actinothoe kerguelensis (Pax, 1922) Actinothoe patagonica (Carlgren, 1899) Aiptasiomorpha elongata Carlgren, 1951 (*) Amphianthus lacteaus (McMurrich, 1893) (c) Amphianthus minutus (Hertwig, 1882a, b) Anemonactis clavus (Quoy and Gaimard, 1833) Anemonia chubutensis Zamponi and Acuña, 1992 Antholoba achates (Drayton in Dana, 1846) Atlantic district 1880 Table 1 (continued ) Species Cactosoma aspera Stephenson, 1918 Cactosoma chilensis (McMurrich, 1904) Capnea georgiana (Carlgren, 1927) Edwardsia intermedia McMurrich, 1893 Edwardsia meridionalis Williams, 1981 Edwardsiella ignota (Carlgren, 1959) Eltaninactis infundibulum Dunn, 1983 Epiactis georgiana (Carlgren, 1927) Galatheanthemun profundale Carlgren, 1956 Glyphoperidium bursa Roule, 1909 Glyphostylum calyx Roule, 1909 Gonactia prolifera (Sars, 1835) (*) Halcampa abtaoensis Carlgren, 1959 Halcampa kerguelensis Hertwig, 1888 Halcampa octocirrata Carlgren, 1927 Halcampella fasciata Rodrı́guez and LópezGonzález, 2002 Halcampella robusta Carlgren, 1931 Halcampoides abyssorum Danielssen, 1890 (*) Halcampoides kerguelensis Pax, 1922 Halcampoides purpurea (Studer, 1879) (*) Halcurias pilatus McMurrich, 1893 Haliactis arctica Carlgren, 1921(*) Halianthella kerguelensis (Studer, 1879) Hormathia armata Rodrı́guez and LópezGonzález, 2001 I III II IV Paciﬁc district V VI VII Bio-cat Depth L-H S H H S-Ss-LLs Ss H ANT SBA A-SBA 404–438 – 140–2186 Ss Ss SBA-O SBA 40 1–20 (36, 75) (8, 16) S-Ss A-SBA 74–800 (7, 8, 14, 17, 36) SBA SBA-O ANT SBA SBA A-SBA A-SBA SBA-O SBA-O A-SBA – 0–22 25–200 0–3 1–500 30–3685 274–4429 1–100 1–40 25–610 214–343 (14) (17, 21, 72) (8, 13, 33) (10) (7, 8, 12, 38) (1, 5, 31, 37, 39) (4, 5, 6, 12, 31, 39, 41) (1, 8, 17, 73) (21, 61,73) (2, 30, 42, 43, 44, 45) Ss A-SBA ANT SBA A-S-O A-SBA 1–300 7–500 40–60 769–2668 36–2580 804–930 118–1227 (1, 8, 21, 46) (46, 47) (21, 24) (2) (2, 8, 31, 47, 48) S-L Ls A-S-O ANT 3947–10190 18–1890 4060–4975 94–930 Ls Ss-Ss* Ss ANT SBA-O SBA SBA ANT ANT 25 30–100 – 45–231 75 SBA A-SBA SBA A-SBA SBA ANT SBA ANT – 45–420 – 11–360 816 375–385 0–73 S Ss-Ss* Ls H Ss S-Ss L-Ls-L H L S S S S-L-H S S Ss-Ss* Ss-Ls-L H L-LsH Ls Ss S S Ss-Ss* Ss-Ss* Ss-L-Ls S-Ss H Ss L-L L-Ls-LLs L-L L-Ls LLs L-H L L-LsLs-H L H L-H S* H L S* L-H L S-Ss Ls L H S L S-Ss Ss Ss L-Ls S L Ss L H Ss References 182–2228 (30) (17, 21, 24) (2, 4, 8, 31) VIII H L-Ls-LLs Ss-Ss* OBS depth 278–589 4646–4648 353–864 (2, 49) (2, 8, 12, 13, 14, 19, 31, 50) (50) (21) (21) (6) (8) (51) 65–454 (85) (4, 14) (14) (8, 12, 34) (1) (52) (12, 14, 31, 34, 53) (54) ARTICLE IN PRESS Choriactis subantarctica Pax, 1922 Cereus herpetoides (McMurrich, 1904) Cnidanthus polaris (Clubb, 1908) Condylanthus aucklandicus Carlgren, 1924 Condylanthus magellanicus Carlgren, 1899 Corallimorphus profundus Moseley, 1877 Corallimorphus rigidus Moseley, 1877 (e) Corynactis carnea Studer, 1879 Corynactis chilensis Carlgren, 1941 Dactylanthus antarcticus (Clubb, 1908) (f) Indian district E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 Carcinactis dolosa Riemann-Zürneck, 1975 Choriactis impatiens (Couthouy in Dana, 1846) Choriactis laevis (Carlgren, 1899) Atlantic district Hormathia lacunifera (Stephenson, 1918) Hormathia pectinata (Hertwig, 1882a, b) Hormathia spinosa (Hertwig, 1882a, b) (*) Hormosoma scotti Stephenson, 1918 Isophellia madrynensis Zamponi and Acuña, 1992 Isosicyonis alba (Studer, 1879) L-H S-L L-H L-Ls-L A-SBA 15–3020 S-Ss 50-1220 3549 16–769 0 H S-Ss-LLs-L-Ls H S-Ss L L-Ls-S L-L H H Ls Ss H Ss-H-L A-SBA 38–800 ANT A-SBA ANT A-SBA A-S-O 140–505 4636 22–507 124–3660 SBA-O SBA SBA SBA-O SBA – 0 50–60 0 0 (75) (69,79) (21,24) (65, 69, 80) (69,78) Ss SBA SBA 36 0 (8) (69, 11) S*-Ss SBA-O 0–17 Ss-Ss* ANT SBA-O 0–30 0–3 (8, 13, 14, 16, 17, 19, 21, 34, 61) (8, 13, 62) (17,72,73) A-SBA SBA-O SBA-O SBA-O A SBA SBA-O 420 109 0 – 567 100 800 (12, 14) (7, 8) (21, 24, 72) (70) (12) (8, 17, 36) (56, 75) SBA-O SBA-O SBA SBA A-S-O SBA-O SBA 2786–2843 800–1000 17–60 9–18 5–80 6–7 – (75, 82) (56, 75) (8) (12) (25, 58, 64, 65, 66,69) (26, 72, 74) (17, 69) ANT SBA ANT SBA ANT SBA SBA – 385 – 1–2 273 2912 H L S-Ss L S* S S*-LLs Ss Ss Ss Ss Ss* Ss* Ss Ss Ss Ss Ls Ss L S* Ss-Ss* Ss S L Ss S* S S-S* Ss Ss S S* Ss Ls Ss* Ss L Ss H H (h) H S Ls S S Ss Ss-Ss* Ss 166–318 94–928 253–338 567–574 2853–2856 3797–3800 (1, 4, 21, 55, 56) (4) (2, 8, 14, 31, 42) (69, 78) (5, 8, 25, 35, 34, 57, 58) (7, 8, 21, 35) (12, 60) (8, 25, 48) (2, 4, 6, 12, 38) 243–337 (69, 77) (14) (69, 77) (8, 62) (4) (4) ARTICLE IN PRESS Ss Ss (2, 8, 14, 30, 31, 37) SBA SBA ANT SBA S L-Ls-L 62.4–1227 1881 Monactis vestita Gravier, 1918 (*) Neoparacondylactis haraldoi Zamponi, 1974 Octineon chilense Carlgren, 1959 Oulactis mucosa (Drayton in Dana, 1846) Parabunodactis imperfecta Zamponi and Acuña, 1992 Parahalcampa antarctica Carlgren, 1927 Paraisometridium pehuensis Zamponi, 1978a, b Parantheopsis cruentata (Couthouy in Dana, 1846) Parantheopsis georgiana (Pfeffer, 1889) Parantheopsis ocellata (Drayton in Dana, 1846) Parantheopsis vanhoeffeni (Pax, 1922) Paranthus crassa (Carlgren, 1899) Paranthus niveus (Lesson, 1830) (*) Peachia hastata Gosse, 1855 (*) Phellia dubia (Carlgren, 1928) Phellia exlex (McMurrich, 1904) Phelliactis lophophelia Riemann-Zürneck, 1973 Phelliactis michaelsarsi Carlgren, 1934 (*) Phelliactis pelophila Riemann-Zürneck, 1973 Phelliogeton falklandicus Carlgren, 1927 Phelliogeton kerguelensis Carlgren, 1928 Phlyctenanthus australis Carlgren, 1949 Phymactis papillosa (Lesson, 1830) Pseudoparactis tenuicollis (McMurrich, 1904) (g) Pycnanthus sp. nov. Ramirezia balsae Zamponi, 1979 Sagartia minima Pax, 1922 Sagartianthus fasciarum Zamponi, 1979 Scytophorus antarcticus (Pfeffer, 1889) Scytophorus striatus Hertwig, 1882a, b Sicyonis crassa Hertwig, 1882a, b L-H E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 Isosicyonis sp. nov. Isotealia antarctica Carlgren, 1899 Kadosactis antarctica (Carlgren, 1928) Limnactinia nuda Carlgren, 1927 Liponema multipora Hertwig, 1882a, b S-L-LsL-Ls S 1882 Table 1 (continued ) Species Sicyonis erythrocephala (Pax, 1922) Sphincteractis sanmatiensis Zamponi, 1976 (i) Stephanthus antarcticus Rodrı́guez and LópezGonzález, 2003 Stomphia selaginella (Stephenson, 1918) Indian district I II III L-S Ls L L L-Ls LLs L L-LsH IV Paciﬁc district V VI S H H L-H H S S-Ss* H H VII Bio-cat Depth A-SBA A-SBA ANT 261–3867 36–199 ANT 9–1674 ANT SBA SBA-O ANT 380–420 3276 0 6–45 OBS depth References 256–1227 (5, 8, 14, 19, 31,82) (25, 67, 81) (59) 122–1026 (5, 14, 19, 30, 31, 37) VIII H-S Ss L-Ls (8, 14) (4) (69, 83, 84 ) (8, 42) ARTICLE IN PRESS Nomenclature and abbreviations: Bio-cat: biogeographic category; Depth: depth, data from literature; OBS depth: observed depth, data from the present study; H: high Antarctic region, continental shelf zone (p1000 m); L: low Antarctic region, off the continent X200 m (islands continental shelf area), near the continent X1000 m (outside continental shelf); Ls: low Antarctic region continental shelf area, (off the continent, islands, p200 m); S: sub-Antarctic region (X200 m); Ss: sub-Antarctic region, continental shelf area (p200 m). S*: outside Southern Ocean (X200 m); Ss*: outside Southern Ocean, continental shelf area (p200 m). Species from the present study indicate in bold letters. Italic letters indicate records from the present study. (*) Bipolar spp., type locality in the north hemisphere, only south hemisphere records; (a) Actinauge verrillii s. st., only records from the south hemisphere; (b) only type material Actinernus elongatus (Hertwig, 1882a, b); (c) Identiﬁcation of Argentinean species uncertain (Riemann-Zürneck, 1986); (d) new combination name (Rodrı́guez and López-González, in preparation); (e) cosmopolitan spp.; only records from south hemisphere; (f) presence data for sector II of the present study provided by underwater pictures; (g) Chilean record taxonomically uncertain (Häussermann, pers. comm.); (h) record from present study; (i) probably synonymous of Corynactis carnea (Riemann-Zürneck, 1986). References: (1) McMurrich, 1893; (2) Dunn, 1983; (3) Carlgren, 1914; (4) Hertwig, 1882a, b; (5) Fautin, 1984; (6) Hertwig, 1888; (7) Carlgren, 1899; (8) Carlgren, 1927; (9) Riemann-Zürneck, 1978; (10) Carlgren, 1924; (11) Zamponi, 1978b; (12) Carlgren, 1928; (13) Carlgren, 1930; (14) Pax, 1922; (15) Quoy and Gaimard, 1833; (16) Dana, 1846; (17) McMurrich, 1904; (18) Rees, 1913; (19) Carlgren, 1939; (20) Parry, 1952; (21) Carlgren, 1959; (22) Acuña et al., 2003; (23) Excoffon and Zamponi, 1995; (24) Sebens and Paine, 1978; (25) Zamponi et al., 1998a; (26) Lesson, 1830; (27) Acuña et al., 2001; (28) Excoffon et al., 1999; (29) Acuña et al., 2004; (30) Stephenson, 1918; (31) Carlgren and Stephenson, 1929; (32) Cramer et al., 2003; (33) Clubb, 1902; (34) Studer, 1879; (35) Riemann-Zürneck, 1980; (36) Riemann-Zürneck, 1975; (37) Grebelny, 1975; (38) Carlgren, 1938; (39) Moseley, 1877; (40) Riemann-Zürneck and Iken, 2003; (41) Carlgren, 1943; (42) Clubb, 1908; (43) Carlgren, 1911; (44) England and Robson, 1984; (45) Dayton et al., 1997; (46) Daly, 2002; (47) Williams, 1981; (48) Excoffon and Acuña, 1995; (49) Carlgren, 1956; (50) Roule, 1909; (51) Rodrı́guez and López-González, 2002; (52) Carlgren, 1921; (53) Carlgren, 1901; (54) Rodrı́guez and López-González, 2001; (55) Genzano et al., 1996; (56) Riemann-Zürneck, 1973; (57) Ridley, 1882; (58) Carlgren, 1949; (59) Rodrı́guez and López-González, 2003; (60) Rodrı́guez and López-González, 2005; (61) Carlgren, 1941; (62) Pfeffer, 1889; (63) Carlgren, 1950; (64) Zamponi, 1977; (65) Cutress, 1971; (66) Pastorino, 1993; (67) Zamponi, 1976; (68) Häussermann, 2004a; (69) Zamponi et al., 1998b; (70) Acuña, 1996; (71) Häussermann and Försterra, 2001; (72) Häussermann and Försterra, 2005; (73) Carter Verdeilhan, 1965; (74) Häussermann, 2004b; (75) Zamponi and Acuña, 1991; (76) Zamponi, 1978a; (77) Zamponi, 1979; (78) Zamponi and Acuña, 1992; (79) Zamponi, 1974; (80) Acuña and Zamponi, 1999; (81) Acuña and Zamponi, 1995; (82) Riemann-Zürneck, 1986; (83) de Oliveira Pires, 1987; (84) Pires, 1988; (85) Carlgren, 1931. E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 Tealianthus pachyderma (Pax, 1922) Tealidium cingulatum Hertwig, 1882a, b Trinidactis errans de Oliveira Pires, 1987 Urticinopsis antarctica (Verrill, 1922) Atlantic district ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 1883 Fig. 1. Map of the Southern Ocean showing the main biogeographic subdivisions. Black and grey lines around the continent indicate the Subtropical and Polar Fronts, respectively. Roman numbers indicate longitudinal sectors deﬁned for the present study (delimited by thicker lines). Arabic numbers in brackets indicate the percentage of shared species between the Atlantic, Indian and Paciﬁc districts. Dot lines indicate different districts. islands distributed around the Antarctic continent in the marine zone between the Antarctic Polar Front and the Subtropical Front have been included in the sub-Antarctic region: New Zealand subAntarctic islands, Macquarie, Kerguelen, Herad and McDonald, Crozet, Prince Edward and Marion. Tristan da Cunha and Gough Island also are considered to be sub-Antarctic (Hedgpeth, 1969, 1970). Furthermore, some smaller districts are recognized as the high and low Antarctic regions, East and West Antarctica in the Antarctic region, and the Magellan district in the sub-Antarctic region (Dell, 1972; De Broyer and Jazdzewski, 1996; Barnes and DeGrave, 2000; Clarke and Johnston, 2003; De Broyer et al., 2004). According to the 2 geographic zones considered above, we have deﬁned the following 5 biogeographic categories for sea anemones included in the present study: ANT (species exclusively present in the Antarctic region), SBA (species exclusively present in the sub-Antarctic region), A-SBA (species present in both the Antarctic and sub-Antarctic regions), SBA-O (species present in and outside the sub-Antarctic region), A-S-O (species present in both the Antarctic and sub-Antarctic regions and outside of them). The study area has been divided for practical comparative purposes into 8 biogeographic sectors (sectors from I to VIII, shown in Fig. 1). These again were grouped into 3 main districts: the South Atlantic district (comprising sectors I–II), the Indian district (comprising sectors III–V), and the Paciﬁc district (comprising sectors VI–VIII). The subdivisions for the deﬁned sectors were chosen according to areas corresponding to zones (as Weddell Sea, Ross Sea, Davis Sea, Scotia Arc Islands, y) recognized by earlier research cruises. 2.3. Bathymetric scope Much of the Southern Ocean lies over deep-sea ﬂoor. The relatively narrow continental shelf of the ARTICLE IN PRESS 1884 E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 Antarctic region is characterized by the unusually great depth of the Antarctic shelf (with an average over 450 m and extending in some places to over 1000 m) (Clarke, 2003; Clarke and Johnston, 2003; Knox, 1994). Based on earlier studies (e.g., Clarke and Johnston, 2003; Linse, 2004; Linse et al., 2006), we consider the depth limit of the Antarctic continental shelf fauna at 1000 m depth. The Antarctic and sub-Antarctic regions have been divided according to the depth range as follows: High-Antarctic region [H]: Antarctic continental shelf (to 1000 m). Low-Antarctic region [L]: area southwards of the Polar Front to the Antarctic continental shelf. Within it, the following have been distinguished: [Ls] Low-Antarctic shelf area, including the shallower shelves around the different islands of the region—from 0 to 200 m, the depth of the continental shelf elsewhere (Walsh, 1988)—and [Ld] Low-Antarctic deep region, including those areas deeper than 200 m. Sub-Antarctic region [S]: area between the Polar Front and the Subtropical Front. Within it the following has been distinguished: [Ss] shelf zone (from 0 to 200 m) and [Sd] outside of the shelf zone (deeper than 200 m). Regions northwards the Subtropical Front are referred as [O], and also distinguished as shallow [Os] (to 200 m) or deep regions [Od] (deeper than 200 m). We have distinguished bathymetric categories within the context of the distinctions above, and considering the species in the different deﬁned areas. If a subindex is not speciﬁed in the bathymetric category, the species is present in the whole bathymetric range of the region (for example, a [HL] species is present in the High- and in the LowAntarctic regions, but in the later it is present above and bellow 200 m depth). The eurybathic or stenobathic nature of the Antarctic benthic shelf fauna can not be strictly compared with that in other continents or islands because of the unusual depth of the continental Antarctic shelf (Clarke, 2003). Furthermore, taxa of Antarctic shelf faunas generally present a wide bathymetric range (Brey et al., 1996). We have considered species with a bathymetric range less than 500 m stenobathic, while species with a wider bathymetric range (4500 m) have been considered eurybathic. 2.4. Latitudinal comparison of faunal composition The composition of the Antarctic sea anemone fauna has been compared with representative faunas from temperate and tropical areas (Mediterranean Sea and Hawaii, respectively). Data for the Mediterranean Sea are from Häussermann (2003); data for Hawaii region are from Häussermann (2006: http://www.Anthozoa.com). We have chosen these regions to compare different ecosystems and because of the availability of the data. We have used the percentage of the number of species (instead of the number of species) to avoid the inﬂuence of the size and different total number of species in the 3 selected areas. The representation of the families in each region is measured by the percentage of the number of genera within each family. The representation of the genera is measured by the number of species within each genus. The possible evolutionary history among the three selected areas is compared at the level of family and genus. 2.5. Classification analysis Faunistic resemblance between areas and biogeographic categories was measured by qualitative Bray–Curtis similarities (Bray and Curtis, 1957) of non-transformed presence/absence data. Clusters and non-metric multidimensional scaling (MDS) were applied to resemblance data to reﬂect similarities in a two-dimensional plane (PRIMER version 5). Nevertheless, only clusters are shown because of the clearer representation they provided in the analysis of these data, and the easily use of the B–C index value to compare the relationship between the different categories and areas considered in this study. 3. Results 3.1. Faunal composition of Antarctic and subAntarctic sea anemones We determine that the Southern Ocean actiniarian and corallimorpharian fauna includes 122 valid species (116 Actiniaria, 5 Corallimorpharia: Table 1). Of these, 28 (representing 23%) are endemic of the Antarctic region [ANT]. A total of 42 species, or 34% of the fauna, has been recorded exclusively from the sub-Antarctic region [SBA]. The Antarctic and sub-Antarctic regions share 22 species (18%) ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 1885 that have not yet been found outside of the Subtropical Front [A-SBA]. There are 24 species (20%) present in sub-Antarctic and outside of Southern Ocean waters [SBA-O]. Furthermore, there are 6 species (5% of the total) present in Antarctic, sub-Antarctic and outside of Southern Ocean waters [A-S-O]. According to these data, the 75% [92 spp. 28 spp. (23%) ANT, 42 spp. (34%) SBA, 22 spp. (18%) A-SBA] of the sea anemone species present in the Southern Ocean (Antarctic and sub-Antarctic regions) are reported exclusively from this biogeographic region. Half of the species in the Antarctic region [56 spp.: ANT, A-SBA, A-S-O], are endemic to that region. Fig. 2 summarizes the above data. The Southern Ocean fauna of sea anemones comprises 83 genera (80 actiniarian and 3 corallimorpharian genera). Forty-eight genera (58%) are distributed in the Antarctic region [6 gen. ANT, 6 gen. A-SBA, 36 gen. A-S-O]; 35 genera (42%) present in the Southern Ocean are only found north of the Polar Front [9 gen. SBA, 26 gen. SBA-O] (Fig. 3). Of the 48 genera in the Antarctic region [ANT, A-SBA, A-S-O], 36 (75%) are also reported from localities north of the Subtropical Front [A-SO], whereas only 12 genera (25%) are distributed only in the Southern Ocean [6 gen. ANT, 6 gen. A-SBA]. The sea anemone fauna in the Southern Ocean comprises six genera (7%) endemic to Antarctic waters [ANT] [Cnidanthus, Glyphoperidium, Glyphostylum, Hormosoma, Stephanthus and Tealianthus]. Fig. 2. Percentages of the different biogeographic categories of Southern Ocean sea anemone species. Fig. 3. Percentages of the different biogeographic categories of Southern Ocean sea anemone genera. ARTICLE IN PRESS 1886 E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 Nine genera (representing 11%: Austroneophellia, Boloceropsis, Condylanthus, Neoparacondylactis, Parahalcampa, Paraisometridium, Phelliogeton, Pseudoparactis and Ramirezia) are exclusively from the sub-Antarctic region [SBA]. Antarctic and subAntarctic regions [A-SBA] share six genera [Artemidactis, Choriactis, Dactylanthus, Isosicyonis, Scythoporus and Sphincteractis] representing 7%; 26 genera (representing 31%) are known only from waters north of the Polar Front [SBA-O]. Finally, 36 genera (43%) are present in Antarctic and sub-Antarctic regions and elsewhere out of the Southern Ocean [A-S-O] (Fig. 3). Therefore, 21 (25%) genera in the Southern Ocean [6 gen. (7%) ANT, 9 gen. (11%) SBA, 6 gen. (7%) A-SBA] are endemic to both Antarctic and sub-Antarctic regions. The other 62 genera (75%) are more widespread, found in the Southern Ocean and elsewhere [26 gen. (31%) SBA-O, 36 gen. (43%) A-S-O]. The majority of the 83 genera (59 gen. or 71%) present in the Southern Ocean are monotypic. The majority of the remaining 24 genera have few species [14 gen. with 2 spp., 5 gen. with 3 spp. and 5 gen. with 4 spp.]. The most specious genera are Actinernus, Actinostola, Aulactinia, Hormathia and Parantheopsis, with 4 species each. None of the 31 families in the Southern Ocean are endemic to the region. Only 10 (32%: Aiptasiomorphidae, Acontiophoridae, Boloceroididae, Condylanthidae, Goniactiniidae, Haliplanellidae, Halcuriidae, Isophelliidae, Metridiidae, Octineonidae) of these families are not found south of the Polar Front, in the Antarctic region. Five families [Actiniidae: 18 gen. (22%), Actinostolidae: 13 gen. (16%), Sagartiidae: 9 gen. (11%), Hormathiidae: 5 gen. (6%), Halcampoididae: 4 gen. (5%)] account for over 60% of the generic diversity in the Southern Ocean. These same 5 families comprise also 65% (with 25 spp., 18 spp., 14 spp., 12 spp., 10 spp., respectively) of the total number of species found in the Southern Ocean. 3.2. Faunal affinities 3.2.1. Affinities of the Antarctic and sub-Antarctic fauna The Antarctic and the sub-Antarctic faunas show 37% of similarity at the species level sharing a total of 22 species [A-SBA]. Antarctic and sub-Antarctic regions have a greater level of similarity (67%) at the generic level. 3.2.2. Southern Ocean in longitudinal sectors The similarity analysis among the different sectors (Fig. 1) show a cline in species number from the areas with a major sample effort (I, II, VI and VIII) to those areas with lower sample effort (III, IV and VII). Sectors VII and III, corresponding to the least studied areas, show the least resemblance with the rest of the sectors (similarity lower than 20%). Sectors VI and II show the highest similarity (bit less than 60%), and this pair was separated of sector V. Sectors I and VIII clustered together (similarity over 50%) (Fig. 4). Nearly 14% of the species (17 spp.) were present in the three main districts (Atlantic, Indian and Paciﬁc) deﬁned for this study, and these are thus considered to have a circumpolar distribution. The Atlantic district [sectors I and II] contains 30 unique species (25%); 17 species (14%) are unique to the Indian district [sectors III, IV and V]; 28 species (23%) are exclusively found in the Paciﬁc district [sectors VI, VII and VIII]. The Paciﬁc and Atlantic districts have the highest percent of shared species, having 21 species (17%) in common. In contrast, the Atlantic and Indian districts share 7 species (6%), whereas Indian and Paciﬁc districts share only 2 species (2%). The faunal afﬁnities of the Antarctic and subAntarctic regions have been analysed in greater detail. The 56 sea anemone species present in the Antarctic region [28 spp. ANT, 22 spp. A-SBA, 6 spp. A-S-O] show different distributions in the sectors deﬁned for the present study (see Fig. 5, Table 2). Within these 8 sectors, there are 2 groups: sectors III and VII, and sectors VI–VIII. Sectors III and VII show over 20% similarity, but this reﬂects shared absence rather than many species in common, as they share only the presence of 1 circumpolar species [Corallimorphus profundus]. Sectors VI–VIII have greater than 70% similarity, and seem to be grouped because they share about 20 species, most of which have a circumpolar or at least a wide distribution and are included in the A-SBA category. Sector I (Antarctic Peninsula area) is characterized by a high degree of endemism, with many species endemic to the Antarctic region [ANT] and present only in this sector. 27% (15 spp.) of sea anemone species in the Antarctic region are circumpolarly distributed. The subdivision of the Antarctic region into East and West Antarctica is substantiated by differences we found regarding the distribution of sea anemone species from the Antarctic region [56 spp.: 28 spp. ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 1887 Fig. 4. Clusters of sea anemone species distributed in the Southern Ocean (ANT, A-SBA, SBA, SBA-O, A-S-O). See Section 2.2 for explanations of abbreviations. ANT, 22 spp. A-SBA, 6 spp. A-S-O]. In East Antarctica [including sectors III-VI (Indian and part of Paciﬁc districts) of the present study] 11% (6 spp.) of the species are exclusive to the district. In West Antarctica [sectors I, II, VII and VIII (Atlantic and part of Paciﬁc districts) of this study] 39% (22 spp.) of the species are conﬁned to this district. These 2 districts share 50% (28 spp.) of their total species of sea anemones. The 94 species present in the sub-Antarctic region [22 spp. A-SBA, 42 spp. SBA, 24 spp. SBA-O, 6 spp. A-S-O] show a different distribution among the deﬁned sectors (see Fig. 6, Table 2). Sector VII is distinguished from the rest because of the absence of any species of sea anemone. Sector III is distinguished by the presence of 9 unique species, all of which have a sub-Antarctic distribution. Sectors I–VIII have an afﬁnity of about 50%, sharing widely distributed species and 12 species only found in these 2 sectors. Of these 12 species, 8 are restricted to the Magellan Province or north of the Subtropical Front [SBA, SBA-O], and the remaining 4 are also present in the Antarctic region [A-SBA]. Sectors II and VI have the highest similarity (about 60%), but share the presence of only 12 species, all of which have an Antarctic component [A-SBA] to an otherwise a wide distribution. The 94 species of the sub-Antarctic region separate into 2 main groups based on their distributions (Fig. 6). One of the groups includes species restricted primarily to the sub-Antarctic region [SBA] and to 1 sector (rarely in 2 sectors). The other group includes widely distributed species and those species present in the Magellan Province [sectors I–VIII]. The species only present in the Paciﬁc side of the Magellan Province can be distinguished from those species found in the Atlantic side or in both sides of it (Fig. 7). Only 6 species of sea anemones are recorded from both the Southern Ocean and elsewhere outside of this region. These 6 species comprised 2 groups (Fig. 8). One group includes the species present at greater depths (Galatheanthemum profundale and Liponema multipora). These 2 species could be considered deepsea species and are distributed almost all around the continent. The second group includes the species present on the continental shelf of South America (Anthothoe chilensis, Antholoba achates and Phlyctenanthus australis) or on the shelf adjacent to subAntarctic islands (Eltaninactis infundibulum). ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 1888 Fig. 5. Clusters of the sea anemone species distributed in the Antarctic region (ANT, A-SBA, A-S-O). See Section 2.2 for explanations of abbreviations. Table 2 Summary of the faunal composition of the Southern Ocean sea anemone fauna by biogegraphic categories and sectors Cat ANT A-SBA A-S-O SBA SBA-O Total Total no. spp. (gen/fam) 28 (6/0) 22 (6/0) 6 (36/21) 42 (9/0) 24 (26/10) 122 (83/31) Atlantic district Indian district Paciﬁc district I II T E III IV V T E VI VII VIII T E 18 19 6 12 14 12 10 2 2 4 21 20 6 14 14 14 1 0 9 6 30 2 6 0 10 3 6 4 1 1 2 3 7 1 3 2 10 13 2 13 5 3 0 0 13 1 17 7 13 5 1 2 0 2 1 0 0 4 18 5 19 14 8 19 6 20 15 3 1 0 15 9 28 Cat, biogeographic category; E, number of endemic species in each district; T, total number of species present in each district. 3.2.3. Bathymetric distribution of the Antarctic sea anemone species Records for the 56 sea anemone species of the Antarctic region have been analysed to discriminate possible trends in bathymetric or geographic distribution (Fig. 9). Twenty-seven species (49%) are considered eurybathic, whereas 28 species (51%) are stenobathic. All except two of the stenobathic species (26 spp.) are distributed in shelf bottoms. ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 1889 Fig. 6. Clusters of the sea anemone species distributed in the sub-Antarctic region (A-SBA, SBA, SBA-O, A-S-O). See Section 2.2 for explanations of abbreviations. More than half (61% or 34 spp.) of the Antarctic sea anemone species are restricted to the continental shelf (o1000 m). Of the 37% (21 spp.) reported from depths greater than 1000 m, only 11% (6 spp.) are restricted to depths exceeding 1000 m. Approximately one-quarter (27% or 15 spp.) of the Antarctic species are reported from both, shelf and deep bottoms (Fig. 9). Only 6 of the 28 sea anemone species exclusively found in the Antarctic region are restricted to the High-Antarctic area [H] (Anthosactis epizoica, Cactosoma aspera, Edwardsia meridionalis, Isosicyonis sp. nov., Sagartia minima and Urticinopsis antarctica). Twelve species are restricted to the Low-Antarctic area [L]; 4 of them are only present in the Low-Antarctic shelf area [Ls] (Glyphostylum calyx, Halcampa octocirrata, Scytophorus antarcticus and Parantheopsis georgiana), whereas 8 are restricted to deeper bottoms [Ld] (Actinernus antarcticus, Actinernus sp. nov. 2, Actinostola georgiana, Bathydactylus valdiviae, Haliactis arctica, Kadosactis antarctica, Phellia dubia and Stephanthus antarcticus). Nine species are present in both areas [HL] (Actinernus sp. nov. 1, Cnidanthus polaris, Halcampella fasciata, Hormathia armata, Hormosoma scotti, Glyphoperidium bursa, Pycnanthus sp. nov., Stomphia selaginella and Tealianthus pachyderma). Actinothoe georgiana was excluded from the analysis because depth range was not indicated in the original description, and no subsequent records have been published including this or other kind of environmental data. Table 3 summarizes the above data. Eight of the 28 endemic Antarctic species (30%) have a depth range wider than 500 m, showing a eurybathic distribution. The remaining 19 species (70%) are stenobathic. ARTICLE IN PRESS 1890 E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 Fig. 7. Afﬁnities of Southern Ocean sea anemone fauna in South America and Antarctica. Of the 22 species found in both Antarctic and sub-Antarctic regions, 11 (50%) have a wide distribution, being present in the High-Antarctic, Low-Antarctic and sub-Antarctic areas [HLS]. The other half are known only from Low-Antarctica and sub-Antarctica [LS]. Four of the 11 HLS species (Artemidactis victrix, Aulactinia octoradiata, Dactylanthus antarcticus and Epiactis georgiana) are found in shallow sub-Antarctic but also at all bathymetric levels considered here [HLSs]. Three of the 11 HLS species (Capnea georgiana, Corallimorphus profundus and Hormathia lacunifera) are found in deep sub-Antarctic bottoms and at all bathymetric levels [HLSd]. Furthermore, there are 2 species in deep sub-Antarctic and Low-Antarctic bottoms also present in the High-Antarctic [HLdSd]: Actinoscyphia plebeia and Sicyonis erythrocephala. Two other species, Bolocera kerguelensis and Isosicyonis alba, have a wide bathymetric range in the Antarctic and sub-Antarctic regions [true HLS]. Five of the 11 LS species are restricted to deep Low-Antarctic bottoms. Three of these (Halcampoides abyssorum, Isotealia antarctica and Parantheopsis vanhoeffeni) have a broad bathymetric range in the sub-Antarctic [LdS], while the remaining 2 (Bathyphellia australis and Corallimorphus rigidus) are restricted to the deep sub-Antarctica [LdSd]. Two species (Edwardsia intermedia and Sphinteractis sanmatiensis) found in shallow LowAntarctic areas are also recorded in all subAntarctic bathymetric levels [LsS]. Finally, 4 of the 11 LS species have a wide vertical distribution in Low-Antarctica; two of them are restricted to deep bottoms in sub-Antarctic [LSd] (Actinauge verrillii and Limnactinia nuda), one is restricted to shallow sub-Antarctica [LSs] (Halcampoides purpurea), and the single remaining species has a wide vertical distribution in both the Low-Antarctica and the sub-Antarctica [true LS] (Choriactis laevis). Table 4 summarizes the above data. A total of 16 of the 22 species (73%) present in both Antarctic and sub-Antarctic waters [A-SBA] show a depth range wider than 500 m, showing a eurybathic distribution, the remaining 6 species (27%) were stenobathic. None of the 6 widely distributed species reported in the Southern Ocean and north of the Subtropical Front [A-S-O] have yet been found in the ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 1891 Fig. 8. Clusters of the sea anemone species distributed in the Southern Ocean and elsewhere (A-S-O). See Section 2.2 for explanations of abbreviations. High-Antarctic [H]. Two of the 6 A-S-O species (Anthothoe chilensis and Phyctenanthus australis) are restricted to shallow depths [LsSsOs]; the other two have a deeper character at least for subAntarctic and outside the Subtropical Front: one of them with a wide vertical distribution in LowAntarctica [LSdOd] (Liponema multipora), and the other one restricted to the deep Low-Antarctica [LdSdOd] (Galatheanthermun profundale). The two remaining species in A-S-O, are more difﬁcult to deﬁne from a bathymetric point of view. Antholoba achates is widely distributed in Low-Antarctica and outside the Subtropical Front, but restricted to shallow bottoms in the sub-Antarctic. The second species, Eltaninactis infundibulum, has been recorded only in Low-Antarctica and in deep bottoms north of the Subtropical Front, but there are no records of it in the sub-Antarctic region, so far. Both species are probably affected by a sampling effort defect in the sub-Antarctic region. Table 5 summarizes the above data. 3.2.4. Faunal composition affinities with other regions The composition of the sea anemone fauna of the Antarctic region has been compared with Hawaiian (as a tropical example) and the Mediterranean Sea (as a temperate example) regions (Table 6). The 3 regions share 5 families (Actiniidae, Corallimorphidae, Edwardsiidae, Hormathiidae and Sagartiidae) but differ notably in composition (Fig. 10). The Mediterranean Sea and Hawaiian region show about 50% similarity, sharing 6 families (Aiptasiidae, Aliciidae, Boloceroididae, Diadumenidae, Isophelliidae and Phymanthidae). Antarctica and the Mediterranean Sea share 4 families (Actinostolidae, Capneidae, Halcampoididae and Haloclavidae). All families shared by Antarctica and Hawaii are also found in the Mediterranean Sea. Twelve families are exclusively distributed in the Antarctic region, being absent in the other 2 areas of this study. The number of families exclusive to either of the other regions is much smaller: 3 in the Mediterranean Sea and 2 in Hawaii (Fig. 10). ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 1892 Fig. 9. Depth range of Antarctic sea anemone species. Grey lines represent species exclusively distributed in the Antarctic region (ANT). Table 3 Summary of the bathymetric categories and subcategories of the sea anemone species exclusively present in the Antarctic region [ANT] Cat H HL L No. spp. (%) Subcat. 6 9 10.9 16.4 – HL HLs HLd 12 21.8 Ls Ld Total 27 49.1 No. spp. Table 4 Summary of the bathymetric categories and subcategories of the sea anemone species present in the Antarctic and sub-Antarctic regions [A-SBA] Cat No. spp. (%) Subcat No. spp. (%) HLS 11 20.0 LS 11 20.0 HLS HLSs HLSd HLdSd LS LsS LdS LdSd LSs LSd Total 22 40.0 2 4 3 2 1 2 3 2 1 2 22 3.6 7.3 5.5 3.6 1.8 3.6 5.5 3.6 1.8 3.6 40.0 (%) 6 3 1 5 10.9 5.5 1.8 9.1 4 8 27 7.3 14.5 49.1 (%) related to the total number of species Southern Ocean sea anemone species [ANT+A-SBA+A-S-O]. Abbreviations: Cat, category; H, species present in High-Antarctic region; HL, species present in High- and Low-Antarctic regions; L, species present in Low-Antarctic region; Subcat, subcategory. (%) Related to the total number of species Southern Ocean sea anemone species [ANT+A-SBA+A-S-O]. Abbreviations: Cat, category; HLS, species present in High- and Low-Antarctic and sub-Antarctic regions; LS, species present in Low-Antarctic and sub-Antarctic regions; Subcat, subcategory. ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 Table 5 Summary of the bathymetric categories and subcategories of the sea anemone species present in the Antarctic and sub-Antarctic regions [A-S-O] Cat No. spp. (%) Subcat No. spp. (%) LO LSO 1 5 1.8 9.1 LS*Od LsSsOs LdSdOd LSsO LSdOd 6 10.9 1 2 1 1 1 6 Total 10.9 (%) Related to the total number of species Southern Ocean sea anemone species [ANT+A-SBA+A-S-O]. Abbreviations: Cat, category; LO, species present in Low-Antarctic region and outside the Southern Ocean region; LSO, species present in Low-Antarctic, sub-Antarctic, and outside of the Southern Ocean regions; Subcat, subcategory; S*, not found in the sub-Antarctic region. Table 6 Summary of the faunal composition at the family, genera and species levels of Antarctica, Hawaii, the Mediterranean Sea, subAntarctica and Southern Ocean Antarctica Hawaii Mediterranean Sea Sub-Antarctica Southern Ocean No. of families No. of genera No. of species 21 13 18 10 31 48 20 39 35 83 56 30 52 94 122 The generic representation of the families shared among the three regions differs (Table 7). Actiniidae has the greatest diversity of the shared families, including 23% of the genera present in Antarctica, 20% of the Hawaiian genera, and 18% of the Mediterranean Sea genera. The next best represented family in Antarctica was Sagartiidae (12% of the genera) followed by Hormathiidae (4%). The opposite situation occurs in the Mediterranean Sea; Hormathiidae has the second higher percentage of the genera (18%), followed by Sagartiidae (13%). In Hawaii, however, these two families represented only 10% of the genera in the region. The shared families Corallimorphidae and Edwardsiidae represent less than 5% of the genera in any of the regions. As with Hormathiidae and Sagartiidae, the representation of Actinostolidae and Hormathiidae in the Antarctic and in the Mediterranean Sea regions are inverse: in Antarctica, Actinostolidae includes 19% of the genera and Hormathiidae 4%, whereas 1893 in the Mediterranean Sea, Hormathiidae includes 18% of the genera and Actinostolidae 3%. As the diversity data for shared families suggest, similarities in faunal composition among the three regions is lower at the generic than at the family level (Fig. 11). Only 1 genus (Edwardsia) is common to all the three regions. The Mediterranean Sea and Hawaii show approximately 25% similarity, sharing 8 genera (Aiptasia, Anemonia, Anthopleura, Bunodeopsis, Calliactis, Corynactis, Diadumene and Telmatactis). Antarctica and the Mediterranean Sea share 5 genera (Actinauge, Actinothoe, Capnea, Halcampoides and Hormathia). Antarctica and Hawaii share only 1 genus (Anthothoe) not also found in the Mediterranean Sea. The best represented genus in Antarctica is Actinernus which comprises 5% of the total present species for the region, whereas Actinia (with 10% of the species) is the best represented in the Mediterranean Sea. Anthopleura is the best represented in Hawaii (with 13% of the species). Most genera in Antarctica and the Mediterranean Sea include fewer than 5% of the total species in that region. However, in Hawaii, about the 50% of the species in the region belong to 1 of 7 genera [Aiptasia (7%), Anthopleura (13%), Boloceroides (7%), Cladactella (7%) Diadumene (10%), Epiphellia (7%), and Edwardsia (7%)]. 4. Discussion 4.1. Diversity of the Antarctic and sub-Antarctic sea anemone fauna Omissions and underestimations of the number of species of Antarctic and sub-Antarctic sea anemones are common in general works dealing with marine Antarctic biodiversity (Arntz et al., 1994, 1997, 2005a; Clarke and Johnston, 2003). This is probably due to the scarcity of reviews and or more general recent works in this group of animals. These factors, combined with the relatively complexity of sea anemones systematics make the understanding of the group difﬁcult for non-specialists. Clarke and Johnston (2003) estimated the number species for the class Anthozoa in the Southern Ocean to be fewer than a 100. Nevertheless, these authors considered the Southern Ocean in its most restricted sense, with the Polar Front as its limit. Fautin (1984) estimated the number of Antarctic and sub-Antarctic sea anemones to be 85 species. Cairns (1982) in his monograph of Antarctic and ARTICLE IN PRESS 1894 E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 Fig. 10. Clusters of the sea anemone faunal composition at family level in three different latitudinal regions. ANT, Antarctica; HAW, Hawaii; MED, Mediterranean Sea. sub-Antarctic scleractinians counted 37 species. Although there are no recent reviews or lists for the members of the subclass Octocorallia, the number of the Southern Ocean species included in this subclass is currently estimated to be around 133 species (López-González, pers. comm.) with preliminary inventories from the eastern Weddell Sea and Antarctic Peninsula citing around 49 species (Arntz and Brey, 2001, 2003). Therefore, the number of anthozoan species in the Southern Ocean (in its wide sense, as considered in the present work) could be approximately 300 species. For ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 Table 7 Percentage of genera within each of the common families of Antarctica, the Mediterranean Sea and Hawaii Actiniidae Sagartiidae Hormathiidae Corallimorphidae Edwardsiidae Actinostolidae Stichodactylidae Antarctica Mediterranean Sea Hawaii 23 12 4 2 2 19 – 18 13 18 5 5 3 – 20 5 5 5 5 – 15 The percentage of the best represented families of the three regions is also provided. comparative purposes, taking into account only waters south of the Polar Front, anthozoan diversity is estimated to be 156 species (Cairns, 1982; López-González, pers. comm.). This is higher than the Clarke and Johnston’s (2003) estimate for the diversity of the group in the United Kingdom (around 120 species). Considering the Southern Ocean in its widest sense (its northern limit the Subtropical Front), the number of Anthozoa is slightly higher than that estimate for the Hawaiian (around 260 species) (data from Clarke and Johnston, 2003 and references therein). Thus, in spite of the extreme temperatures, seasonal availability of food, and the long reproductive periods for Antarctic anthozoans, their diversity in Antarctica is as high or higher than in other regions. The parallel evolution of such a rich fauna apart from the rest of the oceans faunas can be explained by the isolation and the antiquity of the continent (from the Palaeocene), together with other aspects such as the lack of predators (Gili et al., 2006). As a direct consequence of the aforementioned underestimations, anthozoans are excluded from the preliminary list of taxa with the highest species richness in the Southern Ocean (see Clarke and Johnston, 2003: Table 13). However, anthozoans (156 species) are among the top 10 most diverse taxa, between pycnogonids (175 species) and ophiuriods (119). 4.2. Faunistic composition 4.2.1. Endemism Many authors have commented on the high degree of endemism of the Southern Ocean benthic fauna (e.g., Arntz et al., 1994, 1997; Clarke and Johnston, 2003). The degree of endemism ranges 1895 from 34% (ascidians) to about 90% (pycnogonids) (Monniot and Monniot, 1983; Clarke and Johnston, 2003). This high degree of endemism reﬂects the long period of evolution in relative isolation (Clarke and Crame, 1989; Clarke et al., 2004). However, different taxa have had different histories and will show different patterns of endemism and diversity, as exempliﬁed by molluscs, which do not present any endemic sub-Antarctic genera (Linse et al., 2006). Southern Ocean sea anemones also show a high level of endemism, with values of 75% at species level. The number of Antarctic and sub-Antarctic sea anemone species shared with waters north of the Subtropical Front polar is very low, representing only 5% of the species considered. The level of endemism of sea anemones restricted to the Antarctic region is lower (23.0%) than that of the sub-Antarctic region (34%). This higher degree of the sub-Antarctic region is expected because the degree of endemism has a strong relationship to the area over which is calculated (Clarke and Johnston, 2003). However, the higher degree of endemism in the sub-Antarctic region may be caused more by the different habitats provided by the South American continental shelves, the groups of islands, and the different current systems of the sub-Antarctic region compare to the more homogeneous, circumpolar conditions present south of the Polar Front. The sub-Antarctic region also has been studied more in detail than the Antarctic region, and the level of detected endemism of the Antarctic region increases with the increasing attention (López-González et al., 2002). Regarding the sea anemone fauna exclusively distributed in the Antarctic region, the endemism degree is 50% at species level. The endemism of the Southern Ocean sea anemone fauna is much lower at genus level. Furthermore, at the family level, there are no endemic groups of sea anemone families. Other taxa, as isopods, cheilostome bryozoans and molluscs, show similar patterns (Brandt, 1991, 1999; Barnes and DeGrave, 2000; Linse et al., 2006). This suggests that Antarctica has been isolated long enough for the evolution of new genera but not long enough for families (Linse et al., 2006). Therefore, part of extant Antarctic fauna must have evolved from common Gondwana Mesozoic ancestors (Gili et al., 2006). As is the case for many of the other well represented taxa in the Southern Ocean, in sea anemones there are many monotypic genera, and ARTICLE IN PRESS 1896 E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 Fig. 11. Clusters of the sea anemone faunal composition at genus level in three different latitudinal regions. ANT, Antarctica; HAW, Hawaii; MED, Mediterranean Sea. relatively few genera within increasingly large numbers of species (hollow curve distribution: Willis and Yule, 1922). Nevertheless, the relationship between this distribution and any underlying evolutionary processes is not yet clear (Clarke and Johnston, 2003). 4.3. Bathymetric distribution The Antarctic benthic shelf fauna generally has a wider depth range than its relatives elsewhere (Brey et al., 1996). This could reﬂect the different extensions of the continental Antarctic ice sheets ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 through its glacial history, in which changes in the extent of the available shelf areas forced the benthic fauna to go deeper to survive (Clarke and Johnston, 2003; Clarke et al., 2004). Despite this, the percentage of stenobathic Antarctic sea anemone species is slightly higher than the eurybathic species. Furthermore, all except two of the stenobathic species are distributed in shelf bottoms. However, many of the species considered stenobathic are only known from one or very few records (see Table 1). A greater percentage of eurybathic sea anemone species are distributed in both Antarctic and subAntarctic regions (over 70% [A-SBA] species), compared to those found only in the Antarctic region (over 30% [ANT] species). This may reﬂect a relationship between the higher tolerance in bathymetric conditions and the wider distribution of the species. More sea anemone species are reported from deep bottoms of the Low-Antarctica [Ld] than in shelf bottoms of the continent [H]. This supports the theory that the Antarctic shelf fauna had been forced to go to deeper bottoms for survival by the increasing size of the ice sheets (Clarke and Crame, 1989; Brey et al., 1996). Furthermore, the greatest number of endemic species restricted to deep bottoms comes from the Antarctic region [ANT]. Although this may reﬂect the sampling effort, it may also reﬂect a radiation in the deep Antarctic. Such a radiation could be explained once more by the differential growth of the ice sheets, or by the Antarctic deep-water supply to the ocean circulation conveyor belt (Fahrbach et al., 1995). However, as the Southern Ocean is contiguous to the other main oceans, there is no reason for those species not to spread to and colonize the deep ﬂoors surrounding the continent. Nevertheless, the Antarctic deepsea fauna shows stronger afﬁnities to the Atlantic and Indian Oceans than to the Paciﬁc Ocean (Clarke, 2003). This could reﬂect the spread circulation pattern of the Weddell Sea deep-water supply (Naveira Garabato et al., 2002). Of the 21 sea anemone species distributed in deep water (41000 m), only 2 are cosmopolitan (G. profundale and L. multipora), invading the Southern Ocean region from the deep sea. These data suggest that the exchange of the fauna from deep-sea bottoms with areas outside the Southern Ocean is very low, a contention supported by distribution patterns of sponges, asteroids and polychaetes (Clarke, 2003). However, the scleractinian fauna of the Antarctic includes a high number 1897 of cosmopolitan species (Cairns, 1982). Most of the sea anemone species inhabiting deep bottoms could be considered eurybathic, typically inhabiting deep ﬂoors that reach the continental shelf of the Antarctic continent. Only 6 species (most of them with a circumpolar distribution) could be considered typical from the continental shelf extending to deeper bottoms. 4.4. Biogeographic affinities The distribution of the sea anemone fauna conﬁrms the basic biogeographic subdivisions of the Southern Ocean and the predominantly circumpolar character of its fauna suggested by Hedgpeth (1971), Arntz et al. (1994), and Clarke and Johnston (2003). The percentage of circumpolar species is higher for the Antarctic than for the Southern Ocean sea anemone fauna, presumably because of the more homogeneous environmental conditions in shelf continental areas in the former, and because of the historical inﬂuence and buffer effect of the sub-Antarctic region between Antarctic and the surrounding oceans. The Atlantic Antarctic district showed the highest number of sea anemone species exclusively found in this area. The remarkable singularity of the Antarctic Peninsula and Weddell Sea areas within the Antarctic region is easily demonstrated by exclusive distribution of many species within these areas. The higher levels of endemism are restricted to this area. The complicated tectonic history of the Scotia Arc area and the variety of habitats that it provides, its close connection to the Magellan region, and the inﬂuence of the Antarctic Circumpolar Current (ACC) make this area biogeographically distinguishable. There are more sea anemone species exclusively known from the Antarctic Peninsula than from the Weddell Sea, suggesting that the Antarctic Peninsula area is a hot spot for diversiﬁcation. The Weddell Gyre probably plays a role in this biogeographic afﬁnity, but determining this requires more data on the sea anemone composition of the southeastern area of the Antarctic Peninsula. The Kergueleian Province in the sub-Antarctic region remarkably differs from the rest, according to the sea anemone fauna. Bivalves suggest a closer afﬁnity of these archipelagos to South America whereas gastropods suggest a closer link to the Antarctic continent (Linse et al., 2006). The sea anemone fauna of the Kergueleian Province shows ARTICLE IN PRESS 1898 E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 no relationship to the rest of the Southern Ocean. However, the records for sea anemones from that area are mainly from the last century (Hertwig, 1882a, b; Carlgren, 1928) and a revision of the material would be desirable before making further conclusions. In the present study, sectors I and VIII clustered with about 50% similarity within sub-Antarctic waters (Magellan Province). Therefore, a Magellan Province is well supported for the sea anemone fauna. A division of the Magellan Province into Paciﬁc and Atlantic sectors with little overlap has been suggested for shallow water sea anemones and polychaetes (Häussermann and Försterra, 2005; Montiel et al., 2005). Although our data apparently contradict the proposed subdivision, the overlap between the Atlantic and Paciﬁc Magellan is actually low (the chosen limit in this study for the two regions was 601W, including part of the records for the Argentinean coast in the Paciﬁc side). The number of species shared by both coasts is approximately 15% (18 species). There are more common species in the polychaete fauna for Antarctica and the Paciﬁc side of South America (28%) than for Antarctica and the Atlantic side (5%) (Montiel et al., 2005). This is much less pronounced for the sea anemone fauna (11% and 10% of common species, respectively). Nevertheless, some of the common records for the Paciﬁc side and Antarctic region (as for the Atlantic side) are taxonomically uncertain (Häussermann and Försterra, 2005). The South American and Antarctic sea anemone fauna afﬁnity is low (15% of common species). This pattern is the opposite to the one found for the polychaete fauna, for which over 60% of the total number of species are shared (Montiel et al., 2005). Nevertheless, the afﬁnity between the Antarctic sea anemone fauna and the South American fauna is the highest compare to other areas of the subAntarctic region, as is shown in other taxa (Linse et al., 2006 and references therein). Regarding faunistic afﬁnities of Bouvet Island compared to other areas of the Southern Ocean (Arntz et al., 2005a, b), the sea anemone fauna clearly suggests a high circumpolar Antarctic component. Furthermore, our data suggest that a high level of endemism is not expected. The fact that 10 of the 31 families of sea anemone distributed in the Southern Ocean are not present south of the Polar Front conﬁrms that the Polar Front represents a biogeographical discontinuity (Clarke et al., 2004). 4.5. Latitudinal affinities of the sea anemone fauna The three regions we have compared for faunistic afﬁnities (Antarctica, Mediterranean Sea and Hawaii) do not have a recent geologic relationship. Hence the differences among the presence of families and genera are assumed to be due to the climatic selection (polar, temperate, and tropical climes, respectively) and to the results of historical distribution of taxa. Indeed, the Antarctic and Hawaiian regions (both with the most different climates) do not share any families not also shared with the fauna of the Mediterranean Sea. There is a pool of families common for the 3 regions. Those are the most important families in terms of number of genera and species within the sea anemones, the most diversiﬁed and present in almost all environments. The intensity of their representation (measured in percentages for comparative purposes) is more or less similar for the 3 regions. Nevertheless, direct consequences of peculiarities of each region are easily shown by the faunal composition: Hawaiian region lacks representation of the family Actinostolidae (which is high in Antarctica). This family is the most abundant in the deep sea and high latitudes (Fautin and Barber, 1999). Stichodactylidae are absent from Antarctica and the Mediterranean Sea, but are fairly well represented in Hawaii. This family is characteristic by shallow tropical coastal waters and coral reefs, and all of its members posses zooxanthellae. The family Hormathiidae is also present in both intertidal waters and tropical waters, but most of its members are from deep bottoms or high latitudes. Some genera within the family live symbiotically with crustaceans and hermit crabs (e.g., Adamsia, Calliactis, y). The different representation of the hormathiid genera in the different regions is remarkable: although Hormathiidae is well represented in Antarctica, none of the symbiotic genera within the family, which are present in the other two regions, are reported from Antarctica. This is explainable by the highly impoverished brachyuran fauna of the Antarctic continent (Clarke and Crame, 1989; Arntz et al., 1994). Furthermore, it is remarkable that most of the common genera for the Mediterranean Sea and the Hawaiian region (8 genera) are absent from the Antarctic region. This may be explained by biological factors: 6 of them are zooxanthellate, 1 is symbiotic with pagurids, and the other is exclusive to shallow water. There are no zooxanthellate ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 genera cited for the Antarctic region, where intertidal and shallow bottoms are highly perturbed by ice impact and coverage (apart from the obvious limited availability of sunlight and low temperatures). 4.6. About the origin of the Antarctic sea anemone fauna As has already mentioned, the diversity of the Antarctic sea anemone fauna suggests that it does not have a single origin. The sea anemone fauna provides examples supporting the 3 main complementary theories for the origin of the Antarctic fauna. An ancestral pool of species from the Gondwana continent is supported by the fact that there are no endemic families from the Southern Ocean. Furthermore, the speciﬁc case of U. antarctica supports this theory. There are only two species of this genus in the world, U. antarctica distributed in the continental shelf of Antarctic region and U. crassa, from South Africa. This suggests that the genus was originated before the Gondwanan break-up. The case of D. antarcticus also could be framed into this theory. D. antarcticus is included in the actiniarian suborder Ptychodacteae. This suborder includes three species distributed in two families, Predactiidae and Ptychodactiidae. Predactiidae includes 2 genera, Dactylanthus and Preactis. Preactis is described from shallow waters of South Africa arguing for a common origin of the family before the break-up of Gondwana. A Gondwanan origin of Antarctic fauna is also supported by similar evidences from other taxa as octocorals, hydrozoans and molluscs (Gili et al., 2006). Invasion from the deep-sea bottoms is supported by 2 species distributed also in deep ﬂoors outside the Southern Ocean (G. profundale, L. multipora). The suggested role of the Scotia Arc as link between Antarctica and South America (Arntz and Rı́os, 1999; Arntz et al., 2005b) is supported by several species. Some of these species are common for the whole southern tip of South America and the Antarctic region (e.g., A. achates), while others are only common along the Atlantic side of South America and in Antarctica (e.g., A. victrix). The species that are only common for the Paciﬁc side of South America and Antarctica are usually from deep waters (e.g., A. plebeia). However, it is often hard to know the direction of this connection with certainty. In the case of A. achates, it seems that it is 1899 a South American species that colonized the Antarctic region through the Scotia Arc because the species lives in shallow waters, is distributed northwards the Subtropical Front, and has been only recorded for the Antarctic region from South Georgia (Fautin, 2006). However, within species distributed only in the Magellan Province and circumpolarly in the Antarctic region (as A. octoradiata) is difﬁcult to infer a point of origin of their distribution. Similarly, regarding the species from the deep sea, it is difﬁcult to assess whether Antarctica was the origin of the species or if they colonized the region through the deep ﬂoors. There are several deep-sea endemic species from the Antarctic region. Different sampling effort further confounds understanding of distribution of deep-sea taxa. Apart from very recent efforts of international research programs such as ANDEEP, the deep-sea ﬂoor of the Antarctic region has been poorly sampled. Therefore, many of the deep-sea species show a very restrictive distribution simply because of the small sampling effort. It is remarkable that many Southern Ocean deep-sea species (e.g., B. kerguelensis, L. multipora, K. antarctica, A. verrillii) are difﬁcult to distinguish from their northern hemisphere congeners based on morphological characters, raising the question of a cosmopolitan character to their distribution or the limited use of traditional morphological characters within these genera. 5. Conclusions 5.1. Faunal composition According to our study, sea anemones show the high degree of endemism at the species level previoslly suggested for the Southern Ocean and the Antarctic benthic fauna (75% and 50%, respectively). Similarly to patterns shown by other taxa, the endemism of the Southern Ocean sea anemone fauna is much lower at genus level (25%) than at the species level; no family is endemic for the region. This suggests that part of extant Antarctic sea anemone fauna must have evolved from common Gondwana Mesozoic ancestors. 5.2. Faunal affinities The distribution of the sea anemone fauna conﬁrms the basic biogeographic subdivisions of ARTICLE IN PRESS 1900 E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 the Southern Ocean. The sea anemone fauna also has a relatively high circumpolar character. The percentage of circumpolar species is higher for the Antarctic region (27%) than for the Southern Ocean (14%). The Atlantic district presents the highest number of exclusive species (25%), followed by the Paciﬁc (23%), and the Indian sectors (14%). The highest value for shared species is between the Paciﬁc and Atlantic districts (17%). Antarctic Peninsula area is outstanding from the rest of the Antarctic areas in having (mostly) Antarctic-endemic species. The Weddell Sea area is also special in having the majority of the Antarctic-endemic species; however, most of these species are also distributed in the Antarctic Peninsula area. Although East Antarctica and West Antarctica share 50% of their species, there is a difference between the species exclusively distributed in both districts (11% and 39%, respectively). In the sub-Antarctic region, the Kergueleian Province is clearly differed from the rest by the presence of 9 unique species. The Magellan Province is also clearly differentiated by several exclusively distributed species (21%). This province and the Antarctic region have 15% of their species in common. The species only present along the Paciﬁc side of the Magellan Province are separated from those species found along the Atlantic side or in both sides of it. The species present in the Southern Ocean and elsewhere reﬂect the 2 paths of colonization suggested for the Antarctic continent. The ﬁrst group reﬂects the emergence of species from deep bottoms elsewhere to the Southern Ocean. The second group reﬂects the colonization via the subAntarctic islands (Scotia Arc or the islands closed to New Zealand). 5.3. Bathymetry The bathymetric patterns of Antarctic sea anemones in the present study conﬁrm the observed tendency of a wide depth range for Antarctic benthic organisms. A greater percent of eurybathic Antarctic sea anemone species are distributed in both Antarctic and sub-Antarctic regions (over 70% species), compared to those found only in the Antarctic region (over 30% species). More species in the Antarctic region are distributed on deep bottoms of the Low-Antarctic region than on shelf bottoms. Over half of the Antarctic sea anemone species (61%) are restricted to the continental shelf (o1000 m); 37% of the species are distributed on sea ﬂoors deeper than 1000 m; and only 2 species are clearly cosmopolitan, invading from the deep-sea. Of the species deeper than 1000 m, only 11% are exclusively found at depths greater than 1000 m. Finally, 27% of the Antarctic species (15) are found on both shelf and deep bottoms. Some of these can be considered deep-water species that reach the Antarctic continental shelf; 6 could be considered distributed in the continental self and extending to deeper bottoms. 5.4. Latitudinal faunal composition affinities The Southern Ocean fauna shows low compositional afﬁnities with the Mediterranean Sea and Hawaiian regions. The best explanation for this low similarity is the adaptation to the different climatic conditions in the regions (polar, tropical and temperate climates). A more detailed revision is needed for further conclusions on the biogeographic patterns and origin of the Antarctic sea anemone fauna. Regrettably, the knowledge of the sea anemone fauna (and particularly its phylogeny) is less advanced than that for other taxa (e.g., Mollusca, Isopoda, y). Therefore, this contribution is a ﬁrst step, conducting the necessary revision and update of the knowledge for any further detailed study on the biogeographic patterns and afﬁnities of the Southern Ocean sea anemone fauna. Acknowledgements Special thanks are addressed to Prof. Wolf Arntz (Alfred-Wegener-Institute, Bremerhaven) who made our cooperation and participation in several Antarctic cruises possible. We also thank Dr. A. Brandt (Institut Zoology, University Hamburg), member of the steering committee of the ANDEEP Project. We extend our acknowledgements to the ofﬁcers and crew of the R/V Polarstern, and many colleagues on board during the EASIZ and ANDEEP cruises for their valuable assistance. M. Daly is thanked for her useful comments and for reviewing the English. Comments by V. Häussermann and another reviewer considerably improved ARTICLE IN PRESS E. Rodrı´guez et al. / Deep-Sea Research II 54 (2007) 1876–1904 this manuscript. Support was provided by a MCTCSIC grant (I3P-BPD2001-1) to E. Rodrı́guez, and Spanish CICYT projects: ANT97-1533-E, ANT981739-E, ANT99-1608-E, REN2001-4269-E/ANT, and CGL2004-20141-E. Additional support was provided by Tree of Life project (NSF 0531763 to M. Daly). References Acuña, F.O., 1996. Adultos de Peachia hastata Gosse, 1855 (Actiniaria: Haloclavidae) en aguas del Golfo San Jorge (Argentina). Neotropica 42 (107–108), 16. Acuña, F.O., Zamponi, M.O., 1995. 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Biogeography of Antarctic sea anemones (Anthozoa, Actiniaria): What do they tell us about the origin of the Antarctic benthic fauna?

Biogeography of Antarctic sea anemones (Anthozoa, Actiniaria): What do they tell us about the origin of the Antarctic benthic fauna?

Biogeography of Antarctic sea anemones (Anthozoa, Actiniaria): What do they tell us about the origin of the Antarctic benthic fauna?

Biogeography of Antarctic sea anemones (Anthozoa, Actiniaria): What do they tell us about the origin of the Antarctic benthic fauna?

Biogeography of Antarctic sea anemones (Anthozoa, Actiniaria): What do they tell us about the origin of the Antarctic benthic fauna?

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