Mesogligorgia scotiae gen. nov., sp. nov. is
described and illustrated from a colony collected in the
Scotia Sea, 2,201–2,213 m in depth, on the ANDEEP-I
cruise. The new taxon is placed in the family Plexauridae
because of: 1) the presence of a horny axis with a crosschambered central core and numerous loculi, 2) retractile polyps in calyces with distinct spicular components,
and 3) armed polyps with large sclerites with a poorlydeveloped collaret and eight well-developed points. The
irregularly distributed sclerites running along the axis,
into a thick mesogloeal coenenchyme, and the elongated
spindles with irregular ends are the most distinctive
characters of the newly proposed genus

López González, Pablo José

English

idUS. Depósito de Investigación Universidad de Sevilla

ORIGINAL ARTICLEPablo J. Lo´pez-Gonza´lezA new gorgonian genus from deep-sea Antarctic waters(Octocorallia, Alcyonacea, Plexauridae)Received: 11 August 2004 / Revised: 19 June 2005 / Accepted: 4 July 2005 / Published online: 25 August 2005 Springer-Verlag and AWI 2005Abstract Mesogligorgia scotiae gen. nov., sp. nov. isdescribed and illustrated from a colony collected in theScotia Sea, 2,201–2,213 m in depth, on the ANDEEP-Icruise. The new taxon is placed in the family Plexauridaebecause of: 1) the presence of a horny axis with a cross-chambered central core and numerous loculi, 2) retrac-tile polyps in calyces with distinct spicular components,and 3) armed polyps with large sclerites with a poorly-developed collaret and eight well-developed points. Theirregularly distributed sclerites running along the axis,into a thick mesogloeal coenenchyme, and the elongatedspindles with irregular ends are the most distinctivecharacters of the newly proposed genus.Keywords Cnidaria Æ Octocorallia Æ Alcyonacea ÆPlexauridae Æ Antarctica Æ MesogligorgiaIntroductionAmong the gorgonian families, Plexauridae is one of therichest in genera and species (Bayer 1956, 1981). Thisfamily is especially well represented in temperate andtropical waters (e.g. Bayer 1961; Grasshoﬀ 1992, 1999,2000; Fabricius and Alderslade 2001), and also in deepwaters (e.g. Wright and Studer 1889; Bayer 1956;Grasshoﬀ 1977, 1986). Although plexaurids are presentin moderately high latitudes (58–68) of the NorthernHemisphere of the Atlantic and Paciﬁc (e.g. Kramp1939; Madsen 1944; Grasshoﬀ 1977; Sa´nchez and Cairns2004; Sanmartı´n and P.J. Lo´pez-Gonza´lez in prep), theyare scarce in the high latitudes of the Southern Hemi-sphere, which are dominated by the families Primnoidaeand Isididae (e.g. Bayer 1996a, b, 1998; Alderslade 1998;Lo´pez-Gonza´lez and Gili 2002).On some recent Antarctic cruises, an extensive col-lection of octocorals has been made in the Weddell Sea,oﬀ the Antarctic Peninsula, and Scotia Sea. Amongthem, two ANDEEP cruises (Antarctic benthic deep-seabiodiversity; ANDEEP-I and ANDEEP-II, both in theaustral summer 2002) were carried out on board the R/VPolarstern in the Scotia Sea to investigate the coloniza-tion history and recent community patterns of Antarcticbenthic fauna. During the ANDEEP-I cruise an unde-scribed gorgonian, here placed in the family Plexauridae,was collected. The aim of this paper is the description ofa new genus and species based on that material.MethodsThe material was collected in the Scotia Sea (Fig. 1)during the ANDEEP-I cruise. The octocorals were sor-ted, labelled and ﬁxed on board. The holotype colonystudied was ﬁxed in buﬀered formaldehyde (4% in seawater) and later preserved in 70% ethanol. Fragmentsfrom diﬀerent parts of the colony were prepared forSEM study following the usual methodology (e.g. Bayerand Stefani 1988; Alderslade 1998), and permanentmounts were made for light microscopy. Colony andsclerite terminology follows Bayer et al. (1983). Thespecimen studied has been deposited in the ZoologischesInstitut und Zoologisches Museum in Hamburg (ZI-ZMH).ResultsSubclass OctocoralliaOrder AlcyonaceaSuborder HolaxoniaFamily Plexauridae Gray, 1859Communicated by R.M. KristensenP. J. Lo´pez-Gonza´lezBiodiversidad y Ecologı´a de Invertebrados Marinos,Departamento de Fisiologı´a y Zoologı´a,Facultad de Biologı´a, Universidad de Sevilla,Reina Mercedes, 6, 41012 Sevilla, SpainE-mail: pjlopez@us.esHelgol Mar Res (2006) 60: 1–6DOI 10.1007/s10152-005-0008-1Mesogligorgia gen. nov.DiagnosisPlexauridae with unbranched (possibly scarcely bran-ched) colonies; holdfast well developed, cone shaped,not calciﬁed. Coenenchyme remarkably thick withabundant mesogloea, in which sclerites are embeddedforming distinct groups. Polyps scattered on all sides ofthe stem; polyps completely retractile in calycesembedded in the coenechymal mesoglea, only distinct aslow dome-shaped verrucae with eight equally developedmesogloeal lobes. Sclerites elongated spindles withirregular edges; calicular sclerites indistinctly convergingin eight points; anthocodial armature symmetrical,forming a poorly distinct collaret and eight well-devel-oped points; ﬂattened sclerites are present on the mainaxis of tentacles, and minute bodies on pinnules.EtymologyThe generic name combines Mesogli- in reference to thedistinct abundance of mesogloea in the thick coenenc-hyme, and –gorgia, a common suﬃx in gorgonian gen-eric names. Gender: feminine.Fig. 1 Type locality of Mesogligorgia scotiae gen. nov., sp. nov.(asterisk)Fig. 2 Mesogligorgia scotiaegen. nov., sp. nov. HolotypeZIZMH (C 11689): a, wholecolony, showing the conicalholdfast, the irregularplacement of polyps and theirregular diameter of thecoenenchyme bearing polyps;b distal end; c a portion of thecolony, showing the lowcalyces, and, due totransparency of the mesogloea,the eight points of theanthocodia and coenenchymalsclerites (cos); d limit betweenthe basal coenenchyme withoutpolyps and the upper part of thecolony with polyps, showing thestrong diﬀerence in diameterand the axis which is nakedbasally (ax). Scale bars:a 12 mm; b–d, 4 mm2Type speciesMesogligorgia scotiae sp. nov. here designated.Mesogligorgia scotiae sp. nov. (Figs. 2–5)Type materialHolotype: ZIZMH (C 11689), one whole colony, AN-DEEP-I cruise, Polarstern ANT XIX/3, stn. 41–4, ScotiaSea, 5923.48’S 603.54’W, 2,201–2,213 m, Agassiztrawl, 27 Jan 2002.DescriptionThe holotype is a complete colony with holdfast, about40-mm high, and unbranched (Fig. 2a). The diameter isirregular along the main stem, about 3.7–8.0 mm, with aclaviform distal end. The coenenchyme of the polyp-bearing distal part, which has abundant translucentmesogloea, can be remarkably thick (0.3–2.5 mm) withrespect to the basal part (Fig. 2d). Horny axis, 1.65 mmin diameter at basal level, has a cross-chambered centralcore and numerous loculi (Fig. 4a, b). The holdfast iscone-shaped, not calciﬁed (Fig. 2a).The polyps are irregularly placed around the stem(Fig. 2b, c). The anthocodiae are completely retractileinto the calyces. Calyces are low, embedded in the co-enechymal mesoglea, only distinct as low dome-shapedverrucae with eight equal mesogloeal lobes, 1.8–2.5 mmin diameter and 0.26–0.43-mm tall (Figs. 2, 3).All sclerites in the colony are elongated spindles withirregular edges, sometimes with bi- or trifurcated ends(Fig. 5). The coenenchymal sclerites (Fig. 5a) are spar-sely and irregularly distributed (Figs. 2b–d, 3, 4a, b),0.47–1.10 mm in length, embedded in the abundantmesogloea. The coenenchymal sclerites can be observedin situ, sometimes running more or less longitudinallyalong the main axis. The calicular sclerites (Fig. 5b),0.55–0.79 mm in length, are indistinctly converging ineight points, forming a deep palisade embedded into thecoenenchymal mesogloea, and can be observed due tothe transparency of the coenenchyme (Figs. 3, 4a, b).The anthocodial armature is symmetrical, forming anindistinct collaret and eight well-developed points withnumerous lines of sclerites (Fig. 4c), 0.39–0.55 mm inlength (Fig. 5c). The tentacular sclerites are ﬂattenedand slightly curved (Fig. 5d), obliquely placed on bothsides of the main axis (Fig. 4d), 0.26–0.39 mm in length.Minute calcareous bodies (< 0.012 mm) are present onpinnules (Fig. 4e).The holotype colony was male, with developingspermatic cysts up to 0.22 mm.ColourThe living holotype was violet, whitish to dirty grey inthe preserved state. The sclerites are colourless.Fig. 3 Mesogligorgia scotiaegen. nov., sp. nov. HolotypeZIZMH (C 11689): a and b,retracted polyps in verticalview, showing the palisade ofcalicular sclerites (cs) inindistinctly converging groupsand calicular aperture withmesogloeal lobes, and —due totransparency of themesogloea—cos; c–e, retractedpolyps in lateral view, showingthe indistinct converging groupsof calicular sclerites in e, andthe eight points sclerites (ps)and calicular border (cb) in dand e. Scale bars: a-e, 2 mm3EtymologyThe speciﬁc name scotiae refers to the geographic areawhere the new species was found.Geographical and bathymetric distributionAt present, Mesogligorgia scotiae is known only fromthe Scotia Sea, depth 2,201–2,213 m.DiscussionThe presence of a horny axis with a cross-chamberedcentral core and numerous loculi, retractile polypsarmed with large sclerites in collaret and points, andcalyces with distinct spicular components clearly supportthe inclusion ofMesogligorgia in the family Plexauridae.As stated above, Plexauridae is one of the richestfamilies in genera and species, although, the new taxonMesogligorgia shows a set of characters (outlined above)not previously found in the family. For the followingcomparisons, additional information of the diﬀerentplexaurid genera can be found in Germanos (1896),Wright and Studer (1889), Ku¨kenthal (1919, 1924), Ba-yer (1956, 1961, 1981), Carpine and Grasshoﬀ (1975),Grasshoﬀ (1977, 1986, 1992, 1999, 2000), Williams(1992), Fabricius and Alderslade (2001) and Sa´nchezand Cairns (2004).Mesogligorgia clearly diﬀers from genera such asPseudopleaxura Wright and Studer, 1889; Eunicea (s.l.)Lamouroux, 1816; Plexaura Lamouroux, 1812;Muriceopsis Aurivillus, 1931 and Psammogorgia Verrill,1868 by the absence of club-shaped sclerites; and fromBebryce Philippi, 1841 and Plexaurella Valenciennes,1855 by the absence of sclerites as stellate plates orstellate forms with four or more rays.A number of plexaurid genera show characteristiccalicular sclerites as thorn-scales or thorn-spindles, suchas Villogorgia (s.l.) Duchassaing and Michelotti, 1860;Acanthacis Deichmann, 1936; Astromuricea Germanos,1895; Dentomuricea Grasshoﬀ, 1977; ParamuriceaKo¨lliker, 1865; Placogorgia Ku¨kenthal, 1919; Lepido-muricea Ku¨kenthal, 1919; Muriceides Studer, 1887;Echinogorgia Ko¨lliker, 1865; Echinomuricea Verrill,1869; Trimuricea Gordon, 1926 or Spinimuricea Grass-hoﬀ, 1992; however, these sclerites are absent in Meso-gligorgia.The presence of capstans clearly distinguish SwiftiaDuchassaing and Michelotti, 1864; Heterogorgia Verrill,1868; Anthoplexaura Ku¨kenthal, 1908 and AlaskagorgiaSa´nchez and Cairns, 2004 from Mesogligorgia. LytreiaBayer, 1981 is characterized by a superﬁcial layer ofsmall coenenchymal tuberculate spheres and double-headed sclerites, and Menacella Gary, 1870 by spindleswith crenulated or foliate tubercles, which are absent inMesogligorgia.Menella Gray, 1870 and Paraplexaura Ku¨kenthal,1909 show surface sclerites with vertically placed leaves,or sculptured with blunt humps, respectively, completelydiﬀerent from the deep layer of elongated spindlespresent in the new taxon here described.Fig. 4 Mesogligorgia scotiaegen. nov., sp. nov. HolotypeZIZMH (C 11689): alongitudinal section of the distalend, showing the retractedpolyps, the cross-chambered ax,some spermatic cysts in one ofthe sectioned polyps, and thethick coenenchyme; b detail of ashowing a sectioned polyp, ax,deep layer of coenenchymalsclerites (coe), thick layer ofmesogloea (me); c detail of thepoorly distinct crown and well-developed eight point of a polypafter dissolution of the softtissue by the use of a solution ofsodium hypochlorite; c lateralview of a tentacle showing theoblique placement of tentacularsclerites, the soft tissue on theright are the pinnules; e atentacular sclerite (out of focus)surrounded by several minutebodies (< 0.012 mm, two ofthem arrowed) which are in thepinnules. Scale bars: a 4 mm; b2 mm; c 1 mm; d 0.5 mm, e0.1 mm4Hypnogorgia Duchassaing and Michelotti, 1864 andMesogligorgia diﬀer in the asymmetrical anthocodialarmature of the former genus. The cylindrical ortubular calyces of Anthomuricea Studer, 1887 andMuricea (s.l.) Lamouroux, 1812 are quite diﬀerentfrom the low mesogloeal calyces of Mesogligorgia. Thesurface sclerites in other genera are discoidal with lo-bate edges like in Discogorgia Ku¨kenthal, 1919; ortuberculate to small prickled spindles like in Astro-gorgia Verrill, 1868 or Elasmogorgia Wright and Stu-der, 1889; which are quite diﬀerent from those presentin Mesogligorgia.The typical two-lobed calyces of CalicogorgiaThomson and Henderson, 1906 and Caliacis Deich-mann, 1936 can be used as a distinguishing character(among others) from Mesogligorgia in which the calic-ular apertures have eight equally developed mesogloeallobes. Although the calyces of Euplexaura Verrill, 1869Fig. 5 Mesogligorgia scotiaegen. nov., sp. nov. HolotypeZIZMH (C 11689): a scleritesfrom the coenemchyme; bsclerites from the calyces; csclerites from the crown andpoints; d sclerites from the axisof the tentacles, the two ﬁrstsclerites are in lateral view.Scale bars: 0.3 mm5are low and inconspicuous, the sclerites are diﬀerentfrom the sclerites of Mesogligorgia.Three plexaurid genera have ﬂattened spindles, The-sea Duchassaing and Michelotti, 1864; ScleracisKu¨kenthal, 1919 and Paracis Ku¨kenthal 1919. However,in these genera coenenchymal sclerites are thick largeplates or ﬂattened spindles tightly ﬁtted as in a mosaic,and there are clear diﬀerences in size and shape betweencoenenchymal and calicular sclerites. In Mesogligorgiaall sclerites (except for the minute bodies found in thepinnules) are similar in shape, only varying in size rangein the diﬀerent parts of the colony. Coenenchymalsclerites are not arranged in a mosaic, running more orless longitudinally in diﬀerent planes, embedded in thethick coenenchyme with abundant mesogloea.Acknowledgements The author acknowledges the valuable assis-tance of the oﬃcers and crew of the R/V Polarstern, and manycolleagues on board during the ANDEEP cruises. I take thisopportunity to extend my thanks to the cruise leader and steeringcommittee of both cruises (ANDEEP-I and ANDEEP-II), espe-cially to Dieter Fu¨tterer and Angelika Brandt, who kindly facili-tated the work on board, and for the opportunity to collaborate inthis Antarctic programme. The author thanks Mercedes Conradifor her valuable assistance during ANDEEP-I cruise, and Asuncio´nFerna´ndez (Scanning microscope services of the University of Se-ville) for her helpful assistance. Support for this work was providedby the MCT projects REN2001-4269-E/ANT and REN2001-4929-E/ANT. 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A new gorgonian genus from deep-sea Antarctic waters (Octocorallia, Alcyonacea, Plexauridae)

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A new gorgonian genus from deep-sea Antarctic waters (Octocorallia, Alcyonacea, Plexauridae)

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idUS. Depósito de Investigación Universidad de Sevilla