homaxinella balfourensis is a species of marine demosponge in the family suberitidae .

it is found in the seas around antarctica and can grow in two forms , either branching out in one plane like a fan or forming an upright club-like structure .

homaxinella balfourensis

animalia - porifera - demospongiae - hadromerida - suberitidae - homaxinella - h . balfourensis
isolation of an antifreeze peptide from the antarctic sponge homaxinella balfourensis . - pubmed - ncbi
steroids from aquatic organisms—xii . sterols from the antarctic sponge homaxinella balfourensis ( ridley and dendy )
steroids from aquatic organisms—xii . sterols from the antarctic sponge homaxinella balfourensis ( ridley and dendy ) - sciencedirect
let ' s do some zoology ! - bush sponge ( homaxinella balfourensis ) …a species . . .
1 . the sterol composition of the sponge homaxinella balfourensis ( ridley and dendy ) has been analysed and seven components detected .
bush sponge homaxinella balfourensis , covered in anchor ice , stock photo , picture and rights managed image . pic . mpc - 135041
white and club shaped or branching , with a smooth surface . homaxinella balfourensis is attached to the substrate by stolons or a root system and grows up to 1m high , with 10cm long branches
homaxinella balfourensis grows relatively rapidly in comparison to other antarctic sponges ( although still very slowly by tropical sponge standards ) . it contains substances with antifreeze properties , and can defend itself to some extent against diatom fouling which might otherwise interfere with respiration and feeding . it is a suspension feeder and is preyed on by seastars . homaxinella balfourensis contains diatoms living within its cells , but their role is unclear .
material examined for comparison . homaxinella balfourensis ( ridley & dendy , 1886 ) , colleted by swedish antarctic expedition , off seymour island , antarctic peninsula , slide bmnh 1933 . 3 . 17 . 104 .
cryomicroscopic image ( magnification × 400 ) of ice grown in the presence of crude extract from the sponge homaxinella balfourensis ( 120 mg / ml solution ) above the freezing point . the characteristic bipyramidal morphology of ice crystals can be observed .
approximately 450 g of the sponge homaxinella balfourensis was collected , lyophilized and frozen from mcmurdo sound , antarctica in december 1993 . the sponge was extracted three times with etoac / ipa 1 : 1 ( lipophilic extract ) followed by three times etoh / h 2 o 1 : 1 ( hydrophilic extract ) .
h . balfourensis produces secondary metabolites which have antibacterial and antifungal properties . they also produce antifreeze proteins and as such they are a subject of much scientific research .
genetic techniques were employed to investigate the archaeal , bacterial and eukaryotic communities associated with the antarctic sponges kirkpatrickia varialosa , latrunculia apicalis , homaxinella balfourensis , mycale acerata and sphaerotylus antarcticus . the sponges and seawater for the analyses were obtained from sites in mcmurdo sound : adjacent to mcmurdo station ( mm ) , scott base ( sb ) and cape armitage ( ca ) .
etoh extracts of the alga desmarestia menziesii , the sponge mycale ( oxymycale ) acerata , and the seastar odontaster validus exhibit cytotoxicity at the two higher concentrations ( 125 and 250 μg / ml ; figure 1 ) . certain cytotoxicity , only at the highest concentration , was found in the alga desmarestia anceps , the sponge isodictya toxophila , and the hemichordate cephalodiscus sp . finally , the sponges isodictya erinacea and homaxinella cf . balfourensis , the ascidiacean synoicum adareanum , and the thaliacean salpa cf . thompsoni were not cytotoxic at the concentrations tested .
cryomicroscopic image ( magnification × 400 ) of ice grown in the presence of crude extract from the sponge h . balfourensis ( 120 mg / ml solution ) just below the freezing point . characteristic growth along the c - axis of ice crystals can be seen .
cryomicroscopic image ( magnification × 400 ) of ice grown in the presence of crude extract from the sponge h . balfourensis ( 120 mg / ml solution ) below the freezing point . further unrestricted growth along the c - axis of ice crystals leads to the total freezing of the solution .
only one species had significant differences in proximate composition between seasons ( table 3 ) . h . balfourensis had higher proportions of c , h , and n in dried tissues in winter than summer [ f ( 1 , 18 ) = 19 . 5 , p < 0 . 01 ] .
four species were not cytotoxic at the concentrations tested . the sponges isodictya erinacea and homaxinella cf . balfourensis have been previously tested and no cytotoxic activity was found ( mcclintock et al . , 1990 ; turk et al . , 2013 ) . similarly , to the polyketide isolated from synoicum adareanum , palmerolide a , which presented no cytotoxicity against several cell lines , in our study the macrophages raw 264 . 7 were not affected by the different concentrations of the extracts tested ( diyabalanage et al . , 2006 ) . likewise , several polyunsaturated acids with hemolytic activity have been isolated from individuals of salpa thompsoni ( mimura et al . , 1986 ) .
homaxinella balfourensis ; lévi , 1964 : 150 , fig . 4 , pl . i , fig . 4 ; koltun , 1964 : 84 , pl . xiii , figs 11 - 12 , 1976 : 190 ; vacelet & arnaud , 1972 : 15 ; boury - esnault & van beveren , 1982 : 46 , pl . vii , fig . 25 , text - fig . 12a - b ; desqueyroux - faúndez , 1989 : 110 , pl . ii , fig . 8 , pl . vii , figs 41 - 42 ; pansini et al . , 1994 : 70 ; barthel et al . , 1997 : 48 ; cattaneo - vietti et al . , 1999 : 540 .
…a species of demosponge that is native to the waters in and around antarctica . like most sponges h . balfourensis is a filter feeder and will filter the water around it for nutrients . small copepods are often seen living on the sponges branches and sometimes bush sponges are known to grow on the upper shells of antarctic scallops ( a . colbecki ) .
( of axinella balfourensis ridley & dendy , 1886 ) ridley , s . o . ; dendy , a . ( 1886 ) . preliminary report on the monaxonida collected by h . m . s . challenger . part i . annals and magazine of natural history . 18 : 325 - 351 , 470 - 493 . page ( s ) : 480 [ details ]
( of axinella balfourensis ridley & dendy , 1886 ) ridley , s . o . ; dendy , a . ( 1887 ) . report on the monaxonida collected by h . m . s . ‘challenger’ during the years 1873 - 1876 . report on the scientific results of the voyage of h . m . s . ‘challenger’ , 1873 - 1876 . zoology . 20 ( 59 ) : i - lxviii , 1 - 275 , pls i - li , 1 map . page ( s ) : 179 - 180 [ details ]
archaeal pcr product was not detected from seawater , h . balfourensis or s . antarcticus samples . 150 archaeal clones ( 50 each from l . apicalis , k . varialosa , and m . acerata ) were screened by rflp analysis , 4 unique operational taxonomic units ( otus ) wre observed . rflp analysis screened 250 sponge - derived bacterial clones , 61 were unique otus not detected during examination of 160 seawater - derived clones and were subsequently sequenced for phylogenetic determination . of the 160 seawater bacterial clones , 103 exhibited unique banding patterns , creating distinct seawater operational taxonomic units ( otus ) .
lectotype bmnh 1887 . 5 . 2 . 18 , locality kerguelen islands . . .
holotype [ from synonym ] bmnh 1887 . 5 . 2 . 18 , locality kerguelen islands ( kerguelen , balfour bay ) [ view taxon ]
van soest , r . w . m ; boury - esnault , n . ; hooper , j . n . a . ; rützler , k . ; de voogd , n . j . ; alvarez , b . ; hajdu , e . ; pisera , a . b . ; manconi , r . ; schönberg , c . ; klautau , m . ; picton , b . ; kelly , m . ; vacelet , j . ; dohrmann , m . ; díaz , m . - c . ; cárdenas , p . ; carballo , j . l . ; ríos , p . ; downey , r . ( 2018 ) . world porifera database .
( of axinella supratumescens topsent , 1907 ) topsent , e . ( 1907 ) . poecilosclérides nouvelles recueillies par le français dans l’antarctique . bulletin du muséum national d’histoire naturelle , paris . 13 : 69 - 76 . page ( s ) : 74 - 76 [ details ]
boury - esnault , n . ; van beveren , m . ( 1982 ) . les démosponges du plateau continental de kerguelen - heard . comité national français des recherches antarctiques . 52 : 1 - 175 . page ( s ) : 46 [ details ]
koltun , v . m . ( 1964 ) . sponges of the antarctic . 1 tetraxonida and cornacuspongida . pp . 6 - 133 , 443 - 448 . in : pavlovskii , e . p . , andriyashev , a . p . & ushakov , p . v . ( eds ) , biological reports of the soviet antarctic expedition ( 1955 - 1958 ) . akademya nauk sssr [ english translation , 1966 , israel program for scientific translation ] . [ details ] available for editors [ request ]
vacelet , j . ; arnaud , f . ( 1972 ) . invertébrés marins des xiième et xvème expéditions antarctiques françaises en terre adélie . 2 . - démosponges . téthys . supplement 4 : 9 - 24 . page ( s ) : 15 [ details ]
( of axinella supratumescens topsent , 1907 ) topsent , e . ( 1908 ) . spongiaires . expédition antarctique française ( 1903 - 1905 ) commandée par le dr jean charcot ( paris ) . 4 : 1 - 37 . page ( s ) : 32 - 34 [ details ]
( of axinella supratumescens topsent , 1907 ) burton , m . ( 1929 ) . porifera . part ii . antarctic sponges . british antarctic ( ‘terra nova’ ) expedition , 1910 . natural history report , london , british museum ( natural history ) . zoology . 6 ( 4 ) : 393 - 458 , pls i - v . [ details ]
( of axinella supratumescens topsent , 1907 ) burton , m . ( 1932 ) . sponges . discovery reports . 6 : 237 - 392 , pls 48 - 57 . [ details ] available for editors [ request ]
intergovernmental oceanographic commission ( ioc ) of unesco . the ocean biogeographic information system ( obis ) , available online at urltoken [ details ]
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cell mol life sci . 2002 dec ; 59 ( 12 ) : 2210 - 5 .
wilkins sp 1 , blum aj , burkepile de , rutland tj , wierzbicki a , kelly m , hamann mt .
department of pharmacognosy ncnpr , school of pharmacy , 400 c faser hall , university of mississippi , mississippi 38677 , usa .
cell mol life sci . ; 59 ( 12 ) : 2210 - 2215 .
cryomicroscopic image ( magnification × 400 ) of ice grown without an antifreeze substance ( negative control ) .
research support , u . s . gov ' t , non - p . h . s .
research support , u . s . gov ' t , p . h . s .
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koltun , v . m . 1964 ,
sponges of the antarctic . part 1 . tetraxonida and cornacuspongida
, ed . pavlovskii , e . p . , andriyashev , a . p . & ushakov , p . v . ( eds ) , academy of sciences of the u . s . s . r . , zoological institute : explorations of the fauna of the seas ii ( x ) . biological reports of the soviet antarctic expedition ( 1955–1958 ) , vol . 2 , pp . 6 - 116 , 428 - 433 ( systematic index ) , pls 1 - 15 , izdatel ' stvo ‘nauka ' , moscow
topsent , e . 1907 ,
poecilosclérides nouvelles recueillies par le français dans l ' antarctique
, bulletin du muséum d ' histoire naturelle . paris , vol . 13 , pp . 69 - 76
ridley , s . o . & dendy , a . 1886 ,
preliminary report on the monaxonida collected by h . m . s . challenger
, annals and magazine of natural history , ser . 5 , vol . 18 , pp . 325 - 351 , 470 - 493
urn : lsid : biodiversity . org . au : afd . taxon : 8c20a26b - 0c09 - 48c0 - bd56 - 2391b3bdf616
urn : lsid : biodiversity . org . au : afd . taxon : 914d038f - 07cf - 4a32 - 8aed - a978c74889bf
urn : lsid : biodiversity . org . au : afd . taxon : c3b62118 - 4693 - 4d0b - b1e2 - 7488341b2c4e
urn : lsid : biodiversity . org . au : afd . taxon : f6805c94 - 7154 - 4368 - b42e - 1ab6500496d6
urn : lsid : biodiversity . org . au : afd . taxon : 1645d75f - 0372 - 4c22 - 8ebb - baf0ec14c1a3
urn : lsid : biodiversity . org . au : afd . name : 434298
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2 . these were separated by argentic column chromatography and studied by gas chromatography - mass spectrometry and by proton magnetic resonance spectroscopy .
3 . it was established that the components were c 27 , c 28 and c 29 fully saturated or side chain unsaturated stanols and colest - 5 - en - 3β - ol as traces .
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topsent , e . ( 1907 ) . poecilosclérides nouvelles recueillies par le français dans l’antarctique .
found on hard substrates ? down to 550m from sub - antarctica to continental antarctica .
antarctic sponges ( porifera , demospongiae ) of the south shetland islands and vicinity : part i . spirophorida , astrophorida , hadromerida , halichondrida and haplosclerida
antarctic sponges ( porifera , demospongiae ) of the south shetland islands and vicinity . part i . spirophorida , astrophorida , hadromerida , halichondrida and haplosclerida 1
esponjas antárticas ( porifera , demospongiae ) das ilhas shetland do sul e áreas próximas . parte i . spirophorida , astrophorida , hadromerida , halichondrida e haplosclerida
maurício campos i , ii ; beatriz mothes i ; inga l . veitenheimer mendes ii
i museu de ciências naturais , fundação zoobotânica do rio grande do sul . rua salvador frança 1427 , 90690 - 000 porto alegre , rio grande do sul , brasil . e - mail : mrcpoa @ urltoken ; bmothes @ urltoken ii programa de pós - graduação em biologia animal , universidade federal do rio grande do sul . avenida bento gonçalves 9500 , 91501 - 970 porto alegre , rio grande do sul , brasil . e - mail : inga . mendes @ urltoken
according to calcinai & pansini ( 2000 ) , antarctic sponges are relatively well known ; however , the continent is so extensive that any new study , even in small areas , will add significantly to present knowledge of this group . although many scientific expeditions have been conducted since the 19 th century , there are still some areas where the sponge fauna is little known , such as the south shetland islands and vicinity ( ríos et al . 2004 ) . in this region , 86 species from 51 genera had been recorded ( extrapolated from data of sarà et al . 1992 ) .
the aim of the present study was to provide a full description of the porifera collected in the ocean area explored by the brazilian antarctic program , at the south shetland islands ( elephant i . , king george i . and livingston i ) and bransfield strait .
the samples were collected through the brazilian antarctic program , at the south shetland islands and in the bransfield strait ( 61º02 ' - 63º44 ' s / 54º16 ' - 62º31 ' w ) ( fig . 1 ) . situated north of the antarctic peninsula , this island group consists of an archipelago formed by king george , elephant and livingston islands , together with other , smaller islands . sampling was carried out on board the r / v
professor besnard ,
between 20 to 412 m depth , by beam - trawl , otter - trawl , scuba diving and other , unspecified collection methods .
taxonomic study was based on the spicules , by dissociated spicule mounts and thick sections of the skeleton , following mothes - de - moraes ( 1978 ) and mothes et al . ( 2004 ) , respectively . preparations for sem study followed silva & mothes ( 1996 ) . spicule measurements are presented as minimum , mean , and maximum lenght , width after the slash ( / ) , n = 50 . the specimens were preserved in 96º gl alcohol and deposited in the porifera collection of museu de ciências naturais , fundação zoobotânica do rio grande do sul , porto alegre , rs , brazil ( mcnpor ) .
other abbreviation used in the text is bmnh ( the natural history museum , london , england ) .
tethya antarctica carter , 1872 : 412 , pl . xx , figs 1 - 10 .
cinachyra antarctica ; burton , 1932 : 264 , 1938 : 5 ; koltun , 1976 : 167 ; desqueyroux , 1975 : 55 , pl . i , figs 10 - 12 ; desqueyroux - faúndez , 1989 : 104 , pl . 1 , figs 3a - c , pl . 6 , figs 33 - 34 ; barthel et al . , 1990 : 122 , 1997 : 47 ; gutt & koltun , 1995 : 230 .
material studied . mcnpor 1959 , st . 4873 , bransfield strait : 63º25 ' s - 62º05 ' w , 66 m , 13 . ii . 1986 , proantar iv ; mcnpor 1978 , 1980 , st . 4874 , bransfield strait : 63º25 ' s62º19 ' w , 135 m , 14 . ii . 1986 , proantar iv .
material examined for comparison . cinachyra antarctica ( carter , 1872 ) , collected by mawson antarctic expedition , locality unknown , slide bmnh 1935 . 10 . 26 . 53 .
description . ( mcnpor 1959 ) ( fig . 2 ) oval specimen ; dimensions , in cm : 4 . 8 diameter , 7 . 0 height ; surface with protruding spicules in long bundles , up to 2 . 0 cm lenght ; oscules not observed ; abundant pores ( < 0 . 1 cm in diameter ) , mainly in the lateral portion . preserved material firm in consistency ; colour beige . mcnpor 1978 consists of two individuals , both of globular format , bearing the same details in comparison to mcnpor 1959 , however their superficial spicule bundles are not so long ( < 1 . 0 cm ) ; dimensions , in cm : 1 . 4 x 1 . 1 , and 0 . 9 x 0 . 8 . mcnpor 1980 is identical to mcnpor 1959 ; dimensions , in cm : 3 . 7 x 2 . 6 x 2 . 4 .
skeleton . ectosome constituted by oxeas ii densely disposed , perpendicular to the surface ( fig . 3 ) . choanosome formed by thick radial tracts of protriaenes i , anatriaenes e oxeas i ( 420 - 810 µm thickness ) , which protrude at the surface ( fig . 4 ) ; between the tracts it can be observed oxeas i , ii , protriaenes ii and sigmaspires randomly arranged .
spicules . megascleres : protriaenes i  with clads of varied length ( 136 - 189 . 6 - 274 / 11 . 5 - 13 . 8 - 18 µm ) cladome 46 - 68 . 7 - 99 µm , rhabdome long , straight and sinuous , filiform at terminal portion ( fig . 5 ) ( 5383 - 9039 - 13984 / 15 - 18 . 6 - 24 µm ) ; protriaenes ii  cladome and rhabdome similar to protriaenes i ( fig . 6 ) ( 655 - 849 - 1026 / 2 . 5 µm ) ; anatriaenes  cladome ( 80 . 5 - 144 . 3 - 237 µm ) with uniform clads ( 87 - 155 . 3 - 221 / 15 - 24 . 3 - 35 µm ) , with a slight apical prominence at their medium portion ( fig . 7 ) , rhabdome long , straight and sinuous ( 7774 - 10878 - 19757 / 23 - 31 - 35 µm ) ; oxeas i  straight , acerate extremities , some of them slightly blunt ( fig . 8 ) ( 3197 - 6016 - 9125 / 32 - 52 - 77 µm ) ; oxeas ii  straight ( fig . 9 ) , acerate extremities ( fig . 10 ) ( 560 - 746 . 3 - 910 / 16 - 19 . 6 - 24 µm ) . microscleres : sigmaspires ( fig . 11 )  often in
c
, a few in
s
shape ( 13 - 15 . 3 - 18 . 5 / < 1 . 0 µm ) . all measurements are given in table i .
remarks . burton ( 1929 ) included the species in cinachyra , considering c . vertex lendenfeld , 1907 as a synonym of c . antarctica , and alleged that the absence of sigmaspires described by carter ( 1872 ) for the holotype could not be correct . koltun ( 1964 ) included in the synonymy the variety monticularis , proposed by kirkpatrick ( 1908 ) , who observed different patterns of pores and oscules ; however , these characters were not strong enough to allow the taxa to be considered distinct .
distribution . indian ocean : kerguelen i . ( carter 1879 ) . south america : south georgia i . ( burton 1932 ) . antarctica : ross sea ( carter 1872 , sollas 1888 ) ; victoria land ( kirkpatrick 1908 , broendsted 1926 , burton 1929 , koltun 1964 ) ; adelie land ( burton 1938 , vacelet & arnaud 1972 ) ; wilhelm ii land ( lendenfeld 1907 ) ; mcrobertson land ( koltun 1964 ) ; enderby land ( koltun 1976 ) ; graham land ( topsent 1917 , desqueyroux 1972 ) ; weddell sea ( barthel et al . 1990 , 1997 , gutt & koltun 1995 ) ; south shetland is . : low i . ( desqueyroux 1975 ) ; bransfield strait ( desqueyroux - faúndez 1989 , present study ) . bathymetry : 18 m ( kirkpatrick 1908 ) to 830 m ( gutt & koltun 1995 ) .
cinachyra barbata sollas , 1886 : 183 ; burton , 1932 : 265 , 1940 : 98 ; koltun , 1976 : 167 ; desqueyroux , 1975 : 55 , pl . i , figs 10 - 12 ; desqueyroux - faúndez , 1989 : 103 , pl . 1 , figs 2a - e , pl . 6 , figs 32 ; barthel et al . , 1990 : 122 , 1997 : 47 ; sarà et al . 1990 : 252 ; pansini et al . , 1994 : 68 , fig . 4 , pl . i , figs 3a - d ; gutt & koltun , 1995 : 230 ; cattaneo - vietti et al . , 1999 : 540 .
material studied . mcnpor 1979 , 2017 , st . 4874 , bransfield strait : 63º25 ' s - 62º19 ' w , 135 m , 14 . ii . 1986 , proantar iv .
material examined for comparison . cinachyra barbata sollas , 1886 , collected by antarctic discovery expedition , locality unknown , slide bmnh 1908 . 2 . 5 . 52g - x .
description . ( mcnpor 1979 ) ( fig . 12 ) globular specimen ; dimensions , in cm : 2 . 5 height , 3 . 5 width , 3 . 2 thickness ; hispid surface ; oscules regularly distributed ( 0 . 1 - 0 . 25 cm in diameter ) , surrounded by spicule brushes that reach 0 . 2 cm in height ; pores not observed . preserved material slightly compressible in consistency ; colour grey with some cleared areas beige . mcnpor 2017 a small sample , with the same characteristics presented by mcnpor 1979 , dimensions , in cm : 1 . 2 height , 1 . 0 width , 0 . 8 thickness ; two oscules observed ( 0 . 1 - 0 . 3 cm in diameter ) .
skeleton . ( fig . 13 ) thick cortex , formed by oxeas ii in palisade , perpendicular to the surface . choanosome constituted by radial spicule tracts formed by protriaenes , anatriaenes and oxeas i ( 120 - 500 µm thickness ) , from the basal portion towards the surface , crossing the cortex and protruding the surface . sigmaspires and protriaenes ii dispersed along the skeleton .
spicules . megascleres : protriaenes i  with clads of varied length ( fig . 14 ) ( 99 - 133 . 5 - 182 / 8 . 0 - 13 - 20 µm ) , cladome 37 - 60 . 5 - 92 µm , rhabdome long and straight ( 2507 - 4071 . 5 - 5360 / 14 - 17 - 25 µm ) ; protriaenes ii  cladome identical to protriaenes i ( fig . 15 ) , rhabdome generally filiform and sinuous toward the terminal portion ( 693 - 1029 . 5 - 1463 / 2 . 5 µm ) ; anatriaenes  cladome ( 100 - 145 . 5 - 184 µm ) with clads ( 137 - 164 . 5 - 207 / 21 - 26 . 5 - 37 µm ) lightly curved toward the rhabdome ( fig . 16 ) , extremity sinuous and filiform ( 2392 - 5380 . 5 - 11220 / 26 - 31 . 5 - 36 µm ) ; oxeas i  slightly curved , acerate points , a few blunted ( fig . 17 ) ( 2001 - 3976 . 5 - 7160 / 25 - 43 . 5 - 72 µm ) ; oxeas ii  slightly curved ( fig . 18 ) , acerate extremities ( fig . 19 ) ( 295 - 525 - 900 / 25 - 43 - 65 µm ) . microscleres : sigmaspires ( fig . 20 )  morphology varying from
c
to twisted forms ( 9 . 0 - 12 . 3 - 16 / < 1 . 0 µm ) . all measurements are given in table . i .
remarks . sollas ( 1888 ) provided an extensive and detailed description of almost all the morphological characteristics , and kirkpatrick ( 1905 ) extended the description with additional details on the oscules and other surface structures , which were also observed in the samples studied for this report .
although there may be doubt in regard to the valid species of cinachyra , in the present study c . barbata and c . antactica were treated as separate species , because of the existence of at least two distinctive morphological characteristics ( external morphology , size and shape of oxeas ii ) , observed not only in the newly collected specimens but also in the comparative material . van soest & rützler ( 2002 ) cited in the diagnosis of the genus the existence of only one species ( in this case c . barbata ) ; however , until now the two species have not been formally synonymized .
distribution . indian ocean : kerguelen i . ( sollas 1886 , 1888 , lendenfeld 1907 , boury - esnault & van beveren 1982 ) . south america : south georgia i . ( burton 1932 , 1940 ) . antarctica : victoria land ( kirkpatrick 1908 , burton 1929 , sarà et al . 1990 , pansini et al . 1994 , cattaneo - vietti et al . 1999 ) ; wilhelm ii land ( koltun 1964 ) ; mcrobertson land ; enderby land ( koltun 1976 ) ; weddell sea ( barthel et al . 1990 , 1997 , gutt & koltun 1995 ) ; south shetland is . : robert i . ; king george i . ( desqueyroux - faúndez 1989 ) ; bransfield strait ( present study ) ; deception i . ( desqueyroux 1975 ) . bathymetry : 2 m ( koltun 1976 ) to 830 m ( gutt & koltun 1995 ) .
tetilla leptoderma sollas , 1886 : 179 ; burton , 1929 : 418 ; koltun , 1976 : 166 ; desqueyroux & moyano , 1987 : 47 ; desqueyroux - faúndez , 1989 : 102 , pl . i , figs 1a - d , pl . v , figs 26 - 28 ; sarà et al . , 1990 : 252 ; barthel et al . , 1990 : 122 , 1997 : 47 ; gutt & koltun , 1995 : 230 ; cattaneo - vietti et al . , 1999 : 540 .
further synonym see burton ( 1929 ) and desqueyroux - faúndez ( 1989 ) .
material studied . mcnpor 2000 , st . 4861 , elephant i . : 61º02 ' s - 54º55 ' w , 362 m , 01 . ii . 1986 , proantar iv ; mcnpor 3143 , st . 4860 , elephant i . : 61º08 ' s - 55º52 ' w , 112 m , 31 . i . 1986 , proantar iv .
description . ( mcnpor 3143 ) ( fig . 21 ) fragment ; dimensions , in cm : 2 . 8 height , 2 . 2 width , 0 . 65 thickness ; hispid surface ; pores and oscules not observed . preserved material hard in consistency ; colour brown . mcnpor 2000 an amorphous , damaged fragment , formed by disperse spicule tracts , with exogenous material , colour grey ; dimensions , in cm : 4 . 8 height , 3 . 4 width , 0 . 8 thickness .
skeleton . ( fig . 22 ) cortical region composed by oxeas ii in parchment ; it was also observed a small amount of foreign material . choanosome made by thick longitudinal multispicular tracts of oxeas i and anatriaenes ( 250 - 530 µm thickness ) , radially disposed , originating from the basal portion until the surface , where it protrudes considerably . microscleres and protriaenes ii dispersed along the choanosome , mainly between the tracts .
spicules . megascleres : protriaenes i  cladome ( 35 - 64 . 5 - 110 µm ) often with unequal clads ( 103 - 155 . 5 - 200 / 4 . 5 - 10 - 15 µm ) ( fig . 23 ) , rhabdome long , straight , extremity sharp - pointed and sinuous ( 4692 - 6749 - 8602 / 9 . 0 - 14 - 20 µm ) ; protriaenes ii  cladome similar to protriaene i ( fig . 24 ) , rhabdome thin and sinuous ( 741 - 926 - 1254 / 2 . 5 µm ) ; anatriaenes  cladome 76 - 130 . 5 - 198 µm , with uniform clads ( 115 - 156 . 5 - 232 / 12 - 20 . 5 - 30 µm ) ( fig . 25 ) , rhabdome identical to protriaenes ( 5440 - 10082 - 13662 / 20 - 21 . 5 - 25 µm ) ; oxeas i  straight , conical and / or acerate extremities ( 3726 - 7278 - 9384 / 32 - 65 - 99 µm ) ( fig . 26 ) ; oxeas ii  straight or slightly curved ( fig . 27 ) , with acerate extremities ( 483 - 974 . 5 - 1728 / 12 - 19 . 5 - 33 µm ) ( fig . 28 ) . microscleres : sigmaspires ( fig . 29 )  in
c
shape , rarely in
s
( 9 . 0 - 13 - 16 / < 1 . 0 µm ) . all measurements are given in tab . i .
remarks . although the two samples of c . leptoderma here identified are only fragments , it is possible to observe that it has certain variation in the external form for such species , corroborating with the affirmation of desqueyroux ( 1975 ) . the two samples from the present study are a bit different ; however the spicules are identical in both samples and confirm the identification .
according to van soest et al . ( 2005 ) , currently the species belongs to the genus craniella .
distribution . indian ocean : kerguelen i . ( boury - esnault & van beveren 1982 ) ; heard i . ; christmas i . ( sollas 1886 , 1888 ) . south america : argentina ( sollas 1886 , 1888 ) ; chile ( desqueyroux & moyano 1987 ) ; falkland is . ; south georgia i . ( burton 1932 ) . antarctica : victoria land ( kirkpatrick 1908 broendsted 1926 burton 1929 , sarà et al . 1990 , cattaneo - vietti et al . 1999 ) ; wilhelm ii land ( lendenfeld 1907 ) ; adelie land ( burton 1938 ) ; mcrobertson land ; princess elisabeth land ; banzare land ; clarie land ( koltun 1964 ) ; enderby land ; sabrina land ( koltun 1976 ) ; graham land ( desqueyroux - faúndez 1989 ) ; weddell sea ( barthel et al . 1990 , 1997 , gutt & koltun 1995 ) ; south shetland is . : greenwich i . ( desqueyroux 1975 ) ; king george i . ( koltun 1964 ) ; clarence i . ( burton 1932 ) ; elephant i . ( present study ) . bathymetry : 4 to 2267 m ( koltun 1976 ) .
tribrachion longispinum lendenfeld , 1907 : 322 , pl . xxiv , figs 1 - 13 .
monosyringa longispinna ; koltun , 1976 : 166 ; barthel et al . , 1990 : 122 , 1997 : 47 ; gutt & koltun , 1995 : 230 .
monosyringa broendstedi burton , 1929 : 415 , pl . iv , fig . 1 , text - fig . 4 .
material studied . mcnpor 3164 , st . ferraz , king george i . : 62º05 ' s - 58º23 ' w , 20 m , 03 . ii . 1985 , proantar iii ; mcnpor 3123 , st . 4743 , bransfield strait : 62º30 ' s - 54º16 ' w , 412 m , 28 . i . 1985 , proantar iii ; mcnpor 3121 , est . 4756 , bransfield strait : 62º58 ' s - 57º10 ' w , 70 m , 02 . ii . 1985 , proantar iii .
description . ( mcnpor 3123 ) ( fig . 30 ) massive , amorphous fragment ; dimensions , in cm : 6 . 8 x 3 . 4 , 1 . 7 thickness ; hispid surface ; the surface has small tubular cylindrical projections ( 0 . 2 - 0 . 8 cm height ) , with the oscular openings on top ( 0 . 1 cm in diameter ) . preserved material firm in consistency ; colour pinkish with greyish regions . mcnpor 3121 and 3164 are identical to mcnpor 3123 , with same consistency and colour , as well as their superficial tubular projections ; dimensions , in cm : 4 . 0 x 2 . 2 , 1 . 8 thickness , and 3 . 5 x 3 . 0 , 2 . 5 thickness , respectively .
skeleton . ( fig . 31 ) cortex composed by microscleres and cladomes of orthotriaenes , together with a great amount of exogenous material and spongin . choanosome with radial arrangement , with megascleres arranged in multispicular tracts ( 230 - 500 µm thick ) , perpendicular to the sponge surface . between the tracts there are abundant microscleres and spongin .
oscular projections are formed exclusively by an arrangement of orthodiaenes regularly overlapped ( fig . 32 ) , involved in a fine membrane in which microscleres are present .
spicules . megascleres : orthotriaenes  cladome 1080 - 1171 . 6 - 1520 µm , with often sinuous clads ( 310 - 579 . 6 - 810 / 62 - 84 . 3 - 100 µm ) ( fig . 33 ) , rhabdome with rounded apical extremity ( 2400 - 4060 . 3 - 4620 / 60 - 85 - 101 µm ) ; orthodiaenes  cladome of varied angle ( 300 - 1184 . 3 - 1800 µm ) , straight to sinuous clads ( 130 - 582 . 6 - 1020 / 16 - 38 - 54 µm ) ( fig . 34 ) , rhabdome straight or slightly curved ( 860 - 2967 - 4700 / 18 - 37 . 3 - 52 µm ) ; oxeas  straight , slightly to sharply curved ; extremities varying from hastate to acerate ( 1100 - 2094 - 3920 / 14 - 24 . 3 - 45 µm ) ( fig . 35 ) . microscleres : oxyasters ( fig . 36 )  05 - 10 rays , slightly microspined , concentrated at apical portion ( 25 - 35 - 45 µm ) ; strongylasters ( fig . 37 )  04 - 07 rays , bearing microspines at the apical portion of the rays ( 10 - 12 . 6 - 16 µm ) . all measurements are given in tab . ii .
remarks . according to koltun ( 1964 ) , monosyringa broendstedi burton , 1929 differs from t . longispinum only in having some bifurcation in regard to the clads of the triaenes and diaenes ; this characteristic has no taxonomic value , being only a modified form .
this species tends to live totally embedded in the substrate , with only the papillae protruding ( barthel et al . 1991 ) . it seems to have an important ecological role , providing a special environment for sea stars , which sometimes are concentrated over and between the papillae .
for the first time , sem photomicrographs of microscleres are provided , making it possible to observe the microspine pattern and the arrangement of the rays in these spicules .
distribution . antarctica : wilhelm ii land ( lendenfeld 1907 ) ; victoria land ( burton 1929 ) ; mcrobertson land ; knox land ; banzare land ( koltun 1964 ) ; enderby land ( koltun 1976 ) ; weddell sea ( barthel et al . 1990 , 1997 , gutt & koltun 1995 ) ; bransfield strait ( present study ) ; south shetland is . : king george i . ( present study ) . bathymetry : 20 m ( present study ) to 1340 m ( koltun 1964 ) .
polymastia invaginata kirkpatrick , 1907 : 271 ; burton , 1929 : 446 , 1932 : 338 1938 : 19 ; koltun , 1976 : 168 ; vacelet & arnaud , 1972 : 14 ; desqueyroux , 1976 : 95 ; desqueyroux & moyano , 1987 : 47 ; desqueyroux - faúndez , 1989 : 106 , pl . ii , figs 5a - d , pl . vi , figs 36 - 37 ; barthel et al . , 1990 : 122 , 1997 : 47 ; gutt & koltun , 1995 : 230 ; pansini & sarà , 1999 : 205 .
material studied . mcnpor 1976 , st . 4874 , bransfield strait : 63º25 ' s - 62º19 ' w , 135 m , 14 . ii . 1986 , proantar iv .
material examined for comparison . polymastia invaginata kirkpatrick , 1907 , collected by antarctic discovery expedition , locality unknown , slide bmnh 1908 . 2 . 5 . 76 .
description . ( fig . 38 ) massive specimen ; dimensions , in cm : 3 . 9 x 2 . 0 , 1 . 7 thickness ; hispid surface ; papillae 0 . 1 - 0 . 25 cm height , with oscular openings at the apex ( 0 . 1 cm in diameter ) . preserved material firm , incompressible in consistency ; external colour beige , darker internally .
skeleton . ( fig . 39 ) upper portion formed by the cortex , which is not easily detachable , 580 - 980 µm thickness , composed by ectosomal tylostyles in palisade , often with the apical extremity protruding through the surface . choanosome formed by a radial arrangement of multispicular tracts , composed exclusively of choanosomal tylostyles ; tracts 270 - 360 µm thick . the spicular arrangement present in the papillae is composed of choanosomal tylostyles , positioned perpendicularly to the surface ( fig . 40 ) .
spicules . megascleres : ectosomal tylostyles  straight or slightly curved , lightly swollen along the shaft ( fig . 41 ) ; tyle well defined ( fig . 42 ) : 120 - 369 . 2 - 660 / 3 . 8 - 13 . 1 - 25 µm , tyle width 5 . 0 - 9 . 4 - 12 . 5 µm ; choanosomal tylostyles  straight ( fig . 43 ) , tyle poorly defined ( fig . 44 ) ; shaft a bit swollen below the tyle : 880 - 1400 - 1860 / 12 . 5 - 21 . 3 - 27 . 5 µm , tyle width 10 - 13 . 4 - 16 . 3 µm .
remarks . both the ectosomal and choanosomal tylostyles are smaller in comparison to previous records ( kirkpatrick 1908 , koltun 1964 , desqueyroux 1976 boury - esnault & van beveren 1982 , desqueyroux - faúndez 1989 ) . only the measurements provided by hentschel ( 1914 ) , who proposed the variety gaussi , are similar to those obtained in the sample studied here . burton ( 1929 ) considered this to be intraspecific variation , and thought it unnecessary to create a new variety ; this affirmation is corroborated by the present study .
although there are small differences in the spicule sizes , the comparative material is quite similar to that observed in the present study , with respect to the general morphology of the spicules and the skeletal arrangement .
distribution . indian ocean : kerguelen i . ; heard i . ( boury - esnault & van beveren 1982 ) . south america : chile ( desqueyroux 1976 , desqueyroux & moyano 1987 ) ; magellan strait ( pansini & sarà 1999 ) ; south georgia i . ; south orkney is . ( burton 1932 1934 ) . antarctica : graham land ( desqueyroux - faúndez 1989 ) ; victoria land ( kirkpatrick 1907 1908 ; burton 1929 ) ; adelie land ( burton 1938 , vacelet & arnaud 1972 ) ; wilhelm ii land ( hentschel 1914 ) ; knox land ( burton 1938 ) ; princess ragnhild land ( koltun 1964 ) ; enderby land ; mcrobertson land ( koltun 1976 ) ; weddell sea ( barthel et al . 1990 , 1997 , gutt & koltun 1995 ) ; bransfield strait ( burton 1932 , present study ) . bathymetry : 18 m ( kirkpatrick 1907 ) to 1592 m ( burton 1938 ) .
material studied . mcnpor 3132 , st . 5062 , elephant i . : 61º12 ' s - 55º40 ' w , 98 m , 26 . ii . 1987 , proantar v ; mcnpor 3130 , st . d , king george i . : 62º05 ' s - 58º23 ' w , 20 m , 26 . ii . 1988 , proantar vi ; mcnpor 3369 , st . d , king george i . : 62º05 ' s - 58º23 ' w , 25 m , 21 . i . 1991 , proantar ix ; mcnpor 3111 , st . c , king george i . : 62º06 ' s - 58º22 ' w , 28 m , 06 . iii . 1988 , proantar vi .
description . ( mcnpor 3132 ) ( fig . 45 ) arborescent specimen , with several ramifications ; dimensions , in cm : 22 . 4 height , 16 . 8 width , branches ranging from 0 . 2 - 0 . 45 in diameter ; microhispid surface , with slight spicule protraction ; oscules not observed . preserved material slightly elastic but firm in consistency ; colour greyish beige . mcnpor 3111 , 3130 and 3369 are all amorphous fragments , bearing the same consistency and colour in comparison to mcnpor 3132 ; the three samples are not ramified and each one consists in cylindrical structures with not more than 10 cm length and 0 . 3 cm in diameter .
skeleton . in transverse section the ectosome is made by discrete bouquets , characterizing the superficial hispidation ( fig . 46 ) . choanosome in longitudinal section with a dense internal axial arrangement formed by multispicular tracts , a great amount of sponging and free spicules ( fig . 47 ) .
spicules . megascleres : styles  straight to slightly curved ( fig . 48 ) , extremities varying from acerate to hastate ( 114 - 339 . 5 - 608 / 2 . 5 - 6 . 8 - 11 . 5 µm ) ( fig . 49 ) . all measurements are given in table iii .
remarks . this species is very common in the antarctic continent , and several studies have treated its chemical composition and ecology ( seldes et al . 1986 , mcclintock 1987 , dayton 1989 , cerrano et al . 2000 , wilkins et al . 2002 ) .
skeletal and spicular features observed in the studied material are in accordance with comparative material . the axial arrangement of the choanosome and general features of ectosomal region are identical in both specimens , as well as the spicules ( remeasured in bmnh 1933 . 3 . 17 . 104 : styles 247 - 423 . 9 - 598 . 5 / 3 . 5 - 7 . 2 - 13 . 8 µm ) .
distribution . indian ocean : kerguelen i . ( ridley & dendy 1886 , 1887 , lévi 1964 , boury - esnault & van beveren 1982 ) . south america : south georgia i . ( burton 1932 , 1934 ) . antarctica : graham land ( topsent 1907 , 1908 , 1917 ) ; victoria land ( kirkpatrick 1908 , burton 1929 , pansini et al . 1994 , cattaneo - vietti et al . 1999 ) ; adelie land ( vacelet & arnaud 1972 ) ; wilhelm ii land ( hentschel 1914 ) ; queen mary land ; knox land ; banzare land ; princess elisabeth land ( koltun 1964 ) ; enderby land ( koltun 1976 ) ; weddell sea ( barthel et al . 1997 ) ; south shetland is . : deception i . ( topsent 1917 ) ; elephant i . ( desqueyroux - faúndez 1989 ; present study ) ; king george i . ( present study ) . bathymetry : 0 m ( desqueyroux - faúndez 1989 ) to 550 m ( koltun 1964 ) .
suberites montiniger carter , 1880 : 256 ; topsent , 1915 : 39 ; burton , 1932 : 335 ; koltun , 1964 : 25 , 1976 : 169 ; gutt & koltun , 1995 : 231 ; barthel et al . , 1997 : 47 ; cattaneo - vietti et al . , 1999 : 540 .
suberella topsenti burton , 1929 : 446 , pl . iv , fig . 5 .
material studied . mcnpor 1988 , st . 4872 , bransfield strait : 63º28 ' s - 62º31 ' w , 168 m , 13 . ii . 1986 , proantar iv .
description . ( fig . 50 ) globular specimen , fixed to a rock fragment ; dimensions , in cm : 2 . 5 cm height , 2 . 2 cm in diameter ; slightly hispid surface , with slightly protruded spicules ; only one oscule present ( 0 . 2 cm in diameter ) , at the apex of sponge body . preserved material hard consistency , colour brown .
skeleton . ( fig . 51 ) ectosome not specialized . choanosome with spicules in confusion , densely arranged and positioned at diverse angles , mixed with abundant spongin . several openings and canals could be observed along the choanosome .
spicules . megascleres : tylostyles  straights , slightly curved , sinuous or somewhat twisted ( fig . 52 ) . tyle ovalate , poorly developed , apical extremity varying from conical to acerate ( fig . 53 ) : 330 - 364 - 410 / 7 . 5 - 8 . 8 - 10 µm , tyle width 7 . 5 - 9 . 0 - 10 µm .
remarks . suberites montiniger presents a taxonomic problem : originally the species was described by carter ( 1880 ) for the barents sea , glacial arctic ocean ; and later topsent ( 1915 ) recorded it for antarctica . our data can shed no light on the question of this disjunct distribution ; although the populations in these regions may be two distinct species , a revision to elucidate this question is beyond the scope of this work .
burton ( 1929 ) , in describing suberella topsenti for antarctica , suggested it as a senior synonym of s . montiniger , alleging that the species described by carter ( 1880 ) showed certain differences in the skeleton . burton ( 1932 ) compared his material with the sample described by carter ( 1880 ) , considering both as identical samples . the lack of distinctive morphological characters in this species may have generated these conclusions , because the external morphology , skeletal architecture and spicules do not show variations that justify considering them as distinct taxa . the use of molecular techniques may assist in developing a more reliable diagnosis .
distribution . arctic ocean , barents sea ( carter 1880 ) . south america : falkland is . ( burton 1932 ) ; burdwood bank ( topsent 1915 ) . antarctica : victoria land ( burton 1929 , koltun 1964 , cattaneo - vietti et al . 1999 ) ; mcrobertson land ( koltun 1976 ) ; weddell sea ( gutt & koltun 1995 , barthel et al . 1997 ) ; bransfield strait ( present study ) . bathymetry : 91 m ( burton 1929 ) to 424 m ( gutt & koltun 1995 ) .
eumastia attenuata topsent , 1915 : 35 - 37 , figs 1 , 2a - b ; burton , 1932 : 335 , 1934 : 44 .
material studied . mcnpor 5484 , st . 4874 , bransfield strait : 63º25 ' s - 62º19 ' w , 135 m , 14 . ii . 1986 , proantar iv .
description . ( fig . 54 ) irregular fragment ; dimensions : 2 . 0 x 1 . 6 cm , 0 . 9 cm thick ; slightly rugose surface , due to the presence of several ridges , not exceeding 0 . 1 cm height . the sample bears a very conspicuous cortex , detachable , slightly translucent , < 0 . 1 cm thick ; oscules < 0 . 1 cm diameter . preserved material lightly compressible in consistency ; colour grayish white externally , light brown internally .
skeleton . ( fig . 55 ) ectosome formed by a cortical region , with a palisade of spicules , which protrude the surface , 530 - 870 µm width . below the cortex subectosomal openings or canals were observed , disposed regularly . choanosome with spicules arranged in confusion , some of them positioned perpendicularly to the surface .
spicules . megascleres : oxeas  straight , smooth ( fig . 56 ) , extremities varying from acerate to conical , with predominance of the latter form ( fig . 57 ) : 350 - 429 . 2 - 480 / 12 . 5 - 15 . 6 - 17 . 5 µm .
remarks . the skeletal architecture and spicules were photographed for the first time , in light microscopy and sem , respectively .
topsent ( 1915 ) recorded the presence of well - developed papillae ; however , in the material studied herein , the surface bears some tiny structures which are not true papillae . measurements of the oxeas are very similar to those related by topsent ( 1915 ) , differing only by the presence of thicker spicules .
distribution . south america : falkland is . ( topsent 1915 , burton 1932 , 1934 ) ; south georgia i . ( burton 1934 ) . antarctica : bransfield strait ( present study ) . bathymetry : 0 - 2 m ( burton 1932 ) to 135 m ( present study ) .
reniera chilensis thiele , 1905 : 467 , pl . 27 , fig . 5 , pl . 32 , fig . 84 .
haliclona chilensis ; burton , 1932 : 265 , 1934 : 11 ; desqueyroux & moyano , 1987 : 50 .
material studied . mcnpor 3139 , st . c , king george i . : 62º06 ' s - 58º22 ' w , 28 m , 06 . iii . 1988 , proantar vi .
description . ( fig . 58 ) specimen composed of unequal tubular projections bonded by the same base ; dimensions : 5 . 2 x 3 . 6 cm , 4 . 0 cm height since the base ; tubes ranging from 2 . 0 - 3 . 0 cm height , 1 . 2 - 1 . 8 cm width ; surface optically smooth , slightly hispid to the touch ; oscular openings at the apex of each tubular projection , 0 . 25 - 0 . 4 cm diameter . preserved material slightly compressible in consistency ; colour brown .
skeleton . ectosome formed by a tangential reticulation ( fig . 59 ) , with multispicular rounded meshes , 100 - 420 µm diameter . choanosome ( fig . 60 ) composed by a network of primary ascending tracts , paucispicular ( 02 - 05 spicules diameter ) , 10 - 50 µm width , connected by secondary tracts , uni - paucispicular , 8 . 0 - 20 µm width ; network bearing irregular meshes , rounded to triangular and / or polygonal , 80 - 180 µm in diameter . scarce spongin , more visible at the nodes of the spicule tracts .
spicules . megascleres : oxeas  smooth , with a slight central bent , rarely fusiform ( fig . 61 ) , extremities often acerate ( fig . 62 ) , but rounded , conical and hastate forms may also occur : 137 . 5 - 163 . 9 - 180 / 2 . 5 - 8 . 9 - 12 . 5 µm .
remarks . the present sample is quite similar to the original description of thiele ( 1905 ) , with tubular projections bearing an oscular opening at their apex . together with such characteristics , the inclusion of this species in the subgenus soestella is corroborated by the presence of a tangential ectosome composed by rounded apertures , in addition to possession of a choanosome with subanisotropic network of paucispicular primary lines , irregularly connected by secondary lines , and spongin at the nodes of the reticulation .
dimensions of oxeas are very similar to those described by thiele ( 1905 ) ; however , burton ( 1932 ) recorded smaller oxeas . thiele ( op . cit . ) observed oxeas with blunted ends , but in the present study extremities are more often pointed . these particularities are all interpreted as intraespecific variations .
distribution . south america : chile ( thiele 1905 , desqueyroux & moyano 1987 ) ; falkland is . ( burton 1932 , 1934 ) . antarctica : south shetland is . , king george i . ( present study ) . bathymetry : 15 m ( burton 1934 ) to 75 m ( burton 1932 ) .
gellius bidens topsent , 1901 : vii , 1908 : 21 , pl . i , fig . 1 , 1917 : 77 ; vacelet & arnaud , 1972 : 19 ; barthel et al . , 1990 : 123 , 1997 : 49 .
material studied . mcnpor 1981 , 1989 , st . 4869 , bransfield strait : 63º33 ' s - 59º15 ' w , 240 m , 08 . ii . 1986 , proantar iv .
description . ( mcnpor 1989 ) ( fig . 63 ) erect specimen ; dimensions , in cm : 4 . 2 x 1 . 2 , 0 . 3 thickness . lightly rugose surface , hispid to the touch . pores and oscules not observed . preserved material friable in consistency ; colour light brown with clearer regions . mcnpor 1981 is identical to mcnpor 1989 , only differing in having grey colour ; dimensions , in cm : 4 . 0 x 1 . 3 , 0 . 4 thickness .
skeleton . ( fig . 64 ) ectosome without specialization , with megascleres in confusion . choanosome with a reticulation composed by paucispicular tracts ( 02 - 03 spicules , 38 - 54 µm thickness ) , interconnected by 01 - 02 spicules , forming some isodictyal meshes ( 180 - 520 µm in diameter ) . nodal spongin present , microscleres irregular or randomly occurring between the tracts .
spicules . megascleres : oxeas  smooth , straight or slightly curved ( fig . 65 ) , acerate extremities ( fig . 66 ) : 440 - 554 . 4 - 660 / 12 . 5 - 16 . 3 - 18 . 8 µm ( mcnpor 1981 ) ; 480 - 610 . 4 - 680 / 13 . 8 - 20 . 4 - 23 . 8 µm ( mcnpor 1989 ) . microscleres : sigmas  smooth ( fig . 67 ) , bearing bifid extremities ( fig . 68 ) : 32 . 5 - 36 . 8 - 40 µm ( mcnpor 1981 ) ; 30 - 35 . 1 - 40 µm ( mcnpor 1989 ) .
remarks . comparison with measurements provided by topsent ( 1901 ) and koltun ( 1964 ) , the samples here studied have thicker spicules . for the first time the spicules were photographed by sem , mainly detailing the extremity of the sigmas , which characterizes the species ( figs 67 , 68 ) .
distribution . antarctica : bellinghausen sea ( topsent 1901 ) ; graham land ( topsent 1908 , 1917 ) ; victoria land ( burton 1929 , 1938 ) ; wilhelm ii land ( hentschel 1914 ) ; adelie land ( vacelet & arnaud 1972 ) ; weddell sea ( barthel et al . 1990 , 1997 ) ; bransfield strait ( present study ) . bathymetry : 30 m ( topsent 1908 ) to 550 m ( topsent 1901 ) .
gellius arcuarius topsent , 1913 : 638 , pl . vi , fig . 11 .
calyx arcuarius ; burton , 1938 : 9 ; koltun , 1976 : 196 ; desqueyroux , 1975 : 71 , pl . iv , figs 53 - 54 ; barthel et al . , 1990 : 123 , 1997 : 49 ; sarà et al . , 1990 : 254 ; gutt & koltun , 1995 : 231 ; cattaneo - vietti et al . , 1999 : 540 .
material studied . mcnpor 3135 , st . c , livingston i . : 62º40 ' s - 59º33 ' w , 270 m , 08 . iii . 1987 , proantar v ; mcnpor 1964 , st . 4871 , bransfield strait : 63º16 ' s - 59º55 ' w , 264 m , 08 . ii . 1986 , proantar iv ; mcnpor 1954 , st . 4875 , bransfield strait : 63º17 ' s - 62º30 ' w , 157 m , 14 . ii . 1986 , proantar iv .
description . ( mcnpor 1954 ) ( fig . 69 ) fan - shaped sponge ; dimensions , in cm : 27 . 5 height , 17 . 8 width , 0 . 5 thickness ; optically smooth surface , on magnifying glass small spicule tract projections were observed ; oscules present in both sides of the sponge , however more concentrated in basal region , in discrete stiffly volcanic projections , never exceeding 0 . 1 cm in diameter . preserved material elastic and compressible in consistency ; colour beige with greyish regions . mcnpor 1964 and 3135 present the same form , texture and colour than mcnpor 1954 ; however the oscules were only observed in one of the sides of the surface ; dimensions , in cm : 15 . 5 height , 6 . 5 width , 0 . 6 thickness , and 11 height , 6 . 5 width , 0 . 4 thickness , respectively .
skeleton . ectosome with a dense tangential reticulation , which are forming triangular to polygonal meshes ( fig . 70 ) , 80 - 170 µm in diameter , unispicular tracts with nodal spongin . choanosome formed by longitudinal multispicular tracts ( fig . 71 ) , 75 - 140 µm thickness , which are interconnected by unispicular tracts bearing the same ectosomal features , only differing in having a more dense reticulation ; toxas occurring around the tracts .
spicules . megascleres : oxeas  smooth , slightly curved and swollen ( fig . 72 ) ; acerate extremities ( fig . 73 ) ( 190 - 215 . 4 - 294 . 5 / 11 . 5 - 18 - 23 µm ) . microscleres : toxas ( fig . 74 )  smooth , of varied opening angles , with sharp - pointed extremities ( 69 - 121 . 4 - 181 . 7 / 1 . 2 - 3 . 7 - 6 . 9 µm ) . all measurements are given in table iv .
remarks . another conspicuous sponge in antarctic waters ; the list of synonyms includes c . stipitatus topsent , 1916 , which does not bear toxas ; burton ( 1932 ) , in comparing samples from both groups , observed that some features presented a subtle variation , in regard to spicules , external morphology and skeleton , and pointed out that such absence does not have taxonomic value .