Table Of Content:
LITHISTID SPONGE SETIDIUMOBTECTUMSCHMIDT, 1879, REDISCOVERED
ANDRZEJ PISERA
Pisera, A. 1999 06 30: Lithistid sponge Setidium obtectum Schmidt, 1879, rediscovered.
Memoirs ofthe QueenslandMuseum 44: 473-477. Brisbane. ISSN 0079-8835.
ThepoorlyknowngenusandspeciesSetidiumobtectumSchmidt, 1879wasrevisedbasedon
the holotype and newly collected material from the Caribbean, and referred to the family
ScleritodermidaeSollas.DPorifera,Rhizomorinelithistids, Setidium, systematicposition.
AndrzejPisera(email:apis(a]twarda.pan.pl), fnstytutPaleobiologiiPAN, id. Twarda51/55,
00-818 Warszawa, Poland; 6January 1999.
The rhizomorine lithistid genus and species the newmaterial. As aresult, Setidium obtectum
Setidium obtectum was established by Schmidt Schmidt, 1879, should be placed in
(1879) based on a unique specimen dredged off Scleritodermidae Sollas, 1888. The presence of
Havanafrom234-439mdepth.Theoccurrenceof sigmaspires, rhizoclone type, as well as the
remarkable, numerous bundles of very long ectosomal skeleton of amphioxeas, make this
oxeas protruding from the inner (upper) surface genus very close to the genus Scleritoderma
ofthespongeconfersuponitaverycharacteristic Schmidt, 1879.
form As a result of its incomplete description
.
andsinglepreviousrecorditssystematicposition
remainedobscure.Recently,newrichmaterialof Family Scleritodermidae Sollas, 1888
Setidium Schmidt, 1879
this sponge was discovered in the collections of
the MarineInvertebrates Museum, University of
Miami, Florida (MIM-RSMAS), dredged from DIAGNOSIS. Rhizomorine sponges bearing on
several localities in the Caribbean (Fig. 1). the surface (mostly the upper one) bundles of
Investigation of this new material and long oxeas protruding from the choanosome;
re-examination of the holotype in Schmidt's ectosomal spicules are amphioxeas that show a
collection at the Museum of Comparative complete transition to rhizoclone desmas.
Zoology, Harvard University (MCZ), permitted Sigmaspire microscleres concentrated around
determination of its characteristics and oscules. Choanosomal skeleton very dense,
establishment ofits taxonomic position. confused and composed of strongly "thorned"
rhizoclones.
SYSTEMATICS REMARKS. This is so faramonotypic genus. It
is close to Scleritoderma, but differs in having
SYSTEMATIC POSITION. Lendenfeld (1903) smooth ectosomal spicules that are amphioxeas
regardedSetidium a synonym ofLeiodermatium and their derivatives while Scleritoderma has
Schmidt, and placed it within Leiodermatidae acanthose microstronayles (Van Soest &
Lendenfeld, which encompasses rhizomorine
Stentoft, 1988).
lithistids without microscleres. Van Soest &
Stentoft(1988)placedSetidiumobtectumamong
rhizomorine lithistids of the family Setidium obtectum Schmidt, 1879
Siphonidiidae Sollas, which is characterised by (Figs 2-4)
an ectosomal skeleton composed of desmas
Setidium obtectum Schmidt, 1879: 30-31, PI. 1, fig. 9, Pi. 2,
without zygosis, and absence ofmicroscleres as fig. 14;Lendenfeld, 1903: 145-148;Van Soest&Stentoft,
well. 1988:74.
The present investigation found that
choanosomal desmas of Setidium obtectum are MATERIAL. HOLOTYPE MCZ6462: off Havana,
234-441m depth, collected Blake Expedition.
typical thorny rhizoclones, and ectosomal MIM-RSMAS G688: off Miami, 26°53'N, 78°16'W,
spiculesaremostlyamphioxeasthatformadense 492mdepth(twospecimens);G1312:offMiami,26°38'N,
tangential layer, showingalltransitional formsto 79°02'W, 516m depth(one deciduous specimen); PI141
rhizoclones. Numerous thorny sigmaspire off Great Inagua, 20°51'N, 73°16'W, 429m depth (4
microsclereswerefoundbothintheholotypeand specimens).
474 MEMOIRS OF THE QUEENSLAND MUSEUM
FIG. 1. Distribution of the known specimens ofSetidium obtectitm Schmidt. H=holotype, Nl, N2=new
material.
FIG. 2. Morphology ofSetidium obtectum Schmidt (scale bars 1cm). A-B, Holotype, lateral and upper side
MCZ
views, 6462, offHavana. C-D, Large deciduous specimen, lateral and upper side views, G1312, off
Miami.E-F,Livingspecimenwithectosomalspicules,lateralanduppersideviews,P1141/2,offGreatInagua.
DESCRIPTION. Shape and structure of the 1997) about 5cm wide, 3cm high, with a wall
skeleton. The holotype is irregular vase-shaped about 1cm thick and rounded margin. The base
(or turbinate - see Boury-Esnault & Rutzler, showsaveryshortpeduncle. Thenewspecimens
SETIDIUMOBTECTUMRHDISCOVF.RED 47S
FIG. 3. Setidium ohtecmm Schmidt. A, Upper surface, bundles ofoxeas protruding from Ihe choanosome.
?oscuia and ectosomal spiculation, PI 141/1, offGreat lnagua (scale bar 2mm). B, Details ofupper surface
showing?osculesandtangeniiallyarrangedectosomalspicules, PI141/1,offGreat lnagua(scalebar500u.m).
(". Upper surface ofthe choanosomal skeleton (UNO; preparation) showing ?oscula and bundles ofoxeas
(broken)protruding from choanosomal skeleton,PI141/1, offGreatlnagua(scale bar 1mm). D, Rhizoclones
on the upper surface ofchoanosomal skeleton (UNO* preparation), note partly incorporated young desma,
oPr1g1a4ni1/sle,dofofxeGarse,atPlIn1a4g1u/a1,(scoaflfeGbraera2t00l|niamg)u.aE,(sLcoawleerba(orutIerm)m)su.rfFa,ceCslhosoew-iunpgoosfti?aopsrcoutlecutmedwbiythatneupmeee-rloiukse
siamaspires, PI 141/1.offGreat lnagua(scalebar20um). G, Uppersurface showing?oscuhim andectosomal
spicules,holotype, MCZ 6462,offHavana(scalebar200^m). H,Close-upof7osculum withsigmaspires, the
holotype, MCZ 6462, offHavana(scale bar20um).
476 MEMOIRS OF THE QUEENSLAND MUSEUM
FIG. 4. Setidium obtectum Schmidt, PI141/1, offGreatInagua. A-C, Sigmaspires (scale bar 5um). D, Young
desma(scalebar lOOum). E-J, ectosomal spicules showingtransitionto desma(scale bars 50um).
range in shape from deep vase or turbinate andoscules.Thesearelessdenselydistributedon
(especiallywhenyoung), toshallowwidelyopen the upper surface and are located in shallow
vase-shapedwithverythickwalls,about 1-1.5cm depressions, sometimes surrounded by aslightly
thick, and with a short massive peduncle. The rised rim of ectosomal spicules. On the lower
margin of the vase is more-or-less square surface ostia are very densely distributed,
(roundedintheholotype)anditssurfaceisnearly practically touching each other, and placed on
smooth or bearing low, wide elevations from tops ofsmall elevations; these elevations are not
which protrude bundles oflong oxeas (now all visible on the surface ofchoanosomal skeleton
broken). Both surfaces are rugose as a result of and thus they are probably formed only by
numerous irregularly to slightly radially ectosomal spiculation.
distributed conules, 2-5mm high, from which
Ostia are surrounded and covered by a
protrudebundlesoflongoxeas,upto20 spicules
each, that are at least 20mm long (now all ttoepe0e.-l5imkemstlrouncgtur(elefnogrtmhedofbyvidseilbilceatpeaorxteaosnluyp)
broken).Becausetheconulesareslightlyoblique
protruding from the surface. These openings on
to the surface, especially in old individuals, they the upper surface measure 160-220um (when
may form kind ofshort, radially alignedridges. ectosomal spicules are present) and
Except forthe tipsofconulesboth surfacesare corresponding canal openings in the
covered with small openings - presumably ostia choanosomal skeletonare230-300um. Thoseon
SET1D1UMOBTECTUMREDISCOVERED All
the lowersurface are slightly largerandmeasure 270ujn longand40umthickormore. Ectosomal
200-260fim (when ectosomal spiculation spicules may be concentrically arranged around
preserved) and corresponding canal openings in oscula.
the choanosomal skeleton are 230-280u,m. Small oxeas protect ostia onthe lower surface
Ectosomal spicules are tangentially arranged forming tepee-like structures around the ostia.
amphioxeas. No other structures are present on Thesespiculesareusuallybrokenbuttheyappear
the surface ofthe choanosomal skeleton beyond to be 300-500um long and 3.5-5um diameter.
thesecanalopeningsthatleadtoostiaandoscula.
Onthesurfaceofthemarginslightlysinuousand Microscleres. Thorny sigmaspires measure 8-
partly opencanals, 0.20-0.25mm wide, run close 13p,m long and upto 1.7jim thick.
to the surface ofthe skeleton from the lower to
ACKNOWLEDGEMENTS
the upper surface ofthe sponge. Similar canals
piercethewallincrosssection.Closetotheouter
The material was kindly loaned for study by
(lower) surface of the choanosomal skeleton
Prof. Nancy A. Voss (Marine Invertebrates
there 5armemnumerous large connected lacunes Museum, RSMAS, UniversityofMiami, Miami,
v0i.s4i-b0l.e bundldeisamoetfeorx.eaIsn tchraotssprsoetcrtuidoen farroematlhseo Florida). All SEM photos were made using a
Philips XL-20 scanning microscope at the
conules on the surface and enter deeply into die Institute of Paleobiology, Polish Academy of
choanosomal skeleton.
Sciences. Special thanks are given to Ardis
Colour. White oryellow when dry or in alcohol, Johnston (Museum of Comparative Zoology,
white when devoid ofectosomal spicules. Harvard University) for loan of Schmidt's
Desmas. Thesearestronglybranchedandthorny material.
rhizoclones measuring 200-400u.m long;
rhizoclones around canals are only tuberculated LITERATURE CITED
on the canal side.
Other megascleres. Large oxeas protrude from BOURY-ESNAULT, N. & RUTZLER, K. 1997.
conulesonbothsurfaces(butaremoredeveloped Thesaurus of sponge morphology. Smithsonian
Contributions toZoology 596: 1-55.
Tonhetyheaurpepeirnvoarniea)blayndbrdoekeepninsothetoctahloalneonsgtohmei.s LENDENFELD, R. VON 1903. Tetraxonia. Das
Tierreich 19: 1-168.
unknown but they are at least 1cm long and 15- SCHMIDT,0. 1879. DieSpongiendesMeerbusenvon
23urn thick. Ectosomal spicules are tangentially Mexico(Verlagvon Gustav Fisher: Jena).
arranged, smooth, regular amphioxeas that are SOEST, R.W.M. VAN & STENTOFT, N. 1988.
120-210u.m longand 10-14|im thick. Theyshow Barbados deep-water sponges. Studies on the
alltransitionstodesmas.Derivativeswithshapes Fauna of Curasao and other Caribbean Islands
modified toward rhizoclone desmas may be 70(215): 1-175.
AN UNUSUAL SUBERITID DEMOSPONGE decomposition processes, linked to the large input of
FROMAMARINEALKALINE CRATER LAKE organic matter from the surrounding vegetation. As a
(SATONDA ISLAND, INDONESIA). Memoirs of result, an intense sulfate reduction occurs in both
theQueenslandMuseum44: 477-478. 1999:-Todate, bottom water bodies, producing high amounts of
theSatondacraterlake, Indonesia, istheonly 'marine' bicarbonate ions. As a result of seasonal mixings
lakeknowntohaveanincreasedalkalinitycomparedto events, waters from the upper layers of these
seawater(Kempe&Kazmierczak, 1990, 1993;Kempe high-alkalinity bottom waters are transferred to the
et al., 1997). The lake was originally filled with well oxygenated mixolimnion, causingaslightrise in
freshwater, asevidenced bythepresenceoffossilpeat alkalinity to 4-5 rneq/1 inthe brackish (32 %o salinity)
deposits(3J50 ,4C-yrsBP).Later,thelakewasrapidly surface waters ('alkalinity pump'; Kempe, 1990;
filledwithseawater,asindicatedbythesettlementofa Kempe & Kazmierczak, 1993; Kempe et al., 1997).
marinefauna.Todaythelakeisdividedintothreewater The pH values ofmixolimnion waters range between
bodies with differing salinities, separated by two 8.3-8.6. As a consequence of raised carbonate
pycnoclines (Kempe & Kazmierczak, 1990, 1993; alkalinities, the lake generally contains a decreased
Kempe et al., 1997). Both bottom water layers are amount ofCa:+.
anaerobicduetointensiveoxygenconsumingbacterial (Cont. over)
