Bryozoa from Heron Island, Great Barrier Reef

79 Pages·1992·26.4 MB·English

by  J S Ryland

.
BRYOZOA FROM HERON ISLAND. GREATBARRIERREEF
RYLANDAND HAYWARD
J.S. PJ.
kviand, J.S. & Hayward. >>.J. L99206 29: Bfyozoa fromHeronIsland,GreatBarrierReef
Memoirsofthe QueenslandMuseum32(1): 223-301.Brisbane.ISSN0079-8835.
Eighty-onespeciesofBryozoaaredescribedfromshallowreefhabitatsaroundHeronIsland,
Queensland.Fourteennewspeciesaredescribed:Putllinadecipiens.P. egretta, P. vulgaris,
Cettepotaria desperab'tlis, Robertsonidra novella, Parasmittina galerita, P. onychor-
rhync/ui, P. turbula, Pleurocodonellina clavicula. Microporella fimbriata, Celleporina
reginae, Rhynchozoon ardeolum, R. limatulumandR.scopulorum.Twenty fourspeciesare
recorded for the first time from Australian waters. 'Qfieron Island, Great BarrierReef,
Bryozoa, taxonomy,newspecies.
J.S. RylandandPJ. Hayward, Marine, EnvironmentalandEvolutionaryResearchGroup.
SchoolofBiologicalSciences, UniversityofWales,Swansea,Singleton Park, SwanseaSA2
8PP, UnitedKingdom; 10June, J99J,
The coral-associated bryozoan fauna of the some 215,000knr. It is to be expected that the
Great Barrier Reef (GBR) is undoubtedly very bryozoan faunawill vary with latitude and, most
diverse, probably comprising several hundred species being essentially subtidal, would be ap-
species. It is, however, poorly known. Thus, in propriately studied and collected by scuba. The
the iate I9th century, when the rich bryozoan present contribution, in which we describe 81
of Victoria and, toaslightly lesserdegree. species,ismanifestly preliminarybeingbasedon
of New South Wales and South Australia, was astill incompleteexamination ofspecimens col-
beingdescribed,theGBRbryozoanswereknown lectedintertidallyonHeronIslandreef,oneofthe
only by afew specimens from HMS Rattlesnake southernmostintheGBR,mainlyoverafewdays
(Busk, 1852a).fromPortDenisonandHolhourne in 1972.
Island (Haswell, 1881) and from A.C. Haddon's Heron Reef is one of 16 comprising the
collections in Torres Strait (Kirkpatnck. 1890a). CapricornGroupwhich,togetherwithfourofthe
d
This lackofstudy continued through mostofthe Bunker Group, he between latitudes 23 and
20th century, with coastal Queensland or GBR 24°S atthesouthernendoftheGBR.Thesereefs
,
*.roans being described in only a few short are separated from Breaksea Spit (Sandy Ci
papers(Livingstone, 1926;Hastings, 1932;Silen, to the southeast and from the mainland coast in
(lLlJi4v2i;ngRsotsosne?,1917942;7R;ylDaanldl,&19S7t4erp1h9e8n4so)na,nd19l5is3t;s tnehle,newihgihlbeoutrhehoSowdaoifnGlRaedesftsoneliebyaCbuoruttis1C50km
Hall, 1984; Winston, 1986). Consequently, the northwards across the Capricorn Channel. The
viewprevailedthatbryozoanswerepoorlyrepre- 200m isobath lies some 16-25km east of the
sented in coral reefs generally and in the GBR Capricorn Group, whilst the mainland is about
particularly (Ryland, 1974). That this must have 70kmtothesouthwest. Amapofthegroup, with
&
been erroneous was evident from Maxwell's bathymetry, is givenby Jell Flood (1977) and
(1968) study of sediments in which bryozoan Mather& Bennett (1984).
fragments, representing a wide diversity of Mean watertemperatures are26-27°C in sum-
species, formed an importantconstituent. Recent merdropping to 20-21°Cin winter,buttempera-
semi-populardescriptionsoftheGBRhavebeen turesover the reefflat may exceed 32°C ordrop
gtven byBennett(1971),Endean(1982)andTal- to 17°C, or even lower (Endean et al. 1956).
?
bot (1984) providing useful background infor- Prevailing winds are southeasterly, or from be-
mation onTthe fauna generally but little oo the tween southeast and east during summer Low-
Bryozoaspecifically. amplitude ocean swells thus approach
TheGBRisextensive,stretchingsome 1900km predominantly from roughly the southeast The
from Lady Elliot Reef(24°07'S) slightly south East Australian Current outside the shelf edge
>
oftheTropic ofCapricorn, to the WarriorReefs flowspolewardsbutthere islittleinformationon
andBramble Cay in the GulfofPapua (9°09TS). thecurrent patterns within the southern GBR. In
GBR
The reefs are dispersed over, and alongtheedge the central the residual flows are deter-
of, the continental shelf and occupy an area of mined by prevailing winds, setting northerly
224 MEMOIRSOPTHEQUEENSLANDMUShUM
duringperiodsofsteadytradewindsbutsoutherly cyclones, e.g. 'Emily* (Apr 1972), 'David' (Jan
during light or variable breezes (Wolanski & 1976) and 'Simon* (Feb 1980). each time being
Pickard. 1985) Releasesofsurfacedrifters in die dredged clear afterwards. The boat channel was
Capricorn Channel suggested a nett southerly extended in 1987-8S (Flood. 1989) and is now
movement (Woodbcad, 1970). Tides are semi- associatedwithalongandsubstantialjetty These
.
diurnal,though successivetidesfrequentlydiffer developments haveaffected sediment deposition
inheight:meanamplitudesare2monspringsand (Coutlay & Flood, 1981). a symptom of a sub-
Ira on neaps. Tidal currents set westerly on the ally altered flow regime over the southern
flood* easterly on theebb. cay-sidc flat. Most ofthe Bryozoa described in
Heron Island, the cay (23°27"S. 151*55*®. is this paperwerecollected from this area in 1972.
situated «*t the leeward (western) end ofan egg- Waternolongerdrainsradiallyfromthereefhere
shaped lagoonal platform reef (Jell & Flood, but (1988) flows strongly along the flattow
1977), toughly 8.5 by 4km with the long axis thechannel.Thereefflatprovided anchcollect-
orientatedESE-WNW(Fig. 1 1. Atitseasternend. ing areain 1972 but seemedto havedel
Heron Reef is separated from the smaller Sykcs markedlyby 1988,evenbeforetheconsequences
Reeffwith which itsharesarecfal platform,bya of the 1986-87 developments (already apparent
3km wide channel of about 15m depth (map in OD water flow) could have affected the living
Jell & Flood, 1977). Thesouthwesternquarterof coral framework.
HeronReefisseparatedbyachannel,about700m The reefflat extends seawards from thecay to
wide and 30m deep, from Wisiari Reef. The theinnersideofthereefrim.Atlowrwatersprings,
disposition of the two reefs ensures that the awayfromtheboat harbour, waterdrainsthrough
western extremity ofHeronReef, and especially gaps and channels in the rim, but the flat never
the northern aspect of it, is well sheltered from wholly dries. The innerpart ofthe flat is largely
direct impact of the tradewind swells, although sandy, with patches of coral nibble and some
•vavesfromthesoutheastarerefractedaroundthe livingcoral,e.g. Poritexeylmdrica. Theouter flat
reef. Wave-transported particles are depositedin is characterized by living coral, extensive
the vicinityofthe cay (Flood. 1974). During the developmentofcrustosecorallinealgae,anddrifts
ehk water fromthereefdrainsinaradial manner ofcoral shingle; »nd is restricted to small pools
(exceptneartheboatchannel,seebelow)untilthe and narrow channels. In 1972 the flat at the
rimhemmesexposed. A shallowlagoonoccupies westernend (beyond theboatharbour)was exten-
the east-central area of the reef. At spring tides sivelycarpetedwithalevel forestofAcroporabut
thereisanextensiveperipheralreefflat,especial- shinglehasincreasingly accumulated since then,
ly at the western end, coveted by 0,5m ofwater The reef rim is higher than the upper level of
ox less. The edge of the reef is then accessible livecoralontheouterflat. Itssurfaceiscemented
from thecaybywading. Accesstootherparts of with crustose coralline algae, and /oanthids
the reef edge at low tide, and tothe drop offfor (especially Pulvthoaspp.)areconspicuous.Coral
ib«, must beby boat. shingle, coral boulders (derived from Acropora
Most descriptions of Heron Island refer more hyacinthus heads), and sometimes large blocks
to thecay thanto the reef(e.g. Steers, 193*) but derived from bummies (plate 30B in SavjHo-
brief accounts of the reef have been given by Kcnt, 1893), accumulate on and just inside the
Endean etai. (1956), Cribb (1966), Jell & Flood rim.Whiletherimpavementisde-voidofhabitats
(1977) and Mather & Bennett (1984). Important suitableforbryozoans,thebouldersconstitutethe
man-made features are the boat channel and the richestmtertidal habitat for them
cayrswesternretainingwall. Marineengineering Thereefslopeisthesublittoralextensionofthe
works up |o 1980 were summarized by Gourlay reefnm Onthewindward(southeasterntosouth-
&
Flood (1981), with particular reference to the western)sideofthereef,theupperslopehasspur
stability of the cay, aidiough iJ>ere have been and groove form and the gradient varies from 1
consequences on the reef flat to the south ofthe in 20 in the southeast to I in 4 southwest of the
cay. In 1945 a gap was blasted in the reef rim, cay (Jell & Flood, 1977). When accessible in
oppositethe northern tipofWistari Reef, topro- calm weather the coral growing on the spais
vnte accessforsmallboats. A wreck(still there) would undoubtedly prove a rich habitat for
was positioned to provide shelter. The gap was Bryozoa. On the lee side ofthereefthespur and
extended in 1966-67 to provide a dredged boat groove formation does notdevelop; rather there
channel and harbour. The channel has sub- is extensive growth of tabular corals, such 3s
sequently been fiUed with sand mobilized by oparu hyacinthu.%. In 1972 some bryozoans
BRYOZOA FROM HERON ISLAND 225
argassum
reel platform
Heron Island and Reef
km
1
23°30'S
152°00'E
26^^^
cay
B 21 23-24 Heron
200 m
FIG. 1. Heron IslandandReef,showinglocationofsamples. ProfilesfromJell & Flood(1977).
were collected by snorkelling and scuba from 1972), by 1988 had developed an abundant and
under such tables, and photographs show the colourful sessile faunaofgreatdiversity.
richness there of sessile fauna. It is such tables In 1988 occasional pieces of drift Sargassum
that,whenstruckbytropicalcyclones,arebroken heavily colonized with bryozoans suchasAetea,
free and hurled onto the edge of the reef. They Crista, Lichenopora and Membranipora and
ultimately settle in the only stable position, with hydroids Eudendrium and Plumularia were col-
the formerattachmentfacingupwards.Thecryp- lected on thebeach ofthecay. At thelime itwas
tic surface is usually somewhat concave, such not known where the Sargassum was growing.
that the boulder rests on its rim; irregularities Subsequently, a bed of Sargassum has been lo-
ensure that water circulates through the space, cated by Lin Baldock and Myriam Preker in
keeping thebouldersurface clearofsediment. In 10-15m waterin thechannel between Heron and
this dark, protected habitat ascidians, bryozoans Sykesreefs.Thespeciesheredifferfromthoseof
and sponges develop in profusion. Thus the boulders and discovery of the Sargassum bed
boulders in the BluePools area, northofthecay, should greatly benefit future studies on the
which were deposited by cyclone 'Emily' (Apr Bryozoa.
MEMOIRSOFTHEQUEENSLANDMUSEUM
MATERIALS tal. Fragments of typically subtidal erect
Bryozoa, such as Triphyllozoon and violet
With the exception of two species of Bugula lodictyum, were also picked up here. (These
found on boulders near Blue Piools in 1988, the boulderswereexaminedin 1988,havingbeen
bryozoans described in this paperare from 14 of onthereeffor 16years.Thefaunaisstillbeing
the 28 samples obtained by JSR in 1972 These studied).
are identified by sample numbers (Fig. 1) as 2J. 14Apr, 1972.Reefcrestsouthofthecay.Most
follows: ofthe flat approaching the crest at this point
was level,easy to walk on, ratherthan being
2. 9 Apr, 1972. On the reef flat south ofthe cay. a forest of heads. Several coral boulders
Bryozoawerecollectedonpieceschippedoff derived from Acropora heads were present.
tabular Acropora, in situ, or from dislodged The living coral of the crest tended to form
heads resting on the sand. Bryozoans were layers (almost shelves). While water on the
presentonundersurfaces,thoughrarelyabun- flatappearedtoebboverthecoral,onthecrest
dant, andlesscommonthansponges. itnoticeablypercolatedthroughthecoral.The
5.11 Apr. 1972. Onthe reefflatWWWofthecay space matrix wouldseemidealforbryozoans
Flat plates ofcoral, the outer parts spread OS being fairly dark and with long periods of
horizontal laminae, the inner were convoluted, waterflow.Thecoral heads typically, though
formingrecessesandcleftsshelieringMargaret- nut invariably, displayed a lower surface
6. 11to,Aplrac,e1co9r7a2l.sN(Pehairdo5Ioopnortihdeaer)eTeafnfdlactelWluNlarWineos.f wzointahtiloin,thwoitthhamtmheiopneriapnhderatlheficnegnetrrsecorveegrieodn
thecay.PlatesofEchinoporawithencrusting while, with Fitogrotw lubes, sponges, com-
bryozoans on thelowersurface. pound ascidians and Bryozoa. The sample
8. 1 1 Apr, 1972- Near5 and 6. Theflat herewasa was a piece of boulder showing a
level platform of abraded Acropora with a coral/bryozoaninterface.
maze of cavities underneath, and coral 22.15 Apr, 1972. Reefcrest at the cleft, northeast
'fingers' risingfromIhcsurface.Theencrust- of(hecay.Thecresthereismorecomplexthan
ingfaunaseemedpoorerthanunderindividua] ji .M.Thereistheactualedge,markedbysurf,
tables. |hen a moat;thecoralthenrisesonto thecrest
11.12Apr, 1972.Onthereefflatwestofthecay. which merges intothezoneofcoral boulders
to the north of the boat channel. Pari of a and rubble (see profile D, fig. 1, fromJell &
well-developed Acropora head which had Flood, 1977).Alongthecrestcoralwasdying
tippedwhensteppedon. Theouterpartswere back,app;irentlybecausecyclone*Emily*had
coatedwithathin,filmyprussianbluesponge. altered the drainage pattern. leaving thecoral
Several Reteporella graeffei and incrusimg heads dry and dying; or live coral had been
specieswerepresent. flattened by pounding with the Acropora
12. 12 Apr, 1972.Onthereefflat, near 11.Below boulders produced by the cyclone. Sample
the actively growing Acropora head, sup- was from these boulders, though most Iodic-
ported by a slenderpedestal, was alayerrep- lyum fragments were unattached.
resentinganearliergrowthlevel.3-5cmthick, 23.16 Apr, 3972. Reef crest soum of the cay;
withsedimentlyingon its uppersurface*The collection made by turning boulders. Tide
lower surface was white, lacking encrusting pOOf; reefedgenotexposed; waterrunningoff
coralline algae, butbearing Tutmtrea, spon- thereefasa sheet.
ges. Filograna, a brachiopod,andbryozoans. 21.17 Apr, 1972. Near 23; from well-incrusted
Below this wascoral rubble.
boulders.
14. 1l2arAgperA,cr1o97p2o.raNehaerad12w.hPiicehcehsadbrboekecnomferofmreea 25.1B Apr, 1972.Collectionfrom4.5-9matcom-
mie made by D.R. Robertson. Included
andturnedupsidedown,thoughcontinuingto Bugula dentata, Nellia simplex and
grow,
Phidoloporidac.
16. 13 Apr, 1972. Crest to the westofthe cleft in
the reefedge, northeast ofthe cay. The crest 26. 18 Apr, 1972. Near25, about3mdepthonthe
here was strewn with boulders deposited (or slope
redistributed) by cyclone *Emily' (1-2 Apr).
The sessile fauna on the Acropora was Holotypes and paratypes of the new species
protectedbytheknobblysurfaceofthepedes- describedhere arein the Queensland Museum.
.
BRYOZOA FROM HERON ISLAND 227
ACKNOWLEDGEMENTS
withlobesextendingbetweenzooidrows,roofed
by finely granular calcification; ooeciostomes
We aregrateful to the Nuffield Foundation for situated at edges of brood chamber, between
the provision ofa Travelling Fellowship to JSR zooid rows.
in 1971/72,tothe Royal Society foratravel
g
in 1988,andtotheAustralianBiological Resour- Lkhenopora Defrance, 1B23
cesSurveyforgenerousfinancialsupportforour
research. Thanks are also due to the Director of With thecharactersofthe family,
theHeron IslandResearch Station, Dr IanLawn, Tvpespecies.LichenoponttarbiruitaDGXTWCc,
and to Miriam Prekcr, who kindly supplied daia 1823.
on the distribution of Sargassum, and Dr P.G.
Flood forfreelygivenadviceandinformationon Lichenopora novaezelandiae(Busk)
the physical environment of Heron Island. PJ. (Rg.2a,b)
Chimonidesand Mary ESpencer-Jones(Natural
History Museum, London) were most helpfMulRin D/scoporeiUi rwoezelandiue Busk. 1875: 32. pi. 30,
facilitating the loan oftype specimens. Dr fig. 2.
I'ordy(SchoolofBiologicalSciences.University Uchenopom mnaezelanJiuc: Brood. 1976: 299.
ofWales, Swansea) is especially thanked for his 17A-C(notfigs 17G-I.=DisporeUasibogaeButg);
valued expertise in scanning electron microg- Hayward & Cook, 1983: 137.
raphy.
Description
SYSTEMATICACCOUNTS L novaezelandiae, asdescribedand figuredby
Busk (1875) and Harmcr (.1915), has uniscn;il
Thetaxonomicorderadopted here followsthat zooid rows and a simple, rounded ooeciostome.
established by Gordon (1984, 1986, 1989b), Brood (1976) appears to have confused his
Taxonomic diagnosesare providedatfamily and figureswiththoseofDisporeUasibogae asuper-
r
genus level, and the species descriptions and ficially similar species in which the zooid row:.
measurements are based on Heron Island are always biseriaJ. Colonies are typically oval
specimens. The synonymies given for each anddomed, and may reach 1Omm in length. This
species are deliberately selective, being limited speciesisprobablyquitecommoninshallowreef
to the original description and the most useful, environments, but it is generally inconspicuift •
recent accounts. Unverified synonymies have Several large colonies were present in the inter-
been avoided. The occurrence ofeach species at stices ofAcropora in sample 2.
HeronIsland,anditswidergeographicaldistribu-
tion, are briefly noted It is intended that a more Distribution
precise account of the ecological distribution of It isdistributed throughout die westernPacific
the bryozoan fauna will be prepared after the fromNewZealandtoJapan,andwestwardstothe
Completion of the present, continuing research eastcoast ofAfrica.
project.
GYMNOLAEMATA
Class Allman, 185o
Class STENOLAEMATA Borg, 1926 OrderCHEILOSTOMIDA Busk, 1852a
OrdCTCYCLOSTOMJDA Busk. 1852a Suborder ANASCINA Levinsen, 1909
Family LICHENOPOR1DAESmkt, 1867 Supcrfamily MEMBRANIPOROIDEA Busk.
1854
Colony encrusting, regularly circular or ova!, Family CALLOPOREDAENorman, 1903
occasionally developing as a Cylinder around
erect substrata; concave or domed, nodular or Colony encrusting, forming coherent or dfe
mamillate, often lobed, bordered by a peripheral junct sheets, or reticulate to umserial runners, dj
laminaofcommonbasal wall. Autozooidsradiat- erect,developingbilaminarplatesorarborescent,
ing fromcentreofcolony,sometimes in irregular vinculariiform growths, attached by an encrust-
quincuncial series, more usually in connate, ing base. Frontal wall ofautozooids with exten-
unisenal ormultiserial rows. Extrazooidal space sivemembrane, sometimes overarchedbyspines
•en zooid rows divided by calcified struts, but always conspicuous; gymnocystal and/bfl
definingpolygonal spaces referred to as alveoli. cryptocystul calcification usually present, often
Brood chambers originating in centre of colony. well developed. Spines present or absent.
MEMOIRSOFTHEQUEENSLAND MUSEUM
228
S«*v*
V
&&5mBBmm
FIG. 2. a,b, Lichenopora novaezetandiae: a, whole colony, X.9; b, detail showing ooeciostomc between two
/.ooid rows, X30. c, Antropora granuitfera, X80. t± Purrllisina vitnirostris, X60. c, Cranosina coronata,
>:50. f, Microporavariperforata, X75.
KRYOZOA FROM HERONISLAND 22V
Avicularia adventitious and/or vicarious, some- Ovicell prominent, hyperstomial. Basal pore
times lacking. OviceJIsgenerally present, hyper- chamberspresent.
stomial, or partly immersed, reduced. Vertical Type species- Membranipora curvirosvis
walls with large basal pore chambers, or mural Hincks, 1862-
septula.
Parellisinacurvirostris(Hincks)
Antropora Norman. 1903 (Fig. 2d)
Colony encrusting. Autozooids with well Membraniporacunirostris Hincks-, 1862: 29: 1880a:
developed cryptocyst; gymnocyst negligible or 153, pi. 20, figs 5,6.
absent.Nospines.Aviculariainterzooidal,small, Ellisinacunnrosins: Harmer, 1926: 228,pi.14, fig.7,
sometimes lacking. Ovicell endozooidal, its Parellisina curviroslriy. Cook, 1968a: 156, text-fig.
presence indicated by a slight thickening at the 16;Winston, 1984:7,fig. 14;Winston&Heimbexg,
distal endoftheautozooid. Basal pore chambers 1986; 6. figs 7,8.
present.
Type species: Membrampora granulifera Description
Hincks, 1880b. Colony forming small, unilaminar patches
Autozooids broadly oval or pear-shaped, com
Antropora granulifera (Hincks) monly 0.5 X0.3mm, the extensive frontal
(Fig. 2c) membraneborderedby araised muralrim; a pair
ofdelicate, evanescent, distal oral spines present
Membranipora granulifera Hincks, 1880b: 72, pi 9, in early ontogeny. Avicularia frequent; distinc-
Jig. 4. tive:rostrumacutetofrontalplane,0.25mmlong.
Antroparagranulifera:Harmer. 1926: 232,pi. 14,figs laterally curved: associated with a kenozooidal
11-14;Cook 1968a: 138.text-fig. 9 polymorph, with a rounded opesia, visible distal
to the rostrum. Ovicell relatively small, the
Description tooecium membranous frontally, exposing
Colony forming flat, unilaminar sheets. granularentooecium.
Autozooids irregularly oval to hexagonal, each
with a raised crenellated rim; 0.4-0.5x0.2- Distribution
0.3mm. Cryptocyst occupying about half total Thisfamiliarspecieshasapantropiealdistribu-
autozooidlength, flatorslightlyconcave,coarse- tion,ranging into temperate regionsin the north
ly beaded; opesiasubtriangular. Atthedistalend east Atlantic and perhaps elsewhere. It forms
ofeach autozooid is a pair(rarely one) ofsmall, small, and generally inconspicuous, colonies on
interzooidalavicularia.eachbuddedfromadisto- hard substrata, particularly biogenic carbonates.
lateral pore chamber; rostrum acute to frontal It is common atHeron Island, occurring in seven
plane, directed distalty or disto-medially, ofthe sample stations reported h
0.07mm long, with a short triangular mandible.
CrassimarginatellaCanu, 1900
Distribution
Antroporagranulifera ispossiblycircumtropi- Colony encrusting; or erect, attached by an
cal in distribution. It has been reported from encrusting base bilaminar or vinculariiforni.
?
Madeira, West Africa, Sri Lanka, Indonesiaand Autozooids with extensiveopesia, borderedbya
the tropical eastern Pacific, but has not been narrow,granularcryptocyst; gymnocyst variably
recordedpreviouslyfrom theGreatBarrierReef. developed. Spines present or absent. Avicularia
It was found at two stations on Heron Island vicarious Ovicell prominent, hyperstomial, or
(samples2and 16),onthereefflatto thesouth of small andcap-like.Verticalwallswith basalpore
the cay, and on thereefedge to the northeast. chambers or mural septula.
Type species: Membraniporacrassimarginata
PareJIisinaOsburn, 1940 Hincks, 1880b
Colony encrusting. Autozooid with narrow Subgenus CorbulellaGordon, 1984
cryptocystalrim,andminimalareaofgymnocyst.
Spines reduced or absent. Avicularia vicarious, Autozooids with well developed gymnocyst,
large, each associated with a small kenozooid. and numerous marginal spines. Avicularia
230 MEMOIRSOFTHEQUEENSLANDMUSEUM
vicarious, with proximal opesia bordered by
spines. Ovicell prominent, hyperstomial, with a
broad frontal fenestra,
Type species: Membranipom corbula Hincks,
1880c.
Crassimarginatella (Corbulella) corbula
(Hincks) (Fig. 3)
MembraniporacorbulaHincks, 1880c;378,pi. 17.fig.
6.
Crassimarqinatelta \Carbttlella) corbula. Gordon.
1984: 29, pi. 3, figs D,E; 1986: 32,pi.5, fig. A.
Description
Colony encrusting, forming a small, flat,
unilaminar sheet Autozooids oval, 0.5X
0,35mm, with large oval opesia, a narrow,
granularcryptocyst and a reduced, smooth gym-
nocyst. Twelve to 18 pairs of spines distributed
around the opesia, the distal one or two pairs
stout,erect,therestthin, incurvedoverthefrontal
membrane. Ovicell spherical, with a transversely
oval frontal fenestra, its distal edge often
developing a short umbo. Avicularium slightly
largerthan autozooids, its distal halfcomprising
a raised, smooth-edged rostrum, supporting a FIG. 3. Crassimargmotella(Corbulella)corbula.
semiellipticalmandible;proximalhalfconsisting
of a shortened opesia bordered by three or four Cranosina coronaia: Winston & Hcimberg, 1986: 6,
pairs ofcurved spines. figs3-6; Hayward, 1988: 281.
Distribution Description
Thisspeciesiswidelydistributedindiewestern Colony forming flat, unilaminar sheets.
Pacific from Japan to New Zealand. A single Autozooids irregularly ov^al to hexagonal.
colony was present in sample 16, from the reef separated by distinct grooves; 0.65-
edge northeast ofthe cay. 0.7Xc.0.4mm. Cryptocyst coarsely beaded, the
beads aligned in ridges, directed medially and
CranosinaCanu & Bassler, 1933 impartingacrenulateedgetothecryptocyst. Dis-
tal etid of autozooid raised, with a hood-like
Colony encrusting. Frontal membrane of borderofsmooth,gymnocyslaicalcificationsup-
autozooid underlainby a broad, peripheral cryp- porting the operculum. Avicularium developed
tocyst; gymnocyst absent. No spines, Avicularia from the distal pore chamber ofeach autozooid,
interzooidal, typically one budded from each its cystid not clearly distinguishable from the
autozooid; mandible setiform. Ovicell reduced, distal wall ofthe autozooid; rostrumtransversely
cndozooidal, or lacking. Large basal pore-cham- orientated, at a slight angle to the frontal plane,
bers present. constricted medially, its disUil end flared; man-
Typespecies.MembraniporacoronaiaHincks, dible setiform, very finely toothed, about0.4mm
1881a- long.
Cranosinacoronata(Hincks) Distribution
(Fig, 2e) A single small colony of this species was
present in sample 16. Itisdistributed throughout
Membranipora coronaia Hincks, 1881a: 147, pi. 10, the Indo-West-Pacific region, from the Philip-
fig- I. pines to Sri Lanka and Mauritius. Also reported
i
BRYOZOA FROM HERON ISLAND 231
fromPuerto Rico (Osburn, 1940) andVenezuela abundant on Mauritian reefs, as part of a
(Winston, 1986), bryozoan sward developed beneath coral
boulders (Hayward, 1988).
FamilyQUADRICELLARIfDAEGordon, I9S4
Superfamilv BUGULOIDEA Gray, 1848
Colony erect, branchings pointed. Autozooids Family BUGULIDAE Gray, 1848
elongate, opesiae extensive; cryptocyst
moderately to well developed; gymnocyst Colony erect and branched, unjointcd,
reduced. Avicularia adventitious, or absent. unilaminar, attached by rhizoids. Zooids long,
Ovicells present or absent. Ancestrula resem- parallel-sided, with almost all ofthe frontal sur-
bling later autozooids. but with a tubular face membranous; lateral walls lightly calcify;)
proximalportionrisingfromanunealcifiedstem. marginal spines usually present. Pedunculate
'bird's head' avicularia characteristicallv
Nellia Busk, 1852b present, Ovicells independent and hyperstomial.
withthe cctoocciummembranous.
Colony erect, branching, jointed; internodes
square-sectioned, consisting offourlongitudinal BugulaOken, 1815
series of autozooids, arranged in alternating,
back-to-back pairs. Autozooids with well-
developed gymnocyst; opesia with broad, Colony erect, growing from an upright an-
cestrula, branching; attached by rhizoids which
proximalborderofcryptocystandsurroundedby
raised mural rim. No spines. Avicularia adven- issue from frontal, lateral and basal surfaces of
theautozooids Thelatterarrangedintwoornune
titious- Ovicells small,partly immersed.
series, alternating; boat-shaped, with the
Typespecies: Nelliaoculato Busk, 1852b.
proximalendforkedandthedistalendofthenext
lowest zooid wedged into the fork, extending
Nellia tenuis Rirmer
beyond it on the frontal side; with a row of
(Fig. lOci
unipnriHjs. nr one to (wo multiporous, septula.
Seen from the front the zooids are usually trun-
NelliatenuisHavmsx* 1926: 245, pi. 14, Hgv 16-17. cate distally and slightly attenuate proximally.
NelliatenuisHayward,1988:286,pi 1,fig a;Gordon. Basal and lateral walls lightly calcified, the
1989a:450. fig.3. membrane occupying most of the front: rjfil
closed by a sphincter and no operculum can be
Description distinguished. One or more spines may be
Colony delicate, inconspicuous, formed from present, usually confined to the distal angles of
internodes l-4mm long, G.25mra wide, dividing the zooid. In most species, a pedunculate
dichotomouslyatinfrequentintervals,mostoften avicularium shaped like abird's head present on
developing simply an undivided series oftwo or the side of all or many zooids. Ovicell hyper
three internodes. Joints between internodes con- stomial. with calcified endooecium and
si'.ting ofslender,cuticulartubes; each internode membranous cctooccium; typicallyglobular, but
finely tapered proximally. Autozooids about sometimes reduced to a hemisphere or less,
0*3 X0.25mm. the narrow, oval opesia compris- closed by the inner vesicle which sometimes
ingaboutthree-fifthsoftotal autozooidlength A forms the majorpart oftbe ovicell.
pair of avicularia at the distal end of each In bi&erial speciesthearrangementofzooidsat
autozooid;rostrapointed, hooked, at rightangles a bifurcation usually conforms to one of three
to long axisofinternode. patterns, originally described by Harmer (1923
as types 3, 4 and 5. The bifurcations are best
Distribution studied from tnr basal side in stainedandcleared
Nelliatenuisisprobablyquitecommoninshal- preparations, but can generally be observed in a
low reefal habitats. At Heron Island, il was piece ofa clean specimen viewed by transmitted
present in samples 14 and 24, from the reef fl:i; light. The pattern of consecutive bifurcations is
west ofthe cay, and the reef crest |o the south. laterally reversed, so that the bifurcations imme-
Harmer(1926)had fragmentary specimens from diatelyaboveandbelowanygivenonearemirror
three localitiesinthe Indo-Ma1aysianregion,and images ofit, For descriptivepurposes the zooids
listed a fourth from the SouthChinaSea. Ryland involved in the bifurcation are distinguished by
(1984) illustrated specimens from Fiji. It was tenets (Fig. 4). The first zooid from which two
232 MEMOIRS OFTHEQUEENSLANDMUSEUM
zooids are budded is referred to as A, ihe one Description
zbeosoiiddes aitb(owvheicAhaanldsoBbuadresCtwaon)dasDBr.esTpheectoivuetleyr cyCotolospniyratlulfitnegd(onfotbroannachsetsal;k,towi1t0hcsmo.mBertaenncdheens-
whiletheinnerzooidsareEandF. Inbifurcations narrow, of uniform width, the zooids biserial.
uftype 3 theaxil isformedbyzooids E and F. In Bifurcationsoftype5,i.e.,withtwozooidswhol-
type 4 the axil is formed by F and G (G being ly enclosed, most obvious in basal view. Zooids
immediatelydistal toEinthesameseries).Zooid 0.6X0.25mm (basal), in Heron Island material.
Eisthusexcludedfromtheaxil,andtheproximal Opesiaoccupyingthree-fifthsormoreofthefron-
partofGconnects withF. Intype5 theenclosing tal surface; the external margin of the zooid in-
process hasbeen furtherextended so thatboth E rolling proximally, narrowing the opesia. Inner
and F arc completely surrounded, and the axil is distalanglewithonespine,outerwithtwo,some-
formed by G and H (Fig. 4). It should be noted, times long, andjointed at the base; a third outer
however, that the connecting portion between G spinesome way below the other two. The spines
and H may be very slender In a furtherdevelop- ofequal size on both sides of the branch, or the
mentoftheenclosingprocess,severalzooidsmay outerones (with reference to the proximal bifur-
be surrounded; the branch then becomes quad- cation) much larger. Avicularia of two kinds:
nserial below thebifurcations. ordinary marginal aviculariaattachedabouttwo-
Type species: Sertularia nentina Linnaeus^ thirds way down the zooid, a little above orjust
1758. below the vortex of the opesia; giant avicularia
present or not. Ordinary aviculariaabout0.2mm
Bugula dentata (Lamouroux) inlength,alittle lessthan thewidthofthebearing
zooid atthepointofattachment; dorsalprofileof
(Fig. 4) rostrum straight, its tip abruptly hooked (rectan-
gular).Giantavicularia,whenpresent,mostoften
AcamarchisdentataLamouroux, 1816; 135,pi. 3,figs replacing normal avicularia on the two outer
3ab. zooids (C, D) at bifurcations; much longer than
t
Bugula dentata: Busk, 1852b: 46, pi. 35, figs 1-5; the width of the bearing zooid; its entire upper
Harmer, 1926: 439 (cum syn.), pi. 30,figs, 5,6; pi. profile convex, the rostral tip sometimes with
32, figs 21-25; Ryland 1974: 343; 1984: 68, fig. 4; lateral cusps; the mandible clavate, with a weak
Winston, 1986:6. terminal point (Harmer, 1926, pi. 32, figs 21,23,
Bugulasp.:DQ&k, 1971,colourplate31 andrearcover, 25)» Ovicells globose, attached somewhat obli-
Coleman, 1977: 80(colourplate), quely overthe innerdistal angle (Harmer, 1926,
FIG. 4. Buguladentata. A,Groupofautozooids,with ovicellsandavicularia. B, Autozooidsinlateral view. C,
Avicularium. D. Basal viewofadichotomy.