Biodiversity of tropical polyclad flatworms from the Great Barrier Reef, Australia

5 Pages·1994·1.4 MB·

by  L J Newman

BIODIVERSITY OFTROPICALPOLYCLAD FLATWORMS
FROM THEGREATBARRIER REEF, AUSTRALIA
LJ. NEWMAN ANDL.R.G.CANNON
Newman, LJ. &. Cannon, LR.G. 1994 0630: Biodiversity oftropical polyclod flatworms
fromtheGreatBarrierReef,Australia.MemoirsoftheQueenslandMuseum36(1): 159-163.
Brisbane.ISSN0079-S835.
Priortoourwork,only 16polycladflatwormshadbeenrecordedfromtheentireGreatBarrier
Reef.Inthepast,thesedelicatewormsproveddifficult tocollectandvirtually impossibleto
fix. Since 1989, we havedocumented 134 species of polyclads (over 90% new) Irum two
locations in the southern Great Barrier Reel. These results indicate thaithe biodiversityof
tropicalmarinepolycladsismuchgreater than was previously thought. Platyhelminthex,
Polyctadida,Jlatworm. colourpattern, biodiversity. Australia, GreatBarrierReef,
L.J.Newman & L.R.G. Cannon, WormsSection, QueenslandMuseum, POBox3300, South
Brisbane, Queensland, Australia41W. M August 199$,
Marine polyclad flatworms (Platyhclminthcs, maintained that the comparative morphology of
Polycladida) arc often regarded as conspicuous the reproductive systemwas anessential tool for
inhabitantsofIruptcal reefsyetsurprisingly little species diagnosis for turbellarians. Serial
is known about either their biology or diversity. reconstruction of the male and female reproduc-
Tropical polyclads are known as pestsofoysters tivestructuresistimeconsumingandhasnotbeen
(Stead, 1907) and giant clams (Newman, el nl . consistently used forspeciesdescriptions
1993), associates ofsoft corals (Camion, 1990),
brirtlcstar.s (Cannon & Grygier, 1991), moHuscv POLYCLADS PRESENT
crustaceans, echinoderms and corals (sec Prud-
hoe, 1985). Lessthan 20studies haveconsidered We collected polyclads by hand from under
Australian polyclads (e.g. Hyman, 1959; Prud- coral rubble at the reef crest and under ledges
hoe, 1977, 1982; Cannon, 1990;Cannonct New- from the reef slope at Heron and One Tree Is-
nun. 1993)andonly 16speciesarerecordedIrorn lands, southern GBR, from 1989 to 1993. All
the Great Barrier Reef (GBR)(Haswdl, 1907. species were examined live before fixation and
Prudhoe, 1985; C—annon& Newman, 1993, New- their COlOUr patterns recorded photographically
manctal„ 1994) andofthesespecies,onlytwo eitherin situ or in the laboratory.
have been described since 1907. Ourstudyoftropicalpolycladshasbeengreatly
The diversity of tropical polyclads is poorly enhanced by the development ofa new Fixation
understoodtoravarietyofreasons.Firstly,many technique which ensures animals are preserved
descriptions arc based on single, immature, Hat, intact and retain their colour patterns (New-
preserved specimens or even only on water man & Cannon, in press). Over 800 specimens
colourillustrations.Secondly,polycladsarerare- (wholemounts and serial sections) with colour
ly collected intact since they tend to fall apart transparencies are lodged at the Queensland
when stressed and as a consequence they are Museum.Forspeciesdescriptions wehaverelied
inadequately represented in museum collections. on examination of morphological characters of
Furthermore, seldom have their colour patterns living animals, colourpattern and on reconstrui-
been adequately recorded Finally, the habitats tion of ihe reproductive anatomy from Ion
andbiologyoftheseflatwormsarepoorlyknown. gitudinal serial sections ofmature animals.
The colourful pseudocerotid polyclads have To date, 134 species belonging to 6 families
been previously identified on the basis of their (Suborders Acotylca and Cotylea) of marine
colour pallern (Hyman, 1954, 1959: Prudhoe, polyclads have been collected from the southern
1985, 1989) and confusion has arisen over the Great Barrier Reef (GBR). We considered 123
reliability of this for species descriptions. Ac- species (over90%) to be new (Table 1) with two
cording to Prudhoe (1985) colour and markings newgenera and one new family.
are the only means by which pseudocerotids can Comparisonofcollectingdata showed that the
be identified (although this was often poorly numberofspeciescollectedpersampling tripdul
recorded) Conversely, Faubcl (1981, 1964) notdiminish withtime.Overall. 1.3lo3.0specie-
160 MEMOIRS OFTHEQUEENSLANDMUSEUM
TABLE 1. Summary of polyclads collected from 140
Heron andOneTreeIslands.
120
Order&Family Genus #knSopwp.n #'Snepwp'.
100
SuborderColylea
BG
Pseudocerolidae
Pseudoceros 5 45 | 60
Pseudobiceros 4 8
Nov.genus#1 8
Nov, genus#2 7
Thysannzoon 2
Acanthozoan u i wntr/i'j«u jumiiviirt) A"nn"*jt Sum*'992 Wlnls»t9» Sunumn'KLl
unidentified 14 FIG. 1.Cumulative totalsofknownand 'new' species
from Heron and OneTree Islands (1989-1993).
Euryleptidae
Ennippta 1 7 possessing similarcolourpatterns to the pseudo-
Cycloporus 8 cerotids (Fig. 2).The Planoceridaewere the most
Nov.Family # 1 1 abundant group of acotyleans: these polyclads
Suborder were generally cryptic, avoiding sunlight and
Acoiylea consequently were moredifficultto find.
Callioplanidae 1 2 Colourdocumentation ofliving flatworms has
Planoceridae 10 proven critical to the studyoftropical polyclads.
Results showed that similar colour patterns oc-
Stylochidae 2
curred in: (I) different families, viz, Pseudo-
unident.
acotvleans 7 ccrotidae and Euryleptidae (Fig. 2 A,B); (2) in
Toial no >pp. ii 123 different genera, viz., Pseudoceros and Pseudo-
biceros (Fig. 2 C,D); and (3) two genera where
werecollectedpersampling day and the number the pattern is the same but the colour is reversed
ofnewspeciescollectedpersamplingdayranged Pseudocerosand Pseudobiceros(Fig. 2 E,F).
from0.4to2.2(Table 2).Thecumulativetotalof Field observations showed that the most com-
new species also rose steadily with each trip and mon polyclads, the pseudocerotids, were found
this number is predicted to continue to increase feedingonavarietyofcolonial ascidiansevident-
with time by the curve (Fig. 1). These results ly showing nonspecifjcity in their diet. During
indicate that more new species can be expected feeding, pseudocerotidsexpand the foldsoftheir
be found from the southern GBR (Fig. 1). Inter- highly ruffledpharynx into the individual zooids
estingly,allofthepreviouslyknownspecieswere of colonial ascidians. Worms collected under
collected during the first sampling trip and boulders at the reefcrest often left feeding scars
remained virtually constant overtime. whenthey wereremovedfrom theirpreyandone
Themostdiverseand abundantpolyclads from species was consistently collected from within
thesouthernGBRbelongtothePseudoccrotidae, the test of its prey, an ascidian. Pseudocerotids
which are generally the most flamboyantly did not feed in aquaria and further study of
coloured flatworms. The Euryleptidae were the preferencesmay behamperedbythedifficulty in
second most diverse family; these worms were keeping ascidians healthy in aquaria. No other
also found to be flamboyantly coloured, often prey was observed being consumed although
TABLE2. Summaryofcollectingdatafrom Heron andOneTree Islands.
Collectingtrip Total#spp. #Spp.known U 'New' spp. #Sampling Tsopipa.l/d#ay sHp'pN^edawy'.
Winter 1989 39 1 I 28 ->2 1.8 1.3
Summer1990-91 15 13 6 2.5 2.2
Winter1991 *>2 12 17 1.3 0.7
Summer1991-92 60 38 23 3.0 1.7
Winter1992 57 23 35 1.6 0.7
Summer 1992-93 51 9 23 2 2 0.4
TROPICALMARINEFLATWORMS 161
these polyclads were also found on sponges and POLYCLADSFUTURE
coralline algae. Callioplanids, however, were
found on several occasions in the field with a Despite their relatively large size (average of
small intact gastropods, Turbo perspeciosus 20-50mm)andtheirconspicuousandflamboyant
(Iredale, 1929),intheirpharynxordigestivetract. colour patterns, polyclads were poorly repre-
FTG. 2.Colourvariationincotyleans. Betweenfamilies: A,Pseudocerotidae;B,Euryleptidae. Betweengenera:
C, Pseudocerossp.;D, Pseudobiceros.Colourreversalbetweengenera: E,Pseudocerossp.;F, Pseudobiceros
hancockanus(Collingwood, 1876).
Mil MEMOIRSOFTHEQUEENSLANDMUSEUM
sentedfromtropicalwatersoftheGBR(Prudboe, photography to determine habits, habitus and
1985;Cannon& Newman, 1993; Newmanetal, habitats.
1994). Clearly anyinference that thesmall num-
ber ofcurrently described species indicates low ACKNOWLEDGMENTS
polyclad diversity in these tropical waters is
wrong. Ourresults haveshownthattheflatworm Many people assisted in the delicate task of
faunaisextremelydiverseatHeronandOneTree collecting polyclads; we wouldespecially like 10
Islands and over 90% of the animals collected thank; Mr A, Flowers, Ms M. Preker, Mr H.
havenotbeendescribed.Thisisthehighestdiver- Peterken, Ms S. Whittingham and Mrs J. Mar-
sity forthese wormsrecorded forone locationin shall. MrA. Flowershelped immenselywithcol-
the world. Furthermore, the notion that these lectingandphotography;MsZ. Khaliland MsC.
marine invertebrates may berare and difficultto Lee did the histological preparations, and Mr B.
find has been proven false by o*ir demonstrated Cowell helped withthe colourplate. Kim Sewell
successincollecting. and Peter Davie made useful comments on the
Examination of live animals has provided the manuscript. We are also grateful to the Heron
opportunity to document new morphological Island Research Station Dirccmr and Ihe
characters such as pharynx shape and size, mar- Managers of the One Tree Island Research Sta-
ginal tentacle shape and marginal and cerebral tion. Dr I. Lawn and Ms M. Prckcr arc thanked
eye arrangement. As a consequence, these new for their support and advice. This project was
taxonomiccharactersarebeingusedtorcdcvcribe generously supportedby P&OPty Ltd/HeronIs-
known species, describe new species and desig- land Research Station ReefFellowship (to L.N.)
AD
nate new genera. and theAustralian ResearchCouncilGrant#
The improved fixation techniques and the use 90318306(toL.R.G.C.I
ofcolourphotography and field observation* on
live animals has enabled us to recognise new LITERATURECITED
characters,which,togetherwilhreconstructu:nut
the reproductive anatomy, will enable new taxa BRUNCKHORST, D.J. 198—8. Amazing aposematic
tobedescribed. phyllidiid nudibranchs some interdisciplinary
perspectives. P.88, In Proceedings of the
We have shown, for example, thai Ihe same Australian Marine Science Association Jubilee
colour pattern can occur in different genera and Conference, Sydney, December 1988.
evenindifferentfamilies.Colourshavealsobeen CANNON. L.R.G. 1990. Apidioplana apluda n.sp., a
found reversed between different genera These new polyclad turbellarian symbtote ofgorgoruan
resultsshowthaicolourpatterncannotreliablyhe corals from theGreat BarrierReef, wilh p review
used todifferentiategeneraor families. Whether of the family Apidioplanidae, Memoirs of 'he
colour pattern alone can be used to separate Queensland Museum 28: 435^142.
species remains unanswered without further CANNON, L.R.G. & GRYGIER.MJ. 1991. The tur-
study andcomparisons madeofthe reproductive llian NotoptcMQ comesn, sp. (Leptoplanidae:
Acotylea: Polycladida) found with the intenidaJ
stracttiTes. brittle star Ophiocoma scolopendrina
The biological significance of flamboyant (Ophiocomidae:Ophiuroidea*inOkinawa,Japan.
coofltohuersseiwnopromlsy.daSdevsemraalypboelyrcellaadtsedatroetrheepotorxtiecdittyo CANNGaOlNax.eaL1.0R:2.3G-.33.& NEWMAN, LJ. 1993&.
contain toxins such as tetrodotoxin (Halstead, Polycladida. Pp. 82-83, PI. 4. In Mather. P.
1978; Miyazawa et al., 1986; Flowers, pers. BBeeanlnettyt,an1d.(Seodsn)s,:lSAydcnoreayl).reel handbook.4(Surrey
comm.). Further studies arc needed on chemical FAUBEL A. 1983. The Polycladida, Ttnbellana.
defenceinpolvcluds in ordertodeterminewhich Proposalandestablishmentofanew system. Part
groupsarek>xu: Certainly, somepseudocerotids The Acolylca. Mmolungcn aus dein hambur
I
are known to mimic toxic opisthobranch mol- gischen zoologischcn Museum und Instttut 80:
luscs (Brunckhurst. 19&8: Gosliner & Behrens, 17*121.
1990;Newman etaL, 1994. 4. The Polycladida, Tutbcllana. Proposal and
TTietrue diversity oftropical marine polyclods sublishment of a new system. Part II. The
Cotylea. Milteilungen aus ilem h0mbvrgi*chee
is now just being recognised. Increased aware- zoologischen Museum und tasxitUtBJ: )8"
ness ofpolyclad diversity is related tc new fixa- GOSLINER, T.M. & BEHRENS. D.W. W'X). Special
tion techniques, accessibility to the reel resemblance, aposematic colouration and
recognition ofthe importance of live study and mimicry in opsuVbranch gastropods. Pp. 127-
TROPICALMARINEFLATWORMS 163
138. In Proceedings ofa Symposium Sponsored phyllidiid nudibranch (Mollusca, Nudibranchia).
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