A putative hybrid of the Murray Crayfish, Euastacus armatus (Crustacea: Decapoda: Parastacidae)

2010·4 MB·English

by  Diana Street

A putative hybrid of the Murray Crayfish, Euastacus
armatus (Crustacea: Decapoda: Parastacidae)
Diana STREET
Geoffrey EDNEY
ROWE
Darryl
Susan H. LAWLER
Department of Environmental Management and Ecology, La Trobe University, Wodonga, VIC
3690,Australia. Email: [email protected]
Citation:Street, D., Edney, G., Rowe, D. & Lawler, S.H. 2010 03 15.A putative hybrid ofthe Murray
Crayfish, Euastacus armatus, (Crustacea: Decapoda: Parastacidae). Memoirs ofthe Queensland
Museum -Nature 55(1):213-224. Brisbane. ISSN 0079-8835.Accepted:June 2009
ABSTRACT
An unusual population of freshwater crayfish of the genus Euastacus found in the
East Buffalo River, Victoria, is morphologically distinguishable from other populations,
and in particular has a marbled or camouflage pattern on the carapace. The cheliped
dactylarspine counts and the number of zygocardiac teeth anteriorto the ventral ear of
the zygocardiac ossicle (TAP) are somewhat reduced but these values overlap with the
range of the most similar species (E. armatus). Genetic sequences from the C01 and
16S mitochondrial DNA regions were also undertaken, and the results indicated that
these animals may representan aberrant population ofE. armatus (the MurrayCrayfish)
or perhaps a hybrid between E. armatus and E. woiwuru, two species that are found
downstream and upstream, respectively, ofthe population investigated. The conservation
status of the population remains unclear. Decapoda, Parastacidae, mitochondrial
DNA, Buffalo River, conservation, MurrayCray, hybrid.
Australian freshwatercrayfish are an ancient streams and rivers, and their preferred habitat
and diversegroup thatare increasingly in need may be at risk due to climatechange.
of conservation (Horwitz 1990a; Merrick 1997;
The Murray Cray, Euastacus armatus (von
O'Brien 2007). Spiny freshwater crayfishes
Martens 1866), has the widest distribution in
of the genus Euastacus are found on the east
the genus, being found in both the Murray
coast of Australia, from the Great Dividing
and Murrumbidgee Rivers and their tributaries
Range in Victoria to isolated mountains in
northern Queensland (Clark 1941; Morgan (McCarthy 2005; Gilligan et al. 2007). The
1986, 1988, 1997). New species have recently speciesisconsidered to beremarkablyinvariant
been described from north-eastern New South morphologically, even across its broad range
(Morgan 1986).
Wales (Coughran 2002, 2005). Most species in
thegenusareconsidered short-rangeendemics Euastacus woiwuru (Morgan 1986) is a small
(Harvey 2002), and looking at a map of their species which occurs on both sides of the Great
distributions (eg. Shull et al. 2005) makes it DividingRangeinVictoria. Thisspecies isfound
easytoseewhy;Euastacusspeciesareusuallylim- in theDandenongrangesnearMelbourne,aswell
ited to a single catchment or mountain top. They asincentralandnorthernVictoria. Itsmostclosely
aremostcommonlyfoundincold,clearmountain related speciesisEuastacuskershawi (Smith1912),
MemoirsoftheQueensland Museum Nature • 2010 • 55(1) • www.qm.qld.gov.au 213
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Street, Edney, Rowe & Lawler
finally able to collect a number of crayfish at
SchultzTrackand upstreamofthesite. Wewere
also thus able to determine that the marbled
population of Euastacus at the Schultz Track
site actually occurred at the boundary between
E. armatus and E. woiwuru populations.
The marbled Euastacus at Schultz Track have
a distinctivecolourpattern on thecarapace (Fig.
1), and a few other characters that differ from
the other spiny crayfish species in the river.
We
originally misidentified these crayfish as
Euastacus crassus (Riek 1969) and included
DNA
the in a large phylogeny of Euastacus
(specimen number KC2654 inShull et al. 2005),
however, its position on the phylogeny showed
clearly that it was not E. crassus (Shull et al.
2005). The specimen was then sent to Dr John
Short oftheQueensland Museum, whosaid he
FIG.1.A,themarbled EuastacusandB,E.arnmtus,both believed it to be a new species (pers. com.). As
foundatSchultzTrackon theEast BuffaloRiver. such it was listed as an undescribed species in
a recent review of the conservation status of
Victorian freshwatercrayfish (O'Brien 2007).
theGippsland spiny crayfish (Shull etal. 2005).
Both E. armatusand E.woiwuru arefound in the For measures to be invoked toward the
Buffalo River in northeast Victoria. management ofcrayfish populations, species
have to be recognised as threatened and in need
In 2002 we visited Dandongadale, on the of protection (Merrick 1997). The conservation
Buffalo River near the junction of the Rose status of the unknown crayfish at Schultz
River, in order to recollect Euastacus woiwuru Trackcould not be clarified until its taxonomic
that had first been collected at that locality by status was resolved. Further collections were
P..Horwitz in 1982 (Morgan 1986). When we interrupted by road closures due to wild fires
searched the area this time we could only find in2003and 2006. Wewerefinallyabletocollect
E. armatus. We continued to search upstream more individuals in 2007, and discovered that
and found an unusual populationofcrayfishat thesite wherewefound the unusual population
Schultz Track in 2002 with a marbled carapace occurred on the species boundary between
(Fig. 1). Further searches of the Buffalo River E. armatus and E. woiwuru. In this study we
were interrupted by the bushfires of 2003, compare the unusual crayfish with other local
which closed some roads for 18 months. When Euastacusspeciesusingboth morphological and
we were able to return to the site, it had been geneticcharacters.
altered by bulldozers and the water was
affected by heavy erosion and ash from the METHODS
We
fire. wereunabletofind anycrayfishatthat
time. In 2006 the fires came again, with heavy Description of the study site. The Buffalo River
fire-fighting taking place near Schultz Track. flows north from the Barry Mountains and
When the roads opened again in 2007, we were joins theOvens Rivernear Myrtleford, Victoria.
214 MemoirsoftheQueensland Museum Nature • 2010 • 55(1)
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Murray Crayfish, Euastacus armatus
was removed for DNA analysis. Because they
can grow their legs back, this allowed us to get
genetic samples without killing the animals. It
did, however, limit the number of specimens
available fortaxonomic work. Somespecimens
werecollected and releasedlivewithoutremov-
ing any legs. They were used to record the
distribution of crayfish in the river (Fig. 2) but
are not partofthe material examined.
Materialcollectedbutnotretained.Oieraxdestructor:
Buffalo River, MannaGumCampsite, VIC, (36°50'S,
146°39'E),5 Mar. 2002,G. Edney, 2
.
Euastacusarmatus. Buffalo River, 1.5kmupstreamof
SchultzTrack, VIC (37°00'S, 146°49'E), 1 May 2007,
G. Edney, 2 9.
,
Taxonomic and morphometric examinations.
A total of 45 crayfish were examined for 38
characteristics and 15 measurements that were
turnedintoratiosfollowingtoMorgan(1986,1987
1997). Twenty eight of these were E. armatus,
seven were E. woizouru, three were £. crassus,
one was E. reiki and six were marbled Euastacus
from the East Buffalo River. A Categorical
Principal Component Analysis (CATPCA) was
performed using SPSS version 15 to determine
which characters best distinguished species.
Material examined for morphological characters.
CurrentlyintheresearchcollectionintheDepartment
destructor. of Environmental Management and Ecology, but
will be deposited in the Museum of Victoria after
South of Lake Buffalo (a man-made reservoir), currentongoingresearchiscompleted.
the Buffalo Riverisadjacenttopine plantations Euastacusarmatus. Tallangatta Creek, VIC, (36°17'S,
athnedAclaptitnleesNtaattiioonnaslaPsarwke.llScahsulSttaztTeraFcokr,eswthaenrde 1C4r7e°e3k3,'EV)I,C2,0(A3p6r°.061'9S9,5,14S7.°2L7a'wEl)e,r,155 Ma2y; K19o9e5t,onGg.
waEaekstiflBoormuaenntdcrhethoaefbotmhvaeerubwplhpeeedrreEBuutafhsfetaalEcoaussRt,ivaeinrs,dianWbeotsuhtte CV&NlISoCMWs,.s,(,S3h(6,_i°3J,0r623l°'e0Sy5.,,'.S1;5,4H6(i1°J,44n57c4'°eE42s)6;,'CME1ru)1e,reJruk2la,6yyBA1puR9ir9rv5ire,lorJ,w1.9SaB9la5oP,aminnaG,ew.s,a;CrNKl.tioPhns.asg,
Buffalojoin (Fig. 2). River,Oxley, VIC, (36°27'S,146°22'E),24June1995,M.
Versteegen, J; Tumbarumba Creek, Tumbarumba,
Collection ofspecimens. Specimens werecoll- NSW, (35°51'S, 148°02'E),9July 1995, M. Versteegen,2
ected using drop nets, bait nets, dip nets and cJ,9;NugNug, BuffaloRiver,VIC, (36°40'S,146°41'E),
by hand. Concerns for the conservation of this 614D6e°c1.1'1E9)9,6,SePp..Su1t9e9r9,,VB;.OHvoelnlsowRaiyv,er, VMICa,nn(3a6°G02u'Sm,
population meant that only two individuals Campsite,BuffaloRiver,VIC,(36°5()'S,146°39'E),5Mar.
could be retained from each site, so some 2002, G. Ednev, a; SchultzTrack, East Buffalo River,
animals were released after a portion of a leg VIC, (36°59'S,T46°48'E), 10Mar. 2002,G. Edney,<J.
Memoirsofthe Queensland Museum Nature • 2010 • 55(1) 215
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Street, Edney, Rowe & Lawler
Euastacus woiwuru. Rollason's Falls, Mt. Buffalo NP, used as the template for a polymerase chain
VIC, (36°42'S, 146°47'E), 15 Feb. 2000, M. Chapman, reaction (PCR).
Dobson's Creek, Fern TreeGully, VIC, (37°52'S,
c1J4;5°19'E), 23 Mar. 2002, K. Sewell, J; West Buffalo Two different PCR products were amplified
River, VIC, (37°02'S, 146°46'E), 23 Nov. 2006, G. from the mitochondrial genome: 720 base pairs
Edney, 2 rj; East Buffalo River, 1.5 km upstream of of the cytochrome c oxidase subunit (COI)
SGc.huEldtnzeyTr,ack,EVaIsCt,B(u3f7f°a00l'oS,Ri1v4e6r°,494'.E5),k3m0Aupprs.t2r0e0a7m, and 503 base pairs of the 16S rRNA. CO1 I was
of Schultz Track, VIC, (37°01'S, 146°49'E), 15 Jul. amplified using the LCO1490 and HC02198
2007, G. Edney, £; Dandongadale River, near Lake primers from Folmeret al. 1994. The 16S rRNA
Cobbler, VIC, (37°01'S, 146S37'E), 30Aug. 2007,G. fragment was amplified using the 16sL and
Edney,9- 1472 primers from Shull et al. 2005. A BioRad
Euastacus rieki. Tumbarumba Creek, Tumbarumba, PTC-0200 DNA Engine Peltier Thermal Cycler
NSW, (35°51'S, 148°02'E), 9 July 1995, M. Versteegen, was used to amplify the DNA, with details of
&
the reaction mixtures and temperature profiles
Euastacus crassus. Basalt Hill, Falls Creek, VIC, 17 available from Street 2007. PCR products were
Jan. 2006, D. Heinze, Native Dog Flat, Buchan sent to Macrogen Inc. (Seoul, Korea) for single
River, VIC, (36°90'S, 148°09'E), 26 Feb. 2000, G. extension DNA sequencing.
Edney, Tributary of Big River, Dartmouth Dam,
<J;
VIC, (36°39'S,147°18'E),26Jan. 2007,G. Edney, V. Material usedforMitochondrial DNAAmplification.
Marbled Euastacus.SchultzTrack, EastBuffalo River, Euastacus armatus. Arml= Manna Gum Campsite,
VIC, (36°59'S, 146°48'E), 10 Mar. 2002, G. Edney, BuffaloRiver,VIC, (36°50'S, 146°39'E),5 Mar. 2002,G.
QRivMerW,V2I6C5,96(,36K°5C92'6S,541,46°J4;8S'cE)h,ul1t0zMTarra.c2k0,02E,asGt.BEudfnfeayl,o SEedpn.ey19,9<9J,;AB.rHmo2ll=oOwvaey,ns,;RAivremr,3V=ICB,ra(3d6°B0e2t'tSs,M1e4m6o°r1iTaEl),,
9;Schultz Track, East Buffalo River, VIC, (36°59'S, Y20a0c7k,aGn.daEnddnaehv;CrAerekm,4VI=C,Bu(f3f6a°2l0o'SR,iv1e4r6,°4V8I'CE),,1209MJaurn..
146°48'E), 10 Jul. 2002, G. Ednev, 2; Schultz Track, 2002,G. Edney,QMW26582, KC2653.
East Buffalo River, VIC, (36°59'S, 146°48'E), 21 Apr.
2007, G. Edney & S. Lawler, 9; Schultz Track, East Euastacuswoiwuru. Woil = East BuffaloRiver, 1.5
GB.ufEfadlnoeyRiv&erS,.'LVaIwCl,e(r3,6°2592'-S, 146°48'E),22Apr. 2007, 3k0mAuppr.st2r0e0a7,mGo.fSEcdhnuelvt,zT<}r;aWcoki,2VI=C,We(3s7t°0B0u'Sf,fa1l4o6°R4i9v'eEr),,
VIC, (37°02'S, 146°46'E), 23 Nov. 2006, G. Edney,
Genetic analysis. The mitochondrial genes COI Woi3=East BuffaloRiver,4.5km upstreamofSchultz
and 16Swereused becausetheyhavebeen used Track,VIC,(37°01'S,146°49'E),15Jul.2007,G.Ednev, 2;
extensively to clarify taxonomy and examine Woi4=Dobson'sCreek,FernTreeGully,VIC,(37°52'S,
evolutionary processes in freshwater crayfish 145°19'E),23 Mar. 2002, K.Sewell,<J; Dandongadale
& River,nearLakeCobbler,VIC,(37°01'S,146°37’E),30
(Crandalletal. 1995, 1999; Versteegen Lawler, Aug. 2007, G. Edney, Woi5 = West Buffalo River,
1997;Lawler&Crandall 1998;Hughes&Hillyer VIC, (37°02'S, 146°46'E),23 Nov. 2006,G. Edney, J.
2003; Austinetal. 2003; Munasingheetal. 2003; Euastacuscrassus.Cral =NativeDogFlat,BuchanRiver,
Shull et al. 2005; Gouws et al. 2006; Ponniah VIC, (36°90'S, 148°09'E), 26 Feb. 2000, G. Edney,
& Hughes2004, 2006). These gene regions have Cra2= Native DogFlat, Buchan River, VIC, (36°90'<SJ,;
been used to find cryptic species in other fresh- 148°09'E), 19 Mar. 2002, G. Edney, KC2649, J; Cra3
water macroinvertebrates (Chenoweth & Hughes =148N°a0t9'iEv)e,2D0oMgarF.la2t0,02B,uGc.haEndneRyiv,erK,C2V7I2C0,. E(u3a6s°t9a0c'uSs,
2003; Bakeret al. 2004). yarraensis.Yar1 = LoveCreek, ViC,(38°48'S, 143°58'E
DNAwasextracted fromtissue(usuallygillor )=, 1CoJcakn.at2o0o0,4,VKI.CSe(w37e°l9l4'&S,G1.45E°d4n9e'yE,)K2C128M3a1r;. Y2a00r2,2
a bit of a leg) using guanidium iso-thiocyanate KC2651.
a(sGIiTn)Cbruafnfdearlalnedtaal.ph(e19n9o5l)-.cThhleorDofNoArmweaxtsrarcetsiuosn- MBuafrfballeodRiEvuears,tVaIcCus,.10UnJukl.l20=02S,cGh.ulEtdzneTvra,c?k;,UEnaks2t
pended in lOOpI, two microlitres of which was = Schultz Track, East Buffalo River, ViC, 10 Mar.
216 MemoirsoftheQueensland Museum Nature • 2010 • 55(1)
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Murray Crayfish, Euastacus armatus
0.01
FIG. 3. Neighbour-joining consensus tree using 16S and COI mitochondrial DNA sequences. Interior
branch testprobabilitiesareshownonnodeswithbootstrapvaluesshown in parentheses,bothusing100,000
replications. Arm=£.armatus,Unk=Marbled Euastacus,Woi = £.woiwuru,Yar= £.yarraensis,Cra= E.crassus
and theoutgroupis Euastacusaustralasieusis. Forinformationon collectionsitessee methodssection.
MemoirsoftheQueensland Museum Nature • 2010 • 55(1) 217
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Street, Edney, Rowe & Lawler
TE.AaBrLmaEtu1.sSaonmdeE.mworopihwoulrougaigcraelecwhiatrahcMteorrsgoafnth(1e98E6u)a,stwahcuoseoxfatmhienBeudffmaalonyRimveorr,eViicntdoirviiad.uaTlhse. characters for
Marbled Euastacus E.armatus E.woiwuru
Numberexamined 6 28 7
TAP 4-5 5-7 7-9
UrocardiacRidge 8 9-10 9-11
0-1 0-3 0-1
Marginalmesal
dactvlarspines
0-5 0-3 2-5
Dorsalmesal
dactylarspines
*
i Mesalcarpalspines 2 2 3
Malecuticlepartition no no yes
Telsonicspines yes yes no
2002, G. Edney, QMW 26596, KC2654, <$; Unk3 = RESULTS
SchultzTrack, EastBuffaloRiver, VIC, 22 Apr. 2007,
G1..5Ekdmneuvp&stSr.eLaamwloefr,Sc2h;uUlntkz4Tr=acEka,stVBIuCf,fa(l3o7°R0i0v'eSr,, Distribution. We found a total of 10 crayfish
146°49'E), 30 Apr. 2007, G. Edney & D. Street (leg intheBuffaloRiverthat,whileclearlybelonging
only);Unk5=EastBuffaloRiver,1.5kmupstreamof to the genus Euastacus, did not resemble any
SchultzTrack,VIC,1 Mav2007,G. Edney&D.Street known species. Three of these 'marbled'
V(lIeCg,on2l2y')A;pUr.nk2600=7,EaGs.tEBdufnfeaylo&RiSv.erL,aSwclheurl;tzUTnrka7ck=, Euastacus were collected in 2002 and seven in
East BuffaloRiver,SchultzTrack, VIC, 22Apr. 2007, 2007. Four ofthe animals caught in 2007 were
G. Edney & D. Street (leg only); Unk8 = Schultz released on site after removing a portion of
Track,EastBuffaloRiver,VIC,(36°59'S,146°48'E),21 a leg for genetic analysis. All of these animals
TArparc.k,20E0a7s,tGB.ufEfdanloeyRi&verS.,LVaIwCl,e3r,Ju2l;yU2n00k79,=G.SEchdunletyz were found in a stretch of river only a few
& D. Street, (legonly). kilometreslong inthe East Buffalo River(Fig.2).
Phylogeny construction. DNA sequences were Euastacusarmatusarewidelydistributed inthe
aligned using Cluster W in the computer Buffalo River below the lake, and in the Ovens
program MEGA Version 4.0 (Kumar et al., 2004; River into which the Buffalo River empties.
Tamura et al., 2007). Only specimens that were They were also found near Dandongadale (the
successfully sequenced for both mitochondrial locality),atSchultzTrack,and 1.5km upstream
gene regions were used for phylogeny con- of Schultz Track, where they occurred in sym-
struction. Euastacus australasiensis (KC2637) was patry with E. woiwuru.
used as an outgroup, and other sequences were Euastacus woiwuru were found on top of
included forcomparison, includingthemarbled Mount Buffalo, where they had not been
KEuCa2s7ta2c0usaKnCd26E.54y,arrEa.eatirsmiastuKsC2K8C2165a3n,dEK.Ccra2s6s5u1s pDraenvdioonusglaydarleceorwdheedr,ebtuhteywehraednboetefnoruencdorndeeadr
(Shull et al. 2005). in 1982 (Morgan 1986). They were also found
A consensus tree for the two gene regions at Schultz Track and 1.5 km, 4.5 km, and 6.8
was constructed using the neighbour joining km upstream from Schultz Track in the East
method in MEGA. Two different probabilities, Buffalo River. Theywerealso found in the West
thebootstrapand interior branch test, were mea- Buffalo River and in the upper Dandongadale
sured for each node on the phylogeny (Fig. 3). River, so theirdistribution is in the headwaters
218 MemoirsoftheQueensland Museum Nature • 2010 • 55(1)
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MurrayCrayfish, Euastacus armatus
of the catchment (See Fig. 2). Both E. armatus was describedbyFrancois (1962), isconsidered
and E. woiwuru arefound in sympatry with the to be a useful character for crayfish taxonomy
marbled Euastacus 1.5 km upstream ofSchultz (Growns & Richardson 1990) and hasbeen used
Track. in the descriptionof Euastacus species (Morgan
The common yabby, Cherax destructor, was 1986; 1988; 1997). The TAP of E. armatus is
found in the Buffalo River, 6 km south of between 5 and 7, while the range of TAP in E.
Dandongadale (Fig. 2), and Engaeus burrows are woiwuru is between 7 and 9 (Morgan 1986).
common throughout the catchment. We have TheSchultzTrackpopulation,orthemarbled
not dug up any burrows oractively sampled the Euastacus, had TAPs at or below the range of
burrowingcrayfish, but the species is probably E. armatus, with at least half of them having
Engaeus cymus (Clark 1936) (Horwitz 1990b). five teeth in one ear and four in the other.
During the taxonomic examinations of old These assymetrical individuals were given a
TAP
collections, we found anothercase of Euastacus score of 4.5, while somel individuals had
armatus in sympatry with another species four teeth in both ears, which is outside of the
of Euastacus. A collection from a single site published range of E. armatus (Table 1).
(Tumbarumba Creek, NSW in 1995) was found All of the six marbled specimens examined
to contain both E. armatus and Euastacus reiki for morphology were small, with occipital cara-
(Morgan 1997). These species both have white pace lengths (OCLs) less than 44 (28, 28, 28, 29,
claws and similar spination, highlighting the 37 43). The larger ones had white on the tips
degree to which different species can appear
of their claws. It is possible that they develop
similar in this genus. One of the characters whiteclawsas theygrow larger. E. armatusalso
used to distinguish E. reiki from E. armatus is change from green or brown claws to white
the TAPcount. as they grow, but the size where this change
Morphological examinations. A total of 45 occurs seems tovary between populations (pers.
obs., SL).
Euastacusspecimenswerescored for38character-
istics and 15 measurements that were turned Genetic analysis and phylogeny. Phylogenies
into ratios according to Morgan (1986, 1987, constructed for the two mitochondrial DNA
1997). Our ratios fell well within the range of regions (16S and COI) produced the same
Morgan'sdata forall thespeciesexamined, and topology. Theconsensustree isshown in Fig.3.
hierarchical cluster analyses in SPSS grouped The phylogeny shows all the marbled Euastacus
TthheeaCniAmTaPlsCiAnttoesstpeicnieSsPSclSusptreorsdu(cSterdeeat 2li0s0t7)o.f tino tthheesmaimteocchloandderwiiatlhDE.NaArmapthuysl.oAgcecnoyr,ditnhge
morphological characters that were most useful
unusual Euastacus is not a separate species from
in differentiating these species of Euastacus. DNA
sAdihfsofhweornretniecnreTslaibistnleetmh1p.ehSacshiuslitnzgTrtaheckmopropphuollaotigoincails gpE.oepanruemlsaatt(uJisio,nehtiosawlde.ivf2ef0re0,r3en)t.mayanayleytsisshuoswintghnautcltehairs
The characters used to distinguish the three DISCUSSION
Euastacusspecies were the malecuticle partition,
telsonic spines, mesal carpal spines and theTAP An unusual population of crayfish of the
(Morgan,1986,1997).Thenumberofteethanterior genus Euastacus was found in a very short
totheposteriormargin ofthezygocardiacossicle stretch of river. This population is designated
ear, or TAP, is a morphological character that the marbled Euastacus in this paper, and its
MemoirsoftheQueensland Museum Nature • 2010 • 55(1) 219
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Street, Edney, Rowe & Lawler
taxonomicstatus remains unclear. Thelocation constraints could result in a bias during inter-
ofthispopulationbetween twodifferentspecies specific matings, particularly if the animals
(Fig. 2) suggests that itcould be a hybrid. involved have a consistent size difference. For
DNA example, we know that small males can mate
Geneticsequencesmitochondrial genes
16S and COI were used to test the hypothesis with larger females, and the species E. armatus
of a hybrid zone. These genes were chosen usually grow larger than E. woiwuru (Morgan
becausethey havebeenused formanystudiesof 1986).
speciation and population structure ofAustralian Someauthorssay that E. armatus is not found
afrnedshHwialtleyerrd,e2c0a0p3o;dsCh(eCrnaonwdaeltlhet&aL,Hu19g9h5e;sH,ug20h0e3s; (inGislylimgpaantertyalw.it20h07o)t.heTrhimsempebrecresptoifonitsmageynubse
ShulletaL,2005;Schultzetal.,2007). dueto thelackofsamplinginareasofpotential
Theuseofthemitochondrialgenecytochrome overlap, because we have found E. armatus
oxidase (COI) to identify species is also known and E. woiwuru at the same site in the Buffalo
as barcoding (Mitchell 2008). Although it has River, and we also identified at least one site
beenused toidentifycrvpticspeciesinCrustacea in New South Wales where E. armatus is found
(Wittetal. 2006)and ininsectgroups(Rubinoff& in sympatry with E. rieki. We did not recognise
Sperling2004;Hebertetal.2004;Smithetal.2006), the sympatry at the time ofcollection (in 1995)
there are also instances in which COI has been because £. rieki had not yet been described
unable to distinguish between species (Meier (Morgan 1997). Euastacus reiki and E. armatus
et al. 2006; Hickerson et al. 2006; Whitworth et are so similar morphologically that we have to
al. 2007). Nevertheless, some authors claim it dissect thegastric mill to tell themapart, which
iseffectivefor measuring hybridisation events,
defining hybrid zones and discovering cryptic makes themvery hard todistinguish in thefield.
species (Rubinoff& Holland 2005). Almost 30 years ago, Euastacus woiwuru were
found near Dandongadale, but only Murray
Failures to resolve species boundaries using
mitochondrial genes are more likely when the Crays(E.armatus)arefound therenow. Euastacus
species have recently diverged, or in cases of woiivuru are now found about 20 kms south of
inter-specific hybridisation (Shaw 2002). Nelson Dandongadale in the Eastand West branchesof
et al. (2007) were able to identify nine species of theBuffalo River.Theapparentmovementofthe
blowfliesusingDNAbarcoding,butmisidentified Murray Cray upstream could be explained by
the one hybrid specimen using this techinique. thealterationofhabitatsby humandisturbance
Our data clearly separated known species or by the warming of the river due to climate
change or many years of drought. Either way,
wofoitwhuerguenfuosrmEiunasgtawceulsl, dweiftihne£.damromnaotpushyalnedtiEc. the change in distribution may indicate that
groups (Fig.3).Themarbled Euastacusfell within the species boundary between E. armatus and
the E. armatus clade using consensus sequences £. woiwuru has been moving for decades. The
of the mitochondrial genes COI and 16S. This fact that an unusual morphological variant is
pattern is suggestive rather than conclusive, found at this boundary is highly suggestive of
however,becausemitochondrialDNAisinherited a hybrid zone. However, if they are hybrids,
directly from the mother without undergoing they do not appear to form a self sustaining
recombination. If the mothers of the hybrids breeding population, because both parent
consistently belong to the species E. armatus, species are present at the localities where the
this pattern would still occur. Behavioural marbled form is found.
220 MemoirsoftheQueensland Museum Nature • 2010 • 55(1)
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Murray Crayfish, Euastacus armatus
MarbledEuastacusaremorphologicallydistinct to be considered a conservation unit (Fraser &
in their colouration and the fact that some of Bernatchez2001).
their TAPs (the number of teeth anterior to the Unique fauna areoften found in unregulated
aprosetbeeriloorwmtahregpiunblofisthheedzryagnogcearodfiaE.caorsmsaitclueseaanrd) headwater streams (Baker et al. 2004), and
this study provides an example of an unusual
E. woiwuru. Interestingly, Morgan states that population ofspiny crayfish. Theconservation
the TAPs of E. woiwuru are generally lower in
status of this population needs to be clarified.
aMnudrrtahyatRaivseprectirimbeuntacroilelselcitkeedtahteDBaunfdfaolnogaRdivaelre, Tprhoecelsosceast.ioCnowisssuabrjeeactlltoowesedvteorarlotahmrefarteeelnyinign
was unusual (Morgan 1986, p. 49). Perhaps this and out of the river, and fires and fire control
location, whichisattheedgeofthedistributionof measurescombined tosignificantly disturb the
both species, contains some unique morpho-
site in 2003 and 2006. Given the fire history of
logical variants. the area, we can expect reduced water flows in
The marbled Euastacus were all very small, thecatchment for decades.
withOCLs (occipitalcarapacelength) below 44
Speciation is a slow process in this genus
mpEoumsa.ssitbHalcoeuwsetvhhaeatrd,thwsehiinmtcaeertbthilepesdlaorcngreatryhsoefiartricenleaamwuasnr,biilqteuides (uPnousnunailahpo&puHluagtihoenso2f0E0.6)a.rmIaftwuse,hitacvoeulfdoustnidllabne
differentenoughtobedeservingofconservation.
juvenile variant, and that these animals grow On the other hand, finding this crayfish at the
into adult Murray Crays with white claws and boundary of two Euastacus species means that
a uniformly coloured carapace. Normally, the possibility of hybridisation must be taken
juvenile Murray Crays do not have the white
seriously, particularly since introgression is a
claws thatarea distinctive feature oftheadults, possibility (Ballard & Whitlock 2004; Funk &
but neither do they have a marbled pattern. Omland 2003; Shaw 2002).
The substrate at this site did not obviously
differ from other stretches of the river where We are planning to sequence nuclear genes
E. armatus juveniles do not show this marbled usingITSprimers (Jietal. 2003) and willcontinue
pattern, but itispossible that there isayet tobe tomakefieldobservations. Investigationoffresh-
identified environmental factoraffecting their watercrayfish speciesboundariesin the Buffalo
colour. Because our permit did not allow us to River may enlighten us about the ecology and
retain and raise these animals, we were unable evolutionofAustralianspinyfreshwatercrayfish.
toconfirm the adultcolourationofthe marbled
specimens. ACKNOWLEDGEMENTS
Many threatening processes are controllable, This research was supported by a series
but for measures to be invoked toward the of permits from Victorian Fisheries (RP906,
management ofcrayfish populations, species RP562, RP751), New South Wales Fisheries
have tobe recognised as threatened and inneed (FSP/CW/135), Victorian Department ofSus-
of protection (Merrick 1997). The sedentary tainability and Environment (10002702 and
nature of crayfish and limited gene flow
10004059) and by animal ethics permits from
between catchments (Fetzner & Crandall 2001; La Trobe University (AEC Invert/03-4(W) and
Gouin et al. 2006) makes them susceptible to AEC07/21(W)).
over-fishingand habitatalteration (Merrick1997;
O'Brien 2007). The first step toward listing a Wewould liketo thankChristineStreet, Susan
population istodetermineifitisdifferentenough Street, Robbie Schaeffer, Kim Sewell, Ryan
Memoirsofthe Queensland Museum Nature • 2010 • 55(1) 221
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'
Street, Edney, Rowe & Lawler
Sewell, David Blair, Phil Suter, Ben Holloway, from north-eastern NewSouth Wales, Australia.
Mick Chapman, Gerry Closs, Michael Shirley, RecordsoftheAustralianMuseum54: 25-30.
Mardi Versteegen, Dean Heinzeand DaleMcNeil 2005. New crayfishes (Decapoda: Parastacidae)
forhelpwithfieldworkandcollections.Wewould fRercoomrdnsorotfht-heeaAsutsetrrnaNlieawn MSuoustehumWa5l7e:s,36A1u-s3t7r4a.lia.
also liketothankWarrenPaul forassistancewith Edney, G.N., Mcneil, D.G. & Lawler, S.H. 2002. The
statistical analyses, Leo McGuire for the use of SwampYabby Cheraxsp.) ofthe Murray River
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