The genus Floresorchestia (Amphipoda: Talitridae) on Cocos (Keeling) and Christmas Islands

2009·6 MB·

by  J K Lowry

MemoirsofMuseumVictoria66: 117-127(2009)
ISSN 1447-2546(Print) 1447-2554(On-line)
http://museumvictoria.com.au/About/Books-and-Journals/Journals/Memoirs-of-Museum-Victoria
The genus Floresorchestia (Amphipoda: Talitridae) on Cocos (Keeling) and
Christmas Islands
J.K. Lowry &R.T. Springthorpe
CrustaceaSection,AustralianMuseum,6CollegeStreet,Sydney,NewSouthWales,2010,Australia(jim.lowry@austmus.
gov.au&[email protected])
Abstract Lowry,J.K. & Springthorpe, R.T. 2009. The genus Floresorchestia (Amphipoda: Talitridae) on Cocos (Keeling) and
ChristmasIslands.MemoirsofMuseumVictoria66: 117-127.
ThewidespreadIndo-WestPacificandCaribbeantalitridgenusFloresorchestiaisreportedfromCocos(Keeling)
andChristmasIslandsforthefirsttimeandanewspecies,F.pooreiisdescribed.Floresorchestiapooreiiscommononthe
beachesofWestIsland,Cocos(Keeling).
Keywords Crustacea,Amphipoda,Talitridae,Cocos(Keeling)Islands,ChristmasIsland,taxonomy,newspecies,Floresorchestia
poorei
Introduction area of investigation because this widespread Indo-West
As partofthe Circum-AustralianAmphipodProject(CAAP) Pacific and Caribbean genus, with little means of dispersal,
ateamofAustralianMuseumbiologists collectedextensively holdsanimportantbiogeography story.
at Cocos (Keeling) Islands and Christmas Island during Location
October 2008. Among the collections was a new species of
Floresorchestia from sheltered sand beaches at Cocos Cocos(Keeling)isanisolatedatollinthenorth-easternIndian
(Keeling) Islands. A small populationofFloresorchestiawas Ocean. Until the 1840’s it was forested and was the site ofa
alsofoundatDollyBeachonChristmasIslandbutnomature huge seabird rookery. In the early 1800s the habitat was
males were collected and we cannot describe it at this time. destroyedandreplacedwithCoconuttrees.Theonlyremaining
TherearefewotherbeachesonChristmasIslandwithsuitable intact habitatinthis set ofislands is atNorth Keeling Island
habitat.Atthetimeofitscollectionthepopulationwas small, about 20 km north ofCocos (Keeling). The islands ofCocos
shelteringundercoconutsandrestrictedtotheedgesofasmall (Keeling) are ringed by white calcareous sand beaches.
streaminthemiddleofDollybeach. Floresorchestiapooreiiscommoninthesupralittoralzoneon
Floresorchestiaisawidespreadcoastalandforest-dwelling these beaches wherever suitable habitat occurs. We strongly
genuswhichoccursmainlyonislandsintheIndianandPacific suspectFloresorchestiapooreiwasliving atCocos (Keeling)
OceansandintheCaribbeanSea.Itisastraightforwardgenus beforethetransformation,butthereis apossibilitythatitwas
torecognizebecauseoftheautapomorphicstridulatingorgans introduced with the Coconut plantations. If they were there
on the epimera. Unfortunately early species such as F. beforethetransformationthenthey shouldbelivingonNorth
pickeringi (Dana, 1853), F. floresiana (Weber, 1892), F. KeelingIsland.
anomala (Chevreux, 1901) and F. ancheidos (K.H. Barnard, Micro-morphologyofFloresorchestia
1916) werenotwell describedinamodern sense andthis has
leadto confusion in lateridentifications. Recently Miyamoto The maxillipedal palp in talitrids may be fully developed,
&Morino(2008)haveproducedmoderndetaileddescriptions reduced to a small rectangular article, reduced to a button-
whichreveal newly recognised species-level characters inthe shapedarticleorfusedtoarticle3ofthepalp.InFloresorchestia
genus.Inthispaperwedescribeanewspecies,F.pooreifrom pooreiitisreducedintoabutton-shapedarticle(fig. 1C).
Cocos(Keeling)Islandsandreportanundescribedpopulation The male gnathopod 1 andfemale gnathopod 2have well
ofFloresorchestiafromChristmasIsland. developedlobes ontheposteriormarginofthemerus, carpus
We think there are unrecognized species hidden in the and propodus (figs ID, H, J, 2D). These lobes are covered in
synonymies ofF. anomala andF.floresiana. Wealso suspect short palmate setae (fig. 2E, F) of Oshel & Steele (1988: 96,
thereareadditionalundiscoveredspeciesscatteredthroughout fig. 16). Palmate setae have a solid base radiating into short
thenumerous Indo-WestPacificislands. This is animportant distaltinesandmaybeusedinraspingorscouring.Theytake
118 J.K.Lowry&R.T.Springthorpe
Figure1.Floresorchestiapooreisp.nov.,A-B,paratype,female,AMP80543:leftmandible;B,leftmandibleincisor;C,paratype,female,AMP80543:
AM
maxillipedpalparticle4.D-J,paratype,male, P80544:malegnathopod1;E,propodusposterolateralserrateseta;F,propodusposterolateralserrate
setae;G,palmanddactylusshowingcuspidatesetaealongpalm;H,memsshowingposteriorlobecoveredinpalmatesetae;I,propoduslateralcuspidate
seta;J,carpusshowingposteriorlobecoveredinpalmatesetae.Scalebars:A,BandDrepresent100pm,Crepresents50pm.
ThegenusFloresorchestia(Amphipoda:Talitridae)onCocos(Keeling)andChristmasIslands 119
Figure2.Floresorchestiapooreisp.nov.,A-C,gnathopod2,paratype,male,AMP80544:B,posteromedialmarginofpalmshowingattenuated
AM
dactylusfittingintogroovewithcuticularpatch;C,cuticularpatch.D-F,gnathopod2,paratype,female, P80543:E,smallpalmatesetaeon
propodus;F,largepalmatesetaeonpropodus.Scalebars:AandDrepresent100pm.
120 J.K.Lowry&R.T.Springthorpe
Figure3. Floresorchestiapooreisp. nov.,A-C,paratype,female,AMP80543:A,pereopod3 dactylus;B,pereopod4dactylus;C,denticulate
patchondactylusofpereopod4;D-G,paratypefemale,AMP80532: D-E,spatulatesetaeonoostegiteofgnathopod2;F,stridulatingorganon
epimera2and3,basisofpereopod7posteriormargin;G,telsonanduropod3.Scalebars:A,B,FandGrepresent100pm,Drepresents20pm.
ThegenusFloresorchestia(Amphipoda:Talitridae)onCocos(Keeling)andChristmas Islands 121
slightly different forms depending on their position on the notched partially cleft orin the case ofF.poorei completely
lobes. Whatever the function these lobes are widespread cleft (fig. 3G). Thetelson appears to be enclosedbythe sides
within the talitrids. In males they are found on different ofurosomite3 andthepeduncleofuropod3.
combinationsofthemerus,carpusandpropodusofgnathopod
1andinfemales,andmalesofanumberofland-hoppergenera, Materialandmethods
theyOoncctuhreosnurgfnaacethoofpothde2.propodus of gnathopod 1 there are The descriptions were generated from a DELTA database
least two types of sensory setae. Both of these setal types (Dallwitz2005)tothetalitridgeneraandspeciesoftheworld.
appearto have pores atthe tips. Cuspidate setae occuralong All material is lodged in the Australian Museum, Sydney
tIhI)e.pAalsmhor(fti,g.sl1eGn)dearn,dshoanrpthperloajteecrtailonanadrimseedsifarlosmurtfhaecesisde(fiogf. u(pApMe)r.liApb;brMeDv,iatmiaonndsibalree;: LAL,,alnotweenrnal;ip;G,MXg,namtahxoiplolda;; MUPL,,
theshaftandarowofdenticlescoversthedistalend.Atthetip maxilliped;P,pereopod;pi,pleopod;T,telson;U,uropod;L,
is adistinctpore. The posterolateral serrate setae (fig. IE, F) left;R,right.
have a long, slender shaft with setules, distal denticles and a
terminalpore,similartotheplumodenticulatesetaeofWatling TalitridaeRafinesque, 1815
(1989,22,fig.4E) andtheserratesetaeofGarm(2004,fig8a,
FloresorchestiaBousfield, 1984
c).
Onmale gnathopod2theanteriormarginofthebasis and OrchestiafloresianagroupBousfield, 1971:267.
ischiumdeveloplateralandmedialflangeswhichformacradle Floresorchestia Bousfield, 1984: 205. —Miyamoto & Morino,
forthe propodus (fig. 2A). The dactylus is distally attenuated 2008:838.
and fits into a groove along the posteromedial margin ofthe
propodus(fig.2B).Atthecornerofthepalmwherethegroove Type species. Orchestia floresiana Weber, 1892, original
designation.
begins thereis adistinctcuticularpatch oftiny denticles (fig.
2C). This patch forms an abrasive pad which may assist Included species. Floresorchestia includes 14 species: F.
holding. ancheidos(K.H.Barnard,1916);F.anomala(Chevreux,1901);
The cuspidate dactylus ofpereopod3 tapers evenly along F. anoquesana (Bousfield, 1971);F. anpingensisMiyamoto &
itsmargin(fig.3A),butthedactylusofpereopod4isthickened Morino, 2008; F.floresiana (Weber, 1892); F. guadalupensis
at the base and a distinct notch occurs along the posterior Ciavatti, 1989; F. hanoiensis Hou & Li, 2003; F. monospina
margin (fig. 3B). Onthe anterodistal margin ofthe dactyli of (Stephensen, 1935); F. pectenispina (Bousfield, 1970); F.
pereopods 3 and4there is a dense patch ofabout 20 rows of pickeringi (Dana, 1853); F. poorei sp. nov.; F. samoana
whatappearstobetinydenticles(fig.3C).Thesepatchesoccur (Bousfield, 1971); F. vitilevana (J.L. Barnard, 1960); F.
in othertalitrids and also onpereopods 5-7. A patch ofwhat yehyuensisMiyamoto&Morino,2008.
appears to be spatulate setae is shown on the dactylus of
pereopods 5 and 6 of Notorchestia naturaliste (Serejo & Description.Head.Mandibleleftlaciniamobilis 5-dentate or
Lowry2008: 186,fig. 18).Thefunctionofthesepatchesisnot 4-dentate. Maxilliped palp article 2 distomedial lobe well
known. developed,article4reduced,button-shaped.
Among female talitrids three types of setae have been Pereon. Gnathopod 1 posterior margin ofmerus, carpus
documented onthe oostegites: simple setae, curl-tipped setae and propodus each with lobe covered in palmate setae; palm
and setae with multi-furcatetips. InFloresorchestiapoorei a transverse. Gnathopod 2 subchelate. Pereopods 2-4 coxae
fourth type occurs. The long slender setae (fig. 3D) become widerthan deep. Pereopods 6-7 longerthan pereopods 3-5.
splayed at the tip (fig. 3E) to form a spatulate locking Pereopod 6 posterior lobe inner view posteroventral corner
mechanism. subquadrate or posteroventral corner rounded. Pereopod 7
Although ‘slits’ onthe epimeral plates ofFloresorchestia basis posterior margin with distinct minute serrations, each
havebeenmentionedmanytimes,onlyBousfield(1970, 1971) withasmall seta.
has everconsideredtheirfunction as stridulating organs. The Pleon. Pleopods all well developed. Pleopod 1 peduncle
serrate posterior margin ofthe basis of pereopod 7 has also with or without sparse marginal setae. Pleopod 2 peduncle
been mentioned many times, most recently by Miyamoto & withorwithoutsparsemarginalsetae;outerramuslongerthan
Morino (2008). We have had aclose lookatthis morphology peduncle.Pleopod3pedunclewithorwithoutmarginalrobust
(figs3F).Thesocalled ‘slits’ arerelativelycomplexstructures setae. Epimera 2-3 each with stridulating organsjust above
with a raised anterior border and an immediately posterior ventral margins. Uropod 1 peduncle distolateral robust seta
hollow bowl or slit. Bousfield (1970, 1971) referred to these present; innerramus with marginal robust setae; outerramus
structuresasstridulatingridgesandweagreethattheseridges withoutmarginalrobustsetaeorwithonelongmidmedialseta
formastridulatingorgan.Andthestridulatorappearstobethe (inmale). Uropod2notsexuallydimorphic; outerramuswith
unique, strongly serrate posterior margin with tiny robust marginalrobustsetae. Uropod3ramus shorterthanpeduncle.
setae onthe basis ofpereopod7. The interestingthing isthat Telsonwithmarginal andapicalrobustsetae.
they occur on both sexes so the function is probably not to Female (sexually dimorphic characters). Gnathopod 1
attractamate. posteriormarginofmerus, carpus andpropodus eachwithout
The telson in Floresorchestia may be entire, apically lobecoveredinpalmatesetae;palmslightlyacute. Gnathopod
122 J.K.Lowry&R.T. Springthorpe
2mitten-shaped. Type locality. Rumah Baru, West Island, Cocos (Keeling)
Islands,IndianOcean(12°09'22"S96°49'41"E).
Habitat. Supralittoral and terrestrial amphipods of tropical
rain forests, mangroves and beaches in the Indo-West Pacific Etymology. Namedforour goodfriend Gary Poore inthanks
andCaribbean. forhis help overthe years and in recognition ofhis immense
contributiontothefieldofcarcinology.
Remarks. Floresorchestia belongs to a group of Indo-West
AM
Pacific genera which includes Microrchestia Bousfield, 1984, Description. Based on holotype, ovigerous female,
Platorchestia Bousfield, 1982, Protorchestia Bousfield, 1982, P80192.
Sinorchestia Miyamoto & Morino, 1999 and Talorchestia Head.Eyelarge(greaterthan 1/3 headlength).Antenna1
Dana, 1853. They all share a 5 dentate left lacinia mobilis, short, rarely longer than article 4 of antenna 2 peduncle.
subchelate male gnathopod 2, well developed pleopods and Antenna2uptohalfbodylength;pedunculararticlesnarrow;
uropod 1 without marginal robust setae on the outer ramus article 5 longer than article 4. Mandible left lacinia mobilis
(except Sinorchestia nipponensis which has marginal robust 5-dentate. Maxilliped palp article 2 distomedial lobe well
setae on the outer ramus). Within the group Floresorchestia, developed,4reduced,button-shaped.
Platorchestia, Sinorchestia and Talorchestia have Pereon. Gnathopod 1 sexually dimorphic; parachelate;
cuspidactylate pereopods. Only Floresorchestia and coxa 1 smallerthancoxa2;posteriormarginofmerus,carpus
Platorchestia have the reduced button-shaped fourth articles and propodus each without lobe covered in palmate setae, in
on the palps ofthe maxilliped and distally attenuated dactyli male only; propodus subrectangular, propodus posterior
on male second gnathopods. Both ofthese genera have wide marginwith3cuspidatesetaealongposteriormargin,propodus
distributions. posteriormarginwith3 serrate setae along posteriormargin;
Floresorchestia monospina (Stephensen, 1935) and F. palm acute, palm with 4 serrate setae; dactylus longer than
pectenispina(Bousfield, 1970)differfromotherspeciesinthe palm. Gnathopod2 sexuallydimorphic;mitten-shaped; coxal
genus in having a long, marginal slender robust seta with a gill simple or slightly lobate; basis anterior margin smooth,
modifiedtip onthe outerramus ofmale uropod 1 (Bousfield basisexpandedproximally;ischiumwithoutposterodistallobe
1970). Floresorchestia hanoiensis Hou & Li, 2003, F. on medial surface; posterior margin of merus, carpus and
malayensis (Tattersall, 1921), F. samoana (Bousfield, 1971) propoduseachwithlobecoveredinpalmatesetae;carpuswell
andF.vitilevana(J.L.Barnard, 1960)differfromotherspecies developed (not enclosed by merus and propodus), posterior
inthegenusinnothavingstridulatingorgansonepimera2and lobe present, projecting between merus and propodus; palm
3.InotherrespectsthesespeciesappeartobeFloresorchestia obtuse, smooth, not lined with robust setae, palm without
andF. hanoiensishas pitting ontheface ofepimera 1 and 2. patchoftinydenticles atcornerofpalm; dactylus subequal in
Floresorchestia pickeringi (Dana, 1853) needs to be lengthtopalm,notattenuateddistally;gillsimple,notincised.
redescribedtoconfirmits statusinthe genus. Pereopods 2-4 coxae wider than deep. Pereopods 3-7
Floresorchestia ancheidos (K.H. Barnard, 1916), F. cuspidactylate. Pereopod 4 subequal or slightly shorter than
anomala (Chevreux, 1901) and F.floresiana (Weber, 1892), pereopod 3; carpus significantly shorter than carpus of
typespeciesofthegenus,areallpoorlydescribedspeciesand pereopod 3; dactylus thickened proximally with a notch
F. anomala and F.floresiana are the source of questionable midway along the posterior margin. Pereopod 5 propodus
synonymies from wide-ranging localities. These species also distinctly longer than carpus. Pereopods 6-7 longer than
need to be redescribed based on new material fromthe type pereopods 3-5. Pereopod 6 not sexually dimorphic; slightly
localitiesusingmoderncharactersasoutlinedbyMiyamoto& shorter than pereopod 7; posterior lobe inner view
Morino (2008) before realistic distributionsforspecies inthe posteroventralcornerrounded,posteriormarginperpendicular
genuscanbedetermined. to ventral margin, posterior lobe with ridge, posterior lobe
with 1-2 marginal setae. Pereopod 7not sexually dimorphic;
Floresorchestiapooreisp.nov. basislateralsulcusabsent,basisposteriormarginwithdistinct
minute serrations, each with a small seta, posterodistal lobe
(Figures 1-7)
present, shallow, broadly rounded; distal articles (merus and
Materialexamined.Holotype:IndianOcean,Cocos(Keeling)Islands, carpus) slender; merus posterior margin evenly rounded;
WestIsland,RumahBaru,(12°09'22"S96°49'41"E),beachwrack,J.K. propodus setationwithoutlargedistaltuftofsetae. Oostegites
LowryandK.B.Attwood,8Oct2008,(stnMIWA819),AMP80192 long(lengthgreaterthan2xwidth),longerthanwide,weakly
(ovigPearroautsypfeesm:atlye,pe9Al.o2Mcamlmi)ty.,AMP80193(mAalMe,11.7mm);AMP801A9M4 setoPslee(o6n-.11Plseeotapeo)d,sseatlalewweiltlhdsepvaetluolpaetde.tiPpsl.eopod 1 peduncle
(many specimensA);M P80532 (female); P80543 (female); with marginal slender setae; biramous, outer ramus shorter
P80544(male); P80549(male).
Other material: Indian Ocean, Cocos (Keeling) Islands, West thanpeduncle, innerramus subequal inlengthto outer; inner
Island, Government House Beach, (12°05'04"S 96°52'54"E), sand ramus with 9 articles; outerramus with 6 articles. Pleopod2
beach,J.K. Lowry,L.E. HughesandK.B.Attwood,7Oct2008,(stn peduncle with marginal slender setae; biramous, innerramus
MI WA780),AMP.80545 (many specimens). Indian Ocean, Cocos subequalinlengthtoouter,outerramusshorterthanpeduncle;
(Keeling) Islands, West Island, beach near “Two Trees dive site”, inner ramus with 7 articles. Pleopod 3 peduncle without
(12°05’04"S96°52'54"E),J.K.Lowry,L.E.HughesandK.B.Attwood, marginal setae. Pleopod3biramous,innerramus subequalin
7Oct2008,(stnMIWA779),AMP.80547(6males,7females). length to outer, outer ramus shorter than peduncle; rami
ThegenusFloresorchestia(Amphipoda:Talitridae)onCocos(Keeling)andChristmasIslands 123
Figure4.Floresorchestiapooreisp.nov.,paratype,male, 11.7mm,AMP80193.
multarticulate;innerramuswith6articles;outerramuswith6 on medial surface; posterior margin of merus, carpus and
articles.Epimera2-3eachwithastridulatingorganjustabove propodus each withoutlobe covered in palmate setae; carpus
ventralmargins.Epimera2 subequalinlengthto epimeron3, triangular,reduced(enclosedbymerusandpropodus),posterior
with 27 ridges. Epimera 3 with 17 ridges, posterior margin lobe absent, not projecting between merus and propodus;
smooth, without setae, posteroventral corner with small propodus subovate; propodus twice as long as wide; palm
subacutetooth,ventralmarginwithoutrobustsetae. Uropod1 acute,linedwithrobustsetae;palmwithcuticularpatchoftiny
not sexually dimorphic, peduncle with 8 robust setae, denticlesatcornerofpalm,posteromedial surfaceofpropodus
distolateral robust seta small; with simple tip; inner ramus withgroove;dactyluslongerthanpalm,attenuateddistally.
subequal in length to outer ramus, with 3 marginal robust
Habitat. Living inthe supralittoral zone on shelteredbeaches
setae; outer ramus without marginal robust setae. Uropod 2
underseaweedsanddebris.
not sexually dimorphic; peduncle with 6 robust setae; inner
ramus subequal in length to outer ramus, with 2 marginal Remarks. Floresorchestiapooreiis currently the only species
robustsetae; 1 marginalrobustsetae. Uropod3pedunclewith inthegenuswithafullyclefttelson.
3 robust setae; ramus shorter than peduncle, ramus linear
Distribution. North-Eastern Indian Ocean. Cocos (Keeling)
(narrowing), with 2 marginal robust setae, with 4-5 apical
Islands(currentstudy).
setae. Telson longer than broad, completely cleft, with 5
marginal andapicalrobustsetaeperlobe.
AM Acknowledgements
Male(sexuallydimorphiccharacters). Basedonmale,
P80193. Gnathopod 1 subchelate, posteriormargin ofmerus, ThankstotheCAAPteam,KateAttwood,LaurenHughesand
carpus andpropodus eachwithlobecoveredinpalmate setae; Michael Stuckey forhelping to collectthe beach-hoppers; to
propodussubtriangularwithwelldevelopedposterodistallobe, TaniaLaity,DepartmentoftheEnvironment,Water,Heritage
anteriormargin with 3 groups ofrobust setae, lateral surface and the Arts (DEWHA) for funding the field work; to Sue
with 2 cuspidate setae, posterolateral surface with 5 serrate Lindsey forthe SEM micrographs; to Anders Garm and Les
setae, propodus posteriormargin without cuspidate or serrate Watling for advice on setal types; to Alan Myers, as always,
setae along posterior margin; palm transverse, dactylus forhisinsightfulcomments;andtoJoTaylorforinvitingusto
subequal in length to palm. Gnathopod 2 subchelate; basis contribute to this book celebrating 30 years of scholarly
slightly expanded; ischiumdistal triangularposterodistal lobe researchbyGaryPoore.
124 J.K.Lowry&R.T.Springthorpe
Figure5.Floresorchestiapooreisp.nov.,holotype,ovigerousfemale,9.2mm,AMP80192.Scalebars: H,Epl-3represent0.5mm,remainder
represent0.2mm.
ThegenusFloresorchestia(Amphipoda:Talitridae)onCocos(Keeling)andChristmasIslands 125
Figure6.Floresorchestiapooreisp.nov.,holotype,ovigerousfemale,9.2mm,AMP80192,paratype,male, 11.7mm,AMP80193. Scalebars
represent0.5mm.
126 J.K.Lowry&R.T.Springthorpe
Figure7. Floresorchestiapoorei sp. nov., holotype, ovigerousfemale, 9.2 mm,AMP80192. Scale bars: P5-7 represent 0.5 mm, remainder
represent0.2mm.