Cairnsichthys rhombosomoides
Creators: name: Hammer, Michael P.
name: Allen, Gerald R.
name: Martin, Keith C.
name: Adams, Mark
name: Ebner, Brendan C.
name: Raadik, Tarmo A.
name: Unmack, Peter J.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Atheriniformes
Melanotaeniidae
Cairnsichthys
Cairnsichthys rhombosomoides

description: Cairnsichthys rhombosomoides (Nichols & Raven, 1928)
CAIRnS RAInbOwfISH
(fIgS 6–7, tAbLES 2–4)
Rhadinocentrus rhombosomoides Nichols & Raven, 1928: 1, Fig. 1 (Holotype: AMNH I-9246, 42 mm SL, Babinda Creek drainage, north-eastern Queensland, Australia, H.C. Raven, October 1921; Paratypes: AMNH I-9241 (1); USNM 143609 (1); AMS IA.4774 (1), 37.5 mm SL; QM I.5002 (1), 31.1 mm SL, collected with holotype—Lake (1971): 27.
Rhadinocentrus (?) rhombosomoides — Munro (1956 –1961): 98.
Cairnsichthys rhombosomoides— Allen & Cross (1982): 105; Merrick & Schmida (1984): 158; Leggett & Merrick (1987): 130; Kleiberg (1988): 215; Allen (1989): 90; Paxton et al. (1989): 349; wager & Jackson (1993): 23; Allen (1995): 45; Herbert & Peeters (1995): 52; Pusey & Kennard (1996): 566; wager (1996): 23; Aarn & Ivantsoff (1997): 112; Pusey et al. (2001): 76; Unmack (2001): 1061; Allen et al. (2002): 143; Pusey et al. (2002): 34; Johnson (2003): 142; Corlis (2004): 538; Pusey et al. (2004): 205 (and unpublished reports cited therein); Sparks & Smith (2004): 722; Allen et al. (2006): 689; Thuesen et al. (2008): 1175; Tappin (2010): 164; Bloom et al. (2012): 1029; Martin & Barclay (2013) (in part): 156; Unmack et al. (2013): 18; Campanella et al. (2015): 15; Ebner et al. (2015): 121; Kroon et al. (2015): 1184.
Material examined (181 SPEcImEnS, 8.0– 64.4 mm SL).
Holotype: AMNH I-9246, 42.0 mm SL, DEtAILS AS AbOvE—ExAmInED DIgItALLY.
Paratypes: AMS IA.4774, 37.5 mm SL; QM I.5002, 31.1 mm SL, cOLLEctED wItH HOLOtYPE.
Other material examined: AMS IB.71, 59.2 mm SL, CAIRnS DIStRIct; AMS IB.72, 51.2 mm SL, CAIRnS DIStRIct; AMS I.22062-001, 5 SPEcImEnS, 22.5–37.6 mm SL, tRIbutARY Of MuLgRAvE RIvER (APPROxImAtELY 17° 17'S, 145° 83'E); AMS I.23308-001, 5 SPEcImEnS, 20.3–54.9 mm SL, tRIbutARY tO HARvEY CREEk, RuSSELL RIvER SYStEm (APPROxImAtELY 17° 15' S, 145° 55' E); NTM S.17700-001, 6 SPEcImEnS, 27.8–52.4 mm SL, SmOkO CREEk, RuSSELL RIvER SYStEm (17° 22.09' S, 146° 00.31' E); NTM S.17801-001, 5 SPEcImEnS, 26.8–36.2 mm SL, NInDS CREEk, JOHnStOnE RIvER SYStEm (17° 34.07'S, 146° 05.24'E); NTM S.17803-001, 41.2 mm SL, FIg TREE CREEk, MuLgRAvE RIvER SYStEm (17° 12.31'S, 145° 54.35'E); NTM S.17805-001, 2 SPEcImEnS, 46.1–51.0 mm SL, POLLY CREEk, NORtH JOHnStOnE RIvER SYStEm (17° 28.56'S, 146° 00.03'E); NTM S.17808-001, 4 SPEcImEnS, 46.8–63.5 mm SL, HARvEY CREEk, RuSSELL RIvER SYStEm (17° 15.51'S, 145° 55.39'E); NTM S.17822-001, 45.5 mm SL, W. SIDE GRAnt HILL, YARRAbAH (16° 55.47'S, 145° 54.18'E); NTM S.17930-001, 11 SPEcImEnS, 16.3–49.9 mm SL, NYLEtA CREEk, LIvERPOOL RIvER SYStEm (17° 48.19'S, 145° 57.14'E); QM I.20144, 44 SPEcImEnS, 8.0– 53.5 mm SL, BAbInDA CREEk tRIb., BAbInDA (17° 20.61'S, 145° 55.48'E); QM I.28750, 3 SPEcImEnS, 39.3–51.1 mm SL, NORtH JOHnStOnE RIvER SYStEm, (APPROxImAtELY 17° 29'S, 146° 02'E); QM I.29391, 5 SPEcImEnS, 39.3–55.1 mm SL, BEHAnA CREEk, MuLgRAvE RIvER SYStEm; QM I.29987, 2 SPEcImEnS, 50.1–50.2 mm SL, LIvERPOOL CREEk (APPROxImAtELY 17° 46'S, 145° 58'E); QM I.32973, 7 SPEcImEnS, 18.4–57.5 mm SL; NInDS CREEk, JOHnStOnE RIvER SYStEm (17° 34.06'S, 146° 05.25'E); QM I.35433, 30 SPEcImEnS, 33.3–64.4 mm SL, HARvEY CREEk, RuSSELL RIvER SYStEm (17° 15.47'S, 145° 55.36'E); WAM P.26311-001, 4 SPEcImEnS, 50.5–56.2 mm SL, FIg TREE CREEk, MuLgRAvE RIvER SYStEm (APPROxImAtELY 17° 13' S, 145° 56'E); WAM P.26392-003, 21 SPEcImEnS, 29.9–65.3 mm SL, HARvEY CREEk, RuSSELL RIvER SYStEm (APPROxImAtELY 17° 16' S, 145° 55'E); WAM P.26713-002, 3 SPEcImEnS, 55.3–63.1 mm SL, HARvEY CREEk, RuSSELL RIvER SYStEm (APPROxImAtELY 17° 15' S, 145° 56'E); WAM P.26969-001, 29 SPEcImEnS, 15.9–45.5 mm SL, tRIbutARY Of LIttLE MuLgRAvE RIvER On wEStERn SIDE Of BELLEnDEn KERR RAngE (APPROxImAtELY 17° 17' S, 145° 47'E).
Diagnosis: A SPEcIES Of Cairnsichthys DIStInguISHED bY tHE fOLLOwIng cOmbInAtIOn Of cHARActERS: DORSAL RAYS IV–VII + 12–16 (IncLuDIng SLEnDER, fLExIbLE SPInE); tOtAL AnAL RAYS 18–22 (IncLuDIng SLEnDER, fLExIbLE SPInE); PEctORAL RAYS 11–13 (uSuALLY 12); LAtERAL ScALES 36–38 (mODE 37) IncLuDIng 2–4 (uSuALLY 3) fROm EnD Of ADPRESSED PEctORAL fIn tO vERtIcAL fROm wItH DORSAL fIn ORIgIn; PREDORSAL ScALES 16–19 (RARELY 19); cHEEk ScALES 3–8; tOtAL gILL RAkERS On fIRSt ARcH 10–15 (uSuALLY 11–12); vERtEbRAE 36–39 (mODE 37); bODY RELAtIvELY DEEP, gREAtESt bODY DEPtH 3.5–4.3 (mEAn 3.8) In SL AnD gREAtESt bODY wIDtH 1.8–2.4 (mEAn 2.1) In HL; SEcOnD DORSAL fIn bASE RELAtIvELY LOng 4.0–5.0 (mEAn 4.5) In SL; cOLOuR In LIfE YELLOwISH bROwn tO gREYISH bROwn On DORSAL HALf, wHItISH OR bLuISH wHItE On vEntRAL HALf; nARROw bLAckISH mID-LAtERAL StRIPE fROm uPPER PEctORAL fIn bASE tO bASE Of cAuDAL fIn, An IncOnSPIcuOuS SEcOnD bLAckISH StRIPE OccASIOnALLY PRESEnt On LOwER SIDES, ExtEnDIng POStERIORLY tO bASE Of POStERIOR PORtIOn Of AnAL fIn; REctAnguLAR bLAck mARk AcROSS uPPER OPERcuLum, ItS vERtIcAL DEPtH uSuALLY LESS tHAn OnE-HALf PuPIL DIAmEtER, wItH YELLOw tO SILvERY AREA ImmEDIAtELY bELOw; bLAckISH bLOtcH On bASE Of PEctORAL fIn ExtEnDIng tO AxIL Of fIn; ADuLt mALE fREquEntLY (ESPEcIALLY In nuPtIAL PHASE) wItH DEEP YELLOw tO DIStInctLY ORAngE-REDDISH cOLOuR On ALL fInS (ExcEPt PEctORAL fInS) IncLuDIng SubmARgInAL bAnD On SEcOnD DORSAL fIn, SImILAR mARgInAL bAnD On AnAL fIn, AnD cAuDAL fIn.
Redescription: bASED On 52 SPEcImEnS 38.9–64.4 mm SL, n = 42 fOR mERIStIc DAtA AnD n = 26 fOR PROPORtIOnAL mEASuREmEntS; AvAILAbLE DAtA fOR tHE HOLOtYPE bASED On vALuES In tHE ORIgInAL DEScRIPtIOn EItHER vERIfIED OR OtHERwISE EStImAtED fROm DIgItAL ImAgERY SHOwn In tAbLES 3–4. DORSAL RAYS IV–VII + 12–16; tOtAL AnAL RAYS 18–22; PEctORAL RAYS 11–13; PELvIc RAYS I,5; bRAncHED cAuDAL RAYS 15; PROcuRREnt cAuDAL RAYS 8–9 + 7–9; LAtERAL ScALES 36– 38; tRAnSvERSE ScALES 10–11; PREDORSAL ScALES 16–19; PREPELvIc ScALES 14–16; cHEEk ScALES 3–8; cIRcumPEDuncuLAR ScALES 12; gILL RAkERS On fIRSt bRAncHIAL ARcH 1–3 + 10–12, tOtAL gILL RAkERS On fIRSt ARcH 10–15; tOtAL vERtEbRAE 36–39. FuLL mERIStIc cOuntS ARE SHOwn In TAbLE 3.
HEAD LEngtH 3.6–4.1 In SL; bODY DEPtH 3.5–4.3 In SL; gREAtESt wIDtH Of bODY 1.8–2.4 In HL; SnOut LEngtH 2.6– 3.6 In HL; EYE DIAmEtER 2.7–3.6 In HL; bOnY IntERORbItAL wIDtH 2.3–2.7 In HL; DEPtH Of cAuDAL PEDuncLE 2.4–2.8 In HL; LEngtH Of cAuDAL PEDuncLE 1.4–1.8 In HL.
JAwS AbOut EquAL, ObLIquE, PREmAxILLA wItH An AbRuPt bEnD bEtwEEn tHE AntERIOR HORIZOntAL PORtIOn AnD LAtERAL PARt; mAxILLA EnDS ALmOSt bELOw AntERIOR EDgE Of PuPIL; mAxILLARY LEngtH 2.2–2.6 In HL; LIPS tHIn; tEEtH vILLIfORm tO nARROwLY cOnIcAL wItH SLIgHtLY cuRvED tIPS, ExtEnDIng On tO OutER SuRfAcE Of LIPS; tEEtH Of uPPER jAw In AbOut 4–5 IRREguLAR ROwS AntERIORLY, REDucED tO 2–3 ROwS POStERIORLY wHERE cLEARLY ExPOSED wHEn mOutH cLOSED; tEEtH In LOwER jAw In AbOut 3–4 IRREguLAR ROwS AntERIORLY, REDucED tO A SIngLE ROw POStERIORLY.
ScALES Of bODY cYcLOID, RELAtIvELY LARgE, AnD ARRAngED In REguLAR HORIZOntAL ROwS; bEgInnIng wItH AbOut 8tH– 11tH ScALE, REmAInIng ScALES Of mIDLAtERAL ROw wItH SmALL ROunDED tO vERtIcALLY ELOngAtE, SHALLOw PIt At cEntRE; ROw Of SmALL, tRuncAtED ScALES ALOng bASES Of DORSAL AnD AnAL fInS; nO ScALES On mEmbRAnOuS PORtIOnS Of fInS ExcEPt SEvERAL ROwS Of SmALL ScALES bASALLY On cAuDAL fIn AnD mODERAtE-SIZED ScALE mEDIALLY At bASE Of PELvIc fInS; ScALE mARgInS SmOOtH wItHOut cREnuLAtIOnS; PREDORSAL ScALES ExtEnDIng fORwARD tO AbOut REAR EDgE Of IntERORbItAL SPAcE; PREOPERcLE (cHEEk) cOvERED wItH 3–8 ScALES; mAIn bODY Of OPERcuLum cOvERED wItH AbOut 7–10 ScALES wItH ADDItIOnAL SmALL ScALES On AntERIOR LImb.
PREDORSAL DIStAncE 1.9–2.2 In SL; PREAnAL DIStAncE 1.8–2.0 In SL; PREPELvIc DIStAncE 2.4–2.7 In SL; LEngtH Of SEcOnD DORSAL fIn bASE 4.0–5.0 In SL; LEngtH Of AnAL fIn bASE 2.7–3.2 In SL.
FIRSt DORSAL fIn ORIgIn AbOut LEvEL wItH OR SLIgHtLY bEHInD AnAL fIn ORIgIn; LOngESt SPInE (uSuALLY tHIRD) Of fIRSt DORSAL fIn 2.2–3.2 In HL, ItS ADPRESSED tIP juSt REAcHIng tO ORIgIn Of SEcOnD DORSAL fIn; LOngESt (gEnERALLY AbOut 5tH) RAY Of SEcOnD DORSAL fIn 2.1–2.8 In HL, ADPRESSED POStERIOR RAYS ExtEnDIng AbOut OnE-HALf LEngtH Of cAuDAL PEDuncLE In mALE SPEcImEnS tO AbOut OnE-tHIRD LEngtH In fEmALES AnD juvEnILES; LOngESt (AbOut 8tH) AnAL RAY 1.9–2.4 In HL; PELvIc fIn tIPS wHEn ADPRESSED juSt REAcHIng tO AnAL fIn ORIgIn; LEngtH Of PELvIc fInS 1.7–2.4 In HL; LEngtH Of PEctORAL fInS 1.3–1.6 In HL; LEngtH Of cAuDAL fIn 1.1–1.4 In HL; cAuDAL fIn mODERAtELY fORkED, cAuDAL cOncAvItY 3.8–8.2 In HL. A SummARY Of PROPORtIOnAL mEASuREmEntS ARE SHOwn In TAbLE 4.
Colour in life: gEnERALLY YELLOw tO bROwnISH On uPPER HALf Of bODY wItH fInE, DARkER bROwn ScALE OutLInE, fREquEntLY wItH YELLOwISH HuE, ESPEcIALLY tHOSE On uPPERmOSt ROw Of bAck AnD juSt AbOvE mIDLAtERAL DARk StRIPE; RELAtIvELY nARROw bLAckISH mIDLAtERAL StRIPE fROm uPPER PEctORAL fIn bASE tO bASE Of cAuDAL fIn, nARROwER On AntERIOR HALf Of bODY, gRADuALLY ExPAnDIng tO AbOut OnE ScALE wIDtH On cAuDAL PEDuncLE, fAInt wHItISH tO YELLOw HuE bELOw StRIPE mAInLY REStRIctED tO tHE AntERIOR HALf Of bODY; LOwER HALf Of bODY bLuISH tO wHItE, SOmEtImES wItH A DIffuSE bLuE tO gREYISH StRIPE PARALLEL tO mAIn StRIPE ExtEnDIng POStERIORLY tO bASE Of POStERIOR AnAL fIn, but StRIPE gEnERALLY AbSEnt OR REPRESEntED bY PAtcHY fAInt mARkS ARRAngED In A LInE; HEAD bROwnISH gREY, LIPS DARk gREYISH AntERIORLY; SmALL REctAnguLAR bLuEISH tO bLAck mARk On tHE uPPER OPERcuLum, SOmEtImES quItE fAInt, ItS vERtIcAL wIDtH uSuALLY LESS tHAn HALf tHE PuPIL DIAmEtER, ALtHOugH SLIgHtLY wIDER In fISH fROm HARvEY CREEk, SILvERY tO YELLOw AREA bELOw mARk; IRIS SILvER tO bLuISH On uPPER HALf AnD YELLOwISH tO SILvER bELOw; fInS mAInLY tRAnSLucEnt tO SLIgHtLY ORAngE bROwn tO REDDISH, wItH fAInt bLuE tO bLAckISH SPOt On bASE Of PEctORAL fIn (fIgS 6–7). COLOuR IntEnSIfIES In nuPtIAL mALES wItH mORE PROmInEnt SubmARgInAL DORSAL AnD mARgInAL StRIPES On tHE SEcOnD DORSAL AnD AnAL fIn.
Colour in alcohol: gEnERALLY bROwn On uPPER HALf Of bODY, wHItISH tO YELLOwISH-tAn On LOwER HALf; nARROw, mID-LAtERAL bLAck StRIPE fROm uPPER EDgE Of PREOPERcuLAR mARgIn tO mIDDLE Of cAuDAL fIn bASE; SEcOnD StRIPE, mucH fAIntER tHAn mID-LAtERAL OnE, SOmEtImES PRESEnt On LOwER SIDE AbOvE AnAL fIn; fInS tRAnSLucEnt YELLOwISH tO wHItISH (FIg. 7).
Distribution and habitat: muSEum REcORDS ARE DISPLAYED In FIguRE 1 AnD MARtIn & BARcLAY (2013) fuRtHER SummARIZED tHE cuRREnt DIStRIbutIOn fOR tHIS SPEcIES, wHIcH ExtEnDS SOutHwARD fROm tHE vIcInItY Of YARRAbAH (13 km EASt Of CAIRnS) tO tHE NORtH HuLL RIvER SYStEm nEAR MISSIOn BEAcH, A LInEAR DIStAncE Of AbOut 120 km. MOSt HIStORIc REcORDS ARE fROm tHE BELLEnDEn KERR RAngE cAtcHmEnt, wHIcH IncLuDES tRIbutARIES Of tHE MuLgRAvE AnD RuSSELL RIvER SYStEmS. HOwEvER, AS nOtED bY MARtIn & BARcLAY (2013), SuRvEYS fROm tHE mID-1980S tO tHE EARLY 2000S HAvE ExtEnDED tHE cORE DIStRIbutIOn SOutH Of tHIS AREA tO tHE NORtH AnD SOutH JOHnStOnE RIvERS, LIvERPOOL CREEk, MARIA CREEk, AnD tHE NORtH HuLL SYStEm. THE YARRAbAH POPuLAtIOn, fIRSt REPORtED bY MARtIn & BARcLAY (2013), IS An AnOmALOuS OutLIER, OccuRRIng In A SmALL (AbOut 0.3 km 2) cAtcHmEnt tHAt IS wELL ISOLAtED fROm tHE cORE DIStRIbutIOn.
THE gEnERAL HAbItAt Of C. rhombosomoides cOnSIStS Of SmALL, PERmAnEnt cREEkS, fLOwIng tHROugH RAInfORESt In fOOtHILL tERRAIn. It uSuALLY OccuRS In tHE PORtIOn Of StREAmS SItuAtED bEtwEEn tHE bASE Of StEEP mOuntAIn RAngES AnD DEEPER, SLOwER fLOwIng, DOwnStREAm SEctIOnS wHIcH cOIncIDE wItH tHE REguLAR PRESEncE Of LARgE PREDAtORY SPEcIES SucH AS Lutjanus argentimaculatus (FORSSkåL, 1775) AnD IntERSPEcIfc cOmPEtItIOn fROm M. splendida. SImILAR tO C. bitaeniatus sp. nov. It PREfERS SHADED SEctIOnS wItH mODERAtE tO SwIft fLOw RAtES AnD AbunDAnt cOvER In tHE fORm Of wOODY DEbRIS, unDERcut bAnkS, AnD InStREAm vEgEtAtIOn SucH AS tREE ROOtS. WAtER quALItY vALuES REcORDED IncLuDE tEmPERAtuRE AnD PH vALuES RAngIng bEtwEEn 15–29°C AnD 4.5–8.4 RESPEctIvELY, HIgH DISSOLvED OxYgEn (> 4.9 mg / L) AnD LOw wAtER cOnDuctIvItY (<65 µS/cm) (ALLEn & CROSS 1982; PuSEY Et AL. 2004).
Remarks: tHE SPEcIES wAS DEScRIbED bY NIcHOLS & RAvEn (1928) bASED On tHE HOLOtYPE (AMNH 9246). THIS wAS tHE LARgESt Of fIvE SPEcImEnS REfERRED tO In tHE ORIgInAL DEScRIPtIOn. COnSEquEntLY, wHILSt nOt StAtED bY NIcHOLS & RAvEn (1928), tHE OtHER fOuR SPEcImEnS ARE cOnSIDERED AS PARt Of tHE tYPE SERIES AccORDIng tO ARtIcLE 72.4.1 AnD 72.4.1.1 Of ICZN (1999).
ALtHOugH wE DID nOt PHYSIcALLY ExAmInE tHE HOLOtYPE, tHE ORIgInAL DEScRIPtIOn wAS AccOmPAnIED bY A DIAgnOStIc DRAwIng, AnD wE ExAmInED 44 cOntEmPORARY SPEcImEnS cOLLEctED fROm tHE tYPE LOcALItY In 1982 (QM I.20144). FuRtHER, wE ExAmInED An x-RAY AnD HIgH RESOLutIOn DIgItAL ImAgE Of tHE HOLOtYPE, wHIcH PROvED tO bE In ExcELLEnt cOnDItIOn fOR An ALmOSt OnE HunDRED YEAR OLD SPEcImEn—mInImAL bODY DIStORtIOn, IntAct ScALES AnD OnLY mInOR DAmAgE tO tHE DIStAL tIPS Of SOmE cAuDAL RAYS. ASSESSIng mERIStIc cOuntS fROm tHE ImAgERY PROvIDED mAtcHIng RESuLtS tO tHE ORIgInAL DEScRIPtIOn, wItH tHE ADDItIOnAL InSIgHt Of tHE RADIOgRAPH IDEntIfYIng An ExtRA SOft RAY In tHE AnAL fIn AnD PREvIOuSLY unAvAILAbLE cOuntS bEIng mADE fOR PREDORSAL ScALES. EStImAtIng mEASuREmEntS fROm HIgH RESOLutIOn ImAgES PROvIDED A cALIbRAtIOn mAtcH bEtwEEn tHE ORIgInAL DEScRIPtIOn fOR SL (42 mm) AnD tYPIcALLY PROvIDED vALuES wItHIn 10% Of tHE ORIgInAL DEScRIPtIOn fOR OtHER mEASuREmEntS, ALtHOugH It wAS EvIDEnt tHAt DIffEREnt APPROAcHES mAY HAvE bEEn uSED On SOmE mEASuREmEntS OR tHERE mAY HAvE bEEn tYPOgRAPHIc ERRORS. COnSEquEntLY, DAtA In TAbLE 4 REPRESEntS A cOmbInAtIOn Of vALuES fROm tHE ORIgInAL DEScRIPtIOn AnD uPDAtED mEASuREmEntS.
Etymology: tHIS SPEcIES wAS nAmED rhombosomoides wItH REfEREncE tO ItS PERcEIvED RESEmbLAncE tO tHE YOung Of Rhombosoma novaeguineae RAmSAY & OgILbY, 1886, A SPEcIES cuRREntLY In tHE Melanotaenia goldei (MAcLEAY, 1883) SPEcIES cOmPLEx.
description: Published as part of Hammer, Michael P., Allen, Gerald R., Martin, Keith C., Adams, Mark, Ebner, Brendan C., Raadik, Tarmo A. & Unmack, Peter J., 2018, Revision of the Australian Wet Tropics endemic rainbowfish genus Cairnsichthys (Atheriniformes: Melanotaeniidae), with description of a new species, pp. 271-294 in Zootaxa 4413 (2) on pages 287-289, DOI: 10.11646/zootaxa.4413.2.3, http://zenodo.org/record/1226945