Cairnsichthys Allen, 1980

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, Zootaxa 4413 (2), pp. 271-294 : 278-279

Genus Cairnsichthys Allen, 1980

Cairnsichthys Allen (1980): 471 (type species, Rhadinocentrus rhombosomoides Nichols & Raven, 1928 by original designation)—Aarn & Ivantsoff (1997): 112.

Diagnosis: A gEnuS Of MELAnOtAEnIIDAE wItH tHE fOLLOwIng cOmbInAtIOn Of cHARActERS (fOLLOwS ALLEn 1980): RELAtIvELY ELOngAtE, LAtERALLY cOmPRESSED bODY; gREAtESt bODY DEPtH 3.5–5.3 In SL; PREmAxILLARIES wItH A DIStInct bEnD bEtwEEn tHE HORIZOntAL AntERIOR PORtIOn AnD LAtERAL PARt; jAw tEEtH vILLIfORm tO cOnIcAL In SEvERAL ROwS, ExtEnDIng OutSIDE Of mOutH AnD cLEARLY vISIbLE wHEn mOutH cLOSED; vOmER AnD PALAtInES tOOtHLESS; IntER-DORSAL PtERYgIOPHORES 2 OR 3; fIRSt DORSAL fIn cOnSIStIng Of 4–7 SLEnDER, fLExIbLE SPInES, SEcOnD DORSAL fIn wItH SLEnDER, fLExIbLE SPInE (SOmEtImES unSEgmEntED OR wItH vERY wEAk SEgmEntAtIOn vISIbLE OnLY unDER HIgH mAgnIfIcAtIOn) AnD 11–15 SEgmEntED RAYS; AnAL fIn wItH SLEnDER, fLExIbLE SPInE AnD 17–22 SEgmEntED RAYS; AnAL fIn ORIgIn On AntERIOR HALf Of bODY; SOft, SEgmEntED RAYS gEnERALLY bRAncHED ExcEPt fIRSt 2–5 RAYS Of SEcOnD DORSAL fIn AnD fIRSt 6–10 RAYS Of AnAL fIn; tOtAL vERtEbRAE 36–40; PARAHYPuRAL AutOgEnOuS; PELvIc gIRDLE wItHOut AntERIOR PROjEctIOnS At vEntRAL mID-LInE; LAtERAL wIng Of PELvIc gIRDLE AncHORED tO fOuRtH PLEuRAL RIb; DORSAL HEAD Of cLEItHRum wItH mODERAtELY DEvELOPED POStERIOR PROjEctIOn; ScALES cYcLOID wItH wELL-DEvELOPED RADII, HORIZOntAL ROwS On bODY At LEvEL Of AnAL fIn uSuALLY 11 (10–11), vERtIcAL ROwS fROm uPPER PEctORAL fIn bASE tO cAuDAL fIn bASE 36–40; tOtAL gILL RAkERS On fIRSt gILL ARcH 10–16 (0–4 + 8–13); SExuAL DIffEREncES SLIgHt, RELAtED mAInLY tO fIn cOLOuRAtIOn.

Remarks: tHE gEnuS IS REStRIctED tO tHE WEt TROPIcS Of nORtH-EAStERn QuEEnSLAnD AnD cOntAInS twO SPEcIES, C. rhombosomoides AnD A nEw SPEcIES DEScRIbED HEREIn. THE tYPE SPEcIES wAS ORIgInALLY PLAcED In Rhadinocentrus REgAn, 1914, A mOnOtYPIc gEnuS InHAbItIng cOAStAL DRAInAgES Of SOutHERn QuEEnSLAnD AnD nORtHERn NEw SOutH WALES. SubSEquEntLY ALLEn (1980) PROvIDED EvIDEncE fOR ItS REcOgnItIOn AS A SEPARAtE gEnuS bASED On tHE fOLLOwIng mORPHOLOgIcAL DIffEREncES wItH R. ornatus REgAn, 1914: (1) ScALE RADII AbSEnt OR wEAkLY DEvELOPED In rhombosomoides , AnD wELL-DEvELOPED In ornatus ; (2) nO DEntIcuLAtIOnS On OtOLItH mARgIn Of ornatus , AnD wELL- DEvELOPED DEntIcuLAtIOnS In rhombosomoides ; (3) nO AntERIOR PROjEctIOnS Of PELvIc gIRDLE At vEntRAL mID-LInE Of rhombosomoides , AnD PROjEctIOnS PRESEnt In ornatus ; (4) LAtERAL wIng Of PELvIc gIRDLE AncHORED tO SEcOnD OR tHIRD RIb In ornatus , AnD fOuRtH RIb In rhombosomoides ; (5) uSuALLY 8–9 HORIZOntAL ScALE ROwS In ornatus , AnD 11 In rhombosomoides [10–11 tHIS StuDY]; (6) PARAHYPuRAL AutOgEnOuS In rhombosomoides , AnD fuSED tO LOwER HYPuRAL PLAtE In ornatus ; (7) vERtEbRAE uSuALLY 35 In ornatus AnD 36 OR 37 In rhombosomoides [36–40 tHIS StuDY]; (8) RELAtIvELY fEw ExtERnAL tEEtH On LAtERAL PORtIOn Of PREmAxILLARY, ARRAngED In A SIngLE ROw In ornatus , AnD numEROuS, ARRAngED In muLtIPLE ROwS In rhombosomoides ; AnD (9) LOwER jAw Of ornatus wItH DEfInItE PROtRuSIOn, AnD tHAt Of rhombosomoides nEARLY EquAL wItH uPPER jAw. THESE DIAgnOStIc DIffEREncES wERE DIScuSSED AnD ILLuStRAtED bY ALLEn (1980). DEtAILED OStEOLOgIcAL RESEARcH bY AARn & IvAntSOff (1997) PROvIDES ADDItIOnAL gEnERIc DIAgnOStIc cHARActERS wHIcH LIkELY ALSO APPLY tO tHE nEw SPEcIES, but REquIRE cOnfIRmAtIOn (E.g. mARkEDLY cOnvEx ROStRAL mARgIn Of tHE vOmER, EncLOSED mAnDIbuLAR SEnSORY cAnAL, PELvIc fIn LAckIng cRAnIAL SPInOuS PROcESS).

Etymology: nAmED wItH REfEREncE tO tHE cItY Of CAIRnS, QuEEnSLAnD, tHE gEnERAL REgIOn wHERE C. rhombosomoides OccuRS. THE gEnDER IS cOnSIDERED mAScuLInE.