Phenacoscorpius mccoskeri Motomura 2017, new species
Creators: name: Motomura, Hiroyuki
Publisher: name: Zenodo
Year: 2017
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Actinopterygii
Scorpaeniformes
Scorpaenidae
Phenacoscorpius
Phenacoscorpius mccoskeri

description: Phenacoscorpius mccoskeri, new species
NeW EngliSH name: MCCOSker’S NO-line SCOrpiOnfiSH FigureS 1, 2
Phenacoscorpius sp.: McCosker & Rosenblatt 2010: 174 (off Darwin Island, Galápagos Islands, Ecuador, eastern Pacific, 01°41ʹN, 91°59ʹW)
Holotype. CAS 86551, 100.5 mm SL, Off DarWin ISland, GalápagOS ISlandS, ECuadOr, eaStern PaCifiC, 01°41ʹN, 91°59ʹW, COll. by J. E. MCCOSker et al., manned SubmerSible Johnson Sea-Link, 515 m deptH, 21 NOv. 1995.
Paratypes. CAS 243875, 66.2 mm SL, KAUM–I. 104643, 77.9 mm SL, Same data aS HOlOtype.
Diagnosis. A SpeCieS Of Phenacoscorpius WitH tHe fOllOWing COmbinatiOn Of CHaraCterS: peCtOral-fin rayS 19– 20, SeCOnd tO nintH rayS branCHed; 5–19 pOred lateral-line SCaleS, pOSteriOrmOSt pOre Situated frOm belOW baSe Of fiftH dOrSal-fin Spine tO anteriOr Of Caudal pedunCle; 46–48 SCale rOWS in lOngitudinal SerieS; palatine teetH preSent; Small Slit beHind fOurtH gill arCH; SeCOnd preOperCular Spine abSent; nuCHal and parietal SpineS diStinCt but JOined at baSe; Head large, lOng, itS WidtH and lengtH 17.7–19.5% (mean 18.8%) Of SL and 46.1–51.9% (48.7%) Of SL reSpeCtively; interOrbital SpaCe brOad, itS WidtH at vertiCal midline Of eye and pOSteriOr end Of preOCular Spine baSe 8.0–8.9% (8.3%) Of SL and 6.2–6.8% (6.4%) Of SL reSpeCtively; pOStOrbital lengtH 24.1–25.2% (24.7%) Of SL; deep Caudal pedunCle, deptH 10.0–11.0% (10.7%) Of SL.
Description. Data fOr HOlOtype preSented firSt, fOllOWed by paratype data (if different) in parentHeSeS. DOrSal fin WitH 12 SpineS; tHird Spine lOngeSt, but SHOrter tHan pelviC-fin Spine lengtH; tHird tO eleventH SpineS prOgreSSively SHOrter; lengtH Of eleventH Spine 2.4 (1.9) in laSt Spine; membrane Of SpinOuS pOrtiOn Of dOrSal fin mOderately nOtCHed. DOrSal fin WitH 8 SOft rayS (9 rayS in 66.2 mm SL paratype); all rayS branCHed, divided intO 2 branCHeS; fOurtH SOft ray lOngeSt, but SHOrter tHan lOngeSt anal-fin SOft ray lengtH; pOSteriOr branCH Of laSt ray JOined by very SHOrt membrane tO Caudal pedunCle. Anal fin WitH 3 SpineS; SeCOnd Spine lOngeSt, but SligHtly SHOrter tHan pelviC-fin Spine lengtH; firSt Spine 1.9 (1.8 in 66.2 mm SL paratype) in SeCOnd Spine, 1.6 (1.4–1.5) in tHird Spine. Anal fin WitH 5 SOft rayS; all rayS branCHed, divided intO 2 branCHeS; SeCOnd (tHird in 77.9 mm SL paratype) ray lOngeSt; pOSteriOr branCH Of laSt ray JOined by very SHOrt membrane tO Caudal pedunCle. PeCtOral fin WitH 19 (20 in 77.9 mm SL paratype) rayS On eaCH Side Of bOdy; SeCOnd tO eigHtH (SeCOnd tO nintH) middle rayS branCHed, divided intO 2 branCHeS, OtHer rayS unbranCHed; tentH (eleventH) ray lOngeSt, but muCH SHOrter tHan bOdy deptH; lOWer rayS COvered WitH tHiCk Skin; pOSteriOr margin Of fin nOt bilObed. PelviC fin WitH 1 Spine and 5 SOft rayS; laSt ray unbranCHed, OtHer rayS branCHed, divided intO 2 branCHeS; SeCOnd ray lOngeSt (left Side Only in HOlOtype), itS lengtH greater tHan lOngeSt anal-fin SOft ray lengtH; laSt SOft ray JOined by membrane tO abdOmen fOr abOut Half itS lengtH. POSteriOr margin Of Caudal fin SligHtly rOunded. Caudal-pedunCle deptH 1.8 (1.7–1.9; mean 1.8) in Caudal-pedunCle lengtH.
POred lateral-line SCaleS 17 and 19 On left and rigHt SideS Of bOdy reSpeCtively (5 and 6 in 66.2 mm SL paratype; 7 and 10 in 77.9 mm SL paratype); 1 (0) Separated pOSteriOrmOSt pOre On left Side anteriOr tO Caudal pedunCle; 2 (0) Separated pOSteriOrmOSt pOre On rigHt Side in middle Of Caudal pedunCle. PredOrSal SCale rOWS betWeen firSt dOrSal-fin Spine Origin and anteriOr end Of nuCHal Spine baSe abOut 10. Gill rakerS On upper limb 7 (6 in 66.2 mm SL paratype) inCreaSing in Size tO angle, lOWer limb 15 (14 in 66.2 mm SL paratype) deCreaSing in Size frOm angle, inCluding 4 (3 in 66.2 mm SL paratype) rakerS On HypObranCHial; tOtal gill rakerS 22 (20 in 66.2 mm SL paratype); lOngeSt raker On firSt gill arCH lOCated at angle, itS lengtH abOut fOur timeS lengtH Of gill filamentS arOund angle; a Small Slit beHind fOurtH lOWer gill arCH. BranCHiOStegal rayS 7. SWimbladder abSent.
BOdy mOderately COmpreSSed anteriOrly, prOgreSSively mOre COmpreSSed pOSteriOrly. Nape and anteriOr bOdy StrOngly arCHed. BOdy deptH relatively SHallOW, leSS tHan Head lengtH. TWO (tHree) Slender unbranCHed tentaCleS; firSt On anteriOr Of pOSteriOr nOStril, SHOrter tHan SeCOnd, SeCOnd On upper pOSteriOr end Of preOCular Spine, tHird On upper pOSteriOr end Of SupraOCular Spine. NO OtHer diStinCt tentaCleS On Head and bOdy. EXpOSed CtenOid SCaleS COvering OperCle and area enClOSed by pOSteriOr margin Of Orbit, upper preOperCular margin and pterOtiC Spine baSe.
EXpOSed CyClOid SCaleS COvering CHeek. Remainder Of Head SCaleleSS. Well eXpOSed CtenOid SCaleS laterally On bOdy, SCaleS beCOming CyClOid On abdOmen, peCtOral-fin baSe and betWeen pelviC-fin baSeS. BOdy SCaleS eXtending OntO peCtOral- and Caudal-fin baSeS.
CepHaliC SenSOry pOreS prOminent On eaCH Side; 3 CirCular pOreS JuSt belOW SubOrbital SpineS, firSt JuSt pOSteriOr tO laCrimal SpineS; SeCOnd equally SpaCed betWeen firSt and tHird; tHird largeSt, belOW end Of SubOrbital SpineS. An elliptiC pOre JuSt belOW pOSteriOr tip Of laCrimal ridge, itS lOngitudinal lengtH SligHtly greater tHan pOSteriOr nOStril diameter. AnteriOr nOStril elliptiC WitH membranOuS flap, lOCated JuSt belOW naSal Spine baSe, itS lOngitudinal lengtH SligHtly greater tHan pOSteriOr nOStril diameter. POSteriOr nOStril CirCular, a membranOuS fOld in Outer margin, lOCated JuSt anteriOr tO preOCular Spine baSe. A pair Of elliptiCal pOreS On interOrbital SpaCe (dOrSal vieW), eaCH pOSitiOned anteriOrly tHrOugH pupil and betWeen preOCular and SupraOCular Spine baSeS, lOngitudinal lengtH greater tHan pOSteriOr nOStril diameter. TWO CirCular pOreS beHind pOSteriOr margin Of Orbit; firSt muCH larger tHan SeCOnd pOre, lOCated betWeen SpHenOtiC and veStigial pOStOrbital Spine; SeCOnd JuSt belOW veStigial pOStOrbital Spine. A CirCular Spine JuSt beHind pOSteriOr end Of tympaniC Spine baSe, itS diameter Subequal tO pOre under veStigial pOStOrbital Spine. An elliptiC pOre JuSt beHind pOSteriOr end Of pterOtiC Spine baSe, itS lOngitudinal lengtH SligHtly SHOrter tHan tHat Of interOrbital pOre. An elliptiC pOre JuSt beHind parietal Spine baSe, itS lOngitudinal lengtH SligHtly greater tHan tHat Of interOrbital pOre. A CirCular pOre betWeen pOStempOral and SupraCleitHral SpineS, diameter Half Of tHat Of interOrbital pOre. Five elliptiC and CirCular pOreS alOng preOperCular margin; uppermOSt 2 (elliptiC) pOreS betWeen upper end Of preOperCular margin and firSt preOperCular Spine, tHird pOre CirCular, JuSt belOW Supplemental Spine baSe Of firSt preOperCular Spine, fOurtH pOre CirCular JuSt abOve SeCOnd preOperCular Spine baSe, fiftH pOre CirCular JuSt belOW tHird preOperCular Spine baSe. UnderSide Of dentary WitH 3 SenSOry pOreS On eaCH Side (ventral vieW); firSt pOre belOW anteriOr edge Of laCrimal bOne, SeCOnd pOre belOW and betWeen tipS Of anteriOr and pOSteriOr laCrimal SpineS, tHird pOre largeSt, On pOSteriOr margin Of dentary. A Small pOre beHind lOWer-JaW SympHySial knOb On eaCH Side.
MOutH large, SligHtly Oblique, fOrming an angle Of abOut 20 degreeS tO HOrizOntal aXiS Of Head and bOdy. POSteriOr margin Of maXilla eXtending beyOnd vertiCal WitH pOSteriOr margin Of pupil, but nOt reaCHing tO vertiCal WitH pOSteriOr margin Of Orbit. Lateral SurfaCe Of maXilla SmOOtH, WitHOut ridgeS, tentaCleS Or SCaleS. WidtH Of SympHySial gap Separating premaXillary teetH bandS SligHtly greater tHan WidtH Of eaCH band. LOWer JaW WitH a SympHySial knOb, underSide Of lOWer JaW SmOOtH WitHOut ridgeS. Upper and lOWer JaWS eaCH WitH a band Of villifOrm teetH Of Subequal lengtH. VOmer and palatine teetH WitH villifOrm teetH (V-SHaped patCH in fOrmer); WidtH Of vOmer Sligltly greater tHan tHat Of palatine.
DOrSal prOfile Of SnOut mOderately elevated, fOrming an angle Of abOut 30–40 degreeS tO HOrizOntal aXiS Of Head and bOdy. NaSal Spine Simple, SHarp, direCted upWard. ASCending prOCeSS Of premaXilla nOt intruding intO interOrbital SpaCe, itS pOSteriOr margin JuSt reaCHing level Of anteriOr margin Of pOSteriOr nOStril (dOrSal vieW). Median interOrbital ridge abSent. InterOrbital ridgeS pOOrly develOped, beginning pOSteriOr tO naSal SpineS and JOining tympaniC Spine baSeS, diverging anteriOrly and pOSteriOrly (dOrSal vieW), Separated by a SHallOW furrOW; nO diStinCt ridge On anteriOr edge Of OCCipital pit. PreOCular Spine Simple, direCted dOrSOpOSteriOrly; tip Of Spine eXtending beyOnd level Of upper margin Of pupil (lateral vieW). SupraOCular Spine Simple, itS tip eXtending SligHtly beyOnd vertiCal midline tHrOugH pupil (lateral vieW); Spine SHOrter tHan preOCular, pOStOCular and tympaniC SpineS. POStOCular Spine Simple, SligHtly Canted laterally. TympaniC Spine Simple, StrOngly pOinted, direCted dOrSOpOSteriOrly. InterOrbital, COrOnal and pretympaniC SpineS abSent. OCCipital pit SHallOW. IndiStinCt tranSverSe ridge anteriOr tO OCCiput almOSt StraigHt (dOrSal vieW). TranSverSe ridge abSent beHind OCCiput betWeen baSeS Of parietal and nuCHal SpineS. Parietal and nuCHal SpineS diStinCt, but JOined at baSe. SpHenOtiC WitH 1 Small Spine, StrOngly pOinted, direCted dOrSOlaterally. POStOrbital Spine veStigial. PterOtiC Spine WitH 2 tipS, rigHt Side Simple (bOtH SideS Simple in 66.2 mm SL paratype; left Side Simple in 77.9 mm SL patratype, rigHt Side WitH 2 tipS), lOCated belOW parietal Spine. RidgeS abSent On area enClOSed by parietal, nuCHal, pterOtiC and lOWer pOSttempOral SpineS. Upper pOSttempOral Spine abSent. LOWer pOSttempOral Spine Simple, itS lOngitudinal baSe leSS tHan tHat Of pterOtiC Spine. SupraCleitHral Spine Simple, StrOngly pOinted (nOt StrOngly pOinted). CleitHral Spine flattened, pOinted, WitH a lOW median ridge.
TWO lateral laCrimal SpineS; anteriOr lateral laCrimal Spine larger tHan pOSteriOr Spine, triangular, nOt StrOngly pOinted; pOSteriOr lateral laCrimal Spine Small, StrOngly pOinted. AnteriOr laCrimal Spine WitH tWO tipS (Single in 77.9 mm SL paratype), direCted ventrOanteriOrly. POSteriOr laCrimal Spine Simple, StrOngly pOinted, direCted ventrOpOSteriOrly; itS Size muCH greater (Subequal) tHan anteriOr laCrimal Spine. SubOrbital ridge WitH 9 and 7 (6, 7 in 77.9 mm SL paratype, 7, 7 in 66.2 mm SL paratype) SpineS On left and rigHt Side Of bOdy, reSpeCtively; firSt Spine anteriOr tO Orbit, SeCOnd tO SiXtH SpineS belOW Orbit, SeventH tO nintH beHind Orbit. SpaCe betWeen ventral margin Of eye and SubOrbital ridge relatively large, inCreaSing pOSteriOrly. SubOrbital pit abSent. PreOperCle WitH 4 SpineS; uppermOSt Spine largeSt, a Supplemental preOperCular Spine On baSe; SeCOnd Spine abSent; tHird tO fiftH SpineS WitHOut a diStinCt median ridge; fiftH Spine minute. PreOperCle SmOOtH, WitHOut Serrae Or SpineS betWeen uppermOSt preOperCular Spine and upper end Of preOperCle. Upper OperCular Spine Simple, WitHOut a diStinCt median ridge. LOWer OperCular Spine Simple, WitH a diStinCt median ridge. SpaCe betWeen upper and lOWer OperCular SpineS WitHOut ridgeS. POSteriOr tip Of upper OperCular Spine nOt reaCHing OperCular margin. POSteriOr tip Of lOWer OperCular Spine eXtending SligHtly beyOnd pOSteriOr OperCular margin. Origin Of firSt dOrSal-fin Spine abOve SupraCleitHral Spine. POSteriOr margin Of OperCular membrane beyOnd vertiCal WitH tHird dOrSal-fin Spine baSe. POSteriOr tip Of peCtOral fin nOt reaCHing (eXtending beyOnd in 77.9 mm SL paratype) tO vertiCal WitH tHird anal-fin Spine baSe. Origin Of pelviC-fin Spine belOW Origin Of peCtOral fin. POSteriOr tip Of depreSSed rigHt Side (left Side) pelviC fin JuSt reaCHing (nOt reaCHing) tO Origin Of anal fin. Origin Of firSt anal-fin Spine SligHtly pOSteriOr tO Origin Of laSt dOrSal-fin Spine.
Morphometrics. EXpreSSed aS perCentage Of SL: bOdy deptH 42. 8 (40.9–45.1); bOdy WidtH 22.9 (21.5–22.3); Head lengtH 48.3 (46.1–51.9); Head WidtH 19.3 (17.7–19.5); SnOut lengtH 12.00 (10.0–12.7); Orbit diameter 13.5 (15.4–16.2); interOrbital WidtH at middle Of eye 8.2 (8.0–8.9); interOrbital WidtH betWeen pOSteriOr end Of preOCular Spine baSeS 6.2 (6.3–6.8); upper-JaW lengtH 24.1 (22.1–25.0); maXillary deptH 8.2 (6.9–7.7); pOStOrbital lengtH 24.1 (24.8–25.2); predOrSal-fin lengtH 46.7 (43.1–49.3); preanal-fin lengtH 71.6 (70.2–70.8); prepelviC-fin lengtH 44.4 (39.9–42.1); firSt dOrSal-fin Spine lengtH 6.3 (7.6 in paratypeS); SeCOnd dOrSal-fin Spine lengtH, tip damaged (11.0 in 66.2 mm SL paratype); tHird dOrSal-fin Spine lengtH 14.3 (16.2 in paratypeS); fOurtH dOrSal-fin Spine lengtH, tip damaged (14.5–15.5); fiftH dOrSal-fin Spine lengtH 12.1 (13.4–14.0); SiXtH dOrSal-fin Spine lengtH 11.2 (12.2–13.3); SeventH dOrSal-fin Spine lengtH 9.8 (10.8–11.8); eigHtH dOrSal-fin Spine lengtH 8.0 (9.4–9.5); nintH dOrSal-fin Spine lengtH 6.6 (7.8–8.2); tentH dOrSal-fin Spine lengtH 5.9 (7.1–7.3); eleventH dOrSal-fin Spine lengtH 5.4 (5.7–6.0); tWelftH dOrSal-fin Spine lengtH 11.0 (11.0–11.4); lOngeSt (fOurtH) dOrSal-fin SOft ray lengtH 19.0 (18.9–19.1); firSt anal-fin Spine lengtH 8.8 (8.9–9.1); SeCOnd anal-fin Spine lengtH 16.4 (16.3–16.9); tHird anal-fin Spine lengtH 13.9 (12.7–13.1); lOngeSt (SeCOnd) anal-fin SOft ray lengtH (tHird in 77.9 mm SL paratype), 21.3 (19.5–21.1); lOngeSt (tentH) peCtOral-fin ray lengtH (eleventH in paratypeS) 33.5 (31.6–34.0); pelviC-fin Spine lengtH 16.8 (17.8–18.5); lOngeSt pelviC-fin SOft ray lengtH, ray damaged (2nd; 24.5–24.9); Caudal-fin lengtH 19.8 (23.0 in 66.2 mm SL paratype); Caudal-pedunCle lengtH 20.1 (19.0–19.2); Caudal-pedunCle deptH 10.9 (10.0–11.0).
Color when fresh, baSed On a COlOr pHOtOgrapH Of tHree type SpeCimenS taken SOOn after Captured (regiStered in KAUM ICHtHyOlOgiCal Image DatabaSe aS KAUM–II. 104643): BOdy brigHt red, WitH WHite ventrally; pOOrly defined WHite blOtCHeS On lateral SurfaCe Of bOdy and Head. SpinOuS pOrtiOn Of dOrSal fin red. SOft-rayed pOrtiOnS Of dOrSal and anal finS and Caudal fin red, WitH WHite diStally. PeCtOral fin red, WitH WHite baSally and SemitranSparent diStally.
Color of preserved specimens. BOdy and all finS Of HOlOtype and paratypeS WHitiSH (FigS. 1–2); bOdy Of paratypeS WitH tiny blaCk SpOtS SCattered On peCtOral-fin baSe, Caudal pedunCle (18–46 SpOtS), and betWeen anteriOr Of peCtOral-fin baSe and anteriOr pOred lateral-line SCaleS.
Habitat. All SpeCimenS COlleCted frOm very Steep rOCky Wall area WitH WHite SpOngeS and StOny COralS, galatHiid CrabS, large ateleOpOdidS (Guentherus altivela), mOridS, SCOrpiOnfiSH (genuS Pontius), and CatSHarkS at 515 m deptH; tHe neW SpeCieS SOlitary, nOt aSSOCiated WitH OtHer animalS (J.E. MCCOSker, perS. COmm.).
Etymology. Named fOr Dr JOHn E. MCCOSker, CalifOrnia ACademy Of SCienCeS WHO COlleCted all Of tHe type SpeCimenS Of tHe neW SpeCieS and kindly made tHem available.
Remarks. Phenacoscorpius mccoskeri Can be eaSily diStinguiSHed frOm all OtHer SpeCieS Of tHe genuS by tHe greater number Of peCtOral-fin rayS [19 Or 20 vS. 16 Or 17 in P. eschmeyeri and P. nebris (ESCHmeyer 1965a; MOtOmura et al. 2012b); 16–18 in P. adenensis, P. longilineatus and P. megalops (MOtOmura 2008; MOtOmura et al. 2012a; OkamOtO et al. 2012); and 17 in P. longirostris (MOtOmura & LaSt 2009)]. Like all SpeCieS Of tHe genuS, eXCept P. longirostris, tHe middle peCtOral-fin rayS in P. mccoskeri are branCHed intO tWO.
Phenacoscorpius mccoskeri HaS a relatively large number Of pOred lateral-line SCaleS (5–19): aSymmetriCally 17 and 19 SCaleS On tHe left and rigHt SideS Of tHe bOdy, reSpeCtively, in tHe HOlOtype, 5 and 6, reSpeCtively, in tHe Smaller paratype, and 7 and 10, reSpeCtively, in tHe larger paratype. PreviOuSly, P. longilineatus Had Had tHe greateSt number Of pOred lateral-line SCaleS repOrted (8–18; MOtOmura et al. 2012a). All Head SpineS Of P. mccoskeri are Well develOped, being relatively lOng, SHarp and prOminent (See FigS. 1–2), COmpared WitH tHOSe Of COngenerS, in WHiCH mOSt Head SpineS are SHOrt, and mOderately Or pOOrly develOped (See alSO P. nebris; ESCHmeyer 1965a: fig. 1).
SpeCieS Of Phenacoscorpius Can be grOuped aCCOrding tO tHe preSenCe Or abSenCe Of palatine teetH (MOtOmura 2008; MOtOmura & LaSt 2009). THOSe WitH palatine teetH inClude P. longisrostris and P. megalops, tHe remaining SpeCieS, inCluding P. mccoskeri, laCking teetH. In additiOn tO number Of peCtOral-fin rayS, P. mccoskeri Can be Separated frOm OtHer SpeCieS in tHe SeCOnd grOup On tHe baSiS Of Several mOrpHOmetriC CHaraCterS: larger Head [WidtH and lengtH 17.7–19.5% (mean 18.8%) Of SL and 46.1–51.9% (48.7%) Of SL, reSpeCtively, vS 13.3–16.6% (14.6%) and 41.0–46.1% (43.6%), reSpeCtively, in P. adenensis, 13.4–14.0% (13.8%) and 44.4–46.0% (45.0%), reSpeCtively, in P. eschmeyeri, 13.6–17.1% (15.6%) and 40.8–46.8% (44.1%), reSpeCtively, in P. longilineatus, and unknOWn and 46.0–48.0% (46.7%), reSpeCtively, in P. nebris]; Wider interOrbital SpaCe [WidtH at vertiCal midline Of eye and pOSteriOr end Of preOperCular Spine baSe 8.0–8.9% (8.3%) Of SL and 6.2–6.8% (6.4%) Of SL, reSpeCtively, vS. 4.0–5.0% (4.7%) and unknOWn, reSpeCtively, in P. nebris, 4.6–6.7% (5.6%) and 4.1–6.1% (4.9%), reSpeCtively, in P. adenensis, 4.7–6.5% (5.6%) and 4.1–5.9% (4.9%), reSpeCtively, in P. longilineatus, 5.0–5.6% (5.3%) and 4.6– 5.1% (4.9%), reSpeCtively, in P. eschmeyeri]; greater pOStOrbital lengtH [24.1–25.2% (24.7%) Of SL vS. 17.7–22.9% (20%) in P. longilineatus, 18.2–23.0% (19.6%) in P. adenensis, and 19.4–22.8% (20.9%) in P. eschmeyeri]; and deeper Caudal pedunCle [deptH 10.0–11.0% (10.7%) Of SL vS. 7.7–9.8% (8.9%) in P. adenensis, 7.7–10.3% (8.6%) in P. longilineatus, and 8.9–9.4% (9.1%) in P. eschmeyeri].
THe bOdy COlOr Of preServed SpeCimenS Of all SpeCieS Of Phenacoscorpius, inCluding P. mccoskeri, iS unifOrmly WHitiSH, eXCept in P. adenensis, P. megalops and P. nebris, WHiCH are diStinCtly blaCkiSH dOrSally (ESCHmeyer 1965a: fig. 1; MOtOmura et al. 2012a: fig. 2; OkamOtO et al. 2012: fig. 1). HOWever, P. mccoskeri Can be diStinguiSHed frOm tHe OtHer unifOrmly WHitiSH SpeCieS by Having a greater number Of Small SpOtS SCattered On tHe Caudal pedunCle [18–46; Fig. 2 vS. a Single SpOt in P. eschmeyeri (MOtOmura et al. 2012b), 1–5 in P. longilineatus (MOtOmura et al. 2012a) and 14–20 in P. longisrostris (MOtOmura & LaSt 2009; fig. 2)].
description: Published as part of Motomura, Hiroyuki, 2017, A new species of the deepwater scorpionfish genus Phenacoscorpius (Teleostei: Scorpaenidae) from the Galápagos Islands, pp. 261-268 in Zootaxa 4323 (2) on pages 262-267, DOI: 10.11646/zootaxa.4323.2.9, http://zenodo.org/record/898991