Ariosoma emmae Smith & Ho, 2018

Smith, David G., Ho, Hsuan-Ching, Huang, Jian-Fu & Chang, Yong-Hsu, 2018, The congrid eel genus Ariosoma in Taiwan (Anguilliformes: Congridae), with description of a new species, Zootaxa 4454 (1), pp. 84-106 : 90-94

Ariosoma emmae Smith & Ho , sp. nov.

EMMA’S SHORT-TAIL CONgER ; 黑錐體糯鰻

FIgS. 1 , 3C , 5 , 6 ; TAbLE 1

Holotype. NMMB-P 26428 (236 MM TL), Off KE-TSu-LIAO, KAOHSIuNg, SOuTHWESTERN TAIWAN, NORTH TIP Of SOuTH CHINA SEA, 18 JuN. 2017, LESS THAN 100 M, cOLL. H.-C. HO.

Paratypes. 9 SPEcIMENS, 149‒242 MM TL. NMMB-P23479 (3, 207‒232), KE-Tzu-LIAO, 13 JuL. 2016. NMMB- P24376 (1, 177), KE-Tzu-LIAO, 27 JuN. 2016. NMMB-P26426 (1, 193), KE-Tzu-LIAO, 18 JuN. 2017. NMMB-P26710 (1, 207), KE-Tzu-LIAO, 17 Aug. 2017. NMMB-P26711 (1, 242), KE-Tzu-LIAO, 17 Aug. 2017. USNM 439058 (1, 160), USNM 439059 (1, 149), KE-Tzu-LIAO, 4 FEb. 2016.

Non-types. NMMB-P12217 (1, 306), DAxI, 22 JAN. 2010 (ALL DATA INcLuDED). NMMB-P27032 (3, 125‒197), cLEARED AND STAINED, KE-Tzu-LIAO, 18 JuN. 2017 (DETAILED MEASuREMENTS NOT TAkEN).

Diagnosis. BODY bLAckISH, ONE WHITISH bAND cROSSINg SNOuT juST ANTERIOR TO EYES; VERTIcAL fINS WITH VERY bROAD cONSPIcuOuS bLAck MARgIN; SNOuT RELATIVELY POINTED; PEcTORAL fIN MODERATE IN SIzE, 29.1‒35.2% HL. PREANAL VERTEbRAE 51‒55, TOTAL VERTEbRAE 127‒133; PREANAL LATERAL-LINE PORES 50‒53, TOTAL PORES 123‒126.

Description. MORPHOMETRIc AND MERISTIc DATA ARE PROVIDED IN TAbLE 1. THE fOLLOWINg VALuES ARE PROVIDED fOR THE HOLOTYPE, fOLLOWED bY RANgE Of PARATYPES IN PARENTHESES. THE VALuES Of NON-TYPES ARE WITHIN RANgE Of TYPE SERIES.

HEAD LENgTH 5.9 (5.4‒5.9) IN TL; PREANAL LENgTH 2.1 (2.0‒2.1); PREDORSAL LENgTH 7.0 (6.1‒7.0); TRuNk LENgTH 3.2 (3.1‒3.5); TAIL LENgTH 1.9 (1.9‒2.0); DEPTH AT gILL OPENINg 19.0 (17.0‒20.9). SNOuT LENgTH 4.4 (4.2‒4.6) IN HL; EYE DIAMETER 6.4 (5.3‒6.4); INTERORbITAL WIDTH 7.3 (6.9‒7.9); uPPER jAW 3.7 (3.3‒3.7); gILL OPENINg WIDTH 8.3 (7.8‒9.7); INTERbRANcHIAL WIDTH 6.0 (5.6‒7.9); PEcTORAL-fIN LENgTH 3.1 (2.8‒3.4).

BODY RELATIVELY STOuT, cYLINDRIcAL ANTERIORLY AND LATERALLY cOMPRESSED THROugH THE POSTERIOR HALf, bEcOMINg MORE cOMPRESSED POSTERIORLY; HEAD MODERATELY LARgE; TIP Of TAIL bLuNT; ANuS AT AbOuT MIDPOINT Of TOTAL LENgTH.

DORSAL fIN bEgINS WELL bEfORE INSERTION Of PEcTORAL fIN; cONTINuOuS AROuND TIP Of TAIL WITH cAuDAL AND ANAL fINS. ANAL fIN bEgINS IMMEDIATELY bEHIND ANuS. PEcTORAL fIN WELL DEVELOPED, POINTED DISTALLY WITH A NARROW bASE. GILL OPENINg MODERATELY LARgE, MucH SMALLER THAN EYE DIAMETER, ITS uPPER END NEARLY OPPOSITE uPPER HALf Of PEcTORAL-fIN bASE; INTERbRANcHIAL WIDTH gREATER THAN gILL OPENINg AND LARgER THAN EYE.

HEAD RELATIVELY LARgE, 16.9% (16.7‒18.4%) TL, DEEPEST AbOuT MIDWAY bETWEEN gILL OPENINg AND TIP Of SNOuT, TAPERINg ANTERIORLY fROM THIS POINT; SNOuT SHORT, POINTED ANTERIORLY IN DORSAL VIEW, ITS LENgTH 1.5 (1.2‒1.5) TIMES EYE DIAMETER, PROjEcTINg SLIgHTLY bEYOND LOWER jAW; LOWER jAW AbOuT SAME LENgTH AS SNOuT; fLESHY PART Of SNOuT VERY NARROW, PROjEcTINg ANTERIORLY SLIgHTLY bEYOND ANTERIOR END Of INTERMAxILLARY TOOTH PATcH ; RIcTuS bELOW AbOuT MIDDLE Of EYE, OR SLIgHTLY bEfORE.

ANTERIOR NOSTRIL SMALL, TubuLAR, NEAR TIP Of SNOuT, DIREcTED VENTROLATERALLY. POSTERIOR NOSTRIL A SMALL PORE, IN fRONT Of MID-EYE LEVEL. UPPER jAW WITH REDucED fLANgE; LOWER jAW WITH DOWNTuRNED fLANgE. TONguE SHORT AND bROAD, ANTERIOR HALf fREE fROM fLOOR Of MOuTH.

LATERAL LINE NEARLY cOMPLETE, fIRST PORE AT LEVEL Of SuPRATEMPORAL cANAL, THE cANAL ExTENDINg TO SLIgHTLY MORE THAN ONE EYE DIAMETER bEfORE cAuDAL-fIN bASE; 4 (4‒6) PREDORSAL, 8 (8‒9) cEPHALIc, 51 (50‒53) PREANAL, AND 123 (123‒126) TOTAL.

HEAD PORES SMALL, SOME MAY bE SLIgHTLY ENLARgED. SO cANAL WITH 6 PORES; THE fIRST (ETHMOIDAL PORE) VERY SMALL, ON VENTRAL SIDE Of TIP Of SNOuT, juST bEfORE THE LIP; THE SEcOND SMALL AND IMMEDIATELY IN fRONT Of AND AbOVE ANTERIOR NOSTRIL; THE THIRD ENLARgED, ON DORSAL SuRfAcE Of SNOuT cLOSER TO ANTERIOR NOSTRIL THAN POSTERIOR NOSTRIL; THE fOuRTH SLIgHTLY ENLARgED, RIgHT AbOVE POSTERIOR NOSTRIL OR SLIgHTLY bEHIND; THE fIfTH SMALL, AT ANTERIOR PORTION Of INTERORbITAL SPAcE; AND THE SIxTH AbOVE POSTERIOR PORTION Of INTERORbITAL SPAcE. IO cANAL WITH 8 PORES, THE fIRST ENLARgED, RIgHT bEHIND ANTERIOR NOSTRIL; THE SEcOND bELOW POSTERIOR NOSTRIL; THE THIRD bELOW ANTERIOR MARgIN Of EYE; THE fOuRTH SLIgHTLY bEHIND RIcTuS uNDER MIDDLE Of EYE; THE fIfTH IN LINE WITH THESE bEHIND RIcTuS uNDER POSTERIOR MARgIN Of EYE; AND 3 IN AScENDINg bRANcH Of cANAL bEHIND EYE. POM PORES 10; 7 IN MANDIbuLAR SEcTION, INcLuDINg 1 bEHIND RIcTuS; 3 IN PREOPERcuLAR SEcTION, IN A LONgITuDINAL ROW. ST PORES 3.

PREDORSAL VERTEbRAE 7 (6‒8); PREANAL VERTEbRAE 52 (51‒55); PREcAuDAL VERTEbRAE 64 (63‒65); TOTAL VERTEbRAE 131 (127‒133).

TEETH SMALL, cONIcAL OR bLuNT. INTERMAxILLARY TEETH cuRVED, IN 4 TRANSVERSE ROWS, SEPARATED fROM VOMERINE TEETH bY A gAPE, PARTLY ExcLuDED fROM cLOSED MOuTH. MAxILLARY AND MANDIbuLAR TEETH IN bANDS, WIDER ANTERIORLY, ROugHLY IN 3 OR 4 ROWS, NARROWER POSTERIORLY, IN 2 ROWS; INNERMOST TEETH bLuNT, THE REST cONIcAL. VOMERINE TEETH fORMINg A LONg TRIANguLAR PATcH, 3 OR 4 TRANSVERSE ROWS IN ANTERIOR PORTION, fOLLOWED bY 1 OR 2 (MOSTLY 1) IRREguLAR ROWS Of bLuNT TEETH.

COLORATION. FRESH AND PRESERVED SPEcIMENS WITH SIMILAR cOLORATION. WHEN fRESH, bODY uNIfORMLY DARk bROWN TO bLAckISH, PALER VENTRALLY, DORSAL AND ANAL fINS WITH VERY bROAD cONSPIcuOuS bLAck MARgIN, cAuDAL fIN WHITE WITH uPPER AND LOWER MARgINS bLAck. DORSAL SuRfAcE Of HEAD DARkER WITH A SINgLE WHITE bAND AcROSS LEVEL Of ANTERIOR MARgIN Of EYES THROugH THE 5TH SO PORES. THE PRESERVED SPEcIMENS ARE SLIgHTLY DARkER IN gENERAL.

MEASuREMENT Of HOLOTYPE (IN MM). HEAD LENgTH 39.9, PREANAL LENgTH 113, PREDORSAL LENgTH 33.6, TRuNk LENgTH 73.1, TAIL LENgTH 123, DEPTH AT gILL OPENINg 12.4, DEPTH AT ANuS 12.9, WITH AT ANuS 9.0, SNOuT LENgTH 9.0, EYE DIAMETER 6.2, INTERORbITAL WIDTH 5.5, uPPER jAW 10.8, gILL OPENINg WIDTH 4.8, INTERbRANcHIAL WIDTH 6.7, PEcTORAL-fIN LENgTH 13.0.

Size. THE LARgEST kNOWN SPEcIMEN ExAMINED IS 306 MM TL. IT APPEARS TO bE A SMALL SPEcIES THAT MATuRES AT AROuND 220 MM TL.

Distribution. THE SPEcIES IS cuRRENTLY ONLY kNOWN fROM SOuTHWESTERN TAIWAN, SOuTHERN TAIWAN STRAIT AND NORTHEASTERN TAIWAN. THE cOLLEcTINg DEPTH IS AbOuT 100 M OR LESS.

Etymology. WE TAkE THE OPPORTuNITY TO NAME THIS fISH AfTER EMMA S. KARMOVSkAYA Of P.P. SHIRSHOV INSTITuTE Of OcEANOLOgY, RuSSIAN AcADEMY Of ScIENcES, fOR HER gREAT cONTRIbuTION TO OuR kNOWLEDgE Of cONgRID EELS.

Remarks. AS MENTIONED AbOVE, THE TYPE SERIES WAS cONfuSED WITH SPEcIMENS Of A. dolichopterum DuE TO THE SIMILAR VERTEbRAL fORMuLA AND bODY cOLORATION. HOWEVER, A. emmae sp. nov. HAS A MODERATELY-SIzED PEcTORAL fIN (29.1‒35.2% HL; FIg. 6 ); A RELATIVELY LONg PREANAL LENgTH (46.9‒49.6% TL) AND TRuNk (28.9‒32.7% TL), AND ONLY ONE WHITISH bAND AcROSS DORSAL SuRfAcE Of ANTERIOR MARgIN Of EYE; WHEREAS A. dolichopterum HAS AN uNuSuALLY LARgE PEcTORAL fIN (40.0‒56.7% HL; FIg. 6 ); A RELATIVELY SHORT PREANAL LENgTH (43.1‒46.8% TL) AND TRuNk (26.6‒29.8% TL), AND fOuR cLEAR WHITISH bANDS AcROSS THE DORSAL SuRfAcE Of HEAD. THE bODY IS gENERALLY DARkER IN A. emmae THAN IN A. dolichopterum . MOREOVER, A. emmae APPEARS TO MATuRE AT AROuND 220 MM TL AND THE LARgEST SPEcIMEN ExAMINED IS 306 MM TL, WHEREAS A. dolichopterum MATuRES AT AROuND 320 MM TL AND ATTAINS AT LEAST 415 MM TL.

Figures

FIGURE 1. LINE draWINg SHOW THE gENEraL arraNgEmENT Of HEad POrES aNd aNTErIOr LaTEraL-LINE POrES. SO, SuPraOrbITaL (6 POrES); IO, INfraOrbITaL (4+4); M, maNdIbuLar (7); POP, PrEOPErcuLar (3); ST, SuPraTEmPOraL cOmmISSurE (3); LL, LaTEraL LINE. ArrOW INdIcaTES THE LOcaLITy Of mEdIaN POrE IN SuPraTEmPOraL cOmmISSurE. FrOm HOLOTyPE Of A. emmae, NMMB-P26428.

FIGURE 3. UPPEr-jaW TEETH Of Ariosoma SPEcIES. A. A. anago, TOU-AE5499. B. A. dolichopectrum, NMMB-P23477. C. A. emmae sp. nov., ParaTyPE, NMMB-P26426. D. A. fasciatum, NMMB-P23571. NOT TO ScaLE.

FIGURE 5. Ariosoma emmae sp. nov. A‒B. HOLOTyPE, NMMB-P26428, 236 mm TL. C. ParaTyPE, NMMB-P24376, 177 mm TL.

FIGURE 6. COmParISON Of PEcTOraL-fIN LENgTH (% HL) vErSuS STaNdard LENgTH bETWEEN A. dolichopterum aNd A. emmae sp. nov.