Ariosoma Swainson, 1838

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 : 85-86

Ariosoma Swainson, 1838

Ariosoma SWaINSON, 1838 : 220 (TyPE SPEcIES: Ophisoma acuta SWaINSON 1839, by SubSEquENT dESIgNaTION Of BLEEkEr, 1864: 20).

Definition. A gENuS Of THE SubfAMILY BATHYMYRINAE WITH bODY STOuT TO MODERATELY ELONgATE, PREANAL LENgTH 41‒52% TL; cAuDAL fIN REDucED AND TIP Of TAIL STIff; POSTERIOR NOSTRIL ExPOSED, IN fRONT Of EYE SOMEWHAT bELOW MID- EYE LEVEL; DORSAL- AND ANAL-fIN RAYS uNSEgMENTED; fLANgE PRESENT ON uPPER LIP; DORSAL fIN bEgINS NEAR LEVEL Of PEcTORAL-fIN bASE; HEAD PORES SMALL, PORES ALONg uPPER jAW LOcATED ON SIDE Of HEAD, RATHER THAN ON LAbIAL fLANgE; ADNASAL PORE AbSENT; TEETH VILLIfORM, NEVER ENLARgED OR fANg-LIkE, THOSE ON INTERMAxILLARY AND DENTARY fORMINg NARROW bAND WITH MuLTIPLE ROWS, AND ON VOMER fORMINg A MODERATELY LONg PATcH.

Description. BASED ON TAIWANESE SPEcIES ONLY. BODY MODERATELY ELONgATE, ROuNDED IN cROSS SEcTION, bEcOMINg MORE cOMPRESSED POSTERIORLY. TRuNk MODERATELY LONg, ITS LENgTH 3.0‒4.0 TIMES IN TOTAL LENgTH; TIP Of TAIL bLuNT, cAuDAL RAYS REDucED IN LENgTH; ANuS AT OR SLIgHTLY bEfORE MIDDLE Of TOTAL LENgTH.

DORSAL fIN bEgINS WELL bEfORE TO AbOVE PEcTORAL-fIN bASE; cONTINuOuS AROuND TIP Of TAIL WITH cAuDAL AND ANAL fINS. ANAL fIN bEgINS IMMEDIATELY bEHIND ANuS. PEcTORAL fIN WELL DEVELOPED, POINTED OR bLuNTLY ROuNDED DISTALLY WITH A NARROW bASE. GILL OPENINg MODERATELY LARgE, uSuALLY SMALLER THAN EYE DIAMETER, ITS uPPER END NEARLY OPPOSITE uPPER HALf Of PEcTORAL-fIN bASE; INTERbRANcHIAL WIDTH AbOuT SAME AS gILL OPENINg AND EYE .

HEAD RELATIVELY LARgE, ITS LENgTH 4.7‒6.6 TIMES IN TL, DEEPEST AT AbOuT OccIPITAL REgION, SLIgHTLY TAPERINg ANTERIORLY fROM THIS POINT; SNOuT SHORT, bLuNT TO SLIgHTLY POINTED ANTERIORLY IN DORSAL VIEW, ITS LENgTH 0.8‒1.5 TIMES EYE DIAMETER, SLIgHTLY PROjEcTINg bEYOND LOWER jAW; LOWER jAW LONgER THAN SNOuT; RIcTuS bEHIND ANTERIOR MARgIN Of EYE.

ANTERIOR NOSTRIL TubuLAR, NEAR TIP Of SNOuT, DIREcTED VENTROLATERALLY. POSTERIOR NOSTRIL A SMALL OVAL PORE, WITH A SLIgHTLY RAISED RIM, AbOuT 3 TIMES ITS DIAMETER IN fRONT Of MID-EYE LEVEL. UPPER jAW WITH A SLIgHT uPTuRNED fLANgE AND LOWER jAW WITH WELL-DEVELOPED, DOWNTuRNED fLANgE. TONguE fREE, MODERATELY LONg, AND bROAD.

LATERAL LINE NEARLY cOMPLETE, THE LAST PORE RuNS TO LESS THAN ONE HEAD LENgTH bEfORE cAuDAL fIN; 3‒11 PREDORSAL, 6‒11 cEPHALIc, 42‒64 PREANAL, AND 106‒158 TOTAL.

HEAD PORES SMALL TO SLIgHTLY ENLARgED ( FIg. 1 ). SO PORES 4‒6; THE fIRST (ETHMOIDAL) TINY, AT VENTRAL TIP Of SNOuT, juST AbOVE LIP; THE SEcOND SMALL, AT DORSAL MARgIN Of ANTERIOR NOSTRIL; THE THIRD ENLARgED, AbOVE bASE Of ANTERIOR NOSTRIL; THE fOuRTH SMALL, AbOVE POSTERIOR NOSTRIL; THE fIfTH AT ANTERIOR PORTION Of INTERORbITAL SPAcE; THE SIxTH AT POSTERIOR PORTION Of INTERORbITAL SPAcE. IO PORES TYPIcALLY 5‒8 (ExcEPT A. fasciatum , WHIcH HAS MuLTIPLE PORES, SEE DEScRIPTION uNDER THE SPEcIES); 4 ALONg uPPER jAW, THE fIRST IMMEDIATELY bEHIND ANTERIOR NOSTRIL, THE NExT 3 ALONg uPPER jAW AbOVE fLANgE, THE fIfTH IN LINE WITH THESE bEHIND RIcTuS; 0‒3 PORES IN AScENDINg bRANcH Of cANAL bEHIND EYE. POM PORES 10; 7 IN MANDIbuLAR SEcTION, 6 bEfORE RIcTuS AND ONE bEHIND; AND 3 IN PREOPERcuLAR SEcTION ExcEPT fOR A. fasciatum WHIcH HAS MORE. ST PORES 0‒3 IN MOST SPEcIES, 1 MEDIAN PORE AND 2 LATERAL PORES AbOVE fIRST LATERAL-LINE PORES; A. meeki HAS NONE AND A. fasciatum MAY HAVE MORE SMALL AND IRREguLARLY ARRANgED PORES.

PREDORSAL VERTEbRAE 5‒12; PREANAL VERTEbRAE 44‒66; PREcAuDAL VERTEbRAE 54‒84; TOTAL VERTEbRAE 116‒162.

TEETH SMALL, cONIcAL OR bLuNT. INTERMAxILLARY TEETH SLIgHTLY ENLARgED, cuRVED, IN 3‒4 TRANSVERSE ROWS, SLIgHTLY VISIbLE WHEN MOuTH cLOSED, THE PATcH cONTINuOuS WITH MAxILLARY TEETH, buT WITH A gAP IN fRONT Of VOMERINE TEETH. MAxILLARY AND MANDIbuLAR TEETH IN bANDS, WIDER ANTERIORLY, ROugHLY IN 4‒5 ROWS, NARROWER POSTERIORLY, IN 1‒2 ROWS; OuTERMOST TEETH SLIgHTLY LARgER THAN INNERMOST. VOMERINE TEETH fORMINg A SMALL TRIANguLAR PATcH, THOSE ON ANTERIOR PORTION SHARP AND cuRVED, fOLLOWED bY SLIgHTLY WIDER bASED buT bLuNT TEETH POSTERIORLY, THE PATcH RuNS TO AbOuT HALf THE LENgTH Of MAxILLARY TEETH ROWS.

COLORATION PALE TO DARk bROWN, VERTIcAL fINS WITH NARROW OR bROAD bLAck MARgIN; bLAck AND WHITE bANDS ON HEAD PRESENT OR AbSENT; A. fasciatum WITH LARgE bLOTcHES ON bODY, WHEREAS AS THE OTHERS HAVE NONE .

DIVERSITY. THE gENuS cuRRENTLY cOMPRISES 31 REcOgNIzED SPEcIES. TWENTY-TWO SPEcIES ARE fOuND IN THE INDO- WEST PAcIfIc OcEAN, WHEREAS SEVEN SPEcIES ARE fOuND IN THE ATLANTIc OcEAN AND TWO IN THE EASTERN PAcIfIc OcEAN. IN THE NORTHWESTERN PAcIfIc OcEAN, THE fOLLOWINg TEN SPEcIES WERE fOuND: Ariosoma anago (TEMMINck & ScHLEgEL, 1846) , A. dolichopterum KARMOVSkAYA, 2015 , A. fasciatum (GüNTHER, 1872) , A. majus (ASANO, 1958) , A. meeki (JORDAN & SNYDER, 1900), A. megalops FOWLER, 1938 , A. sazonovi KARMOVSkAYA, 2004, A. scheelei (STRöMMAN, 1896), A. shiroanago (ASANO, 1958) , AND A NEW SPEcIES DEScRIbED HERE.

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.