Ariosoma megalops Fowler, 1938

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 : 101-103

Ariosoma megalops Fowler, 1938

BIgEYE SHORT-TAIL CONgER ; 大眼錐體糯鰻

FIguRES 9C , 11 ; TAbLE 3

Ariosoma megalops FOWLEr, 1938 :12, fIg. 1 (TyPE LOcaLITy: MacaO, HONg KONg). SmITH, 1999:1686.

Material examined. 76 SPEcIMENS, 67.5‒213 MM TL (^ MEANS DATA TAkEN) . CHINA. ANSP 68287 (1, 136), HOLOTYPE, MAcAO, 7 APR. 1931 . ANSP 68288 (1, 155), PARATYPE, HONg KONg . TAIWAN. ASIZP 61840 (1, 182), HSINcHu, WESTERN TAIWAN . ASIZP 61841 (1, 191), HSIN-cHu, WESTERN TAIWAN . ^ NMMB-P1400 (1, 193, fORMERLY THUP 4179 ), DONg-gANg, PINgTuNg, 21 JuL. 1979 . ^NMMB-P3010 (1, 161), NO DATA. ^ NMMB-P3209 (3, 131‒170), TAINAN, 10 FEb. 1966 . NMMB-P13163 (1, 163), NO DATA. ^ NMMB-P25292 (1, 187), KE-Tzu-LIAO, KAOHSIuNg, 31 OcT. 2016 . ^NMMB-P25628 (1, 161), KE-Tzu-LIAO, 7 DEc. 2016. ^ NMMB-P26984 (1, 135), DONg-gANg, PINgTuNg, 19 JuL. 2017 . ^NMMB-P26985 (1, 121), DONg-gANg, 9 Aug. 2017. ^NMMB-P27891 (5, 179‒192), KE-Tzu-LIAO, 28 MAR. 2015. VIETNAM. ^NMMB-P12298 (30, 138‒208), PHEN THIET, 25 NOV. 2010. ^NMMB-P12300 (7, 122‒200), ^NMMB-P12306 (1, 201), MuI NE, 15 APR. 2011. ^NMMB-P12310 (2, 65‒105), PHEN THIET, 13 APR. 2011. USNM 399972 (4, 181‒203), MuI NE, 28 JAN. 2010. USNM 399973 (3, 150‒213), MuI NE, 29 JAN. 2010. PHILIPPINES. USNM 102584 (5, 84‒123), ILOILO, PANAY, 6 APR. 1929 . USNM 102634 (1, 144), ILOILO, PANAY, 3 APR. 1929 . USNM 102833 (1, 172), ILOILO, PANAY, 6 APR. 1929 . USNM 122952 (2, 118‒124), ILOILO, PANAY, 6 APR. 1929 . USNM 135277 (1, 67.5), VISAYAS, PANAY, 30 MAR. 1908.

Diagnosis. A SMALL SPEcIES uSuALLY LESS THAN 200 MM TL; EYE LARgE, EYE DIAMETER 20.1‒25.3% HL; DORSAL-fIN ORIgIN uSuALLY bEHIND INSERTION Of PEcTORAL fIN, SOMETIMES juST AbOVE IT; TOTAL VERTEbRAE 116‒121; TOTAL LATERAL-LINE PORES 106‒116; bODY PALE gRAYISH, WITHOuT ANY MARkS ON HEAD AND bODY. MYORHAbDOI PRESENT (INTERMuScuLAR bONES AbOVE THE EPINEuRALS AND bELOW THE EPIPLEuRALS).

Description. BODY MODERATELY SLENDER, ANuS SLIgHTLY bEfORE MIDLENgTH, DORSAL-fIN ORIgIN AbOVE TO WELL bEHIND INSERTION Of PEcTORAL fIN. JAWS SMALL, SNOuT RELATIVELY bLuNT, uPPER jAW PROjEcTINg SLIgHTLY bEYOND TIP Of LOWER jAW, INTERMAxILLARY TEETH PARTLY cONcEALED WHEN MOuTH cLOSED. EYE WELL DEVELOPED, MIDDLE Of EYE OVER RIcTuS.

TEETH SMALL, cONIcAL, MuLTISERIAL; MAxILLARY AND INTERMAxILLARY TEETH cONTINuOuS, THOSE ON INNERMOST ROW Of MAxILLARY bLuNT. SMALL TEETH bETWEEN INTERMAxILLARY AND VOMERINE PATcHES. VOMERINE TEETH SHARP ANTERIORLY, fOLLOWED bY LARgE AND STOuT TEETH, fORMINg A NARROW ELONgATE PATcH ENDINg bEHIND MIDPOINT Of MAxILLARY TOOTH PATcH.

BODY uNIfORMLY DEEP gRAYISH DORSALLY AND MucH PALER VENTRALLY, DORSAL WITH VERY THIN bLAck MARgIN AND VENTRAL fIN uSuALLY cLEAR uNIfORMLY. HEAD AND SNOuT EITHER LIgHT cOLOR OR WITH INDISTINcT bANDS, SNOuT bLAckISH.

Size. A SMALL SPEcIES, THE LARgEST SPEcIMEN ExAMINED IS 213 MM. A 190-MM fEMALE HAS NuMEROuS RIPE EggS, buT THE AcTuAL SIzE AT MATuRITY MIgHT bE SMALLER.

Distribution. KNOWN fROM CHINA, TAIWAN, VIETNAM, AND THE PHILIPPINES. THIS SPEcIES APPEARS TO bE AbuNDANT IN SHALLOW WATERS Of VIETNAM.

Remarks. OuR SPEcIMENS WERE PREVIOuSLY IDENTIfIED AS YOuNg Of OTHER SPEcIES, MOSTLY AS A. dolichopterum . HOWEVER, A. megalops HAS THE DORSAL-fIN ORIgIN OVER OR bEHIND THE INSERTION Of THE PEcTORAL fIN (VS. bEfORE) AND MANY fEWER TOTAL VERTEbRAE AND LATERAL-LINE PORES, AND cAN bE SEPARATED fROM OTHER TAIWANESE SPEcIES EASILY. THE 182-MM SPEcIMEN (ASIZP 61840) HAS bOTH DORSAL AND ANAL fINS LAckINg THE bLAck MARgINS, WHEREAS THE 191-MM SPEcIMEN (ASIZP 61841) HAS THE DORSAL fIN WITH A NARROW bLAck MARgIN AND THE ANAL fIN uNIfORMLY cLEAR. THE bLAck MARgINS ON DORSAL fIN MAY DEVELOP WITH AgE, AND THE ANAL fIN IS ALWAYS cLEAR WITHOuT A bLAck MARgIN.

Ariosoma megalops cLOSELY RESEMbLES Ariosoma scheelei , ANOTHER SMALL SPEcIES WITH A LOW VERTEbRAL cOuNT AND THE DORSAL-fIN ORIgIN OVER OR SLIgHTLY bEHIND THE PEcTORAL-fIN bASE. THEY ARE MOST EASILY DISTINguISHED THE NuMbER AND ARRANgEMENT Of THE POM PORES. Ariosoma megalops HAS 10 PORES: SEVEN IN THE MANDIbuLAR SEcTION, INcLuDINg ONE bEHIND THE RIcTuS, AND THREE IN THE PREOPERcuLAR SEcTION, ALL IN A LONgITuDINAL ROW. Ariosoma scheelei HAS 12 POM PORES: 8 IN THE MANDIbuLAR SEcTION, WITH TWO bEHIND THE RIcTuS, AND fOuR IN THE PREOPERcuLAR SEcTION, THE LAST ONE IN THE AScENDINg bRANcH Of THE cANAL AbOVE THE OTHERS. IN ADDITION, A. megalops HAS MYORHAbDOI, AND A. scheelei DOES NOT, buT THIS cHARAcTER cAN ONLY bE SEEN ON A RADIOgRAPH. THESE TWO SPEcIES ARE LARgELY ALLOPATRIc IN DISTRIbuTION. Ariosoma megalops IS kNOWN ONLY fROM CHINA, VIETNAM, TAIWAN, AND A SMALL AREA IN THE cENTRAL PHILIPPINES. Ariosoma scheelei IS WIDELY DISTRIbuTED IN THE PAcIfIc buT HAS NOT bEEN REcORDED NORTH Of THE PHILIPPINES.

KOTTHAuS (1968) DEScRIbED TWO SMALL SPEcIMENS (86 AND 142 MM) AS “ Ariosoma SPEc (A)” AND “ Ariosoma SPEc. (b)” fROM Off ADEN AND SOMALIA. THEY HAD 110 AND 114 VERTEbRAE, RESPEcTIVELY, cOuNTS THAT MATcH ONLY A. megalops AND A. scheelei AMONg kNOWN SPEcIES. ONE Of THE SPEcIMENS, SPEc (b), HAD 10 POM PORES, WHIcH WOuLD MATcH A. megalops . WITHOuT RE-ExAMININg THE SPEcIMEN, HOWEVER, WE cANNOT cONfIRM ITS IDENTIfIcATION.

Figures

FIGURE 9. UPPEr-jaW TEETH Of Ariosoma SPEcIES. A. A. majus. B. A. meeki. C. A. megalops, NMMB-P12306. D. A. shiroanago, NMMB-P17984. NOT TO ScaLE.

FIGURE 11. Ariosoma megalops FOWLEr, 1938, NMMB-P25292, 187 mm TL.