Macrocephenchelys nigriventris, Lin & Shao & Smith, 2018

Lin, James, Shao, Kwang-Tsao & Smith, David G., 2018, The eel genus Macrocephenchelys (Anguilliformes: Congridae) in Taiwan, with description of a new species, Zootaxa 4454 (1), pp. 186-199 : 194-197

publication ID	https://doi.org/ 10.11646/zootaxa.4454.1.15
publication LSID	lsid:zoobank.org:pub:B5405D56-2A3B-4037-9A11-F7F61BF434BD
DOI	https://doi.org/10.5281/zenodo.6490257
persistent identifier	https://treatment.plazi.org/id/03CEB104-FF8E-FFED-5FAF-27CA29C34990
treatment provided by	Plazi
scientific name	Macrocephenchelys nigriventris
status	sp. nov.

Treatment

Macrocephenchelys nigriventris new species

FIg. 3C View FIGURE 3 , 5 View FIGURE 5 , 6 View FIGURE 6 , 7 View FIGURE 7 , TABLe 1

Holotype: TOU-AE 6893, 221 MM TL, MATURe feMALe, WITH MATURe egg SIze 1 MM, NAN-fANg-AO, YILAN, NORTHeASTeRN TAIWAN, AT A DePTH Of APPROxIMATeLY 200 MeTeRS, 19 JUL. 2012.

Paratypes (27 SPeCIMeNS, 153–241). Pingtung, southwestern Taiwan: ASIZP 80331 View Materials (1, 189), DA-PONg BAY, 5 MAR. 2003 . NMMB-P 7094 (1, 233), HSIAO-LIU-CHIOU, 180 M, 26 DeC. 2003. NMMB-P 7137 (1, 223), 26 DeC. 2003; NMMB-P 20976 (1, 205), 12 MAR. 2014; NMMB-P 21162 (1, 188), 2 APR. 2014; NMMB 23961 (1, 220). 17 FeB. 2016; NMMB 24395 (1, 192), 24 AUg. 2016; NMMB 24396 (1, 198), 24 AUg. 2016; NMMB 24397 (1, 226), 24 AUg. 2016; NMMB 24741 (1, 180), 11 OCT. 2016; NMMB 24785 (1, 223), 7 APR. 2016; TOU-AE 6846 (1, 202, MATURe feMALe,), 4 FeB. 2013; USNM 402449 (2, 193–200), NOV. 2009; USNM 437355 (3, 153–220), 28 SeP. 2013; USNM 437356 (1, 223), 2 OCT. 2015; USNM 437357 (4, 210–241), 6 NOV. 2016; USNM 438232 (1, 168), 2009; ALL COLLeCTeD fROM Off DONg-gANg fISHINg PORT.

Yilan, northeastern Taiwan: TOU-AE 6754 (1, MATURe feMALe, 216 MM), DA-xI , YILAN, NE TAIWAN, 16 OCT. 2012 ; TOU-AE 7228 (1, 212); USNM 268811 View Materials (1, 207), DA-XI, TAIWAN, 30 SeP. 1969 ; ALL COLLeCTeD fROM Off DAxI fISHINg PORT. TOU-AE 6894 (1, MATURe feMALe, 180 MM), NAN-fANg-AO, 19 JUL. 2012 .

Diagnosis. Macrocephenchelys nigriventris ReSeMBLeS M. brevirostris AND M. soela IN ITS MORe ROBUST BODY AND THe PReSeNCe Of fLeSHY PAPILLAe ON THe HeAD AND SeNSORY PITS ON THe VeNTRAL SURfACe Of HeAD AND BODY. IT DIffeRS fROM BOTH IN HAVINg A CONSPICUOUS PATCH Of MeLANOPHOReS AROUND THe ANUS. IT fURTHeR DIffeRS fROM M. brevirostris IN A LeSSeR PReANAL LeNgTH (24.4–28.0 %TL VS. 27.1–33.5), feWeR PRe-ANAL LATeRAL-LINe POReS (19–24 VS. 25–32), 2 MANDIBULAR POReS (VS. 3), AND feWeR VeRTeBRAe (125–135 VS. 147–154). IT DIffeRS fROM M. soela IN THe MORe POSTeRIOR DORSAL-fIN ORIgIN (OVeR TIP Of PeCTORAL fIN VS. MIDDLe Of PeCTORAL fIN) AND THe NUMBeR Of VeRTeBRAe (125–135 VS. 151). IT IS THe SMALLeST Of THe KNOWN SPeCIeS; THe LARgeST SPeCIMeN IS 241 MM TL VS. 703 IN M. brachialis , 460 IN M. brevirostris , AND 300 IN M. soela ; MATURe feMALeS WeRe fOUND AS SMALL AS 180 MM.

Description. MeASUReMeNTS IN PeRCeNT %TL: PAL 24.4–28.0, TAIL 75.0–75.6, TR 12.5–15.7, PDL 16.7–19.8, HL 10.4–12.7, DGO 4.4–6.0, DA 3.4–5.6. IN %PAL: TR 49.2–57.8, PDL 64.6–77.8, HL 42.2–50.8. IN % HL: S 18.3 –27.4, E 8.3 –14.9, IOW 10–18.7, UJ 18.6–25.5, LJ 17.1–22.5, GO 7.7–14.8, IB 19.7–38.7, PL 38.3–53.3. POReS: PALL 19–24, PDLL 13–14, PGLL 5–6. SO 3, IO 4+1+0, POM 5 (2 + 3), ST 0 (ONe PARATYPe, TOU-AE 6754, HAS 1 PORe NeAR fIRST LATeRAL-LINe ON THe LefT SIDe Of ST CANAL). FIN RAYS: PADR 19–26, PR 12–13. VeRTeBRAe: PDV 12–16, PAV 22–25, PCV 31–36, TV 125–135.

BODY MODeRATe, CYLINDRICAL ANTeRIORLY, LATeRALLY COMPReSSeD POSTeRIORLY, TAIL SLeNDeR BUT NOT gReATLY ATTeNUATe. ANUS LOCATeD ANTeRIORLY, BefORe MID-BODY, PReANAL DISTANCe ABOUT ONe fOURTH TL. PeCTORAL fIN WeLL DeVeLOPeD, SLeNDeR, THe eND Of PeCTORAL fIN ReACHINg LeVeL Of DORSAL-fIN ORIgIN. DORSAL fIN CONfLUeNT WITH ANAL fIN AND CAUDAL fIN; ORIgIN Of DORSAL fIN BeHIND gILL-OPeNINg, AT MID-LeNgTH Of TRUNK AND ABOVe TIP Of PeCTORAL fIN; fIN HeIgHT ABOUT ONe fOURTH BODY DePTH. CAUDAL fIN MODeRATeLY DeVeLOPeD. GILL OPeNINg LATeRAL, UPPeR eDge CLOSe TO LATeRAL-LINe.

HeAD SHORT, BULBOUS. SNOUT BLUNT, SWOLLeN, LeNgTH gReATeR THAN eYe DIAMeTeR (E 52.9–66.1 % Of S), TIP SOfT AND fLeSHY. UPPeR jAW LONgeR THAN LOWeR jAW. SMALL fLeSHY PAPILLAe ON UNDeRSIDe Of SNOUT, BeHIND ANTeRIOR NOSTRIL ALONg UPPeR jAW, ON CHeeK BeLOW eYe LeVeL, SURfACe Of CHIN, AND BeYOND eYe ALMOST TO LeVeL Of gILL OPeNINg. EYe MODeRATe IN SIze, ROUND. RICTUS ReACHINg TO OR SLIgHTLY BeHIND LeVeL Of ANTeRIOR MARgIN Of eYe. ANTeRIOR NOSTRIL TUBULAR, jUST BeHIND TIP Of SNOUT, OPeNINg ANTeROLATeRALLY; POSTeRIOR NOSTRIL eLLIPTICAL, LOCATeD BefORe ANTeRIOR MARgIN Of eYe SLIgHTLY ABOVe MID-eYe LeVeL.

MAxILLARY AND DeNTARY TeeTH SMALL, CONICAL, MULTISeRIAL, ROWS WIDeR AT ANTeRIOR eND; INTeRMAxILLARY TeeTH CONICAL, SOMeWHAT LARgeR THAN MAxILLARY AND DeNTARY TeeTH, IN ABOUT 2 TRANSVeRSe ROWS; VOMeRINe TeeTH IN A SHORT OVAL PATCH, SMALL AND CONICAL AT ANTeRIOR eND, BLUNTeR IN MIDDLe AND POSTeRIOR PART, exTeNDINg LeSS THAN HALfWAY TO eND Of MAxILLARY TOOTH ROW ( FIg. 7 View FIGURE 7 ).

CePHALIC SeNSORY POReS SMALL, INCONSPICUOUS. THRee SO POReS: fIRST ON UNDeRSIDe Of SNOUT TIP, SeCOND DIReCTLY ABOVe, THIRD ABOVe AND BeHIND SeCOND AT LeVeL Of ANTeRIOR NOSTRIL. ST PORe ABSeNT exCePT ONe PARATYPe, TOU-AE 6754, WHICH HAS A SINgLe PORe ON LefT SIDe Of CANAL, NeAR LATeRAL LINe. IO CANAL WITH fIVe POReS: fIRST PORe ADjACeNT TO BASe Of ANTeRIOR NOSTRIL; SeCOND AND THIRD POReS ReLATIVeLY CLOSe TOgeTHeR ON LOBe-LIKe PART Of UPPeR LIP; fOURTH PORe AT POSTeRIOR eND Of UPPeR LIP; fIfTH PORe BeHIND RICTUS, BeLOW MIDDLe Of eYe; NO POReS BeHIND eYe. FIVe POM POReS, TWO ON MANDIBULAR SeCTION AND THRee ON PReOPeRCULAR; fIRST AND SeCOND POReS ON fRINge Of LOWeR LIP AT ANTeRIOR eND Of LOWeR jAW; THIRD, fOURTH AND fIfTH POReS TUBULAR, eVeNLY DISTRIBUTeD BeHIND POSTeRIOR eDge Of eYe TO MID-WAY BeTWeeN eYe AND gILL-OPeNINg, THe fIfTH PORe BeLOW LeVeL Of fIRST LATeRAL-LINe PORe. MANY SMALL, ROUND PIT-LIKe STRUCTUReS ON VeNTRAL PART Of THROAT AND ABDOMeN TO LeVeL Of ANUS; SeT IN 8 ROWS fROM VeNTRAL VIeW, 4 ROWS ON eACH SIDe; ABOUT 20 POReS BefORe gILL-OPeNINg AND APPROxIMATeLY 70 POReS TO ANUS IN THe INNeRMOST ROW.

FReSH SPeCIMeNS DARK ABOVe AND MOSTLY PALe BeLOW WITH SILVeR SKIN ( FIgS. 5 View FIGURE 5 , 6 View FIGURE 6 ). DORSAL PART Of HeAD, BODY AND TAIL DeNSeLY COVeReD WITH ReLATIVeLY LARge MeLANOPHOReS; POSTeRIORLY ON TAIL THe MeLANOPHOReS DeSCeND TO VeNTRAL MARgIN, COVeRINg eNTIRe TAIL. ANUS SURROUNDeD BY INTeNSe BLACK PIgMeNT; A DeNSe PATCH Of MeLANOPHOReS ON POSTeRIOR HALf Of ABDOMeN IN fRONT Of ANUS, exTeNDINg ABOUT AN eqUAL DISTANCe BeHIND ANUS ON eACH SIDe Of ANAL fIN. HeAD AND TAIL WITH A HINT Of PURPLe COLOR. ORAL AND gILL CAVITY BLACK. VeRTICAL fINS TRANSPAReNT ANTeRIORLY, AND BLACK POSTeRIORLY TO CAUDAL fIN, WITH A WHITe MARgIN.

Etymology. FROM THe LATIN, nigri -, BLACK, DARK, AND - ventris, UNDeR SIDe, BeLLY, RefeRRINg TO THe CONSPICUOUS BLACK PIgMeNT ON THe POSTeRIOR ABDOMeN AND ANUS.

Distribution. TWeNTY eIgHT SPeCIMeNS KNOWN fROM NORTHeASTeRN AND SOUTHWeSTeRN TAIWAN. FOUR SPeCIMeNS ARe ADULT feMALeS WITH MATURe OVARY AND eggS AT SMALL BODY SIze (180–221 MM).

Remarks. ONe SPeCIMeN fROM USNM 402449 HAD A MORe POSTeRIOR DORSAL-fIN ORIgIN THAN ANY Of THe OTHeR SPeCIMeNS: PReDORSAL LeNgTH 23.1 % TL AND 84.2% PAL AND 20 PReDORSAL VeRTeBRAe. THe HIgHeST VALUe fOR THeSe CHARACTeRS IN THe OTHeR SPeCIMeNS WeRe 19.0, 77.8, AND 16 ReSPeCTIVeLY. NO OTHeR DIffeReNCeS WeRe APPAReNT, AND THe POSTeRIOR DORSAL-fIN ORIgIN SeeMS TO Be AN ANOMALY.

DNA Analysis. PARTIAL COI SeqUeNCeS WeRe OBTAINeD fOR THe MITOCHONDRIAL geNeS. THe NeIgHBOR-jOININg PHeNeTIC TRee ( FIg. 8 View FIGURE 8 ) WAS geNeRATeD BY THe MEGA 5, BASeD ON A KIMURA 2-PARAMeTeR (K2P) MODeL IN 10,000 BOOTSTRAPS. THe TRee SHOWS THAT M. brachialis , M. brevirostris , AND M. nigriventris BeLONg TO THRee SePARATe CLADeS. WITHIN THe PHeNeTIC TRee, THe MeAN PAIRWISe DISTANCe IS 7.1 % (SE=0.007; MINIMUM DISTANCe Of 0.00, AND MAxIMUM DISTANCe Of 14.4 %, N=13).

THe M. brachialis CLADe DIffeRS fROM THe M. brevirostris CLADe BY 14.1 % ON AVeRAge (SE=0.016; MINIMUM DISTANCe Of 13.7 % AND MAxIMUM DISTANCe Of 14.3 %). THe M. brevirostris CLADe DIffeRS fROM THe M. nigriventris CLADe BY 10.1 % ON AVeRAge (SE=0.014; MINIMUM DISTANCe Of 9.6 % AND MAxIMUM DISTANCe Of 10.6 %). THe M. brachialis AND M. nigriventris CLADeS DIffeR BY 13.9 % ON AVeRAge (SE=0.017; MINIMUM DISTANCe Of 13.7 % AND MAxIMUM DISTANCe Of 14.4 %).