Dysomma taiwanense Ho, Smith &Tighe, 2015

Ho, Hsuan-Ching & Tighe, Kenneth A., 2018, Three new species of the cutthroat eel genus Dysomma, with comments on the variation of D. taiwanense (Anguilliformes: Synaphobranchidae), Zootaxa 4454 (1) : -

Dysomma taiwanense Ho, Smith &Tighe, 2015

FIg. 8 ; TablEs 1‒2

Dysomma taiwanensis Ho, Smith & Tighe, 2015:87 , figs. 1‒2 (type locality: Daxi, Yilan, northeast Taiwan, depth ca. 200-400 meters).

Specimen examined. TypE sErIEs. LIstEd In Ho et al. (2015).

Additional specimens. 52 spEcImEns, 136‒474 mm TL. Dong-gang , Pingtung, SW Taiwan. NMMB-P3845 (2, 203‒279), 21 Mar. 1979 . NMMB-P16453 (1, 136), 2 FEb. 2012. NMMB-P21720 (1, 194), 25 Oct. 2011. NMMB-P23482 (1, 210), 11 Jun. 2013. NMMB-P24383 (12, 149‒354), 22 Jul. 2016. NMMB-P24392 (2, 315‒322), 24 Aug. 2014. NMMB-P24733 (1, 209), 11 Oct. 2016. NMMB-P25965 (1, 419), 29 Mar. 2017. NMMB- P26037 (3, 288‒324), 15 Apr. 2017. NMMB-P26160 (1, 280), 30 Mar. 2017. NMMB-P26161 (1, 362), 30 Mar. 2017. NMMB-P26220 (1, 385), 23 Jun. 2017. NMMB-P26399 (1, 304), 12 Jul. 2017. NMMB-P26448 (2, 333‒358), 23 Jun. 2017. NMMB-P26472 (1, 378), 19 Jul. 2017. NMMB-P26475 (1, 320), 19 Jul. 2017. NMMB- P26689 (8, 244‒355), 10 Jul. 2017. NMMB-P26693 (2, 228‒335), 29 Mar. 2017. NMMB-P26696 (1, 395), 16 Jun. 2017. NMMB-P26697 (1, 256), 16 Jun. 2017. NMMB-P26699 (3, 215‒262), 9 Aug. 2017. NMMB-P26701 (1, 334), 10 Jun. 2017. Daxi , Yilan, NE Taiwan. NMMB-P1754 (1, 474), 9 SEp. 2003 . NMMB-P26400 (1, 361), 1 Jul. 2017. Nan-fang-ao, Yilan, NE Taiwan. NMMB-P16288 (1, 205), 16 Mar. 2012 . NMMB-P16383 (1, 158), 14 Mar. 2012.

Diagnosis. PEctoral fIn prEsEnt. Dorsal-fIn orIgIn slIghtly In front of lEvEl of pEctoral-fIn basE; anus wEll bEhInd tIp of pEctoral fIn; trunk vEry short; two IntErmaxIllary tEEth; 4 compound tEEth on vomEr; sInglE row of 5‒11 small compound tEEth followEd by 0‒8 small tEEth on lowEr jaw; hEad porEs: IO 4, SO 3, M 6, POP 0, AD 1, F 0, ST 0; latEral-lInE porEs: prEdorsal 3‒5, prEpEctoral 3‒7, prEanal 7‒12, total 29‒49, thE last at about half of total lEngth. VErtEbraE: prEdorsal 7‒10, prEanal 12‒17, total 134‒140; MVF 9-14-137. Body unIformly brownIsh, lowEr part of postErIor onE-EIghth of body darkEr, wIth black basE and margIn on rEar part of anal fIn and lowEr part of caudal fIn.

Remarks. Ho et al. (2015) dEscrIbEd D. taiwanense (as Dysomma taiwanensis ) basEd on four spEcImEns, two collEctEd from northwEstErn TaIwan and two collEctEd from southwEstErn TaIwan. ThEy statEd that two smallEr spEcImEns (E.g. two paratypEs from southwEstErn TaIwan) havE 1‒3 smallEr EmbEddEd tEEth on thE lowEr jaw whErEas thE two largEr spEcImEns (holotypE and onE paratypE collEctEd from northEastErn TaIwan) havE only 7 largE compound tEEth.

ThE spEcImEns ExamInEd In thE prEsEnt study show that all spEcImEns havE 5‒10 largE wIdEly spacEd compound tEEth followEd by 0‒8 small tEEth whIch arE dEnsE In arrangEmEnt. ThE total lowEr-jaw tEEth arE 6‒15. AftEr ExamInIng many spEcImEns, thE rangE of mErIstIcs Is ExpandEd slIghtly, thus thE abovE dIagnosIs Is modIfIEd accordIngly.

Dysomma taiwanense Is most sImIlar to D. formosa dEscrIbEd abovE In havIng thE tIp of thE pEctoral fIn usually In front of thE anus and a sInglE row of compound and small tEEth on thE lowEr jaw, although thE lattEr charactEr Is varIablE In thEsE two spEcIEs. ThE numbEr of compound tEEth and total tEEth arE clEarly fEwEr In D. taiwanense than In D. formosa , and thE total vErtEbraE arE clEarly morE In D. taiwanense than In D. formosa wIthout ovErlap ( TablE 2).

Figures

FIGURE 8. Dysomma taiwanense Ho, Tighe & Smith, 2015. A. NMMB-P25965, 419 mm TL. B. NMMB-P26161, 362 mm TL. C. Same as B, lateral view of head. Arrows indicate origin of dorsal fin (above) and anus (below).