NAT. 町ST. B 肌L. SIAM Soc. 54(2): 285-293 ，2006 MAKARARAJA CHINDWINENSIS ，A NEW GENUS AND SPECIES OF FRESHWATER DASYATID PASTINACHINE STINGRAY FROM UPPER MYANMAR Tyson Tyson R. Robert l- ABSTRACT Makararaja Makararaja chindwinensis new genus and species is described from a single mature female female specimen from the Chindwin Ri ver ，Irr awaddy basin ， in northem My 飢 m 釘. De spite 白e round round disc and somewhat slender tail ，i臼 relationships 釘 enot with the whiptailed stingrays of 由巳 subfamily Dぉyatinae ，but wi 白 the flagtailed stingray genus Pastinachus. Makararaja and and Pastinachus (of which Hypolophus is a junior synonym)ωge 出巴 rform the new dasyatid subfamily subfamily Pastinachinae. Key Key words: Dasyatidae ，Makararaja chindwinensis ，Myanm 訂， new genus ，Pas 血 achinae ，stingx 百y 問 TRODUCTION Despite Despite hearsay accounts of 企'eshwater cart i1 aginous fishes or elasmobranchs 泊出e Irr awaddy basin and elsewhere wi 血in Myanmar ， no reliably docum 叩ted spec 泊lens have come to light un ti1 the distinctive stingray that is the subject of 出is article. 百le only preserved preserved spec 加len was obtained in the Chindwin Ri ver during fieldwork by the author 泊 collaboration collaboration with the Myanmar Department of Fisheries in April 2003. Whi1 e clearly related related to the marine and e町 yhal 泊 e dasyatid genus Pastinachus Ruppell 1829 (formerly Hypolophus Hypolophus Muller and Henle ，1837) ， it differs markedly from previously described species and and represents a new genus. Local fishermen report it is 合equently caught 泊 the Chindwin River River between Kampti and Tam 印刷and also for some distance downs 回 am from Taman 血i. Th e holotype of 血e new species is deposited in the Zoological Reference Collection (ZR C)， Raffles Museum for Biodiversity Research ，National University of Singapore. Pastinachinae Pastinachinae new subfamily Pastinachinae 釘 e whiptailed stingrays or Dasyatidae di 百'ering 企om other members of the the fam i1 y in having the upper jaw very strongly 訂 'cuate and with coηespondingly shaped toothplates. toothplates. Lower jaw anteroposteriorly elongate. 百le teeth are pavement-like. Tail thicker ne 紅 base than in Dasyatinae and with sp 加e in 回目ion relatively far posterior. Ventral cutaneous cutaneous ta i1 fold well developed. Two genera ，Pastinachus ， with P. sephen and several unrecognized unrecognized or undescribed species perhaps including P. sankur or P. fluviatilis (Ham i1 ton 1822) 1822) (R OBERTS ， 1998; LAST EI AL. ，2005) ，加 d Ma 初 raraja new genus ， with a single species. 百le new genus di 釘ers markedly from Pastinachus in having a nearly oval disc IResearch Associate IResearch ，Smithsonian Tropical Resear 官h Institute; tysonregalecu S@ yahoo.com 285 286 TYSON R. ROBERTS with with the dorsal surface wi 出 minute dermal denticles versus a “di 叩 lond ・shaped" or 丸紅ongly rhomboidal" disc with the central p紅 t of its dorsal surface with relatively large dermal dermal denticles. τ'h e widely used stingray genus name Hypolophus Muller & Henle 1837 (wi 血 generic type type species R 可a sephen Forsskal 1775) is now recognized as a junior synonym of Pastinachus Pastinachus Ruppell 1829 (w 抽出e same generic type species) (PAXTON ET AL. ， 1989: 43; LAST & COMPAGNO ， 1999: 1482; and ROSENBERGER ， 2001: 615). All of the species 訂 e superficially superficially rather sirnilar ， with a thick ， diamond-shaped or rhomboidal disc; heavy dermal denticulation denticulation in middle of 白e upper surface of the disc; a thick-based tail ， with well developed developed ventral cutaneous membrane; and a sting located relatively far pos 旬riorly on 白e tail tail (Figs. 1-2). Pastinachinae Pastinachinae may be referred to by the common name “flag-tailed stingrays" in reference reference to the conspicuous ven 回 1 cutaneous tail membrane (山 o after the 百聞name for P. P. sephen: pla gaben tong). Note on Raja fluviatilis (Fig. 2) ー-S ometimes placed in Hi mantura ，Raja fluviatilis Hamilton Hamilton 1822 (type locality Ganges) belongs in Pastinachus. If the n釘 ne is available (see ROBERTS ， 1998) it is either ajunior synonym of P. sephen or a valid sp 配 ies of Pastinachus. Raja Raja sankur Har 凶lton 1822 is 白e next available junior synonym of R. fluviatilis (op cit ふ Makararaja new genus Type species.-Makararaja chindwinensis new species Formerly Formerly all of 出e species of Pastinachinae could be assigned to a single genus ， Hypolophus or Pastinachus (F igs. 1-2). 官 le new genus described here differs 企om all other other dasyatid genera 担 having a nearly round disc with the dorsal surface with pe 紅 I organs organs and other dermal denticles so minute 白紙 it seems to lack them. It also differs 加 tail tail mo 甲hology. Fl oor of mouth with four pap i1l ae: two 泊 the middle and one to each side (versus (versus five in Pastinachus ， with three 也 the middle of 出emou 血). In other past 泊achines the the tail is exceptionally stout proxin 凶 ly ， and the sting insertion is located ti 紅白 er posteriorly. τ'h e tail has a well-developed v印刷1 cutaneous membrane but its depth is much less 白m in in Pastinachus. 官le s由19 泊se 凶on is relatively far posterior comp 釘 'ed to non-pas 血 achines ， but but not so far posterior as in Pastinachus. Th e base of the tail is more slender 由加担 Pastinachus Pastinachus but not so slender as in Himantura and other dasyat 泊 genera. Pectoral Pectoral fm pterygiophores 105-1 07? versus 111-126 泊 Pastinachus (Peter Last ，pers. comm. 11 Jan 2005). In the shape of 由e jaws and toothplates Makararaja is basically s加担紅白 Pastinachus. Makararaja chindwinensis new species Figures Figures 3-8 Holotype. ー ZRC 50566 ， 385 mm disc width ， mature female ，Chindwin River about 20 km downstream 仕om Kh amti ， 19 April2003 ，Tyson R. Roberts (血 e new species is well known to fishermen 加出 e stretch of the Chindwin River between Kh amti and Taman 也i. According According to 出e fisherman who caught it 出e holotype is full grown. From the remarks of several several fishermen the species does not get much larger). MAKARARA .l A C /-I IN DW INENS IS，A NEW GENUS AN D SPEC IES OF ST INGRA Y 287 Fi gllr e 1. Pa :、lilla c! III S cr se ph ell (from D AY ，1 875) Figllr e 2. R旬。 Jl lllliali /i s H amilt on 1822 . Thi s nom in al sp巴cles IS 1巴I" erabl e to Pa slina clllls. It is eith 巴ra Jun l or sy nonym of P ‘l" eph c lI or a va lid spec i es (fro l11 R O tlERT S. 1998) . Not e d iffere n ces in c1 i sc shap e ancl ve ntral tail -folcl co mp 山 ecl to P. cf seph ell in F ig. 1 288 288 TY SON R. Ro日ERT S Fig llr e 3. Makararaja chilldwill ell sis. H ololype，Z R C 50566. 385 111111 fe l11 ale Figure Figure 4 . Pea rl spin es and d巴nli cl巴S near ce nl er of dor sal slI rf ace of di sc. a-b ，P 乱、 tilla c! III S cI seph ell ，Z R C 50645 ，3 15 111m ma le; c-d Makararaja chilld ll' ellsis ，Z R C 50566 ，50 566 ，385 111111 f巴，l11 al e.(a and c al sa l11 e sca le，b= 53% 0 1" d) MAKARAR A .l A C HI N DW INENS IS，A N EW GENUS AND SPEC IES OF ST INGRA Y 28 9 a FigUl 巴 5. Maka rar aja chindwin ellS is. Jaw t巴巴 th .a，u pper j aw; b，lowe rj aw Fig ur e 6. Makararaja chilldw ill ell sis . Rad iograp h of jaw sw it h m out h s hut 290 T YSON R. R OBERTS Figure 7. Makararaja chindwinensis. Porr ion of ta il with stings. a, lateral vie w; b, dorsal view. Fi gure 8. Makararaja chindwinensis. Spiral va lve. MA ιほ A丸4J AC Hl NDWINENSIS ，A NEW GENUS AND SPECmS OF ST 町 GRAY 291 Comparative material of Pastinachus.-Pastinachus cf sephen ，ZRC 50645 ， 3: 297-315 mm ，Singapore ， Jurong Fish Port ， K. L Iij1 and M. Manj 吋i，Feb 1997. Diagnosis.-A small species of freshwater dasyatid. Maximum disc size reportedly about about 500 mm and maximum weight 3-4 kg. Disc with slightly 住iangul 訂 shape ， but mo 詑 nearly nearly round than in any known species of Southeast Asian freshwater dasyatid species (Fig. (Fig. 3) ， and very distinct 企'O m the tri 個別l訂 or diamond-shaped disc of Pastinachus (Figs. 1-2). 1-2). Pearl buttons and other dermal denticles of dorsal disc surface minute ，f; 紅 smaller than than those of Pastinachus (Fig. 4). Pectoral fm radial pterygiophores (propterygial + mesopterygial mesopterygial + metapterygial=total) 51 + 8 + 46 -4 8? = 105-10 7? Pelvic fm pterygiophores 2ι27. Discrete vertebral centra about 130. Tail with a long but relatively low-ly 同 ventral fin fin fold (F ig. 7). Sting very slender ，stiletto-like ， with very 血le point (Fig. 7). Sting with 59 barbs on left side ，70 on right side. Spiral valve tums 16- 17 (Fig. 8) (versus 20 泊 some Pastinachus). Pastinachus). Morphometric characters.-See Table 1. Table Table 1. Ma 初 raja chindwinensis measurements of holotype in mm/% of disc width Di sc width 385 mm Disc Disc length 2 390 /1 0 Maximum width across pelvic fins 199/5 1. 6 Extemal Extemal width betw 田 n pelvic f泊 origins 99/25.7 Le ast 泊t釘 spiracular width 68.5/17.8 Extemal Extemal eye bulge 25.0/6 .4 Snout Snout leng 出3 78/20.3 Spiracle Spiracle leng 出 29.5n.7 M 蹴加um intemarial width 48/12 .4 Wid 血 of mouth opening at lower jaw 37ρ.6 Width of first gill slit 12.5β2 Wid 白 of fi 加 1 gill slit 8/2 .1 Least Least distances between successive gill slits: First First and second 84/2 1.