206 BULLETIN 188, UNITED STATES NATIONAL MUSEUM 



BALANTIOCHEILOS MELANOPTERUS (Sleeker) 



Barius melanopterus Bleeker, 1851 (26), p. 11 (Bandjermassing, Borneo). 



Balantiocheilus melanopterus Bleeker, 1865 (347), p. 35 (Siam). — Weber and 

 DE Beaufort, 1916, vol. 3, p. 206, fig. 76 (Siam).— Hora, 1923b, p. 159 

 (Nontaburi).— FowLEK, 1934a, p. 127 (Chieiigmai) ; 1937, p. 200, figs. 185, 

 186 (Bangkok, Kemarat). 



BaktJitiochilus melanopterus Bleeker, 1865 (356), p. 176 (Siam). 



Puntius melanopterus Sauvage, 1881, p. 163 (Siam). 



Outside of Thailand this species appears to be known only from 

 Borneo, Sumatra, and Malaya. The species must, however, occur in 

 Indo-China, as it is reported from Kemarat, on the Mekong, where 

 it forms the boundary between Thailand and Cambodia. 



This fish ranges throughout the basin of the Menam Chao Phya, 

 being recorded from Bangkok to Paknampo, the Meping at Chieng- 

 mai, the lower Menam Nan and Bung Borapet, and the Menam Sak 

 below the irrigation barrage at Dlia Luang. Its principal center 

 of abundance is the Paknampo region, where at times it is very 

 numerous. 



While a length of 35 cm. is reported for Borneo and Sumatra, the 

 largest examples met with in Thailand have been about 20 cm. 



B. melanoptetnis may be recognized readily by its peculiar horse- 

 shoe-shaped mouth, with a pocket behind the lower lip, and the jet- 

 black distal parts of the dorsal, caudal, anal, and ventral fins. 



The fish has the ability to leap high out of the water. A sheer 

 jump of 2 meters was once observed in the lower Menam Nan. 



The local vernacular names have reference to its striking colora- 

 tion. Those heard in different parts of Central Thailand are pla 

 hang niai (burnt-tail fish), pla hang yio or iew^ and pla nam lang 

 hung dam. 



Genus SCAPHIODONICHTHYS Vinciguerra 



Scaphiodoniclithys Vinciguerra, Ann. Mus. Civ. Storia Nat, Genova, ser. 2, vol. 9, 

 p. 285, 1889-90. (Type, ScaphiodonicJith^s iurmanicus Yinciguevra..) 



The genus Scaphiodonichthys is very close to the genus Seniiplotus 

 of Burma and India. The principal difference is in the number of 

 branched dorsal rays, which in the present genus range from 9 to 12, 

 while in Sevniplotus the minimum number is 20. In a letter Dr. Sun- 

 der Lai Hora, of the Indian Museum in Calcutta, wrote : 



The nature of the mouth in Semiplotiis and ScapJiiodonichthys suggests their 

 very close affinity. In fact, the latter is distinguished from the former by the 

 possession of fewer rays in the dorsal fin. The Siamese form [8. acanthopterus] 

 with increased number of branched rays [as compared with 8. bunnamcusl 

 sliows that 8emiplotus may have given rise to forms with fewer rays. It is 

 quite possible that there may be some other forms yet to be discovered with a 

 number of branched rays intermediate between 12 and 20. When svich forms are 

 found, Semiplotus and Scaphiodonichthys will have to be regarded as congeneric, 

 with possibly subgeneric rank. 



