FRESH-WATER FUGU OR PUFFERFISHES OF THE GENUS TETRAODON FROM THE MEKONG BASIN, WITH DESCRIPTIONS OF 2 NEW SPECIES

The fresh waters of the Mekong basin are inhabited by five species of the pufferfish genus Tetraodon Linnaeus, 1758 (sensu late): the widely distributed T. leiurus Bleeker, 1851; two previously described specie s endemic to the Mekong, T. baileyi Sontirat, 1989 and T suvattii Sont irat & Soonthornsathit, 1985; one new species endemic to the Mekong, T . barbatus; and another new species, T. abei, also found in the Chao P hraya and Meklong basins. Tetraodon baileyi has now been collected num erous times but only in or near rapids; T. abei, T. barbatus and T. su vattii are often but not exclusively associated with rapids or at leas t swift flowing streams; while T. leiurus is found in almost all habit ats except rapids. Tetraodon abei and T. barbatus are closely related to T. leiurus, from which they differ most strikingly in coloration. T etraodon suvattii differs from all of the others in having a strongly upturned mouth and light and dark stripes or spots radiating outwards from the eye. Tetraodon baileyi, the most distinctive Mekong pufferfis h, has head and body more or less extensively covered with dermal cirr i and is entirely scaleless.