MYANMAR CATFISH 



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Fig. 1 Diagrammatic representation of tooth patches on jaws and palate of Rita species. A. Rita sacerdotum Anderson, 184 mm, SU 39869. Scale bar 

 = 1 mm.; B. Rita kuturnee (Sykes), 97 mm, SU 34868. 



peninsular India are substantially smaller (36 to 103 mm) than any 

 of the specimens listed from Myanmar (184 to 318 mm). In the 

 Ayeyarwaddy specimens that I examined (22 to 285 mm), the eye 

 length is always 8 to 10 times in the head length. Curiously, despite 

 the observation that the Ayeyarwaddy specimens has small eyes, 

 Jayaram used the eye size of/?, kuturnee to help distinguish it from 

 R. chrysea, a species for which he lists the eye diameter as '3.76 

 (2.83 to 5.22)' in head length. Clearly he did not take into account 

 the Ayeyarwaddy specimens in this diagnosis of R, kuturnee. 



The shape of the palatal tooth patches, a characteristic on which 

 Jayaram placed heavy emphasis, also differs between Rita kuturnee 

 and the Ayeyarwaddy form. The 'pear-shaped' tooth patches that 

 Jayaram (1966, Figure lb) described and illustrated as characteristic 

 of R. kuturnee appear, in fact, to be those of the Ayeyarwaddy river 

 species, and not R. kuturnee. In all of the specimens of R. kuturnee 

 that I examined, the palatal tooth patches are slender, crescent- 

 shaped arches that are either separated at the midline (Figure lb), or 

 meet only for the width of a single row of teeth. The palatal tooth- 

 patches in Rita kuturnee have stout conical teeth, larger in size than 

 those of the premaxilla, rather than the broadly rounded, or molari- 

 form ones that predominate in the palate of the Ayeyarwaddy species 

 (Figure la). As with the size of the eye, it is possible that Jayaram 

 assumed that his specimens of R. kuturnee from peninsular India 

 were juveniles, with incompletely developed palatal tooth patches, 

 and that the adult condition in the peninsular population is like that 

 in the Ayeyarwaddy specimens. Even in the smallest examined 

 specimens from the Ayeyarwaddy basin the palatal tooth patches are 

 broadly in contact across the midline and are composed primarily of 

 molariform teeth. Thus, I conclude that the Ayeyarwaddy form is not 

 conspecific with Rita kuturnee. 



The Ayeyarwaddy River Rita population has never been consid- 



ered conspecific with either of the two other Indian Rita species, R. 

 chrysea Day, 1 877 and R. gogra (Sykes, 1839), and I have found no 

 reason to assign either name to theAyeyarwaddy fishes. Rita chrysea, 

 restricted to the Mahanadi River and nearby tributaries in Orissa and 

 considered to be the smallest species of Rita (Talwar & Jhingran, 

 1991), is characterized by a large eye (2.8 to 5.2 in HL) and by 

 having a broad, nearly rectangular, patch of molariform teeth that 

 extends across the midline of the palate (Jayaram, 1966 ).Rita gogra, 

 which is sometimes listed as Rita pavimentata (Valenciennes, 1840) 

 (e.g., Misra, 1976; Talwar & Jhingran, 1991), is known only from 

 rivers of the Deccan region of peninsular India, including the 

 Krishna, Harda, Godavari, Tungabhadra, Manjra, Bhima, and Mutha- 

 Mula (Jayaram, 1966). Although similar in overall appearance with 

 the Ayeyarwaddy Rita, R. gogra can be distinguished immediately 

 by the unusual shape of its head. The dorsal surface of the head, 

 posterior to the orbits, is dominated by a bilaterally symmetrical 

 swelling formed by massive extensions of the adductor mandibulae 

 muscle that cover the cranial roofing bones. All other species of Rita, 

 including the Ayeyarwaddy species, have the dorsal surface of the 

 cranium covered only with skin, through which the cranial roofing 

 bones can easily be palpated. In addition, theAyeyarwaddy Rita can 

 be distinguished from R. gogra by the color of the mental barbel 

 (black in R. gogra, white in the Ayeyarwaddy species). The palatal 

 tooth-patch in R. gogra has finely conical teeth anteriorly and 

 increasingly large molariform teeth posteriorly (Jayaram, 1966). 



Thus, it must be concluded that the Ayeyarwaddy Rita is not 

 conspecific with any of its Indian congeners. The only remaining 

 name that might apply is Rita sacerdotum, which was described 

 from theAyeyarwaddy. The description and published illustration of 

 that species, however, only vaguely resembles a Rita, and character- 

 istics of the Ayeyarwaddy species are either absent from the 



