22 



D.J. SIEBERT 



Fig. 13 Holotype of Sundasalanx mesops, female, MZB 6098, 20.7 mm 

 SL. 



Fig. 14 Holotype of Sundasalanx megalops, MZB 6100, male, 25.5 mm 

 SL. The melanophore cap of the prootic bulla is clearly visible, the 

 myotomal pigment line is clearly interrupted above the pelvic fins, 

 melanophores associated with anal fin pterygiophores are clearly 

 visible, and the vivid swatch of melanophores on the lower caudal fin 

 lobe characteristic of males is clearly evident. The wavy striations of the 

 posterior half of the intestine are discernible posterior to the pelvic fins. 



Fig. 15 Holotype of Sundasalanx platyrhynchus , MZB 5944, 19.2 mm 

 SL. 



congeners and S. platyrhynchus by size of eye, snout length, and 

 colour pattern. Other Barito River Sundasalanx have discernibly 

 larger eyes (Figs 1 1-15; Table 1), have a snout:eye ratio < 1, lack a 

 ring of melanophores around the basipterygium in maturing males, 



Fig. 16 Dorsal view of the head of Sundasalanx platyrhynchus. 



and possess melanophores on the posterior wall of the cardiac 

 compartment in males. Table 4 summarises diagnostic features of all 

 described species of Sundasalanx. 



Sexual dimorphism. Sundasalanx malleti is sexually dimorphic 

 for colour pattern. Unbleached cleared-and-stained materials that 

 are identifiable as male or as female show a difference between sexes 

 in pigmentation of the basipterygium and lower caudal-fin lobe. 

 Males have a more intense mark on the lower caudal-fin lobe, the 

 result of a greater density of melanophores that make up the lower 

 caudal lobe swath. Males with maturing or mature testes also 

 possess additional pigmentation around the basipterygium that was 

 not observed in any female. Minimally, females, males, and juve- 

 niles possess a single melanophore just anterior to the pelvic-fin 

 origin. The basipterygium of males is marked by additional 

 melanophores along its side and across its posterior edge between 

 the pelvic-fin bases so that it is completely encircled with 

 melanophores. 



ECOLOGY. Sundasalanx malleti was captured in turbid flowing 

 waters over silty, clayey substrates along banks adjacent to main- 

 stream currents and at depths up to 1 m. Children with fly-screen 

 scoop nets, working bankside shallows before dusk for small fishes 

 for the evening meal, captured them in great abundance. The same 

 shallows worked during daylight usually yielded no or few 

 Sundasalanx. Thus 5. malleti probably inhabits deeper waters dur- 

 ing daylight hours, moving to shallower areas at dusk, possibly to 

 escape predation. Fishes captured in the same habitat withS. malleti 

 were many species of small and juvenile cyprinids and catfishes, 

 Nemacheilus sp., Homaloptera sp., and chandids. 



Remains of insects and crustaceans are observable in guts of 

 cleared and stained specimens. 



Etymology. This species is named after John Valentine Granville 

 Mallet, former Prime Warden of the Worshipful Company of Fish- 

 mongers, whose enthusiasm, encouragement, and support have 

 made possible the continuation of a research programme on fresh- 

 water fishes of Southeast Asia. 



