

SCHISMATORHYNCHOS REVISION 
of dorsal fin falciform, first few anterior principal rays long. Caudal 
fin forked. 
Lateral line nearly straight, with 33 scales to end of hypural plate; 
5 Yascales above lateral line to dorsal origin; 4/2 scales below lateral 
line. Vertebrae usually 33 (2 of 35 individuals with 32), usually with 
17 precaudal vertebrae and 16 caudal vertebrae. Number of pairs of 
pleural ribs usually 13. 
Colour in alcohol dark above, lighter below (Fig. 7). Scale 
pockets of scale rows to at least 2 scales rows below lateral line with 
a distinct, dark crescent. A dark lateral stripe evident, terminating in 
a distinctly triangular precaudal spot. In larger individuals stripe 
consists of coloration centred over 3 scale rows; stripe on lateral line 
scale row begins below posterior end of dorsal fin, on Ist scale row 
above lateral line stripe beings at dorsal origin and ends at precaudal 
spot, on 2nd scale row above lateral line stripe begins midway 
between occiput and dorsal origin and ends midway along peduncle; 
in small individuals stripe evident on lateral line scale row only. 
Small individuals with a prominent mark on side at 5th or 6th scale 
along lateral line (Fig. 1b), usually a scale above and below lateral 
line darkened along with | or 2 scales on lateral line. Dorsal and 
caudal fins dusky, interradial membranes heavily marked with 
melanophores. Interradial membranes of pectoral and pelvic fins 
lightly marked with melanophores. 
ETYMOLOGY. The species name endecarhapis is formed from the 
Greek words endeka (eleven) and rhapis (rod), referring to the 
modal number (11) of branched rays in dorsal fin. It is proposed as 
a noun in apposition. 
DISTRIBUTION. Schismatorhynchos endecarhapis is known from 
the Barito River above Muara Teweh and from Sungai Pinoh of the 
Kapuas River system (Fig. 5). Whether or not the species occurs in 
the lower reaches of these watersheds where streams are larger is not 
yet known. In the Barito small individuals were seined at creek 
mouths and on sand bars along the mainstream. 
REMARKS. The largest individual was taken by hook and line, 
baited with beetle larvae, below floating houses at Desa Maruwei, 
indicating that the species is an opportunistic feeder even though the 
length of its intestine would indicate it is predominately a herbivore. 
Intrageneric comparisons 
Species of Schismatorhynchos are easily distinguished from one 
another and gross differences are employed in the key to species. 
The meristic information of Table 3 is summarised graphically in 
Figure 8. Axis 1, which can be interpreted as an axis of dorsal fin 
branched ray and caudal vertebrae counts, provides a dimension 
along which S. endecarhapis is clearly separable from S. hetero- 
rhynchos and S. holorhynchos. Axis 2, interpreted as an axis of 
overall vertebral pattern and rib count, separates S. hetero- 
rhynchos and S. holorhynchos. Figure 9 summarises the morpho- 
metric information of Table 1. Complete separation of the three 
species is achieved in the two dimensions of Axis | and Axis 2. 
Axis | is interpreted as a head length/dorsal-fin base length axis. 
Axis 2 is a contrast of dorsal-fin base length and caudal peduncle 
depth. 
TUBERCULATION PATTERNS. Species specific tubercle distribution 
patterns in Schismatorhynchos are evident at small size. The regions 
of the snout which will eventually contain large tubercles are 
apparent at sizes smaller than 30 mm SL in S. endecarhapis. and 
S. holorhynchos, well before the tubercles undergo obvious enlarge- 
ment. 
107 
-14 -9 1 6 
-4 
AXIS 1 
Fig. 8 Graphical joint summary of the meristic information for species of 
Schismatorhynchos with 0.95 confidence ellipses of samples 
(S. heterorhynchos = ; S. holorhynchos = @; S. endecarhapis = A). 
Standardised discriminant function for: Axis | = 0.03 x anal fin position 
+ 0.26 x peduncular vertebrae count — 1.68 x caudal vertebrae count — 
1.49 x precaudal vertebrae count — 0.09 x rib count — 0.04 dorsal fin 
position — 0.75 x number of branched rays in dorsal fin; Axis 2 = 0.01 x 
anal fin position + 1.32 x caudal vertebrae count + 0.05 x peduncular 
vertebrae count + 1.23 x precaudal vertebrae count — 0.57 x rib count — 
0.03 x dorsal fin position — 0.49 x number of branched rays in dorsal 
fin; Wilk’s lambda = 0.001, df 7,2,173, p < 0.0001. 
5. 
2.4 
AXIS 2 

“8.050 
-2.8 
AXIS 1 
-5.4 -0.2 2.4 5.0 
Fig.9 Graphical joint summary of the selected morphometrics of species 
of Schismatorhynchos with 0.75 confidence ellipses of samples 
(S. heterorhynchos = @; S. holorhynchos = @; S. endecarhapis = A). 
Standardised discriminant function for: Axis 1 = 2.39 x body depth + 2.01 
x dorsal base + 1.55 x predorsal length — 1.21 caudal peduncle depth — 
0.49 x eye length — 3.77 x head length — 0.88 x snout length; Axis 2 = 0.98 
x body depth + 4.90 x caudal peduncle depth + 0.85 x eye length + 0.74 x 
predorsal length — 5.28 x dorsal base — 1.40 x head length — 0.91 x snout 
length; Wilk’s lambda = 0.04, df 7,2,229, p < 0.0001. 
