102 
D.J. SIEBERT AND A.H. TJAKRAWIDJAJA 

Fig. 3 Snout tubercles of: A. S. heterorhynchos, MZB 8612, 136.4 mm Sl]; B. S. holorhynchos, FANH 68550, 77.6 mm Sl; C. S. endecarhapis, MZB 
6092, 179.0 mm SI. 
this species, which appears considerable. A photograph of a small, 
medium and large specimen is presented in Figure 2. Selected 
morphometric ratios, meristic information, and vertebral counts are 
reported in Tables 1-3. 
Head relatively long, with a comparatively small eye, increased 
head length due to an elongate, pointed snout with a well developed 
rostral fold (=rostral cap of Roberts, 1989) which is hypertrophied in 
support of heavy tuberculation. Snout divided by a deep horizontal 
cleft above Ist infraorbital bone (Io 1). Upper (ethmoidal) lobe 
consists of connective tissue outgrowth from front edge of 
mesethmoid, supports large tubercles; in dorsal view its anterior 
edge indented in midline to form left and right anterior lobes. 
Anterior extension of rostral cap also consists of a connective mass 
which supports anterior tubercles of snout. Two pairs of barbels 
present, anterior pair small, posterior pair longer, but hidden in a 
deep recess at corner of mouth. 
Mouth inferior, broad, C-shaped, usually a little wider than long 
(mean Mw:MI1 = 1.3; range = 0.9-1.6., SE= 0.05, n=32). Lower jaw 
equipped with an emergent, thin, flexible, extremely long cornified 
cutting edge which is much longer than posterior extent of upper and 
lower lips. Posterior tips of cutting edge of lower jaw extend behind 
a vertical line from middle of eye. 
Large, unicuspid, pyramidal tubercles, with 3—5 sides, present in 
and around rostral cleft (Fig. 3A). Tubercles also present around 
dorsal edges of upper lobe of snout formed by rostral cleft, on upper 
and lower interior surfaces of rostral cleft, between eye and nares, on 
upper half of Io 1, and over dorsal and anterior aspects of rostral cap. 
Large tubercles absent from dorsal surface of head except for those 
found at dorsal edges of upper lobe of snout. 
Shape of S. heterorhynchos changes with size (Fig. 2). Smallest 
specimens examined have a relatively round body. Between 100 mm 
Sl and 150 mm S] body depth and compression increases. Above 170 
mm Sl] body shape is deep and decidedly compressed. 
Dorsal fin falcate, with first two principal fin-rays greatly elon- 
gated in large individuals, when depressed extending beyond anal-fin 
origin to more than mid-way along caudal peduncle. Dorsal fin 
height nearly 50% of SL in largest individuals examined. Increase in 
length of first two principal dorsal-fin rays strongly allometric with 
respect to Sl, with allometric coefficient much greater than unity 
(Fig. 4). Pectoral fin of large individuals slightly longer than head 
length, but in small individuals much shorter than head length. 
Pelvic fin inserted behind dorsal-fin origin, at 4th branched ray of 
dorsal fin. 
Lateral line usually with 31 or 32 scales (Table 2) to end of 
hypural plate, slightly curved, running in middle of caudal peduncle 
posteriorly; 5% scales above lateral line to dorsal origin; 4% scales 
below lateral line. All specimens examined with 31 vertebrae, 
usually with 15 precaudal vertebrae and 16 caudal vertebrae (Table 
3). Number of pairs of pleural ribs usually 12. 
In alcohol dorsum dark, with ventral half of body creamy. A wide, 
dark lateral band present, centred on lateral line, beginning at 
operculum and extending to distal tips of middle rays of caudal fin. 
Upper anterior corner of lateral stripe, where it meets hind edge of 
operculum, intensified to form a dark mark, prominent in smaller 
individuals but less so in larger individuals. Lateral band two scale 
rows wide, includes lower % of scale row above lateral line scale row 
and upper % of scale row below lateral line scale row. Lateral band 
may be evident only on the posterior half of the body on large 
individuals. Dorsal, pectoral, pelvic, anal, and upper and lower lobes 
of caudal fin clear. 
Table 1 Selected morphometric variables for species of Schismatorhynchos;, the mean is followed (+) by the standard deviation; the range is reported as 
the minimum and maximum observation; sample size is reported in column headings. 

S. heterorhynchos n=38 
S. holorhynchos n=8 1 S. endecarhapis n=19 

Head length 
Snout length 
Eye length (%HL) 
Eye length 
Predorsal length 
Body depth 
Caudal peduncle depth 
Dorsal-fin base length 

26.6+1.4 22.6-28.9 
12.5+1.1 10.8-14.2 
18.6+1.8 13.5—20.8 
4.9+0.6 3.4— 6.0 
47.6+1.5 43.6-50.4 
27.0+2.9 21.9-35.6 
12.4+1.0 11.0-15.4 
17.7+1.6 12.4—22.3 
25.4+1.2 21.5—27.7 
9.6+1.0 6.9-11.2 
22.3+2.8 17.7-28.8 
5.940.8 4.4— 7.4 
47.8+2.2 39.2-52.8 
27.5+1.7 23.0-30.5 
12.8+0.6 11.2-13.8 
16.141.1 12.4-18.9 
24.5+1.4 20.5-27.0 
8.740.9 6.9-10.2 
23.1+3.4 18.3-30.8 
5.741.0 4.1- 7.7 
47.7+1.4 45.5-5S0.2 
25.0+1.9 21.4-28.6 
11.1+0.5 10.2-12.2 
24.6+1.8 22.4-29.3 
