
SCHISMATORHYNCHOS REVISION 
105 
Table 3 Vertebrae, branched rays in dorsal fin, and pairs of pleural ribs counts for species of Schismatorhynchos; the mean is followed (+) by the standard 
deviation; the range is reported as the minimum and maximum observations; sample size is reported in the column heading. 

S. heterorhynchos n=38 
S. holorhynchos n=99 S. endecarhapis n=45 
Vertebrae 31+0.0 
Precaudal vertebrae 15.94+0.23 15-16 
Caudal vertebrae 15.1+0.23 15-16 
Peduncular vertebrae 5.4+0.50 5— 6 
Dorsal fin position 8.0+0.23 7- 9 
18.9+0.23 18-19 
32.0+0.10 31-32 
33.040.15 32-33 
Anal fin position 
Branched dorsal-fin rays 8+0.0 
Ribs 12.3+0.47 12-13 
rays in dorsal fin (S. endecarhapis with 11 branched rays in dorsal 
fin); snout pointed, without cleft (S. heterorhynchos with deep cleft 
in snout), tuberculate, tubercles conical, becoming multicuspid to 
stellate in individuals about 60 mm SL and greater (S. heterorhynchos 
with pyramidal tubercles; S$. endecarhapis with simple, conical 
tubercles); a round blotch on caudal peduncle (S. heterorhynchos 
and S. endecarhapis without round blotch on caudal peduncle). 
DESCRIPTION. The largest specimen available for study is about 
102 mm SI, however the species grows considerably larger in Sungai 
Sebangu (K.Martin-Smith, pers. comm.) The overall form of the 
body is shown in Figure 6. Selected morphometric ratios, meristic 
information, and vertebral counts are reported in Tables 1-3. 
Snout pointed, tuberculate, tubercles moderate in size, absent 
from region of the cleft in snout of S. heterorhynchos. Two pairs of 
barbels, anterior pair small and fitting in grove, posterior pair hidden 
in deep recess at mouth corner. 
Mouth C-shaped, usually distinctly wider than long (mean Mw:MI 
= 1.8. range 1.3—2.2, SE 0.07, n=10). Cutting edge of lower jaw 
emergent, its tips extend posteriorly to vertical line from anterior 
margin of pupil. Lateral lobe of lower lip thick. 
Snout and dorsal surface of head posterior to nares and body 
anterior to dorsal fin tuberculate. Snout heavily tuberculate. Tuber- 
cles in region of snout well-developed, conical, multicuspidate in 
larger specimens (Fig. 3B) but simple in specimens less than about 
60 mm SL. Rostral tubercles present laterally on first infraorbital (Lo 
1), around tip of snout, over dorsal surface of tip of snout, between 
nares, and between nares and eye. Tubercles absent from a patch 
between front edge of ethmoid and anterior part of snout that 
corresponds in position to the deep cleft in snout of S. heterorhynchos 
(Inger and Chin, 1962). Region between dorsal fin and nares covered 
by numerous fine tubercles. 
Dorsal fin origin in advance of pelvic fin, margin slightly convex. 
Pelvic fin origin at 3rd branched ray of dorsal fin. Pectoral fin less 
than head length. Caudal fin forked. 
Lateral line complete, slightly curved, running in the middle of 
caudal peduncle posteriorly, usually with 31 scales to end of hypural 
plate (Table 2), 5% scales above lateral line to dorsal origin; 44% 
scales below lateral line. Vertebrae usually 32, usually with 16 
precaudal and caudal vertebrae. Number pairs of pleural ribs usually 
10 or 11. 
In alcohol dark from above, creamy below. Indistinct, dark, lateral 
band present, its origin before origin of dorsal fin. Band width 
equivalent to width of one scale row, anteriorly lateral band lies 
above lateral line, posteriorly lateral band lies over lateral line. 
Precaudal spot present, very distinct in small individuals, larger but 
may be obscure in larger individuals. Side of body above middle of 
pectoral fin with a few scales darkly marked. 
ETYMOLOGY. The name holorhynchos is from the Greek words 
holos, meaning whole or entire, and rhynchos, meaning snout. It is 
16.0+0.17 15-16 16.9+0.32 16-17 
16.0+0.14 16-17 16.1+0.36 15-17 
5.8+40.48 5-7 5.8+0.44 5-6 
7.9+0.30 7— 8 8.0+0.0 
19.0+0.46 19-20 20.1+0.32 20-21 
8.0+0.10 7- 8 11.0+0.40 10-12 
10.3+0.51 9-11 12.7+0.45 12-13 
in reference to the new species’ snout, which lacks the deep cleft 
found in the snout of its sister species, S. heterorhynchos. 
DISTRIBUTION. Materials of S. holorhynchos originate from within 
the Rejang River basin, Sarawak, Malaysia and the Kinabatangan 
River basin, Sabah (North Borneo), Malaysia (Fig. 5). The species 
has also been collected to the south of the Kinabatangan River, in the 
Segama River basin in Sabah (K.Martin-Smith pers. com.). The 
Sarawak and Sabah localities from which S. holorhynchos has been 
taken are distant from one another and the Rejang and Kinabantangan 
rivers which it is know to inhabit flow off Borneo in different 
directions and into different seas. It would be remarkable if S. 
holorhynchos was discovered not to inhabit some of the many river 
basins lying between the two rivers from which it has been collected. 
Schismatorhynchos endecarhapis sp. nov. (Figs 1C,3,5,7) 
Schismatorhynchos heterorhynchos, Roberts, 1989: 79, Fig. 58. 
HOLOTYPE. MZB 6092 (179.0 mm SL): Indonesia; Kalimantan 
Tengah; Barito River drainage; Sungai Laung at Desa Maruwei 
(0°21.986'S 114°44.103'E); hook and line; col. D.J. Siebert, A.H. 
Tjakrawidjaja and O. Crimmen; 15-18 Jul 1992; field no. DS-12- 
L992: 
PARATYPES. BMNH 1993.5.12:1-19 (19, 61.9-41.8 mm S); Indo- 
nesia; Kalimantan Tengah; Barito River basin; mouth of small 
stream at Project Barito Ulu base camp on Sungai Busang; seine; 
col. D.J. Siebert, A.H. Tjakrawidjaja and O. Crimmen; 27-28 Jan 
1991; field no. 3-DJS-1991. MZB 3434 (1, 88 mm Sl); Indonesia; 
Kalimantan Barat; Kapuas River basin; rocky channel in main- 
stream of Sungai Pinoh at Naga Saian, 45 km S of Nagapinoh; 
0°43'S 111°38.5'E); rotenone; col.T.R. Roberts and S. Wirjoatmodjo; 
26 Jul 1976; field no. Kapuas 1976-29. 
NON-TYPE MATERIALS. Borneo (Barito River basin, Kalimantan 
Tengah, Indonesia) - BMNH 1993.5.12:52—61 (10, 43.3—22.3 mm 
Sl); sand bars of Sungai Joloi above its confluence with Sungai 
Busang; seine; col. D.J. Siebert, A.H. Tjakrawidjaja and O. Crimmen; 
8 Feb 1991; field no. 13-DJS-1991. BMNH 1993.5.12:62-74 (13, 
48.0-26.5 mm Sl); sand bars of Sungai Murung around Project 
Barito Ulu base camp on Murung River; seine; col. D.J. Siebert, 
A.H. Tjakrawidjaja and O. Crimmen; 12 Feb 1991; field no. 16- 
DJS-1991. BMNH 1993.5.31-51 (21, 48.2-19.4 mm Sl); Barito 
River at Desa Muara Laung; 0°34.576'S 114° 44.205'E; seine; D.J. 
Siebert, A.H. Tjakrawidjaja and O. Crimmen; 20-22 Feb 1991; field 
no. 22-DJS-1991. BMNH 1993.5.12:20-30 (11, 46.7-34.4 mm S); 
sand bars of Sungai Busang at Project Barito Ulu base camp on 
Sungai Busang; seine; D.J. Siebert, A.H. Tjakrawidjaja, O. Crimmen; 
14-15 Feb 1991; field no. 18-DJS-1991. 
Borneo (Kapuas River basin, Kalimantan Barat, Indonesia) — 
MZB 3434 (1, 88 mm SI); Sungai Pinoh at Naga Saian; O°43'S 
