98 
pattern from the upper part of the Barito River basin, Kalimantan 
Tengah, Indonesia (central Borneo) in Jan—Feb 1991, and a larger 
specimen was taken subsequently in July 1992, again from the upper 
part of the basin. The species proved difficult to identify to genus, 
with a dorsal fin branched ray count of 11, a modal count of 33 
lateral-line scales, the upper and lower lips not continuous around 
the corner of the mouth, and an undivided, moderately tuberculate 
snout. This Barito River material appeared identical to the illustra- 
tion of a specimen from the Kapuas River identified as S. 
heterorhynchos by Roberts (1989; Fig. 58). Examination of Kapuas 
materials deposited by Roberts in the Museum Zoologicum 
Bogoriense confirmed that the Barito materials are conspecific with 
the Kapuas specimen Roberts illustrated. However, the disparity in 
the counts of branched rays of the dorsal fin between the Barito— 
Kapuas materials and that of S. heterorhynchos (eight branched rays 
in the dorsal fin), and differences in colour pattern, led us to 
conclude the Barito-—Kapuas materials in question are not S. 
heterorhynchos, but instead are from a previously unrecognised 
species of Schismatorhynchos. 
In order to investigate the development of the snout cleft in S. 
heterorhynchos, we examined small specimens from northeastern 
Borneo identified as S. heterorhynchos (see Inger & Chin, 1962), 
along with additional material collected in 1991 in Sarawak, Malay- 
sia. Differences in snout tubercle structure and colour pattern led us 
to conclude that the Sabah and Sarawak materials do not conform to 
S. heterorhynchos either, but instead belong to yet another unrecog- 
nised species. 
More material has become available recently from the Kapuas 
River, western Borneo (Sungei Sibau, an upper basin tributary of the 
Kapuas River). This material possesses, even as juveniles of small 
size, the oro-labial features of S. (Schismatorhynchos), a deeply cleft 
heavily tuberculate snout and a colour pattern like that described for 
S. heterorhynchos. Thus, at least two species of Schismatorhynchos 
live within the Kapuas River basin, one species with a cleft snout and 
another with an undivided snout. 
To summarise our observations and clarify the status of material 
identified in the literature as S. heterorhynchos, we revise the genus 
Schismatorhynchos, describing two new species. 
MATERIALS AND METHODS 
Methods of measuring and counting follow Hubbs and Lagler 
(1949). Vertebral (following Siebert & Guiry, 1996) and fin-ray 
counts were taken from radiographs. Statistical analyses were car- 
ried out using SYSTAT for WINDOWS, version 6.0 (SPSS, Inc. 
1994), Institutional abbreviations are as follows: BMNH — The 
Natural History Museum, London; FMNH — The Field Museum of 
Natural History, Chicago; MZB —Museum Zoologicum Bogoriense, 
Bogor; USNM — United States National Museum of Natural History, 
Washington, D.C.; ZMA — Zoological Museum, Amsterdam. 
The systematics and generic taxonomy of cyprinid fishes related 
to Labeo Cuvier, 1817, i.e. those with a vomero-palatine organ, is in 
a state of flux and is likely to remain so for some time to come. There 
is considerable disagreement in the modern analytical literature as to 
what subgroups should be recognised, just what their limits ought to 
be, and at what rank they should be recognised (compare Reid 
(1985; Table 1, p. 15) with Rainboth (1996; p. vii) to see conflict at 
all the levels just mentioned). As regards this revision of 
Schismatorhynchos, we adopt Rainboth’s rank of tribe for the entire 
group of cyprinids with a vomero-palatine organ, and use the 
informal name labeonin when referring to them in a general way. We 
D.J. SIEBERT AND A.H. TJAKRAWIDJAJA 
accept Reid’s restriction of Labeo, and, for the most part, his notions 
of relationships within labeonins when discussing the limits of 
Schismatorhynchos, because his groupings have been laid out fol- 
lowing cladistic principles. We use Tylognathus Heckel (sensu 
Bleeker, 1863; Reid, 1985, p. 277) when discussing our exclusion of 
Nukta Hora from Schismatorhynchos because we are not sure of the 
limits of Bangana Hamilton. Cyprinus nukta Sykes, 1838 may 
belong in Bangana, but that assessment is beyond the scope of this 
study. 
GENERIC ACCOUNT 
Schismatorhynchos Bleeker, 1855 
Schismatorhynchus Bleeker, 1863; unjustified emendation. 
Type species Lobocheilos heterorhynchos Bleeker, 1853; type by 
monotypy. 
DIAGNOsIS. Labeonins (sensu Reid, 1982, 1985; 1. vomero-pala- 
tine organ present, 2. neural complex of the Weberian apparatus in 
direct contact with supraoccipital region, 3. terete process of the 
basioccipital, 4. superficial labial fold developed posterior to the 
lower jaw) with a large, fleshy, sub-conical, rostral cap (=rostral fold 
of Weber & de Beaufort, 1916); two pairs of barbels, posterior pair 
in a deep recess at the corner of the mouth (largely to completely 
hidden in large material); mouth inferior, wide, C-shaped; lower jaw 
with an extremely long, thin, flexible, horny, cutting edge (Fig. 1A— 
C); no superficial labial fold in advance of the upper jaw; upper lip 
separated from rostral cap, moderately fleshy, adnate to upper jaw; 
upper lip and lower lip not continuous around corner of mouth 
(separated by extensions of the cutting edge of lower jaw); lower lip 
reflected from lower jaw, thick, very fleshy, fringed, with a distinct, 
elongate, longitudinally oriented, fleshy, lateral lobe in which the 
mandibular laterosensory canal is located (=frenulum of Weber & de 
Beaufort, 1916; Fig. 1A—C); no transverse postlabial groove sepa- 
rating lower lip from gular region. 
REMARKS. ‘The present diagnosis makes use of many oro-labial 
features and excludes the subgenus Nukta from Schismatorhynchos. 
Additional information on the oro-labial features is presented below, 
with an explanation of our exclusion of Nukta. 
Good series of small individuals are available for both new 
species, making possible study of certain aspects of the late ontog- 
eny of the mouth. Schismatorhynchos is a labeonin, as delimited by 
Reid (1982, 1985). It appears to lack the superficial labial fold 
anterior to the upper jaw that characterises a large subgroup of these 
fishes, such as Garra, Epalzeorhynchos, Osteochilus, and Labeo. At 
small size (< 30 mm SI) the upper lip is distinguishable as a ridge of 
papillate tissue closely associated with the upper jaw. This ridge 
thickens and becomes fully adnate to the upper jaw with growth, so 
that by a size of 50 mm SI no distinction between the upper jaw and 
upper lip is apparent, unlike members of the subgroup of labeonins, 
such as Epalzeoprhynchos, with a scarcely developed, or regressed, 
but nevertheless distinguishable superficial labial fold anterior to the 
upper jaw. Thus, Schismatorhynchos appears to reside within a 
relatively primitive assemblage of labeonin genera, which includes 
Tylognathus (sensu Bleeker, 1963; Reid, 1985; p. 287) and Lobo- 
cheilus, but for which relationships have yet to be worked out. 
More clear is that the extremely elongate cutting edge of the lower 
jaw, which results in the separation of the upper and lower lips 
around the corner of the mouth, and the development of a lateral 
frenulum are distinct specialisations within labeonins and unique 
among cyprinids. These oro-labial specialisations of Schismato- 
