Redescription of a rare threadfin (Perciformes:
Polynemidae), Polydactylus macrophthalmus (Bleeker,1858), with designation of a lectotype and notes on
distributional implications
Hiroyuki Motomura1*, Martien J. P. van Oijen2, Isaäc J. H. Isbrücker3, and Yukio Iwatsuki4
1

Miyazaki University, The United Graduate School of Agricultural Sciences, Kagoshima University, 1-1 Gakuen-kibanadai-nishi,
Miyazaki 889-2192, Japan (e-mail: a02113u@cc.miyazaki-u.ac.jp)
2
National Museum of Natural History, P.O. Box 9517, 2300 RA Leiden, The Netherlands (e-mail: oijen@naturalis.nnm.nl)
3
Zoölogisch Museum Amsterdam, Universiteit van Amsterdam, P.O. Box 94766, 1090 GT Amsterdam, The Netherlands(e-mail: isbruecker@science.uva.nl)
4
Division of Fisheries Sciences, Faculty of Agriculture, Miyazaki University, 1-1 Gakuen-kibanadai-nishi, Miyazaki 889-2192,
Japan (e-mail: yuk@cc.miyazaki-u.ac.jp)
Received: November 1, 2000 / Revised: March 2, 2001 / Accepted: March 15, 2001

IchthyologicalResearch©The Ichthyological Society of Japan 2001

Ichthyol Res (2001) 48: 289–294

Abstract A rare threadfin, Polydactylus macrophthalmus (Bleeker, 1858), having long
been included in the genus Polynemus, is redescribed on the basis of 9 specimens and alectotype designated. Polydactylus macrophthalmus is characterized by the following combination of characters: 7 pectoral filaments, upper 3 filaments extending beyond posterior
margin of hypural; 13 or 14 pectoral fin rays; 87–94 pored lateral line scales; 11 scales above
lateral line, 15 or 16 below; 10–12 upper series gill rakers, 15 or 16 lower, 26 or 27 total;
occipital profile concave in adults; second spine of first dorsal fin very strong; pectoral fin
rays long (mean 24% [range 24–26%] of SL). The presently known distribution of thespecies, including the Kapuas River, Kalimantan, and the Musi and Batanghari Rivers,
Sumatra, Indonesia, apparently reflects the ancient Central or North Sunda River during
the last period of lowered sea levels, ca. 12 000 years ago.
Key words

T

Polynemidae · Redescription · Polydactylus macrophthalmus · Distribution

o date, eight genera of the worldwide family Polyne
midae have been recognized, including Eleutheronema Bleeker, Filimanus Myers, Galeoides Günther,
Pentanemus Günther, Parapolynemus Feltes, Polydactylus Lacepède, Polynemus Linnaeus (Feltes, 1993) and
Leptomelanosoma Motomura and Iwatsuki, recently
proposed for a polynemid fish previously known as Polydactylus indicus (Shaw) (Motomura and Iwatsuki, 2001).
The rare threadfin, Polynemus macrophthalmus
Bleeker, 1858, was originally described on the basisof 2 specimens from Palembang, the Musi River,
Sumatra, Indonesia. Although the species had beentreated as a member of Polynemus since its originaldescription (e.g., Weber and de Beaufort, 1922; Myers,
1936; Kottelat et al., 1993), Feltes (1993) included it in
Polydactylus (name only), but gave neither reasons nor
an indication of materials examined. Nine examples ofthe species, including all those recorded from museum
collections plus a live specimen, clearly exhibited the
diagnostic characters of Polydactylus, given by Feltes(1993) and Motomura and Iwatsuki (2001); e.g., largeeye, pectoral fin base shorter than upper jaw length, thebasisphenoid in contact with the prootic and a simple
swimbladder.
The species is herein redescribed in detail, includinginternal characters and photographs, as a member of
Polydactylus, and a lectotype designated. Distributional
implications of the species are also discussed and some
habitat notes included.

Methods
Counts and measurements generally follow Hubbs andLagler (1947) and Feltes (1991), with some modifications
following Motomura et al. (2000). Standard length andtotal length are expressed as SL and TL, respectively.
Terminology of the supraneural and epineural bones
follows Mabee (1988) and Patterson and Johnson (1995),
respectively. The formula for configuration of thesupraneural bones, anterior neural spines and anterior
dorsal fin pterygiophores follows Ahlstrom et al. (1976).

290

H. Motomura et al.

Fig. 1. Lectotype of Polynemus macrophthalmus Bleeker, 1858, RMNH 6015, 129 mm SL, Palembang, Musi River, Sumatra,Indonesia

The osteological characters were confirmed from X-ray
photos taken of all specimens. The swimbladder was confirmed from MNHN 1891-571, ZMA 114.431 (215 mm
SL, 1 of 3 specimens) and ZMA 114.432, abdomens ofthese being already dissected. Institutional codes follow
Leviton et al. (1985), with an additional institutional
abbreviation as follows: Division of Fisheries Sciences,
Miyazaki University, Japan (MUFS).

Polydactylus macrophthalmus(Bleeker, 1858)(English name: river threadfin)(Figs. 1, 2)
Polynemus macrophthalmus Bleeker, 1858a: 10 (type locality:
Palembang, Musi River, Sumatra, Indonesia).
Polynemus borneensis (not of Bleeker): Vaillant, 1893: 109(Kapuas River, Kalimantan, Indonesia).
Lectotype. RMNH 6015, 129 mm SL, Palembang, Musi
River, Sumatra, Indonesia, collected by J. T. van Bloemen
Waanders.
Paralectotype. RMNH 33967, 117 mm SL, same data as
lectotype.
Other material (n ⴝ 7, 88–344 mm SL, all fromIndonesia). MNHN 1891-571, 344 mm SL, Kapuas River,
Kalimantan (identified as Polynemus borneensis by Vaillant,
1893); MUFS 18293, 88 mm SL, correct locality unknown, but
most likely Kapuas River, Kalimantan (purchased fromaquarium fish shop); UMMZ 171714, 184 mm SL, Palembang,Musi River, Sumatra; ZMA 114.431, 3 specimens, 141–221 mm
SL, Jambi, Batanghari River, Sumatra; ZMA 114.432, 166 mm
SL, Kapuas River, Kalimantan.

Diagnosis. A species of Polydactylus with the following combination of characters: 7 pectoral filaments, upper 3 filaments extending beyond caudal fin base; 13 orFig. 2. Life stages of Polydactylus macrophthalmus. A MUFS
18293, 88 mm SL. B ZMA 114.431, 1 of 3 specimens, 141 mm SL.
C ZMA 114.432, 166 mm SL. D UMMZ 171714, 184 mm SL. E
MNHN 1891-571, 344 mm SL

Redescription of Polydactylus macrophthalmus

291

Table 1. Counts and measurements of Polydactylus macrophthalmus, including the lectotype, paralectotype, and non-type
specimens
Lectotype of
Polynemus
macrophthalmus
RMNH 6015

Paralectotype of
Polynemus
macrophthalmus
RMNH 33967

Non-type specimens of
Polydactylus
macrophthalmus(n ⫽ 7)

Standard length (mm)

129

117

88–344

Counts (modes)
Dorsal fin rays
Anal fin rays
Pectoral fin rays
Pectoral filaments
Pelvic fin rays
Pored lateral line scales
Scales above/below lateral line
Gill rakers

VIII-I, 14
III, 11
14
7
I, 5
88
11/16
11 ⫹ 16 ⫽ 27

VIII-I, 14
III, 11
13
7
I, 5
88
⫺16
11 ⫹ 16 ⫽ 27

VIII-I, 13–14 (14)III, 11
13–14 (14)7I, 5
87–94 (88)
11/15–16 (16)
10–12 (11) ⫹ 15–16 (16) ⫽ 26–27 (27)

Measurements (means)
Head length
Body depth
Second body depth
Body width at pectoral fin base
Snout length
Dermal eye opening
Orbit diameter
Interorbital width
Postorbital length
Upper jaw lengthPre-1st dorsal fin lengthPre-2nd dorsal fin length
Preanal fin length
First dorsal fin origin to anal fin origin
Pelvic fin origin to anal fin origin
Second dorsal fin base length
Anal fin base length
Longest pectoral fin length
Longest pectoral filament length (3rd)Pectoral fin baseLongest pelvic fin ray length (1st)Longest 1st dorsal fin spine length (3rd)Second dorsal fin spine length
Longest 2nd dorsal fin ray length (2nd)Longest anal fin spine length (3rd)Longest anal fin ray length (2nd)Caudal peduncle length
Caudal peduncle depth
Upper caudal fin lobe length
Lower caudal fin lobe length

31
22
24
9
5
6
7
6
19
14
36
61
66
41
30
16
13
19a
Broken
10
15a
19
9
20
10
17
27
11
36a
Broken

30
22
24
9
5
5
7
6
19
13
35
60
63
39
29
16
13
24
Broken
10
16a
19
10
19
11
Broken26
11
39
Broken29–33 (31)22–28 (25)
22–28 (25)
9–16 (12)
5–7 (5)
4–6 (5)
5–8 (7)
5–6 (6)18–21 (19)
13–15 (14)34–38 (36)60–65 (61)
63–67 (65)
38–45 (41)
26–34 (29)
15–18 (16)
13–14 (13)24–26 (24)161–192 (176)
10–11 (10)18–20 (19)
18–21 (19)
9–10 (10)19–23 (21)
9–11 (10)19–21 (20)
25–27 (26)
9–12 (11)38–46 (42)36–40 (32)

Data are expressed as percentages of standard length; modes and means in parentheses, including data of type specimensaSlightly damaged at tip

14 pectoral fin rays; 87–94 pored lateral line scales; 11
scales above lateral line, 15 or 16 below; 10–12 upper
series gill rakers, 15 or 16 lower, 26 or 27 total; occipitalprofile concave in adults; second spine of first dorsal finvery strong; pectoral fin rays long (mean 24% [range 24–26%] of SL).
Description. Counts and proportional measurements as percentages of SL of the lectotype, paralecto-

type and other material of Polydactylus macrophthalmus
are given in Table 1. Characters given in the diagnosis are
not repeated. Data for the lectotype are presented first,
followed by other specimen data (if different) in parentheses.
Body oblong, compressed; maxilla covered with scales;
orbit diameter greater than snout length; lower lip welldeveloped; posterior margin of maxilla extending be-292yond level of posterior margin of adipose eyelid; depthof posterior portion of maxilla shorter than dermal eye
opening; villiform teeth in broad bands on vomer,
palatines and ectopterygoids; all pectoral fin rays
unbranched; (third pectoral filament longest, extending
beyond posterior tips of caudal fin lobes); (fourth pectoral filament extending slightly beyond anal fin origin);second dorsal fin base longer than anal fin base; distance
between pelvic and anal fin origins less than (or approximately equal to) head length; caudal peduncle depth 2.4(2.1–2.9) in caudal peduncle length; lateral line simple,
extending from upper end of gill opening to upper end oflower caudal fin lobe; (swimbladder well-developed);
lower tip of seventh proximal pterygiophore of firstdorsal fin directed forward; formula for configuration of
supraneural bones, anterior neural spines and anterior
dorsal pterygiophores 0/0/0⫹2/1⫹1/1⫹1/1/1/; vertebrae
10 ⫹ 14; 6 epineurals.
Life color notes.—Based on a color transparency of
MUFS 18293, 88 mm SL: upper sides of head and trunk
tinged silvery-blue, becoming more silver on lower sides;
posterior margins of first dorsal, second dorsal and caudal fins grayish-black, other parts hyaline; tips of pelvic
and anal fins white, other parts transparent; pectoral finhyaline; pectoral filaments white.
Color of preserved specimens.—Head and body lightyellow dorsally, pale yellow ventrally (grayish in typespecimens); posterior margin of first dorsal, second dorsal and caudal fins grayish-black, other parts pale yellow;
pelvic and anal fins and pectoral filaments pale yellow;
pectoral fin transparent.
Distribution and habitat. Polydactylus macrophthalmus is currently known only from three rivers on two
Indonesian islands: Kapuas River, Kalimantan, and Musiand Batanghari Rivers, Sumatra (Fig. 3). These rivers
were part of a single large river, the ancient Central orNorth Sunda River, on the Sundaland during the Pleistocene, the last cold period being about 12 000 years ago(see Morley and Flenley, 1987, Fig. 5.5; Fig. 3, dottedlines). Geographic evidence indicates that the species waswell adapted to the freshwater basins in this extensive
Pleistocene river, whereas other Polydactylus species are
generally found in saltwater habitats (e.g., Motomura etal., 2000, 2001a,b). The Sundaland presently being submerged to a depth of ca. 100 m (Morley and Flenley,1987), P. macrophthalmus is now restricted to the threepresently known localities in the South China Sea (Fig. 3).
According to Roberts (1989), the similar distributions are
exhibited by ca. 12 freshwater species (e.g., Arius
melanochir Bleeker, Channa melanoptera Bleeker andOsteochilus borneensis Bleeker).
The species has much longer pectoral filaments and amore slender body than other Polydactylus species,

H. Motomura et al.

Fig. 3. Distributional records (dots) for Polydactylus
macrophthalmus and outline of the ancient Central or North
Sunda River, ca. 12 000 years ago (dotted lines)

which generally inhabit marine waters. Such morphological characters have been considered as an adaptation
to a freshwater existence, owing to their occurrence in
Polynemus species restricted to freshwater or estuarine
habitats (e.g., Talwar and Jhingran, 1992; Rainboth,
1996). The character of the long pectoral filaments has
been considered to be useful as a sense organ to search
for food in muddy waters (first author, personal observation, aquarium of Kasetsart University, Thailand).
Furthermore, data of specimens examined in this study
indicated that they had been collected from Jambi and
Palembang, located ca. 75 km up the Batanghari andMusi Rivers, respectively (i.e., completely freshwaterbasins). Accordingly, Polydactylus macrophthalmus isconsidered to be more heavily dependent on a freshwater habitat than other congeners. Accordingly, because of
the marine barriers to further dispersal, the species isbelieved to have the most restricted distribution in thefamily.
Remarks. The date of publication of the originaldescription of Polynemus macrophthalmus has almost
always been treated as 1858–1859 (Weber and de Beaufort, 1922; Roberts, 1989; Eschmeyer, 1998), because theexact publication date was omitted from the reprint andBleeker (1878: 116) himself subsequently referred to that
article as having been published in 1858–1859. Bleeker
customarily indicated the time of completion of eachmanuscript in the concluding sentence at the end andoften referred to such dates in subsequent bibliographies.
In this case, the date indicated on the reprint by Bleeker
was December 1857. In Bleeker’s (1878) posthumously
published bibliography, his papers were listed in chronological order, 42 papers comprising numbers 175–216,

Redescription of Polydactylus macrophthalmus

inclusive, having been published in 1858. The first paper
published in 1859, number 217, was written in October
1858. Furthermore, 4 papers (numbers 176–179, inclusive) were cited as having been included in Volume 5 ofActa Societatis Regiae Scientiarum Indo-Néêrlandicae(Bleeker, 1863 [in Bleeker, 1862], 1878). Following
Articles 21.3 and 21.6 of the International Code of Zoological Nomenclature (ICZN, 1999), Bleeker’s paper
number 176, including the original description of
Polynemus macrophthalmus, is herein considered as having been published in 1858. Moreover, Bleeker (1858b,
published in August) already included a full reference tothis paper.
Bleeker (1858a) described Polynemus macrophthalmus as a new species on the basis of 2 syntypes, 168
and 182 mm TL. Subsequently, Hubrecht (1879) reported
2 examples (group A, 2 specimens) of that species,
which were registered as RMNH 6015. Bleeker’s (1983)
figure of Polynemus macrophthalmus (as Trichidion
macrophthalmus) is here considered to have been basedon the larger of the two syntypes, owing to Bleeker’s
habit of reproducing figures at life size in the “Atlas.”According to Article 72.5.6 of the International Code ofZoological Nomenclature (ICZN, 1999), we herein designate RMNH 6015 (129 mm SL, 182 mm TL) as the lectotype of Polynemus macrophthalmus, the other specimen
being a paralectotype (reregistered as RMNH 33967,
117 mm SL, 168 mm TL).
Polydactylus macrophthalmus has long been treated asa member of Polynemus since its original description(Weber and de Beaufort, 1922; Myers, 1936; Roberts,
1989; Kottelat et al., 1993). However, examination of thenine specimens available to this study, including the
newly-designated lectotype and paralectotype, showedthat they differed from Polynemus species in having alarge eye (orbit diameter greater than snout length vs.
less than snout length in Polynemus), the pectoral fin
insertion well below the midline on the lateral body (vs.
near midline), a basisphenoid present (vs. absent) and 24
vertebrae (vs. 25) (Feltes, 1993). Furthermore, the specimens clearly conformed to the following diagnostic
characters of Polydactylus, given by Feltes (1993) andMotomura and Iwatsuki (2001): tooth plate on vomer
simple; width of tooth band on upper and lower jaws
wider than space separating tooth bands on opposing
premaxilla; basisphenoid in contact with prootic; pectoral fin base including base of pectoral filaments less thanupper jaw length; swimbladder simple, not extending
beyond anal fin origin. Accordingly, the species is here
included in the genus Polydactylus.
Comparisons. Polydactylus macrophthalmus can beeasily distinguished from other congeners by the very
long upper 3 pectoral filaments, extending beyond the293

caudal fin base (vs. not reaching caudal fin base in othercongeners). Polydactylus species are known to have variously 4–10 pectoral filaments (Feltes, 1993); those with 7
pectoral filaments include only 3 species, viz. P. macrophthalmus (Bleeker, 1858), P. multiradiatus (Günther,
1860), and P. sextarius mullani (Hora, 1925), all from the
Indo-Pacific region.
In addition to the difference in pectoral filament
length, Polydactylus macrophthalmus differs from P.
multiradiatus in having lower anal fin ray counts (11 vs.
17–18 in the latter; Marshall, 1964), higher pored lateralline scale counts (87–94 vs. 58–59; Marshall, 1964) and aconcave occipital profile in adults (vs. nearly straight; thisstudy). Furthermore, P. macrophthalmus is clearly distinguished from P. sextarius mullani by the higher counts ofpored lateral line scales, and scales above and below thelateral line (87–94 and 11/15 or 16, respectively, vs. 46–50
and 6 or 7/9 or 10, respectively, in the latter), lower gillraker counts (26 or 27 vs. 32–35), a concave occipitalprofile in adults (vs. nearly straight), vomerine toothpresent (vs. absent) and a large black spot absent anteriorly on the lateral line (vs. present).
Polydactylus macrophthalmus is similar to P.
macrochir, endemic to northern Australia and southern
New Guinea (Motomura et al., 2000), in having a concave occipital profile in adults (see Motomura et al.,2000, fig. 2C; Fig. 2C–E) and the second spine of thefirst dorsal fin more robust than other spines of thefirst dorsal fin (Motomura et al., 2000). However, P.
macrophthalmus differs from the latter in having higher
counts of pectoral filaments (7 vs. 5 in the latter) andpored lateral line scales (87–94 vs. 70–76), and lower
gill raker counts (26–27 vs. 32–35) (Motomura et al.,2000).
Comparative material examined. Polydactylus macrochir (Günther, 1860): 41 specimens, including the holotype,were examined for comparative purposes. The collection
data for 36 of these were given by Motomura et al. (2000),with remaining specimen data as follows: CSIRO 4583-03,
92 mm SL, Poriri Island, Irian Jaya, Indonesia; CSIRO 5245-01,
106 mm SL, mouth of Ajkwa River, Irian Jaya, Indonesia;
RMNH 24526, 2 specimens, 147–149 mm SL, Merauke River,Irian Jaya, Indonesia; RMNH 25085, 126 mm SL, Merauke
River, Irian Jaya, Indonesia. Polydactylus multiradiatus(Günther, 1860): FMNH 63917, 177 mm SL, Brisbane River,Queensland, Australia; FRLM 23414-23417, 4 specimens, 130–144 mm SL, Rumahtiga fish market, Poka, Ambon, Indonesia;
FRLM 23471-23474, 4 specimens, 136–141 mm SL, Passo fish
market, Ambon, Indonesia. Polydactylus sextarius mullani(Hora, 1925): ANSP 77129, 2 specimens, 52–82 mm SL, off
Mumbai, India; ANSP 77527, 4 specimens, 49–94 mm SL, off
Mumbai, India; ANSP 105539, 151 mm SL, Mumbai, India;
USNM 358690, 4 specimens, 42–117 mm SL, off Kathiawar Peninsula, India; ZSI-F 10747 (holotype of Polynemus sextarius
mullani), 157 mm SL, Mumbai, India; ZSI-F 10748-10750 (3294

H. Motomura et al.

paratypes of Polynemus sextarius mullani), 92–106 mm SL,
Mumbai, India.
Acknowledgments We are most grateful to M. Sabaj (ANSP),
A. Graham (CSIRO), S. Kimura (FRLM), G. Duhamel, J.-C.
Hureau, and P. Pruvost (MNHN), D.W. Nelson (UMMZ), S.L.
Jewett, L. Palmer, S.J. Raredon, and J.T. Williams (USNM) and
A.K. Karmakar (ZSI-F) for specimen loans and opportunities
to examine specimens. We are also grateful to S. Kimura(FRLM), T. Yoshino (URM-P) and Y. Motomura (Miyazaki,
Japan) for their assistance. We thank K. Sasaki (BSKU) for
kindly providing a reference and T. Onishi (Marine World
Uminonakamichi Aquarium, Fukuoka, Japan) for his help withacquisition of a live specimen. Lastly, we thank G.S. Hardy(Thames, New Zealand), who read the initial manuscript andoffered helpful comments. This study was supported in part bya grant awarded to the first author by Research Fellowships of
the Japan Society for the Promotion of Science for Young
Scientists.

Literature Cited
Ahlstrom EH, Butler JL, Sumida BY (1976) Pelagic
stromateoid fishes (Pisces, Perciformes) of the eastern
Pacific: kinds, distributions, and early life histories and observations on five of these from the northwest Atlantic. Bull
Mar Sci 26:285–402
Bleeker P (1858a) Zevende bijdrage tot de kennis dervischfauna van Sumatra. Visschen van Palembang. Acta
Soc Sci Indo-Néêrl 5:1–12
Bleeker P (1858b) Ichthyologiae archipelagi Indici prodromus.
I. Siluri. De visschen van den Indischen Archipel beschrevenen toegelicht. I. Siluri. Acta Scocietatis Regiae Scientiarum
Indo-Néêrlandicae, of Verhandelingen der Natuurkundige
Vereeniging in Nederlandsch-Indië 4:v–viii, 1–353; Naschrift
354–370
Bleeker P (1862) Atlas ichthyologique des Indes OrientalesNéêrlandaises, publié sous les auspices du Gouvernementcolonial nérlandais. Tome I. Scaro’des et Labro’des. F. Muller,
Amsterdam
Bleeker P (1878) Levensbericht van Pieter Bleeker, door
hemzelven. Overgedrukt uit het Jaarboek der Koninklijke
Academie ven Wetenschappen 1877:11–159
Bleeker P (1983) Atlas ichthyologique des Indes OrientalesNéêrlandaises. Plates for planned tomes 11–14. Smithsonian
Institution Press, Washington, DC
Eschmeyer WN (ed) (1998) Catalog of fishes, vol 3. Generaof fishes, species and genera in a classification, literaturecited and appendices. California Academy of Sciences, San
Francisco
Feltes RM (1991) Revision of the polynemid fish genus
Filimanus, with the description of two new species. Copeia
1991:302–322
Feltes RM (1993) Parapolynemus, a new genus for the polynemid fish previously known as Polynemus verekeri. Copeia
1993:207–215
Hubbs CL, Lagler KF (1947) Fishes of the Great Lakes region.
Bull Cranbrook Inst Sci (26):i–xi ⫹ 1–186

Hubrecht AA (1879) Catalogue des collections formées etlaissées par M.-P. Bleeker. De Breuk & Smits, Leiden
ICZN (International Commission on Zoological Nomenclature) (1999) International Code of Zoological Nomenclature, 4th edn. Adopted by the General Assembly of theInternational Union of Biological Sciences. International
Trust for Zoological Nomenclature, London
Kottelat M, Whitten AJ, Kartikasari SN, Wirjoatmodjo S (1993)
Freshwater fishes of western Indonesia and Sulawesi.
Periplus, Jakarta
Leviton AE, Gibbs RH Jr, Heal E, Dawson CE (1985)
Standards in herpetology and ichthyology: Part I. Standard
symbolic codes for institutional resource collections in herpetology and ichthyology. Copeia 1985:802–832
Mabee PM (1988) Supraneural and predorsal bones in fishes:development and homologies. Copeia 1988:827–838
Marshall TC (1964) Fishes of the Great Barrier Reef
and coastal waters of Queensland. Angus and Robertson,
SydneyMorley RJ, Flenley JR (1987) Late Cainozoic vegetationaland environmental changes in the Malay Archipelago. In:
Whitmore TC (ed) Biogeographical evolution of the Malay
Archipelago. Clarendon Press, Oxford, pp 50–59
Motomura H, Iwatsuki Y (2001) A new genus, Leptomelanosoma, for the polynemid fish previously known as Polydactylus indicus (Shaw, 1804) and a redescription of the species.
Ichthyol Res 48:13–21
Motomura H, Iwatsuki Y, Kimura S, Yoshino T (2000) Redescription of Polydactylus macrochir (Günther, 1867), a seniorsynonym of P. sheridani (Macleay, 1884) (Perciformes:
Polynemidae). Ichthyol Res 47:327–333
Motomura H, Iwatsuki Y, Kimura S (2001a) Redescriptionof Polydactylus sexfilis (Valenciennes in Cuvier and Valenciennes, 1831), a senior synonym of P. kuru (Bleeker, 1853)
with designation of a lectotype (Perciformes: Polynemidae).
Ichthyol Res 48:83–89
Motomura H, Iwatsuki Y, Yoshino T (2001b) A new species,
Polydactylus siamensis, from Thailand and redescription of
P. plebeius (Broussonet, 1782) with designation of a neotype (Perciformes: Polynemidae). Ichthyol Res 48:117–126
Myers GS (1936) A new polynemid fish collected in the Sadong
River, Sarawak by Dr. William T. Hornaday. J Wash Acad Sci
26:376–382
Patterson C, Johnson GD (1995) The intermuscular bones andligaments of teleostean fishes. Smithson Contrib Zool 559:1–
83
Rainboth WJ (1996) Fishes of the Cambodian Mekong. FAO
species identification field guide for fishery purposes. FAO,
Rome
Roberts TR (1989) The freshwater fishes of western Borneo(Kalimantan Barat, Indonesia). Mem Calif Acad Sci 14:i–
xii ⫹ 1–210
Talwar PK, Jhingran AG (1992) Inland fishes of India andadjacent countries, vol 2. Balkema, Rotterdam
Vaillant ML (1893) Contribution a l’étude de la fauna
ichthyologique de Bornéo. Nouv Arch Mus Hist Nat 5:1–
112
Weber M, de Beaufort LF (1922) The fishes of the IndoAustralian Archipelago, vol 4. Heteromi, Solenichthyes,
Synentognathi, Percesoces, Labyrinthici, Microcyprini. Brill,
Leiden