A new genus, Leptomelanosoma, for the polynemid fish
previously known as Polydactylus indicus (Shaw, 1804)and a redescription of the species
Hiroyuki Motomura1 and Yukio Iwatsuki2
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
Faculty of Agriculture, Miyazaki University, 1-1 Gakuen-kibanadai-nishi, Miyazaki 889-2192, Japan(e-mail: yuk@cc.miyazaki-u.ac.jp)
Received: September 19, 1999 / Revised: June 9, 2000 / Accepted: July 10, 2000

IchthyologicalResearch©The Ichthyological Society of Japan 2001

Ichthyol Res (2001) 48: 13–21

Abstract A new genus, Leptomelanosoma, is proposed for the polynemid fish, Polydactylus
indicus (Shaw, 1804). The genus differs from all other genera in the family Polynemidae by
the following combination of characters: anterior one-third of lower jaw with small teeth
extending onto lateral surface, adjacent portion of lip poorly developed; ethmoid notcovered dorsally by frontals; sphenotics visible dorsally between anterior margins of parietal and pterotic; upper and lower caudal fin lobes very long, filamentous; swimbladder withmany appendages inserted into lateral walls of abdominal cavity; grayish-black body. The
type species, Polydactylus indicus, is redescribed as Leptomelanosoma indicum.
Key words Polynemidae · New genus · Redescription · Leptomelanosoma indicumT

he circumtropical family Polynemidae, a common
inhabitant of coastal, brackish or fresh waters(Smith, 1949; Munro, 1955, 1967; Menon, 1974; Menonand Babu Rao, 1984; Feltes, 1991, 1993; Nelson, 1994), ischaracterized by 3 to 16 detached lower threadlike pectoral fin rays. This unique character has been considered
to operate as a sense organ, enabling polynemids tosearch for food in muddy waters (Marshall, 1964; Munro,
1967; Smith, 1986; Grove and Lavenberg, 1997).
Feltes (1991, 1993) recognized seven genera, Eleutheronema (Bleeker, 1862), Filimanus (Myers, 1936), Galeoides (Günther, 1860), Parapolynemus (Feltes, 1993),
Pentanemus (Günther, 1860), Polydactylus (Lacepède,1803) and Polynemus (Linnaeus, 1758), with a total of
33 species in the family. About half the members
were included in Polydactylus, characterized by thefollowing combination of characters: large eye, toothplate on vomer simple or absent, width of tooth bandon upper and lower jaws wider than space separating
tooth bands on opposing premaxilla, basisphenoid incontact with prootic, pectoral fin insertion well below
midline on lateral body, length of uppermost pectoral
filaments less than standard length (except P.
macrophthalmus), pectoral fin base (including base ofpectoral filaments) less than upper jaw length andswimbladder not extending beyond anal fin origin(Feltes, 1993).

Polydactylus indicus (Shaw, 1804), which is widely distributed in the Indo-Australian Archipelago, shares thesecharacters. However, it is herein considered as a monotypic new genus, on the basis of morphological characters
including body coloration. The type species of the new
genus is also redescribed.

Methods
Methods for counts and measurements generally followed Hubbs and Lagler (1947) and Feltes (1991), being
made on the left side wherever possible. In addition,dermal eye opening was taken as the greatest distance
between the fleshy margins of the eye. The length of thepectoral fin base was measured from the base of theuppermost pectoral fin ray to the base of the lowermost
pectoral filament, and those of the upper and lower caudal fin lobes from middle of the posterior margin of thehypural plate to the posterior tip of the longest caudal fin
ray of the upper and lower lobes, respectively. Gill raker
counts were made on the first arch, the upper count being
given first (lower counts including a raker at angle).
Standard length is expressed as SL.
Osteological examinations were based on specimens
stained in alizarin red-S and radiographs, in 27 species,
representing the seven polynemid genera being ex-

14

H. Motomura and Y. Iwatsuki

amined overall (see Comparative material examined).
Osteological terminology generally followed Rojo
(1991). In addition, terminology of the supraneuralbones follows Mabee (1988), and the formula for
configuration of the supraneural bones, anterior neuralspines and anterior dorsal fin pterygiophores, Ahlstrom
et al. (1976). Institutional codes followed Leviton et al.
(1985), with additional institutional abbreviations as follows: Fisheries Science Course, Department of Animal
Sciences, Miyazaki University, Japan (MUFS); Phuket
Marine Biological Center, Thailand (PMBC); Shanghai
Fisheries University, China (SFU).

Leptomelanosoma gen. nov.
Type species. Polynemus indicus Shaw, 1804: 155[type locality: Vizagapatnam, India, based on “Maga
Booshee” of Russell (1803: 68, fig. 184)].
Diagnosis. A genus of Polynemidae with the following combination of characters: swimbladder with many
appendages inserted into lateral walls of abdominal cavity (Fig. 1); anterior one-third of lower jaw with small
teeth extending onto lateral surface, adjacent portion of
lip poorly developed (Fig. 2); tooth plate of vomer oval
(Fig. 3); ethmoid not covered dorsally by frontals (Fig. 4);
sphenotics visible dorsally between anterior margins ofparietal and pterotic (Fig. 4); upper and lower caudal fin
lobes very long, filamentous (Fig. 5); grayish-black body(Fig. 5).
Remarks. Although the new genus, Leptomelanosoma, shares many characters given by Feltes (1993) for
Polydactylus, the former differs from Polydactylus andother polynemid genera in having a conspicuous
swimbladder with many appendages (Fig. 1A,B). In allother polynemid genera, the swimbladder is simple orabsent (Table 1). Leptomelanosoma has numerous appendages in two rows along the entire and vicinity of
middle of lateral surface of the swimbladder (Cuvier in
Cuvier and Valenciennes 1829: p. 385; this study: Fig. 1A).
The appendages arising along the entire lateral surface
are longer than those in the other row, restricted to thevicinity of middle of the swimbladder (Fig. 1A). The appendages of both rows were fully inserted into the lateralwalls of the abdominal cavity (Fig. 1C). Such a characterhas never before been reported in other fishes, although
the swimbladder of sciaenid and sillaginid fishes varies in
configuration with species (Sasaki, 1989; McKay, 1992).
Character condition of swimbladder with many appendages of Leptomelanosoma is derivative among the family
Polynemidae because other genera of the family andmost percoids possess a simple, carrot-shaped swimbladder (Sasaki, 1989; this study).

Fig. 1. Swimbladder and abdominal cavity of Leptomelanosoma indicum, URM-P 12700, 198 mm SL. A Swimbladderin dorsal view. B Swimbladder in ventral view. C Abdominal
cavity in ventral view (arrows indicate holes into which theswimbladder appendages were inserted). Anterior to left ineach case. Bars 5 mm

The anterior portion of the lower jaw lip of Leptomelanosoma and Parapolynemus (specimen over ca.
70 mm SL) are poorly developed, and the adjacent teeth
extend onto the lateral surface of the dentary (Fig.
2A; Table 1). In the remaining genera of the family, except Eleutheronema, the lower jaw lip is well developed
and the dentary teeth restricted to the dorsal surface(Fig. 2B; Table 1). The lower jaw lip in Eleutheronema
occurs only on the posterior one-third of the jaw(Table 1).
The vomerine tooth plate of Leptomelanosoma, especially in adults, is oval, compared with semicircular or
triangular in other polynemids (Fig. 3A,B; Table 1), except for Eleutheronema, in which it is triangular in outline with smaller deciduous tooth plates on either side
(Marathe and Bal, 1958: Fig. 5a; Feltes, 1993; this study).

A new polynemid genus

15

Fig. 2. Left lateral view of upper and lower jaws. A Leptomelanosoma indicum, URM-P 29076, 129 mm SL. B Polydactylus
virginicus, CAS 104888, 92 mm SL. Bars 5 mm

Fig. 4. Dorsal view of neurocranium. A Leptomelanosoma
indicum, URM-P 12700, 198 mm SL. B Polydactylus virginicus,
CAS 104888, 92 mm SL. EP, epiotic; E, ethmoid; EX,
exoccipital; F, frontal; LE, lateral ethmoid; N, nasal; PA, parietal; PT, pterotic; SP, sphenotic; SU, supraoccipital. Bars 5 mm

Fig. 3. Ventral view of dentition of premaxilla and roofof oral cavity. A Leptomelanosoma indicum, URM-P 29076,
129 mm SL. B Polydactylus virginicus, CAS 104888, 92 mm SL.
ECT, ectopterygoid; PAL, palatine; PM, premaxilla; V, vomer.
The numerous tiny teeth are not illustrated. Bars 5 mm

Furthermore, the tooth plates of the palatines andectopterygoids of Leptomelanosoma are wider andshorter than those of Polydactylus (Fig. 3A,B).
In most polynemids, the ethmoid is covered dorsallyby the frontals (Fig. 4B; Table 1), whereas in Leptomelanosoma, it is dorsally exposed between the nasals oneither side (Marathe and Bal, 1958: fig. 2b; this study: Fig.
4A; Table 1). Furthermore, the sphenotics of Leptomelanosoma are dorsally exposed between the anterior margins of the parietal and pterotic (Marathe and Bal, 1958:
fig. 2b; this study: Fig. 4A; Table 1), but the sphenotics ofother polynemid genera are covered by the frontals (Fig.
4B; Table 1). The sphenotics of all polynemid genera

including Leptomelanosoma are laterally exposed, being
similar to that of the majority of percoids (e.g., Sasaki,
1989; Heemstra and Randall, 1993).
The upper and lower caudal fin lobes of both Leptomelanosoma and Parapolynemus are extremely long andfilamentous (Table 1), although they are easily damaged
at the tips. This character is not found in other polynemid
genera (Table 1). Despite this similarity, Leptomelanosoma differs from Parapolynemus in having
shorter pectoral fin rays (less than head length vs greaterthan head length in latter), shorter pectoral filaments(less than SL vs much greater than SL), five pectoral
filaments (vs six or seven, usually seven), five infraorbitals (vs three), basisphenoid present (vs absent) andgreater adult size (attaining ca. 100 cm SL vs ca. 10 cm
SL).
The characters of lower jaw and caudal fin lobes in
Leptomelanosoma and Parapolynemus are considered tobe the homoplasy because each genus belongs to a different lineage in the Polynemidae. There are two major
lineages in the family (Feltes, 1991; this study): one, including Parapolynemus and Polynemus, is characterized

16

H. Motomura and Y. Iwatsuki

Fig. 5. Drawing (A) of the “Maga Booshee” of Russell (1803) and Leptomelanosoma indicum (B), MUFS 16846, 262 mm SL,
Kalairt fish landing port, Chennai, India(English name: Indian threadfin)(Figs. 1A–C, 2A, 3A, 4A, 5A, B)

Ocean and Australia); Day, 1876: 179 (India); Weber and deBeaufort, 1922: 205 (Indo-Australian Archipelago); Munro,
1955: 97 (Ceylon); Kagwade, 1970: 5, Fig. 2 (India); Menon,
1974: POLYN Poly 1 (eastern Indian Ocean and western
central Pacific Ocean); Jayaram, 1981: 348 (India); Menonand Babu Rao, 1984: POLYN Poly 1 (western Indian Ocean).
Polynemus sele Hamilton, 1822: 226 (type locality: estuaries ofGanges, India).
Polynemus uronemus Cuvier in Cuvier and Valenciennes, 1829:
385 (type locality: unknown, new name for P. indicus Shaw,
1804); Bleeker, 1849: 58 (Surabaya, Java, Indonesia).
Polynemus gelatinosus McClelland, 1843: 181, pl. 6 (type locality: Bengal, India, new name for P. sele Hamilton, 1822).
Trichidion indicum; Bleeker, 1868: 293 (Bintan, Indonesia);
Bleeker, 1983: 22, pl. 454, fig. 1 (locality unknown, originally
Polynemat pl. 2, unpublished plate by P. Bleeker).
Trichidion indicus; Fowler, 1905: 501 (mouth of Baram River,
Kalimantan, Malaysia).
Polydactylus indicus; Smith, 1949: 327 (South Africa); Smith,
1986: 721, fig. 233.2 (South Africa); Talwar and Jhingran,1992: 910 (India); Mansor et al., 1998: 87, pl. 92, fig. 270 (South
China Sea).

Polynemus indicus Shaw, 1804: 155 [type locality:
Vizagapatnam, India, based on “Maga Booshee”of Russell(1803: 68, fig. 184)]; Cantor, 1849: 1011 (Malay Peninsula);
Bleeker, 1854: 427 (India); Günther, 1860: 326 (east IndianMaterials (31 specimens, 97–710 mm SL). AMS B. 8136,
211 mm SL, Chennai (5Madras), India; AMS I. 27630-004,
27630-034, 2 specimens, 149–160 mm SL, Kuala Kurau, Malaysia (5° N, 100°259 E); ANSP 88347, 205 mm SL, Mumbai

by a reduction of the size of the orbit and modification of
the associated structures (see Feltes, 1993: Fig. 5) and thepectoral fin insertion relatively high on the body; theother, including Eleutheronema, Filimanus, Galeoides,
Leptomelanosoma, Pentanemus and Polydactylus, has amoderate to large orbit and the pectoral fin insertion
relatively low on the body.
The body color of Leptomelanosoma is blackish, compared with that of other genera, in which it is silver orsilvery-golden. The genus is currently represented by asingle species.
Etymology. From the Greek “lepto” meaning slender, “melano” black and “soma” body, in reference to theslender body tinged with black. The gender is neuter.

Leptomelanosoma indicum (Shaw, 1804)

A new polynemid genus

17

Table 1. Comparison of genera in the family Polynemidae
Swimbladder

Teeth and lip of lower jaw

Tooth plate of vomer

Ethmoid andsphenotics

Tips ofcaudal fin

Eleutheronema

AbsentTeeth extending onto
lateral surface of anterior
two-thirds, adjacent portionof lip absent

Dentate, large, triangularin outline with smaller
deciduous tooth plates oneither side

Not dorsally
exposedNot
filamentous

Filimanus

Present, simple

Teeth restricted to dorsal
surface, lip well-developed

Dentate, small, triangularNot dorsally
exposedNot
filamentous

Galeoides

Present, simple

Teeth restricted to dorsal
surface, lip well-developed

Edentate

Not dorsally
exposedNot
filamentous

Leptomelanosoma
gen. nov.

Present, withappendages

Teeth extending onto
lateral surface of anterior
one-third, adjacent portionof lip poorly developed

Dentate, large, oval

Dorsally
exposedFilamentous

Parapolynemus

AbsentTeeth restricted to dorsal
surface, lip well-developed
but, in larger specimens(over ca. 70 mm SL), teeth
extending onto lateralsurface of anterior
one-third, adjacent portionof lip poorly developed

Edentate

Not dorsally
exposedFilamentous

Pentanemus

Present, simple

Teeth restricted to dorsal
surface, lip well-developed

Edentate

Not dorsally
exposedNot
filamentous

Polydactylus

Present, simple

Teeth restricted to dorsal
surface, lip well-developed

Edentate or dentate, large,
semicircular or triangularNot dorsally
exposedNot
filamentous

Polynemus

AbsentTeeth restricted to dorsal
surface, lip well-developed

Edentate or dentate, small,semicircularNot dorsally
exposedNot
filamentous(5Bombay), India; FSKU 96814, 182 mm SL, Tawau, Sabah,
Malaysia (dissected following counts and measurements);
MNHN 4347, 2 specimens, 139–164 mm SL, Mumbai(5Bombay), India; MNHN 1977-0240, 317 mm SL, Kuala
Lumpur, Malaysia; MNHN A.3034, 2 specimens, 97–104 mm
SL, Mumbai (5Bombay), India; MNHN A.3035–3036, 2 specimens, 101–189 mm SL, Ganges River, India; MNHN A.3037, 2
specimens, 240–254 mm SL, Pondicherry, India; MNHN A.3047,
235 mm SL, Mumbai (5Bombay), India; MUFS 16846, 262 mm
SL, Kalairt fish landing port, Chennai (5Madras), India; MUFS
17010, 215 mm SL, Chinatown market, Singapore; PMBC 6742,
2 specimens, 161–248 mm SL, Myanmar, north Andaman Sea(15°18.39 N, 97°13.89 E); QM I. 26191, 103 mm SL, Pagan Island,
Indonesia; UMMZ 225574, 3 specimens, 112–122 mm SL,
Songkhla, Thailand; URM-P 12700, 198 mm SL, Samyan
market, Bangkok, Thailand (dissected following counts andmeasurements); URM-P 13776, 294 mm SL, Samyan market,
Bangkok, Thailand; URM-P 29076, 129 mm SL, Bangkok, Thailand; USNM 201807, 710 mm SL, Pakistan (23° N, 68°089 E);
USNM 345342, 215 mm SL, Myanmar, north Andaman Sea(15°159 N, 95°159 E); USNM 357732, 338 mm SL, Palk Bay, Sri
Lanka (9°299 N, 79°28–479 E); USNM 357761, 2 specimens,
200–243 mm SL, India (22°459 N, 68°249 E).

Description. Counts and proportional measurements as percentages of SL of Leptomelanosoma in-dicum are given in Table 2. Characters given in thegeneric diagnosis are not repeated.
Body oblong, compressed; obtusely conical snout
projecting strongly beyond upper jaw, its length slightly
greater than orbit diameter; eye covered with adipose
eyelid; upper lip absent; maxilla covered with deciduous
scales; posterior margin of preopercle serrated; villiform
tooth in broad bands on vomer, palatines and ectopterygoids; posterior margin of maxilla extending far beyond
posterior margin of adipose eyelid; all pectoral fin rays
unbranched; tip of longest pectoral filament extending
far beyond posterior margin of pelvic fin; origin of second dorsal fin base in advance of that of anal fin base;second dorsal fin base longer than anal fin base; anal finbase shorter than upper jaw length; second spine of firstdorsal fin very strong in adults; dorsal, anal and caudal
fin bases covered with scales; lateral line extending fromupper end of gill opening to upper end of lower caudal
fin lobe; caudal peduncle depth 2.0–2.3 in caudal
peduncle length; highly developed foramina present on
pterotic; lower tip of seventh proximal pterygiophore offirst dorsal fin directed forward; formula for configura-

18

H. Motomura and Y. Iwatsuki
Table 2. Counts and measurements for Leptomelanosoma indicum, expressed as percentages of standard length (n 5 31)
Standard length (mm)Fork length (mm)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
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 lengthPre-anal fin length
First dorsal fin origin to anal fin origin
Pelvic fin base to anal fin baseSecond dorsal fin base length
Anal fin base length
Longest pectoral fin length (3rd or 4th)
Longest pectoral filament length (5th)Pectoral fin base length
Longest 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 lengtha
Lower caudal fin lobe lengthaa97–710
110–761
VIII-I, 12–13 (13)III, 10–11 (11)
12–14 (14)5I, 5
69–72 (70)
7–8 (8)/9–12 (10)
8–9 (8) 1 10–12 (11) 5 18–21 (19)30–34 (32)
22–25 (23)
21–26 (23)
11–15 (13)
5–7 (6)
3–5 (4)
4–6 (5)
7–9 (8)
21–23 (22)
14–15 (15)35–37 (36)
58–63 (61)64–69 (67)
38–43 (40)
28–33 (31)
15–18 (17)
13–16 (14)19–22 (21)28–45 (37)
8–10 (8)
13–16 (14)17–19 (18)
7–10 (9)18–21 (19)
7–11 (9)15–19 (17)21–25 (23)
10–12 (11)39–71 (58)
36–78 (60)

Includes broken caudal fin lobes

tion of supraneural bones, anterior neural spines andanterior dorsal fin pterygiophores /0/012/111/1/1/111/;
vertebrae 10 1 14; six epipleural ribs.
Fresh color notes.—Based on color transparencies of
MUFS 16846, 262 mm SL (Chennai, India) and MUFS
17010, 215 mm SL (Singapore): head and upper sides oftrunk tinged slightly blackish-brown, becoming deep
black on lower sides; snout and abdominal regions blackish; membranes of first and second dorsal fins and caudal
fin blackish, distal part of these fins black; pectoral
fin membrane deep black; origin of pectoral filaments

dusky-yellowish, grading to blackish posteriorly; pelvic
fin origin dusky-yellowish, other parts dusky-white.
Color of preserved specimens.—Origin of pectoral filaments and pelvic fin white; other body colors lighter thanin fresh specimens.
Distribution. Leptomelanosoma indicum is widelydistributed in the Indo-West Pacific, being currently
known from South Africa (Smith, 1949, 1986),
Mozambique, Madagascar, Mauritius, western India, andSri Lanka (Menon and Babu Rao, 1984), and eastern
India, Bangladesh, Myanmar, Thailand, Malaysia,

A new polynemid genus

Fig. 6. Localities of specimens of Leptomelanosoma indicum
examined in this study

Singapore, Indonesia, southern New Guinea, and northern Australia (Menon, 1974). Localities of specimens of
the species examined in this study are indicated in Fig. 6.
Ecological note. Collection sites of the specimens
examined indicated that the species occurs in coastal
waters and estuaries, being similar habitats to those occupied by other polynemids. Underwater observations (atUnderwater World Aquarium, Singapore) of Leptomelanosoma indicum indicated that the species usually
spread the pectoral filaments, but may also remain motionless on the substrata. Observations (by the authors)
were of a specimen in a dimly lit artificial cave.
Remarks. Leptomelanosoma indicum (Shaw, 1804)
can be easily distinguished from other polynemid species
by the combination of five pectoral filaments, long caudal
fin lobes and a grayish-black body. Polynemus indicus, theoldest available name for a polynemid species having theabove characters, was proposed by Shaw (1804), for
the “Maga Booshee” of Russell (1803), whose descriptionof the species included a correct figure (Fig. 5A) but
lacked a formal scientific name and gave no indication of
any type specimens. Although the description of P. indicus
by Shaw (1804) and that earlier by Russell (1803) werevery poor, Russell’s drawing clearly indicates five pectoral
filaments, long caudal fin lobes and a grayish-black body.
Subsequently, Hamilton (1822) described Polynemus
sele as a new species from estuaries of the Ganges River,India. This description also gave no indication of any
type specimens. In fact, the present whereabouts of all ofHamilton’s (1822) types, including the holotype of P. sele,
are unknown; they are not held in BMNH and related
British and Indian museums (Hora, 1929; A.-M. Hine,
personal communication). However, the diagnostic characters of five pectoral filaments and long caudal fin lobes
given in the original description of P. sele are consistent
with those of L. indicum (Shaw, 1804). An initial unpub-

19

lished plate of P. sele Hamilton, 1822, subsequently
published by McClelland (1843, pl. 6), also shows fivepectoral filaments, long caudal fin lobes and a grayishblack body. Furthermore, Hamilton (1822) wrote “TheMaga booshee [5P. indicus Shaw, 1804] of Russell has
certainly a strong resemblance to the Sele [5P. sele] of
the Ganges.” Although P. sele was said to differ from the“Maga Booshee” of Russell (1803) in having seven firstdorsal fin spines (vs eight spines in the latter) and 14
second dorsal fin rays (vs 15 rays), the first spineof the first dorsal fin was apparently overlooked by
Hamilton (1822) because of its very small size.
Cuvier in Cuvier and Valenciennes (1829) described
Polynemus uronemus, being a new name for P. indicus
Shaw, 1804. Furthermore, McClelland (1843) described P.
gelatinosus, from Bengal, India, being a new name for P.
sele Hamilton, 1822, at that time including Hamilton’s(1822) unpublished plate. Both new names, P. uronemus
and P. gelatinosus, have no standing in nomenclature
because the names do not have taxonomic priority.
Bleeker (1868, 1983) and Fowler (1905) assigned
Polynemus indicus to Trichidion (Klein), published in
1749. Being a pre-Linnaean name, however, it has nostanding in nomenclature. Although Walbaum, in 1792,
republished Klein’s Trichidion, the International Commission on Zoological Nomenclature (ICZN, Opinion21) declared the reprinted names of Klein to be unavailable under the Code (Myers, 1936).
Comparative material examined. An asterisk indicatesthat the specimens were dissected. All specimens were X-rayed,
except for Filimanus heptadactyla, NTM S. 14784–007, F. sealei,
AMS IB. 1462–1463, Galeoides decadactylus, ZMB 569, andPolydactylus sextarius, ZMB 565. Eleutheronema tetradactylum:
FRLM 23412, 228 mm SL; MUFS *14465, 14484, 2 specimens,
164–167 mm SL; MUFS *14479, 227 mm SL; MUFS 14997,
213 mm SL; SFU 3837, 194 mm SL; URM-P 10904, 153 mm SL.
Filimanus heptadactyla: NTM S. 14784–007, 2 specimens, 112–113 mm SL. F. perplexa: PMBC 5913, 111 mm SL. F. sealei: AMS
IB. 1462–1463, 2 specimens, 130–147 mm SL; USNM 57844 (holotype of Polydactylus opercularis Seale & Bean, 1907), 123 mm
SL. F. similis: URM-P 12605, *12611, 12639, 3 specimens, 104–
115 mm SL. F. xanthonema: FRLM 15716, 62 mm SL. Galeoides
decadactylus: CAS 98606, 126 mm SL; USNM *348379, 2 specimens, 108–110 mm SL; ZMB 569 (holotype of Polynemus
decadactylus), 175 mm SL. Parapolynemus verekeri: AMS I.
2770 and I. 2771 (lectotype and paralectotype), 2 specimens,
54–72 mm SL; MUFS *18281, 75 mm SL; MUFS 18282–18286, 5
specimens, 63–92 mm SL; NTM S. 14487–005, 10 specimens, 61–
82 mm SL. Pentanemus quinquarius: CAS *50055, 2 specimens,
135–143 mm SL; ISH 1089–1964 at ZMH, 137 mm SL; ISH
1275–1964 at ZMH, 131 mm SL; ISH 130–1977 at ZMH,
136 mm SL; ISH 1493–1964 at ZMH, 2 specimens, 107–137 mm
SL; ISH 158–1962 at ZMH, 7 specimens, 86–170 mm SL; ISH
159–1962 at ZMH, 123 mm SL; ISH 177–1963 at ZMH, 2 specimens, 142–167 mm SL; ISH 307–1959 at ZMH, 2 specimens,
108–184 mm SL; USNM 348378, 2 specimens, 94–110 mm SL.

20

H. Motomura and Y. Iwatsuki

Polydactylus approximans: USNM 65621, 153 mm SL. P.
macrochir: QM I. *25090, 580 mm SL. P. microstomus: MUFS
14159, 154 mm SL. P. multiradiatus: FRLM 23414–23417, 4
specimens, 130–144 mm SL; FRLM 23471–23474, 4 specimens,
136–168 mm SL. P. nigripinnis: FRLM 21472, 139 mm SL;
FRLM 23413, 161 mm SL. P. octonemus: USNM 739 (syntypes),
2 specimens, 62–79 mm SL; USNM 155666, 130 mm SL. P.
oligodon: NSMT-P 54096–54107, 11 specimens, 104–174 mm
SL; USNM *300465, 122 mm SL. P. opercularis: USNM 41054,
184 mm SL; USNM 119740, 138 mm SL. P. plebeius: FRLM
1624, 178 mm SL; MUFS *14124, *14298, 2 specimens, 165–
175 mm SL; SFU 3832, 171 mm SL; URM-P 24672, 132 mm SL;
YCM-P 25293, 3 specimens, 103–150 mm SL. P. quadrifilis:
ISH 298–1959 at ZMH, 214 mm SL. P. sexfilis: URM-P 36431–
36433, 3 specimens, 62–72 mm SL. P. sextarius: MUFS *14486,
131 mm SL; MUFS 15628–15630, 3 specimens, 128–145 mm SL;
ZMB 565 (holotype of Polynemus sextarius), 125 mm SL. P.
virginicus: CAS *104888, 2 specimens, 92–105 mm SL; USNM
133675, 225 mm SL. Polynemus dubius: URM-P 13930, 138 mm
SL. P. hornadayi: USNM 100632 (holotype), 193 mm SL. P.
melanochir: FSKU 21007–21008, 2 specimens, 116–137 mm SL;
URM-P 29087, 147 mm SL. P. multifilis: NSMT-P 54112,
145 mm SL. P. paradiseus: BSKU *21200, 139 mm SL; NSMT-P
21776, 132 mm SL; URM-P 10847, 165 mm SL.
Acknowledgments We express our sincere thanks to S.
Kimura (FRLM) and T. Yoshino (URM) for critical reading of
early version of the manuscript and for providing advice, information and specimens for our study. We greatly appreciate thefollowing persons and institutions for specimen loans: W.G. Saul
(ANSP); Y. Machida and K. Sasaki (BSKU); W.N. Eschmeyer
and T. Iwamoto (CAS); H. Ida (FSKU); K. Matsuura and G.
Shinohara (NSMT); H.K. Larson (NTM); S. Bussarawit and U.
Satapoomin (PMBC); H.-L. Wu (SFU); D.W. Nelson (UMMZ);
J. Finan, S.L. Jewett, G.D. Johnson, L. Palmer, S.J. Raredon and
J.T. Williams (USNM); M. Hayashi (YCM); H. Wilkens (ZMH).
We are most grateful to M. McGrouther (AMS) for a loan of thelectotype and paralectotype of Parapolynemus verekeri, A.-M.
Hine (BMNH) for information on the type of Polynemus sele,
S.L. Jewett, L. Palmer and J.T. Williams (USNM) for opportunities to examine the syntypes of P. octonemus, the holotype of
Polydactylus opercularis Seale & Bean and the holotype of
Polynemus hornadayi, and H.-J. Paepke (ZMB) for his provision of type data and photographs of P. decadactylus and P.
sextarius. We thank V. Lheknim and P. Pholpunthin (Faculty of
Science, Prince of Songkhla University, Thailand), M.N.
Venugopal and A. Chakraborty (Department of Fishery Biology, College of Fisheries, India), and A. Choochern (Bangkok,
Thailand) for their assistance in field work at various times.
Lastly, we thank Y. Motomura (Miyazaki, Japan) for her assistance and G.S. Hardy (Thames, New Zealand), who read theinitial manuscript and offered helpful comments. This study
was supported in part by grants awarded to the first author by
the Fujiwara Natural History Foundation (Tokyo, Japan), theSasakawa Scientific Research Grant from the Japan Science
Society (Tokyo, Japan) and the Ito Foundation for the Advancement of Ichthyology (Tokyo, Japan).

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