International Scholarly Research Notices

International Scholarly Research Notices / 2012 / Article

Research Article | Open Access

Volume 2012 |Article ID 860768 | https://doi.org/10.5402/2012/860768

Simon Weigmann, "Contribution to the Taxonomy and Distribution of Six Shark Species (Chondrichthyes, Elasmobranchii) from the Gulf of Thailand", International Scholarly Research Notices, vol. 2012, Article ID 860768, 24 pages, 2012. https://doi.org/10.5402/2012/860768

Contribution to the Taxonomy and Distribution of Six Shark Species (Chondrichthyes, Elasmobranchii) from the Gulf of Thailand

Academic Editor: J. D. Reimer
Received22 Nov 2011
Accepted02 Jan 2012
Published29 Apr 2012

Abstract

A collection of nine shark specimens from six different species, obtained in 1993 from the Gulf of Thailand, was examined in this study. The sharks were determined, morphometrically and meristically analyzed, photographically documented, and compared with relevant literature. Additionally, further available material from the fish collections of the Zoological Museum Hamburg, the Senckenberg Naturmuseum Frankfurt, and the Muséum national d’Histoire naturelle, Paris, was examined by way of comparison. Contrary to most references, prominent dorsal ridges were detected in several specimens of Chiloscyllium griseum. Additionally, one of the specimens had a very unusual big ocellar blotch on the head which had not been reported for this genus before. For Paragaleus randalli, it could be proven that the teeth morphologically deviate strongly from those shown in literature due to having much larger cusps. Furthermore, the known distribution area of Paragaleus randalli could be extended considerably eastwards by about 2000 km. For a seventh species, Paragaleus tengi, differences between the actual morphology of upper lateral teeth and those drawn in the original description were detected.

1. Introduction

About 500 of the more than 1200 globally known species of Chondrichthyes are sharks, including the world’s biggest fish species [1]. The highest diversity of Chondrichthyes can be found in the East Indian Ocean [24], where the catches of elasmobranch fishes have increased significantly over the last decades from 18 600 t in 1950 to 77 700 t in 1997 [5]. Today Indonesia has the world’s largest chondrichthyan fishery [3]. Extensive targeted fishery and bycatch belong to the most important reasons for the recent decline of the populations of many elasmobranch species [6, 7]. Sharks are especially susceptible to population declines because the lifestyle of many species is characterized by late attainment of sexual maturity, slow growth, and low reproductive output [2, 8, 9]. Due to the numerous population declines, it is very important to develop management and protection programs for many elasmobranch species, which require well-founded knowledge about the taxonomy, distribution, and abundance of the species. However, although many new elasmobranch species have been described in recent years [1, 1013], the knowledge on many known species is still scarce due to the often very old and sketchy original descriptions like those by Müller and Henle [14]. Another reason for the gaps in knowledge is the often insufficient declaration of elasmobranch catches by fishermen, who classify most caught specimens simply as “diverse Elasmobranchii” or “small sharks” instead of making a more detailed determination [5, 15].

In order to make a contribution to the filling of these knowledge gaps, a collection of nine shark specimens from the Gulf of Thailand and many comparative specimens were examined in this study. Thailand was the fifth most important chondrichthyan fishing nation in the East Indian Ocean in 1997 with 5600 t officially landed [5]. The examined Thai specimens belong to the Carcharhinidae species Carcharhinus dussumieri, the two Hemigaleidae species Hemigaleus microstoma and Paragaleus randalli, the Sphyrnidae species Sphyrna lewini and the two Hemiscyllidae species Chiloscyllium griseum and C. punctatum.

The Carcharhinidae is by far the most speciose shark family in Thai and adjacent waters with 30 species [16]. Its members are characterized by two nonspiny dorsal fins, nasoral grooves and barbles, an under, or beyond-the-eyes located mouth and nictitating eyelids [17] as well as a precaudal pit and an intestinal valve of scroll type [18]. The second most speciose family in this region is the family Triakidae with only seven species [16]. The family Hemigaleidae is represented in the region by four species [16]. It is morphologically similar to the family Carcharhinidae, but all of its members have an intestinal valve of spiral type [18]. The Sphyrnidae, represented by four species in Thai and adjacent waters [16], have a cephalofoil, a uniquely formed head with lateral, bladelike expansions [18]. The Hemiscyllidae with four species in the region [16] are—like all Orectolobiformes—characterized by the presence of an anal fin, two equal-sized, nonspiny dorsal fins, barbles, nasoral grooves, and a short mouth that ends in front of the eyes [19]. The species of Hemiscyllidae in particular have a slender, conical body, large spiracles, and short barbles [17].

This study provides extensive morphometrical analyses for six shark species for most of which such detailed morphometrics have not been published before. Additionally, tooth row counts are given for all specimens from the Thailand collection as well as morphological descriptions and comparisons with relevant literature.

A morphologically correct image of upper anterolateral teeth of Paragaleus randalli is shown here for the first time. Furthermore, the known distribution area of Paragaleus randalli is extended.

2. Material and Methods

The examined Thai collection of nine sharks from six different species was collected by Matthias Stehmann during a Thailand expedition that took place from the 5th to the 11th December 1993 after the fourth Indo-Pacific Fish Conference (IPFC). The specimens were acquired from local fishermen in the two Thai harbors shown in the map in Figure 1: Cha-Am (12°49′N, 100°E) and Pak Phanang (8°20′N, 100°15′E). According to the fishermen, the sharks were caught nearby those harbors. All specimens were fixed in 4% formaldehyde solution soon after the catch and preserved in 70% ethanol afterwards.

The map was generated using ArcMap 9.3.1 by ESRI [20] and based on the Global Relief Model ETOPO 1 of the National Geophysical Data Center (NOAA) [21]. The country borders were visualized by means of the shapefiles supplied by ESRI for the ArcExplorer-Java Edition for Education 2.3.2 (AEJEE) [22]. Land below the sea level was colorized in the color of the lowest land elevation class using Adobe Photoshop CS 4 [23].

Additionally to the nine specimens from the Thai collection, the following material from the fish collections of the Zoological Museum Hamburg (ZMH), the Senckenberg Naturmuseum Frankfurt (SMF) and the Muséum national d’Histoire naturelle, Paris (MNHN) was examined by way of comparison.

2.1. Carcharhinus dussumieri

ZMH 2137: male postembryo, 264 mm total length (TL) and female postembryo, 335 mm TL, China: Futschau, Fokien, 8 Sep. 1911, Cons. G. Siemssen. ZMH 2149: male postembryo, 247 mm TL, male postembryo, 262 mm TL and female postembryo 246 mm TL, China: Futschau, Fokien, 9 Sep. 1904, Cons. G. Siemssen. ZMH 25479: female postembryo, 260 mm TL, Indonesia: Sumatra.

2.2. Carcharhinus sealei

ZMH 103117 (ISH 145-1965): female, 855 mm TL (with two female embryos of 365 and 373 mm TL) and female, 875 mm TL, off Pakistan: 22°10′N, 68°34′E, RV “Meteor” station 230a/65, Indian Ocean Exped., 8 Mar. 1965, 45–56 m deep, Kutter Trawl, uncataloged material: juvenile male, 530 mm TL, Sokotra Islands: 12°39′N, 53°27′E–12°36′N, 53°20′2′′E, RV “Vityaz” cruise 17 station 2567, 28 Oct. 1988, 41–43 m deep, BOT 30 m. Adult male, 850 mm TL, Sokotra Islands: 12°04.8′N, 53°12.6′E–12°09.2′N, 53°10.1′E, RV “Vityaz” cruise 17 station 2829, 15 Jan. 1989, 36–40 m deep, 29 m-Shrimp Trawl.

2.3. Hemigaleus microstoma

ZMH 120307 (ISH 57-1982): juvenile male, 540 mm TL, Indonesia: Moyo Island: 8°18′S, 117°35′E, RV “Jurong”, Jun. 1981, 150 m deep, Bottom Trawl, T. Gloerfelt-Tarp.

2.4. Paragaleus randalli

Paratype ZMH 103119 (ISH 150-1965): adolescent male, 590 mm TL, Arabian Sea: 22°01-02′N, 68°10-15′E, RV “Meteor” station 229a/65, Indian Ocean Exped., 7 Mar. 1965, 88–94 m deep. Paratype SMF 28109: adult male, 685 mm TL, Arabian Gulf: Kuwait: 28°42.88′N, 48°26.30′E–28°44.07′N, 48°27.64′E, 24 Apr. 1995.

2.5. Sphyrna lewini

ZMH 5326: female postembryo 385 mm TL, female postembryo 410 mm TL, and female postembryo 415 mm TL, Thailand: Kokra, RV “Meteor”, 14 May 1966, 25 m deep, Trawl. ZMH 10212: juvenile male, 473 mm TL, China: Prov. Fokien, 18 Dec. 1905, Cons. G. Siemssen. ZMH 22417: head only, width of cephalofoil: 223 mm, Gold Coast: Lahou, 14 Mar. 1929. ZMH 25482: female postembryo, 329 mm TL and female postembryo, 356 mm TL, Tonga, Palze. ZMH 101459 (ISH 139-1962): juvenile female, 510 mm TL, Guinea: 8°50′–9°47′N, 13°38′–14°05′W, fishing boat “Hilda”, Oct./Nov. 1962, 13–40 m deep, Bottom Trawl. ZMH 101553 (ISH 201-1963): female embryo 188 mm TL, female embryo 198 mm TL, female embryo 203 mm TL, male embryo 197 mm TL, male embryo 204 mm TL, male embryo 205 mm TL, and male embryo 206 mm TL, Guinea: Conakry: 09°45′N, 14°05′W, fishing boat “Hilda”, 4 Feb. 1963, 10–13 m deep, Kutter Trawl. ZMH 104704 (ISH 1019-1966): juvenile male, 563 mm TL, South Brasil: 32°45′S, 51°02′W, RV “Walter Herwig” station 218/66, 10 Jun. 1966, 75 m deep, 140′-Ground Trawl. ZMH 113340 (ISH 266–1975): juvenile male, 1060 mm TL, Pacific: North Mexico: 24°02′N, 111°04′W, RV “Weser” station 187, 6 Jan. 1975, 70 m deep, Bottom Trawl. Uncataloged material: juvenile female, 615 mm TL, without data. juvenile female, 820 mm TL, Northwest Madagascar: 12°34′2”S, 48°39′1′′E, RV “Vityaz” cruise 17 station 2591, 11 Nov. 1988, 53 m deep, BOT 30 m.

2.6. Chiloscyllium arabicum

ZMH 1370: juvenile male, 361 mm TL, Arabian Sea: India, Maharashtra State, off Alibag, German Indian Ocean Expedition, 25 Nov. 1955, v. Maydell. ZMH 1371: male postembryo, 115 mm TL, Arabian Sea: India, Karnataka State, North Kanara, off Karwar, German Indian Ocean Expedition, 14 Feb. 1956, v. Maydell. ZMH 25397 (ISH 1–1961): juvenile male, 320 mm TL, Arabian Sea: India, Maharashtra State, off Alibag, German Indian Ocean Expedition, 25 Nov. 1955, v. Maydell.

2.7. Chiloscyllium griseum

ZMH 1372: juvenile female, 175 mm TL, Arabian Sea: India, Maharashtra State, off Alibag, German Indian Ocean Expedition, 25 Nov. 1955, v. Maydell. ZMH 1373: juvenile male, 149 mm TL, Arabian Sea: India, Karnataka State, North Kanara, off Karwar, German Indian Ocean Expedition, 14 Feb. 1956, v. Maydell. ZMH 10114: juvenile male, 515 mm TL, Ceylon (Sri Lanka): Colombo, 27 Jul. 1904, John Hagenbeck. ZMH 100420 (ISH 229-1962): juvenile male, 205 mm TL, Arabian Sea: India, Karnataka State, North Kanara, off Karwar, German Indian Ocean Expedition, 14 Feb. 1956, v. Maydell. Paralectotypes MNHN 1009: adult male, 453 mm TL, female, 520 mm TL and adult male, 548 mm TL, India: Kerala State, Malabar, Dussumier. Lectotype MNHN 1010: juvenile male, 374 mm TL, India: Kerala State, Malabar, Dussumier. Paralectotype MNHN 1011: female, 524 mm TL, India: Kerala State, Malabar, Dussumier.

2.8. Chiloscyllium indicum

ZMH 5325: adult male, 415 mm TL, Thailand: Prachuap Khiri Khan, 13 Oct. 1965, 40 m deep, Trawl. ZMH 10121: female, 445 mm TL, Singapore.

2.9. Chiloscyllium plagiosum

ZMH 10115: female, 470 mm TL and female postembryo, 138 mm TL, China: Futschau, Fokien, 1 Jun. 1911, Cons. G. Siemssen. ZMH 10116: female, 555 mm TL (with abnormal caudal, first dorsal, and anal fin) and female, 580 mm TL, China: Futschau, Fokien, 1 Apr. 1905, Cons. G. Siemssen. ZMH 10117: juvenile male, 538 mm TL, China: Futschau, Fokien, 18 Dec. 1905, Cons. G. Siemssen. ZMH 10119: female, 499 mm TL, China: Canton. ZMH 10122: juvenile female, 267 mm TL, Manila, 1878. ZMH 22303: adult male, 650 mm TL, China: Futschau, Fokien, 1906, Cons. G. Siemssen. ZMH 22307: juvenile male, 447 mm TL, Bohol, 1874, Semper.

2.10. Chiloscyllium punctatum

ZMH 5324: juvenile male, 322 mm TL and juvenile female, 335 mm TL, Thailand: Prachuap Khiri Khan, 22 Nov. 1965, 40 m deep, Otter Trawl. ZMH 120168 (ISH 53-1982): semiadult male, 720 mm TL and adult female, 900 mm TL, Indonesia: South Java: 7°28′S, 109°12′E, RV “Jurong”, 1981, 45 m deep, Bottom Trawl, T. Gloerfelt-Tarp.

Descriptions in literature were analyzed for a seventh species, Paragaleus tengi. Morphometrics and meristics were done following Compagno [24] with very minor modifications. The habitus photographs were taken with a Nikon D90 and a Nikkor 18–105 mm zoom lens and afterwards reworked using Adobe Photoshop CS4 [23]. Detail photographs were taken using a Canon EOS 350D, a Tamron 28–200 mm zoom lens, and a Soligor Extension Tube. For verifying the tooth row counts, radiographs were taken of all specimens from the Thai collection with a 1979 launched MG 101 X-ray equipment for radiography by Philips.

3. Results

The nine examined Thai specimens represent six different shark species from two orders, four families, and five genera. Their classifications, numbers of individuals, and catch locations are shown in Table 1.


ClassSubclassOrderFamilyGenusSpeciesNumberHarbor

Chondrichthyes
Elasmobranchii
Carcharhiniformes
Carcharhinidae
Carcharhinus
dussumieri1PP
Hemigaleidae
Hemigaleus
microstoma1PP
Paragaleus
randalli1PP
Sphyrnidae
Sphyrna
lewini2PP
Orectolobiformes
Hemiscyllidae
Chiloscyllium
griseum2CA
punctatum2PP

The abbreviations of the harbors stand for CA: Cha-Am and PP: Pak Phanang.

The following species descriptions refer to the specimens from the Thai collection if not otherwise stated. However, the available comparative specimens were always checked for correspondence in the described characters.

Typical characteristics which proved to be important for the determination are provided, as well as comparisons with relevant literature and—in the case of more complex determination procedures—differences to similar species. Furthermore, comments about aberrations in the examined specimens from the descriptions in literature and possible mistakes or problems in the references including taxonomically problematic cases are given. These themes are not part of the conclusion chapter, but have been included directly in the results chapter to allow direct comparisons with the species descriptions. Three habitus photographs are shown for each of the nine examined specimens from the Thai collection. A distribution map is given for Paragaleus randalli due to the newly discovered occurrence. For distribution maps of the other examined species, see for example Compagno et al. [17]. Measurements of all nine specimens from the Thai collection can be found in Tables 2–10. A collection of 24 batoids from the same expedition was described by the author in a previous paper [25].

3.1. Carcharhinus dussumieri (Müller and Henle) [14]

Carcharhinus dussumieri is a common, but heavily fished species, which is distributed from the Arabian Sea over the shelf areas of the northern and eastern Indian Ocean until South Japan in the north [17].

The specimen of Carcharhinus dussumieri (ZMH 25683) was caught by local fishermen in the Gulf of Thailand near Pak Phanang on the 7th December 1993. It is a 75 cm long male with fully developed claspers (Figure 2(c)) and thus can be considered to be adult. Following Compagno et al. [17], Carcharhinus dussumieri reaches a maximal total length of 100 cm.

Three habitus photographs of specimen ZMH 25683 are shown in Figure 2 and its measurements in Table 2.


Measurement[mm][%TL]

TL, total length750100.0
FOR, fork length61481.9
PRC, precaudal length55574.0
PD2, pre-D2-length45861.1
PD1, pre-D1-length25033.3
HDL, head length16021.3
PG1, prebranchial length12116.1
PDP, prespiracular length
POB, preorbital length597.9
PP1, prepectoral length14719.6
PP2, prepelvic length32543.3
SVL, snout—anterior vent length34345.7
PAL, preanal fin length45760.9
IDS, interdorsal space18124.1
DCS, dorsal (D2)—caudal space628.3
PPS, pectoral—pelvic space15220.3
PAS, pelvic—anal space8210.9
ACS, anal—caudal space597.9
PCA, pelvic—caudal space19325.7
VCL, anterior vent—caudal tip l.40053.3
PRN, prenarial length222.9
POR, preoral length456.0
EYL, eye length16.42.2
EYH, eye height13.61.8
ING, intergill length 1st to last slit385.1
GS1, 1st gill slit height (unspread)172.3
GS2, 2nd gill slit height202.7
GS3, 3rd gill slit height212.8
GS4, 4th gill slit height20.32.7
GS5, 5th gill slit height141.9
P1A, pectoral anterior margin l.11815.7
P1B, pectoral base length415.5
P1I, pectoral inner margin length445.9
P1P, pectoral posterior margin length9012.0
P1H, pectoral height (base end to tip)9913.2
P1L, pec. length (ant. base to post. tip)7910.5
SOD, subocular pocket depth60.8
CDM, dorsal caudal margin length19025.3
CPV, preventral caudal margin length92.512.3
CPU, upper postventral C margin l.8811.7
CPL, lower postventral C margin l.405.3
CFW, caudal fork width547.2
CFL, caudal fork length597.9
CST, subterminal C margin length192.5
CSW, subterminal caudal width182.4
CTR, terminal caudal margin length415.5
CTL, terminal caudal lobe length537.1
D1L, D1 total length11815.7
D1A, D1 anterior margin length12016.0
D1B, D1 base length7810.4
D1H, D1 vertical height739.7
D1I, D1 inner margin length395.2
D1P, D1 posterior margin length749.9
D2L, D2 total length7610.1
D2A, D2 anterior margin length476.3
D2B, D2 base length445.9
D2H, D2 vertical height263.5
D2I, D2 inner margin length314.1
D2P, D2 posterior margin length425.6
P2L, pelvic total length709.3
P2A, pelvic anterior margin length51.56.9
P2B, pelvic base length395.2
P2H, pelvic height = max. width344.5
P2I, pelvic inner margin length222.9
P2P, pelvic posterior margin length395.2
ANL, anal fin total length739.7
ANA, anal fin anterior margin length466.1
ANB, anal fin base length415.5
ANH, anal fin vertical height243.2
ANI, anal fin inner margin length334.4
ANP, anal fin posterior margin l.39.55.3
HDH, head height at P origin8010.7
TRH, trunk height at P base end8711.6
ABH, abdomen height at D1B end10013.3
TAH, tail height at pelvic base end689.1
CPH, caudal peduncle height293.9
DPI, D1 midpoint—pectoral base end709.3
DPO, D1 midpoint—pelvic origin709.3
PDI, pelvic midpoint—D1 base end709.3
PDO, pelvic midpoint—D2 origin11014.7
DAO, D2 origin—anal fin origin30.4
DAI, D2 base end—anal base end50.7
MOL, mouth length (arc radius)354.7
MOW, mouth width506.7
ULA, upper labial furrow length
LLA, lower labial furrow length
NOW, nostril width121.6
INW, internarial width30.54.1
ANF, anterior nasal flap length3.50.5
INO, interorbital space, “bony”608.0
SPL, spiracle length
ESL, eye—spiracle space
HDW, head width at middle gill slits7910.5
TRW, trunk width at P base ends7610.1
ABW, abdomen width at D1B end678.9
TAW, tail width at pelvic base ends547.2
CPW, C peduncle width at C origin253.3
CLO, clasper outer margin length739.7
CLI, clasper inner margin length7810.4
CLB, clasper base width101.3
Barbel length
Width of cephalofoil

As described for this species by Last and Stevens [1], it has a conspicuous black tip to the second dorsal fin while all other fins do not have distinct markings (Figures 2(a), 2(b)). Additionally, the species has a low interdorsal and no lateral ridge on the tail stock, the first dorsal-fin origin is over, or slightly anterior to, the free rear tips of the pectoral fins and the second dorsal fin originates over, or usually a little bit behind, the anal fin origin [1].

The most obvious character, the dark tip to the second dorsal fin, is also present in diverse other species of the genus Carcharhinus, but there is only one further species, Carcharhinus sealei (Pietschmann) [26], in which all fins except the second dorsal fin are plain and without blotches [18]. However, contrary to Carcharhinus sealei, the teeth of the examined specimen have no cusplets and the first dorsal fin is triangular (Figure 2(a)), whereas it is falcate in Carcharhinus sealei [18]. Furthermore, the examined specimen has—as described for Carcharhinus dussumieri by Compagno [18]—semifalcate pectoral fins (Figure 2(a)), while those of C. sealei are strongly falcate. Additionally, the mouth width of the examined specimen is 6.9% of its total length. Following Compagno [18] the mouth width is 6.4 to 8.3% of total length in Carcharhinus dussumieri, whereas it is 4.2 to 6.6% in C. sealei.

The examined specimen ZMH 25683 has 26 tooth rows each in the upper and lower jaw. Last and Stevens [1] list 25 to 28 (seldom 24–31) tooth rows in the upper and also 25 to 28 (sometimes 22–32) in the lower jaw for Carcharhinus dussumieri. Fowler [27] specifies 24 to 25 tooth rows per jaw for this species. Carcharhinus sealei usually has 26 tooth rows in the upper and 25 rows in the lower jaw [28].

3.2. Hemigaleus microstoma Bleeker [29]

Despite the intensive commercial use of this species, populations are growing due to rapid reproduction rates. However, the known distribution area is patchy: it consists of the Red Sea, South India, parts of Southeast Asia, and East China [17].

The specimen of Hemigaleus microstoma (ZMH 25682) was caught by local fishermen in the Gulf of Thailand near Pak Phanang on the 7th December 1993. It is a mature male of 79 cm total length with fully developed claspers (Figure 3(b)). This corresponds with the description by Compagno et al. [17], after whom this species matures at about 60 cm total length and reaches a maximal length of 94 cm.

Three habitus photographs of specimen ZMH 25682 are shown in Figure 3 and its measurements in Table 3.


Measurement[mm][%TL]

TL, total length790100.0
FOR, fork length66083.5
PRC, precaudal length60576.6
PD2, pre-D2-length47560.1
PD1, pre-D1-length22027.8
HDL, head length15519.6
PG1, prebranchial length11915.1
PDP, prespiracular length8010.1
POB, preorbital length567.1
PP1, prepectoral length14618.5
PP2, prepelvic length34043.0
SVL, snout—anterior vent length35544.9
PAL, preanal fin length49062.0
IDS, interdorsal space20525.9
DCS, dorsal (D2)—caudal space769.6
PPS, pectoral—pelvic space19024.1
PAS, pelvic—anal space12015.2
ACS, anal—caudal space729.1
PCA, pelvic—caudal space22027.8
VCL, anterior vent—caudal tip l.43555.1
PRN, prenarial length253.2
POR, preoral length546.8
EYL, eye length202.5
EYH, eye height162.0
ING, intergill length 1st to last slit374.7
GS1, 1st gill slit height (unspread)222.8
GS2, 2nd gill slit height253.2
GS3, 3rd gill slit height243.0
GS4, 4th gill slit height232.9
GS5, 5th gill slit height172.2
P1A, pectoral anterior margin l.11915.1
P1B, pectoral base length344.3
P1I, pectoral inner margin length374.7
P1P, pectoral posterior margin length8210.4
P1H, pectoral height (base end to tip)10012.7
P1L, pec. length (ant. base to post. tip)688.6
SOD, subocular pocket depth60.8
CDM, dorsal caudal margin length17822.5
CPV, preventral caudal margin length8410.6
CPU, upper postventral C margin l.79.510.1
CPL, lower postventral C margin l.334.2
CFW, caudal fork width425.3
CFL, caudal fork length546.8
CST, subterminal C margin length212.7
CSW, subterminal caudal width162.0
CTR, terminal caudal margin length445.6
CTL, terminal caudal lobe length587.3
D1L, D1 total length11013.9
D1A, D1 anterior margin length11814.9
D1B, D1 base length8210.4
D1H, D1 vertical height607.6
D1I, D1 inner margin length25.53.2
D1P, D1 posterior margin length557.0
D2L, D2 total length789.9
D2A, D2 anterior margin length678.5
D2B, D2 base length567.1
D2H, D2 vertical height384.8
D2I, D2 inner margin length222.8
D2P, D2 posterior margin length415.2
P2L, pelvic total length688.6
P2A, pelvic anterior margin length658.2
P2B, pelvic base length435.4
P2H, pelvic height = max. width415.2
P2I, pelvic inner margin length273.4
P2P, pelvic posterior margin length405.1
ANL, anal fin total length627.8
ANA, anal fin anterior margin length526.6
ANB, anal fin base length445.6
ANH, anal fin vertical height293.7
ANI, anal fin inner margin length192.4
ANP, anal fin posterior margin l.303.8
HDH, head height at P origin698.7
TRH, trunk height at P base end7910.0
ABH, abdomen height at D1B end8610.9
TAH, tail height at pelvic base end567.1
CPH, caudal peduncle height22.52.8
DPI, D1 midpoint—pectoral base end9011.4
DPO, D1 midpoint—pelvic origin789.9
PDI, pelvic midpoint—D1 base end8510.8
PDO, pelvic midpoint—D2 origin11214.2
DAO, D2 origin—anal fin origin101.3
DAI, D2 base end—anal base end20.3
MOL, mouth length (arc radius)162.0
MOW, mouth width445.6
ULA, upper labial furrow length121.5
LLA, lower labial furrow length7.81.0
NOW, nostril width14.51.8
INW, internarial width293.7
ANF, anterior nasal flap length5.30.7
INO, interorbital space, “bony”486.1
SPL, spiracle length20.3
ESL, eye—spiracle space81.0
HDW, head width at middle gill slits638.0
TRW, trunk width at P base ends688.6
ABW, abdomen width at D1B end617.7
TAW, tail width at pelvic base ends526.6
CPW, C peduncle width at C origin17.52.2
CLO, clasper outer margin length567.1
CLI, clasper inner margin length638.0
CLB, clasper base width81.0
Barbel length
Width of cephalofoil

Contrary to the genera Chaenogaleus and Hemipristis, the cusps of the lower anterolateral teeth of all Hemi- and Paragaleus species do not protrude from the mouth and the gill slits are clearly shorter compared to the eye length [18]. In contrast to the species of the genus Paragaleus, both described Hemigaleus species have—following Compagno [18]—anterolateral teeth with short cusps in their upper jaws (Figure 4) as well as strongly falcate pelvic and dorsal fins and a falcate ventral lobe of the tail fin (Figure 5(a–d)).

Additionally, the two species of Hemigaleus have 6 to 20 tooth rows more in the lower than in the upper jaw, whereas all Paragaleus species have between one less and five more.

The examined specimen has 25 tooth rows in the upper and 37 rows in the lower jaw.

Due to the lateral white blotches on its body (Figure 3(c)) and the white margins of the dorsal and pelvic fins as well as the anal fin and the ventral part of the caudal fin (Figure 5(a–d)), the examined specimen was determined as Hemigaleus microstoma, which has about 32 tooth rows in the upper jaw according to Fowler [27]. The other species of Hemigaleus, H. australiensis White, Last and Compagno [30], has a plain body and, instead of the white fin margins, a second dorsal and caudal fin with dark margins and tips [17].

3.3. Paragaleus randalli Compagno, Krupp and Carpenter [31]

Paragaleus randalli is an inshore species, which lives in shallow water to 18 m depth on the continental shelf. Abundance and commercial use are unknown. The known distribution area includes only few small regions in the northern Indian Ocean, which partially are far away from each other: the Arabian Gulf, the Gulf of Oman, India, and Sri Lanka [17].

The specimen of Paragaleus randalli (ZMH 25681) was caught by local fishermen in the Gulf of Thailand near Pak Phanang on the 7th December 1993. Therefore, this specimen was caught about 2000 km more easterly than the former easternmost record from East India. The fully developed claspers (Figure 6(a)) of the 75 cm long specimen show that it is mature, which corresponds with the total length of at least 81 cm and maturing size of 60–70 cm, which are mentioned by Compagno et al. [17].

Three habitus photographs of specimen ZMH 25681 are shown in Figure 6. A distribution map for Paragaleus randalli is pictured in Figure 7, in which the distribution area after Compagno et al. [17] is marked in red and white stripes and the catch location of specimen ZMH 25681 as a blue spot. Its measurements can be found in Table 4.


Measurement[mm][%TL]

TL, total length750100.0
FOR, fork length62082.7
PRC, precaudal length57076.0
PD2, pre-D2-length45060.0
PD1, pre-D1-length21528.7
HDL, head length15020.0
PG1, prebranchial length11114.8
PDP, prespiracular length7510.0
POB, preorbital length52.57.0
PP1, prepectoral length14018.7
PP2, prepelvic length32042.7
SVL, snout—anterior vent length33544.7
PAL, preanal fin length47062.7
IDS, interdorsal space19526.0
DCS, dorsal (D2)—caudal space8511.3
PPS, pectoral—pelvic space16021.3
PAS, pelvic—anal space11014.7
ACS, anal—caudal space7510.0
PCA, pelvic—caudal space22530.0
VCL, anterior vent—caudal tip l.43057.3
PRN, prenarial length324.3
POR, preoral length46.56.2
EYL, eye length172.3
EYH, eye height9.51.3
ING, intergill length 1st to last slit385.1
GS1, 1st gill slit height (unspread)17.52.3
GS2, 2nd gill slit height18.52.5
GS3, 3rd gill slit height212.8
GS4, 4th gill slit height21.52.9
GS5, 5th gill slit height172.3
P1A, pectoral anterior margin l.9312.4
P1B, pectoral base length304.0
P1I, pectoral inner margin length385.1
P1P, pectoral posterior margin length557.3
P1H, pectoral height (base end to tip)7810.4
P1L, pec. length (ant. base to post. tip)678.9
SOD, subocular pocket depth8.51.1
CDM, dorsal caudal margin length16522.0
CPV, preventral caudal margin length668.8
CPU, upper postventral C margin l.7710.3
CPL, lower postventral C margin l.202.7
CFW, caudal fork width395.2
CFL, caudal fork length49.56.6
CST, subterminal C margin length243.2
CSW, subterminal caudal width15.72.1
CTR, terminal caudal margin length395.2
CTL, terminal caudal lobe length537.1
D1L, D1 total length8911.9
D1A, D1 anterior margin length8311.1
D1B, D1 base length678.9
D1H, D1 vertical height506.7
D1I, D1 inner margin length253.3
D1P, D1 posterior margin length597.9
D2L, D2 total length668.8
D2A, D2 anterior margin length526.9
D2B, D2 base length506.7
D2H, D2 vertical height324.3
D2I, D2 inner margin length212.8
D2P, D2 posterior margin length43.55.8
P2L, pelvic total length658.7
P2A, pelvic anterior margin length567.5
P2B, pelvic base length374.9
P2H, pelvic height = max. width324.3
P2I, pelvic inner margin length172.3
P2P, pelvic posterior margin length314.1
ANL, anal fin total length577.6
ANA, anal fin anterior margin length445.9
ANB, anal fin base length40.55.4
ANH, anal fin vertical height222.9
ANI, anal fin inner margin length182.4
ANP, anal fin posterior margin l.25.53.4
HDH, head height at P origin638.4
TRH, trunk height at P base end729.6
ABH, abdomen height at D1B end719.5
TAH, tail height at pelvic base end547.2
CPH, caudal peduncle height212.8
DPI, D1 midpoint—pectoral base end7510.0
DPO, D1 midpoint—pelvic origin739.7
PDI, pelvic midpoint—D1 base end709.3
PDO, pelvic midpoint—D2 origin12216.3
DAO, D2 origin—anal fin origin81.1
DAI, D2 base end—anal base end10.1
MOL, mouth length (arc radius)182.4
MOW, mouth width324.3
ULA, upper labial furrow length121.6
LLA, lower labial furrow length81.1
NOW, nostril width91.2
INW, internarial width23.53.1
ANF, anterior nasal flap length3.50.5
INO, interorbital space, “bony”425.6
SPL, spiracle length10.1
ESL, eye—spiracle space70.9
HDW, head width at middle gill slits526.9
TRW, trunk width at P base ends587.7
ABW, abdomen width at D1B end516.8
TAW, tail width at pelvic base ends435.7
CPW, C peduncle width at C origin162.1
CLO, clasper outer margin length557.3
CLI, clasper inner margin length618.1
CLB, clasper base width91.2
Barbel length
Width of cephalofoil

The distribution map for Paragaleus randalli was generated using ArcMap 9.3.1 [20] and based on the shapefiles supplied by ESRI for the ArcExplorer-Java Edition for Education 2.3.2 (AEJEE) [22]. The distribution area and catch location were drawn with Adobe Photoshop CS4 [23].

Contrary to the genera Chaenogaleus and Hemipristis, the cusps of the lower anterolateral teeth of all Para-and Hemigaleus species do not protrude from the mouth (Figure 6(c)), and the gill slits are clearly shorter compared to the eye length [18]. The examined specimen differs from the genus Hemigaleus—following Compagno [18]—in having anterolateral upper teeth with long cusps (Figure 8(a)), whereas they have short cusps in both Hemigaleus species. Additionally, the pelvic and dorsal fins and the ventral lobe of the caudal fin are not falcate in the examined specimen (Figure 6(c)), while these fins are falcate in Hemigaleus [18]. A further character that classifies the examined individual clearly to the genus Para-and not Hemigaleus is the number of tooth rows: the examined specimen has 29 tooth rows each in the upper and lower jaw. According to Compagno [18], the genus Paragaleus possesses one less to five more tooth rows in the upper than in the lower jaw, whereas there are 6 to 20 tooth rows more in the upper than in the lower jaw in Hemigaleus.

The examined specimen was determined as Paragaleus randalli because its second dorsal fin and the dorsal lobe of the caudal fin have light margins (Figure 6(b)), which is not present in any other species of the genus following Compagno et al. [17]. Furthermore, the examined specimen has two narrow black lines ventrally on the snout (Figure 6(a)). According to Compagno et al. [17], the only Paragaleus species that have such lines are P. randalli and P. tengi (Chen) [32]. The studied specimen was not determined as Paragaleus tengi because it has—like described for P. randalli by Compagno et al. [31]—a long and narrowly rounded prenarial snout, whereas it is rounded in P. tengi and has clearly larger pectoral fins than those described for P. tengi (Figure 6(a)).

The ratio length of the longest gill slit to the eye length is 1.2 in the examined specimen. According to Compagno et al. [17], this ratio would be suggestive of Paragaleus tengi, because they specify a ratio of 1.2 to 1.3 for P. tengi and about 1 for P. randalli. However, when analyzing the original description of Paragaleus randalli [31], one can see that already in only 14 measured specimens the longest gill slit is between 0.9 and 1.3 times as long as the eye of the respective animal. Accordingly, the specimen ZMH 25681 is in line with Paragaleus randalli even in this character and the information in Compagno et al. [17] should be extended correspondingly.

The fact that male Paragaleus tengi specimens mature not until 78–88 cm total length [17] is another criterion for the exclusion of P. tengi in the determination of the 75 cm long mature Thai specimen.

As already mentioned, the examined specimen of Paragaleus randalli (ZMH 25681) has 29 tooth rows per jaw. Following Compagno et al. [31], this species has 28–30 rows in the upper and 28–33 in the lower jaw. Paragaleus tengi, in contrast, has 26 tooth rows in the upper and 27 in the lower jaw [32].

It appears that the drawing of a left, anterolateral tooth from the upper jaw of the paratype SMF 28109 of Paragaleus randalli (Figure 8(b), white arrow) in the original description [31] and, therefore, also in Compagno et al. [17] is inaccurate: the drawn tooth looks similar to the anterolateral teeth of Hemigaleus microstoma (Figure 4) due to its short cusp, which is much shorter than in the examined specimen ZMH 25681 (Figure 8(a), white arrow). The examination of paratype SMF 28109 proved that the cusps are not really shorter than in specimen ZMH 25681. Possibly a blunt tooth was drawn by Compagno et al. [31], because the intact teeth have clearly longer cusps than in their drawing. Hence, their morphology is very similar to that of the teeth of the examined specimen ZMH 25681 (Figure 8(a)) as well as to that of the teeth of paratype ZMH 103119 (ISH 150-1965), which was also examined by way of comparison.

A comparison of the upper teeth of the mentioned Paragaleus randalli specimens with the tooth drawings in the original description of P. tengi [32] reveals conspicuous morphological differences because the drawn upper teeth of P. tengi hardly bear cusplets (Figure 9). However, the photograph of upper teeth of Paragaleus tengi in Compagno [33] indicates that the drawing of Chen [32] is apparently imprecise, because the teeth pictured in Compagno [33] do have distinct cusplets (Figure 10) and, hence, look very similar to those of P. randalli.

3.4. Sphyrna lewini (Griffith and Smith) [34]

Sphyrna lewini can be found in shelf regions as well as adjacent deep water areas to over 275 m depth. However, this species lives mainly inshore. It is found worldwide in all warm temperate and tropical seas. Although it is still common and widespread, it is extremely heavily fished in most regions [17] so that, without catch limitations, strong population decreases can be expected.

The two specimens of Sphyrna lewini (ZMH 25679 and ZMH 25680) were caught by local fishermen in the Gulf of Thailand near Pak Phanang on the 7th December 1993. Considering the maximal total length of 420 cm and the size at birth of 42 to 55 cm of this species [17], the two examined specimens with total lengths of 51.3 cm and 58 cm, respectively, are young juveniles caught shortly after birth.

Three habitus photographs of each of the specimens ZMH 25679 and ZMH 25680 are shown in Figures 11 and 12 and their measurements in Tables 5 and 6.


Measurement[mm][%TL]

TL, total length580100.0
FOR, fork length42573.3
PRC, precaudal length38566.4
PD2, pre-D2-length32556.0
PD1, pre-D1-length14024.1
HDL, head length13523.3
PG1, prebranchial length10117.4
PDP, prespiracular length
POB, preorbital length386.6
PP1, prepectoral length12521.6
PP2, prepelvic length25343.6
SVL, snout—anterior vent length26545.7
PAL, preanal fin length31554.3
IDS, interdorsal space11920.5
DCS, dorsal (D2)—caudal space406.9
PPS, pectoral—pelvic space11620.0
PAS, pelvic—anal space447.6
ACS, anal—caudal space345.9
PCA, pelvic—caudal space11019.0
VCL, anterior vent—caudal tip l.31854.8
PRN, prenarial length264.5
POR, preoral length396.7
EYL, eye length132.2
EYH, eye height111.9
ING, intergill length 1st to last slit386.6
GS1, 1st gill slit height (unspread)162.8
GS2, 2nd gill slit height193.3
GS3, 3rd gill slit height213.6
GS4, 4th gill slit height19.43.3
GS5, 5th gill slit height152.6
P1A, pectoral anterior margin l.73.512.7
P1B, pectoral base length325.5
P1I, pectoral inner margin length264.5
P1P, pectoral posterior margin length467.9
P1H, pectoral height (base end to tip)60.510.4
P1L, pec. length (ant. base to post. tip)559.5
SOD, subocular pocket depth50.9
CDM, dorsal caudal margin length18531.9
CPV, preventral caudal margin length69.512.0
CPU, upper postventral C margin l.12221.0
CPL, lower postventral C margin l.33.55.8
CFW, caudal fork width498.4
CFL, caudal fork length467.9
CST, subterminal C margin length162.8
CSW, subterminal caudal width132.2
CTR, terminal caudal margin length25.54.4
CTL, terminal caudal lobe length345.9
D1L, D1 total length8715.0
D1A, D1 anterior margin length9917.1
D1B, D1 base length6310.9
D1H, D1 vertical height6811.7
D1I, D1 inner margin length234.0
D1P, D1 posterior margin length6210.7
D2L, D2 total length518.8
D2A, D2 anterior margin length274.7
D2B, D2 base length223.8
D2H, D2 vertical height152.6
D2I, D2 inner margin length305.2
D2P, D2 posterior margin length315.3
P2L, pelvic total length478.1
P2A, pelvic anterior margin length335.7
P2B, pelvic base length315.3
P2H, pelvic height = max. width295.0
P2I, pelvic inner margin length315.3
P2P, pelvic posterior margin length345.9
ANL, anal fin total length549.3
ANA, anal fin anterior margin length325.5
ANB, anal fin base length335.7
ANH, anal fin vertical height172.9
ANI, anal fin inner margin length234.0
ANP, anal fin posterior margin l.325.5
HDH, head height at P origin6911.9
TRH, trunk height at P base end7312.6
ABH, abdomen height at D1B end66.511.5
TAH, tail height at pelvic base end5910.2
CPH, caudal peduncle height28.54.9
DPI, D1 midpoint—pectoral base end427.2
DPO, D1 midpoint—pelvic origin7212.4
PDI, pelvic midpoint—D1 base end539.1
PDO, pelvic midpoint—D2 origin6811.7
DAO, D2 origin—anal fin origin101.7
DAI, D2 base end—anal base end30.5
MOL, mouth length (arc radius)203.4
MOW, mouth width406.9
ULA, upper labial furrow length
LLA, lower labial furrow length1.50.3
NOW, nostril width11.82.0
INW, internarial width109.518.9
ANF, anterior nasal flap length
INO, interorbital space, “bony”14725.3
SPL, spiracle length
ESL, eye—spiracle space
HDW, head width at middle gill slits549.3
TRW, trunk width at P base ends559.5
ABW, abdomen width at D1B end488.3
TAW, tail width at pelvic base ends406.9
CPW, C peduncle width at C origin172.9
CLO, clasper outer margin length
CLI, clasper inner margin length
CLB, clasper base width
Barbel length
Width of cephalofoil15326.4


Measurement[mm][%TL]

TL, total length513100.0
FOR, fork length38474.9
PRC, precaudal length34567.3
PD2, pre-D2-length30058.5
PD1, pre-D1-length14027.3
HDL, head length11823.0
PG1, prebranchial length9117.7
PDP, prespiracular length
POB, preorbital length305.8
PP1, prepectoral length11221.8
PP2, prepelvic length23044.8
SVL, snout—anterior vent length24046.8
PAL, preanal fin length28555.6
IDS, interdorsal space11522.4
DCS, dorsal (D2)—caudal space377.2
PPS, pectoral—pelvic space9819.1
PAS, pelvic—anal space336.4
ACS, anal—caudal space316.0
PCA, pelvic—caudal space8717.0
VCL, anterior vent—caudal tip l.27152.8
PRN, prenarial length234.5
POR, preoral length367.0
EYL, eye length11.52.2
EYH, eye height12.52.4
ING, intergill length 1st to last slit295.7
GS1, 1st gill slit height (unspread)142.7
GS2, 2nd gill slit height152.9
GS3, 3rd gill slit height173.3
GS4, 4th gill slit height152.9
GS5, 5th gill slit height132.5
P1A, pectoral anterior margin l.6312.3
P1B, pectoral base length254.9
P1I, pectoral inner margin length214.1
P1P, pectoral posterior margin length397.6
P1H, pectoral height (base end to tip)5210.1
P1L, pec. length (ant. base to post. tip)448.6
SOD, subocular pocket depth30.6
CDM, dorsal caudal margin length16432.0
CPV, preventral caudal margin length6011.7
CPU, upper postventral C margin l.9919.3
CPL, lower postventral C margin l.224.3
CFW, caudal fork width397.6
CFL, caudal fork length407.8
CST, subterminal C margin length152.9
CSW, subterminal caudal width12.52.4
CTR, terminal caudal margin length21.54.2
CTL, terminal caudal lobe length305.8
D1L, D1 total length7314.2
D1A, D1 anterior margin length8817.2
D1B, D1 base length57.511.2
D1H, D1 vertical height5610.9
D1I, D1 inner margin length183.5
D1P, D1 posterior margin length458.8
D2L, D2 total length469.0
D2A, D2 anterior margin length244.7
D2B, D2 base length214.1
D2H, D2 vertical height11.52.2
D2I, D2 inner margin length254.9
D2P, D2 posterior margin length254.9
P2L, pelvic total length428.2
P2A, pelvic anterior margin length336.4
P2B, pelvic base length275.3
P2H, pelvic height = max. width25.55.0
P2I, pelvic inner margin length16.53.2
P2P, pelvic posterior margin length254.9
ANL, anal fin total length499.6
ANA, anal fin anterior margin length316.0
ANB, anal fin base length29.55.8
ANH, anal fin vertical height183.5
ANI, anal fin inner margin length214.1
ANP, anal fin posterior margin l.244.7
HDH, head height at P origin5210.1
TRH, trunk height at P base end6011.7
ABH, abdomen height at D1B end6713.1
TAH, tail height at pelvic base end499.6
CPH, caudal peduncle height234.5
DPI, D1 midpoint—pectoral base end203.9
DPO, D1 midpoint—pelvic origin5811.3
PDI, pelvic midpoint—D1 base end479.2
PDO, pelvic midpoint—D2 origin5711.1
DAO, D2 origin—anal fin origin142.7
DAI, D2 base end—anal base end20.4
MOL, mouth length (arc radius)173.3
MOW, mouth width31.56.1
ULA, upper labial furrow length
LLA, lower labial furrow length20.4
NOW, nostril width112.1
INW, internarial width9318.1
ANF, anterior nasal flap length
INO, interorbital space, “bony”12524.4
SPL, spiracle length
ESL, eye—spiracle space
HDW, head width at middle gill slits438.4
TRW, trunk width at P base ends479.2
ABW, abdomen width at D1B end387.4
TAW, tail width at pelvic base ends336.4
CPW, C peduncle width at C origin173.3
CLO, clasper outer margin length
CLI, clasper inner margin length
CLB, clasper base width
Barbel length
Width of cephalofoil13225.7

The posterior margins of the lateral blades of head are arching posterolaterally in the examined specimens as described for Sphyrna lewini by Compagno [18]. As typical for this species following Compagno et al. [17], the broadly arched and narrow-bladed head of the examined specimens has a central notch and two smaller lateral indentations (Figures 11(a), 11(c), 11(d), and 12(b)). Further characteristics according to Compagno et al. [17] are the only moderately high first dorsal fin and the dark-tipped lower caudal fin lobe, second dorsal fin, and pectoral fins (Figures 11(b), 11(d)).

Both examined specimens (ZMH 25679 and ZMH 25680) have 33 tooth rows each in their upper and in their lower jaws. Last and Stevens [1] list 32 to 33 (seldom 32 to 36) for the upper and 31 to 33 (sometimes 30 to 34) for the lower jaw of Sphyrna lewini. Following Bass et al. [35], this species has 32 tooth rows in the upper and 31–33 rows in the lower jaw.

3.5. Chiloscyllium griseum Müller and Henle [14]

Chiloscyllium griseum is an inshore and quite common shark species that lives on rocks and in lagoons from 5 to 80 m depth. Its distribution area ranges from Pakistan and India over most parts of Southeast Asia to Papua New Guinea in the south and East China and South Japan in the north [17].

The two specimens of Chiloscyllium griseum (ZMH 25675 and ZMH 25676) were caught by local fishermen in the Gulf of Thailand near Cha-Am in about 30 m depth on the 5th December 1993. The maximal total length of Chiloscyllium griseum is about 77 cm, and the males mature at a total length of about 45 cm [17]. Hence, the two examined specimens with total lengths of 56 cm and 59.5 cm, respectively, are probably adult.

Three habitus photographs of each of the specimens ZMH 25675 and ZMH 25676 are shown in Figure 13 and their measurements in Tables 7 and 8.


Measurement[mm][%TL]

TL, total length560100.0
FOR, fork length
PRC, precaudal length42575.9
PD2, pre-D2-length32057.1
PD1, pre-D1-length22039.3
HDL, head length12522.3
PG1, prebranchial length9016.1
PDP, prespiracular length51.59.2
POB, preorbital length43.57.8
PP1, prepectoral length9717.3
PP2, prepelvic length20536.6
SVL, snout—anterior vent length21137.7
PAL, preanal fin length40071.4
IDS, interdorsal space417.3
DCS, dorsal (D2)—caudal space529.3
PPS, pectoral—pelvic space6712.0
PAS, pelvic—anal space160.528.7
ACS, anal—caudal space00.0
PCA, pelvic—caudal space214.538.3
VCL, anterior vent—caudal tip l.35363.0
PRN, prenarial length13.32.4
POR, preoral length274.8
EYL, eye length11.42.0
EYH, eye height61.1
ING, intergill length 1st to last slit34.56.2
GS1, 1st gill slit height (unspread)12.52.2
GS2, 2nd gill slit height14.52.6
GS3, 3rd gill slit height15.72.8
GS4, 4th gill slit height13.52.4
GS5, 5th gill slit height142.5
P1A, pectoral anterior margin l.77.513.8
P1B, pectoral base length407.1
P1I, pectoral inner margin length376.6
P1P, pectoral posterior margin length559.8
P1H, pectoral height (base end to tip)6712.0
P1L, pec. length (ant. base to post. tip)74.513.3
SOD, subocular pocket depth
CDM, dorsal caudal margin length13624.3
CPV, preventral caudal margin length
CPU, upper postventral C margin l.
CPL, lower postventral C margin l.
CFW, caudal fork width
CFL, caudal fork length
CST, subterminal C margin length203.6
CSW, subterminal caudal width173.0
CTR, terminal caudal margin length234.1
CTL, terminal caudal lobe length315.5
D1L, D1 total length66.511.9
D1A, D1 anterior margin length6311.3
D1B, D1 base length50.59.0
D1H, D1 vertical height43.57.8
D1I, D1 inner margin length203.6
D1P, D1 posterior margin length34.56.2
D2L, D2 total length6912.3
D2A, D2 anterior margin length6411.4
D2B, D2 base length519.1
D2H, D2 vertical height35.56.3
D2I, D2 inner margin length173.0
D2P, D2 posterior margin length29.55.3
P2L, pelvic total length70.512.6
P2A, pelvic anterior margin length549.6
P2B, pelvic base length285.0
P2H, pelvic height = max. width44.57.9
P2I, pelvic inner margin length244.3
P2P, pelvic posterior margin length427.5
ANL, anal fin total length5910.5
ANA, anal fin anterior margin length
ANB, anal fin base length54.59.7
ANH, anal fin vertical height14.52.6
ANI, anal fin inner margin length6.51.2
ANP, anal fin posterior margin l.
HDH, head height at P origin5910.5
TRH, trunk height at P base end6411.4
ABH, abdomen height at D1B end35.56.3
TAH, tail height at pelvic base end397.0
CPH, caudal peduncle height173.0
DPI, D1 midpoint—pectoral base end11720.9
DPO, D1 midpoint—pelvic origin508.9
PDI, pelvic midpoint—D1 base end488.6
PDO, pelvic midpoint—D2 origin94.516.9
DAO, D2 origin—anal fin origin8515.2
DAI, D2 base end—anal base end8715.5
MOL, mouth length (arc radius)
MOW, mouth width35.56.3
ULA, upper labial furrow length122.1
LLA, lower labial furrow length81.4
NOW, nostril width30.5
INW, internarial width22.54.0
ANF, anterior nasal flap length
INO, interorbital space, “bony”254.5
SPL, spiracle length9.51.7
ESL, eye—spiracle space
HDW, head width at middle gill slits7413.2
TRW, trunk width at P base ends6812.1
ABW, abdomen width at D1B end325.7
TAW, tail width at pelvic base ends366.4
CPW, C peduncle width at C origin132.3
CLO, clasper outer margin length
CLI, clasper inner margin length
CLB, clasper base width
Barbel length132.3
Width of cephalofoil


Measurement[mm][%TL]

TL, total length595100.0
FOR, fork length
PRC, precaudal length45075.6
PD2, pre-D2-length34057.1
PD1, pre-D1-length22537.8
HDL, head length13021.8
PG1, prebranchial length94.515.9
PDP, prespiracular length528.7
POB, preorbital length447.4
PP1, prepectoral length10918.3
PP2, prepelvic length22037.0
SVL, snout—anterior vent length23239.0
PAL, preanal fin length42070.6
IDS, interdorsal space477.9
DCS, dorsal (D2)—caudal space589.7
PPS, pectoral—pelvic space8013.4
PAS, pelvic—anal space17128.7
ACS, anal—caudal space00.0
PCA, pelvic—caudal space24541.2
VCL, anterior vent—caudal tip l.38063.9
PRN, prenarial length14.52.4
POR, preoral length274.5
EYL, eye length111.8
EYH, eye height6.61.1
ING, intergill length 1st to last slit386.4
GS1, 1st gill slit height (unspread)14.32.4
GS2, 2nd gill slit height152.5
GS3, 3rd gill slit height162.7
GS4, 4th gill slit height142.4
GS5, 5th gill slit height142.4
P1A, pectoral anterior margin l.81.513.7
P1B, pectoral base length41.57.0
P1I, pectoral inner margin length376.2
P1P, pectoral posterior margin length599.9
P1H, pectoral height (base end to tip)6911.6
P1L, pec. length (ant. base to post. tip)7612.8
SOD, subocular pocket depth
CDM, dorsal caudal margin length14524.4
CPV, preventral caudal margin length
CPU, upper postventral C margin l.
CPL, lower postventral C margin l.
CFW, caudal fork width
CFL, caudal fork length
CST, subterminal C margin length183.0
CSW, subterminal caudal width162.7
CTR, terminal caudal margin length213.5
CTL, terminal caudal lobe length22.53.8
D1L, D1 total length74.512.5
D1A, D1 anterior margin length7011.8
D1B, D1 base length559.2
D1H, D1 vertical height437.2
D1I, D1 inner margin length193.2
D1P, D1 posterior margin length376.2
D2L, D2 total length70.511.8
D2A, D2 anterior margin length6611.1
D2B, D2 base length559.2
D2H, D2 vertical height366.1
D2I, D2 inner margin length172.9
D2P, D2 posterior margin length335.5
P2L, pelvic total length7011.8
P2A, pelvic anterior margin length569.4
P2B, pelvic base length274.5
P2H, pelvic height = max. width457.6
P2I, pelvic inner margin length294.9
P2P, pelvic posterior margin length406.7
ANL, anal fin total length6611.1
ANA, anal fin anterior margin length
ANB, anal fin base length6110.3
ANH, anal fin vertical height142.4
ANI, anal fin inner margin length5.40.9
ANP, anal fin posterior margin l.
HDH, head height at P origin589.7
TRH, trunk height at P base end7011.8
ABH, abdomen height at D1B end37.56.3
TAH, tail height at pelvic base end386.4
CPH, caudal peduncle height16.52.8
DPI, D1 midpoint—pectoral base end12521.0
DPO, D1 midpoint—pelvic origin599.9
PDI, pelvic midpoint—D1 base end528.7
PDO, pelvic midpoint—D2 origin10317.3
DAO, D2 origin—anal fin origin9015.1
DAI, D2 base end—anal base end9916.6
MOL, mouth length (arc radius)
MOW, mouth width386.4
ULA, upper labial furrow length122.0
LLA, lower labial furrow length91.5
NOW, nostril width2.50.4
INW, internarial width244.0
ANF, anterior nasal flap length
INO, interorbital space, “bony”20.53.4
SPL, spiracle length7.51.3
ESL, eye—spiracle space
HDW, head width at middle gill slits7312.3
TRW, trunk width at P base ends7011.8
ABW, abdomen width at D1B end355.9
TAW, tail width at pelvic base ends406.7
CPW, C peduncle width at C origin12.52.1
CLO, clasper outer margin length
CLI, clasper inner margin length
CLB, clasper base width
Barbel length132.2
Width of cephalofoil

Contrary to the similar species Chiloscyllium arabicum Gubanov [36], the two examined specimens have faded stripes on their caudal fin and the base of the second dorsal fin is not longer than that of the first dorsal fin (Figures 13(b), 13(c), and 13(f)). The rudimentary dark and light bands clearly show that the two examined specimens do not belong to Chiloscyllium arabicum because this species is plain-colored in all stages without any color patterns. Additionally, Chiloscyllium arabicum has only been reported from the northwestern Indian Ocean, from the Persian Gulf to the western coast of India [17]. A striped pattern of alternating dark and light bands (which is very distinct in juveniles but pales almost completely into plain brown or gray when maturing) is only present in three species of Chiloscyllium: C. griseum, C. hasseltii Bleeker [29], and C. punctatum Müller and Henle [14]. Of these species Chiloscyllium punctatum can be excluded from the determination of the two examined specimens because in this species the posterior margins of the dorsal fins are concave and the free rear tips are elongated [37], whereas in the specimens ZMH 25675 and ZMH 25676 the dorsal fins have convex posterior margins and not elongated free rear tips (Figures 13(c), 13(d)).

The two examined specimens differ from Chiloscyllium hasseltii in having only pale dark bands compared to the light bands as well as broader and, therefore, fewer light bands. In Chiloscyllium hasseltii the dark bands are more distinct and black edged and there are more and narrower light bands [19]. Furthermore, the height of the first dorsal fin is 7.8% of total length in specimen ZMH 25675 and 7.2% in ZMH 25676. Following Dingerkus and DeFino [37] and Gloerfelt-Tarp and Kailola [38], this ratio is over 6.6% in Chiloscyllium griseum and less than that in C. hasseltii. Additionally, the height of the second dorsal fin compared to the total length is 6.3% in ZMH 25675 and 6.1% in ZMH 25676. This ratio is over 5.8% in Chiloscyllium griseum and less than 5.8% in C. hasseltii [37, 38]. The same values for these two ratios are given by Compagno [19] in his key to species. However, in his detailed descriptions of both species the values for the first and second dorsal fins are interchanged in each species because the height of the first dorsal fin is specified as being smaller than that of the second one. In the Thai and comparative specimens as well as following Compagno et al. [17], Compagno [24] and Dingerkus and DeFino [37], the first dorsal fins are higher than the second ones in both species.

The third proportion mentioned by Compagno [19] is the ratio between the interdorsal space and the total length. In specimen ZMH 25675 this ratio is 7.3% and in ZMH 25676 it is 7.9%. Compagno [19] lists a ratio of 8.7–11.5% for Chiloscyllium griseum and 6.6–11.1% for C. hasseltii. Therefore, both examined specimens are rather accord with the description of Chiloscyllium hasseltii than with that of C. griseum regarding this ratio. However, this proportion seems to be rather insignificant due to its high margin of variation.

In contrast to Compagno [19], who indicates that the base of the first dorsal fin is longer than that of the second one in Chiloscyllium griseum, the bases of both fins are about equal in length in each of the two examined specimens. The only species of Chiloscyllium, in which the first dorsal fin base is not longer than the second one, are C. arabicum and C. punctatum, which can be excluded from the determination due to the earlier mentioned differences. In Chiloscyllium arabicum the base of the second dorsal fin is even longer than that of the first one [17, 19, 24].

Although the dorsal ridges of Chiloscyllium griseum are not prominent following Compagno [19, 24] or even absent after Compagno et al. [17], both examined specimens have distinct pre—and interdorsal ridges. The Chiloscyllium griseum specimens which were examined by way of comparison also have quite prominent to prominent ridges pre—and interdorsally. According to Compagno [19, 24] and Compagno et al. [17], only Chiloscyllium arabicum, C. indicum, and C. plagiosum have prominent dorsal ridges but these species can be excluded from the determination of the examined Thai specimens by means of other, unambiguous differences. Dingerkus and DeFino [37] specify the dorsal ridges of Chiloscyllium griseum at least as quite prominent, but slightly less pronounced than in C. arabicum.

One highly unusual character can be found in the specimen ZMH 25676, which has a very big ocellar blotch on the head (Figure 13(f)). Such a blotch has not been described before for a species of the genus Chiloscyllium and is probably the remains of an untypical juvenile color pattern.

Specimen ZMH 25675 has 29 tooth rows in the upper and 27 rows in the lower jaw, specimen ZMH 25676 has 31 and 27 tooth rows. Fowler [27] lists 30 to 32 tooth rows per jaw for Chiloscyllium griseum.

3.6. Chiloscyllium punctatum Müller and Henle [14]

Chiloscyllium punctatum lives in coral reefs and, possibly, also in offshore soft bottoms to at least 85 m depth. Its distribution area ranges from East India over most parts of Southeast Asia to the whole northern coast of Australia in the south and East China and South Japan in the north [17].

The two specimens of Chiloscyllium punctatum (ZMH 25677 and ZMH 25678) were caught by local fishermen in the Gulf of Thailand near Pak Phanang on the 7th December 1993. Last and Stevens [1] list a maximal total length of at least 132 cm (144 cm in captivity) with the males maturing at 82 cm and the females at 87 cm total length. Accordingly, both examined specimens with total lengths of 56 cm and 61.7 cm, respectively, have to be considered as juveniles. This is also evidenced by the not-yet-well-developed claspers of the male specimen ZMH 25678 (Figure 14(f)).

Three habitus photographs of each of the specimens ZMH 25677 and ZMH 25678 are shown in Figure 14 and their measurements in Tables 9 and 10.


Measurement[mm][%TL]

TL, total length560100.0
FOR, fork length
PRC, precaudal length42275.4
PD2, pre-D2-length31055.4
PD1, pre-D1-length21037.5
HDL, head length11520.5
PG1, prebranchial length8515.2
PDP, prespiracular length498.8
POB, preorbital length437.7
PP1, prepectoral length8915.9
PP2, prepelvic length18332.7
SVL, snout—anterior vent length19534.8
PAL, preanal fin length39570.5
IDS, interdorsal space5710.2
DCS, dorsal (D2)—caudal space5710.2
PPS, pectoral—pelvic space6411.4
PAS, pelvic—anal space17230.7
ACS, anal—caudal space00.0
PCA, pelvic—caudal space23041.1
VCL, anterior vent—caudal tip l.36364.8
PRN, prenarial length71.3
POR, preoral length193.4
EYL, eye length101.8
EYH, eye height40.7
ING, intergill length 1st to last slit274.8
GS1, 1st gill slit height (unspread)132.3
GS2, 2nd gill slit height152.7
GS3, 3rd gill slit height162.9
GS4, 4th gill slit height162.9
GS5, 5th gill slit height13.52.4
P1A, pectoral anterior margin l.7313.0
P1B, pectoral base length305.4
P1I, pectoral inner margin length356.3
P1P, pectoral posterior margin length407.1
P1H, pectoral height (base end to tip)6411.4
P1L, pec. length (ant. base to post. tip)6110.9
SOD, subocular pocket depth
CDM, dorsal caudal margin length11320.2
CPV, preventral caudal margin length
CPU, upper postventral C margin l.
CPL, lower postventral C margin l.
CFW, caudal fork width
CFL, caudal fork length
CST, subterminal C margin length193.4
CSW, subterminal caudal width152.7
CTR, terminal caudal margin length254.5
CTL, terminal caudal lobe length305.4
D1L, D1 total length7914.1
D1A, D1 anterior margin length7413.2
D1B, D1 base length549.6
D1H, D1 vertical height478.4
D1I, D1 inner margin length24.54.4
D1P, D1 posterior margin length488.6
D2L, D2 total length79.514.2
D2A, D2 anterior margin length6912.3
D2B, D2 base length6211.1
D2H, D2 vertical height39.57.1
D2I, D2 inner margin length203.6
D2P, D2 posterior margin length427.5
P2L, pelvic total length5710.2
P2A, pelvic anterior margin length559.8
P2B, pelvic base length234.1
P2H, pelvic height = max. width376.6
P2I, pelvic inner margin length223.9
P2P, pelvic posterior margin length356.3
ANL, anal fin total length5910.5
ANA, anal fin anterior margin length
ANB, anal fin base length539.5
ANH, anal fin vertical height15.52.8
ANI, anal fin inner margin length91.6
ANP, anal fin posterior margin l.
HDH, head height at P origin55.59.9
TRH, trunk height at P base end62.511.2
ABH, abdomen height at D1B end427.5
TAH, tail height at pelvic base end427.5
CPH, caudal peduncle height20.53.7
DPI, D1 midpoint—pectoral base end11019.6
DPO, D1 midpoint—pelvic origin458.0
PDI, pelvic midpoint—D1 base end447.9
PDO, pelvic midpoint—D2 origin8815.7
DAO, D2 origin—anal fin origin7914.1
DAI, D2 base end—anal base end7513.4
MOL, mouth length (arc radius)
MOW, mouth width346.1
ULA, upper labial furrow length91.6
LLA, lower labial furrow length61.1
NOW, nostril width20.4
INW, internarial width213.8
ANF, anterior nasal flap length
INO, interorbital space, “bony”223.9
SPL, spiracle length81.4
ESL, eye—spiracle space
HDW, head width at middle gill slits6211.1
TRW, trunk width at P base ends6511.6
ABW, abdomen width at D1B end35.56.3
TAW, tail width at pelvic base ends397.0
CPW, C peduncle width at C origin142.5
CLO, clasper outer margin length
CLI, clasper inner margin length
CLB, clasper base width
Barbel length112.0
Width of cephalofoil


Measurement[mm][%TL]

TL, total length617100.0
FOR, fork length
PRC, precaudal length49580.2
PD2, pre-D2-length35257.1
PD1, pre-D1-length22536.5
HDL, head length12119.6
PG1, prebranchial length9114.7
PDP, prespiracular length528.4
POB, preorbital length457.3
PP1, prepectoral length10817.5
PP2, prepelvic length21034.0
SVL, snout—anterior vent length22035.7
PAL, preanal fin length44071.3
IDS, interdorsal space7111.5
DCS, dorsal (D2)—caudal space589.4
PPS, pectoral—pelvic space6811.0
PAS, pelvic—anal space20032.4
ACS, anal—caudal space00.0
PCA, pelvic—caudal space25541.3
VCL, anterior vent—caudal tip l.39964.7
PRN, prenarial length121.9
POR, preoral length233.7
EYL, eye length11.51.9
EYH, eye height50.8
ING, intergill length 1st to last slit315.0
GS1, 1st gill slit height (unspread)14.32.3
GS2, 2nd gill slit height16.42.7
GS3, 3rd gill slit height17.22.8
GS4, 4th gill slit height16.82.7
GS5, 5th gill slit height172.8
P1A, pectoral anterior margin l.8113.1
P1B, pectoral base length284.5
P1I, pectoral inner margin length406.5
P1P, pectoral posterior margin length467.5
P1H, pectoral height (base end to tip)7011.3
P1L, pec. length (ant. base to post. tip)6410.4
SOD, subocular pocket depth
CDM, dorsal caudal margin length14022.7
CPV, preventral caudal margin length
CPU, upper postventral C margin l.
CPL, lower postventral C margin l.
CFW, caudal fork width
CFL, caudal fork length
CST, subterminal C margin length172.8
CSW, subterminal caudal width172.8
CTR, terminal caudal margin length20.53.3
CTL, terminal caudal lobe length284.5
D1L, D1 total length8914.4
D1A, D1 anterior margin length8914.4
D1B, D1 base length6510.5
D1H, D1 vertical height447.1
D1I, D1 inner margin length23.53.8
D1P, D1 posterior margin length508.1
D2L, D2 total length7612.3
D2A, D2 anterior margin length7311.8
D2B, D2 base length599.6
D2H, D2 vertical height406.5
D2I, D2 inner margin length18.53.0
D2P, D2 posterior margin length396.3
P2L, pelvic total length6210.0
P2A, pelvic anterior margin length6210.0
P2B, pelvic base length457.3
P2H, pelvic height = max. width386.2
P2I, pelvic inner margin length193.1
P2P, pelvic posterior margin length396.3
ANL, anal fin total length6510.5
ANA, anal fin anterior margin length
ANB, anal fin base length558.9
ANH, anal fin vertical height172.8
ANI, anal fin inner margin length91.5
ANP, anal fin posterior margin l.
HDH, head height at P origin548.8
TRH, trunk height at P base end589.4
ABH, abdomen height at D1B end406.5
TAH, tail height at pelvic base end406.5
CPH, caudal peduncle height172.8
DPI, D1 midpoint—pectoral base end13221.4
DPO, D1 midpoint—pelvic origin487.8
PDI, pelvic midpoint—D1 base end619.9
PDO, pelvic midpoint—D2 origin12319.9
DAO, D2 origin—anal fin origin8814.3
DAI, D2 base end—anal base end7812.6
MOL, mouth length (arc radius)
MOW, mouth width284.5
ULA, upper labial furrow length9.71.6
LLA, lower labial furrow length4.50.7
NOW, nostril width2.50.4
INW, internarial width223.6
ANF, anterior nasal flap length
INO, interorbital space, “bony”223.6
SPL, spiracle length91.5
ESL, eye—spiracle space
HDW, head width at middle gill slits6210.0
TRW, trunk width at P base ends619.9
ABW, abdomen width at D1B end29.54.8
TAW, tail width at pelvic base ends365.8
CPW, C peduncle width at C origin13.52.2
CLO, clasper outer margin length152.4
CLI, clasper inner margin length274.4
CLB, clasper base width50.8
Barbel length132.1
Width of cephalofoil

As described for Chiloscyllium punctatum by Last and Stevens [1]—and contrary to all other species of the genus—the examined specimens have dorsal fins with concave posterior margins and elongated free rear tips (Figures 14(b), 14(e)). Additionally, following Last and Stevens [1], the origin of the first dorsal fin is situated far anteriorly (over the anterior base of the pelvic fins), the bases of both dorsal fins are about equal in length, there are no lateral ridges on the body and the origin of the anal fin is situated about under or slightly behind the free rear tip of the second dorsal fin (Figures 14(b), 14(e)).

Both examined specimens show faded alternating dark and bright bands, which are remains of the distinct juvenile color pattern of this species (Figures 14(a), 14(b), 14(d), and 14(e)). Additionally, both specimens—especially specimen ZMH 25677—have black spots on the body (Figures 14(a), 14(b), 14(d), and 14(e)) as typical for older juveniles of the species following Dingerkus and DeFino [37]. Adult specimens of Chiloscyllium punctatum are almost plain brown, similar to those of C. arabicum, C. griseum, and C. hasseltii [37].

Specimen ZMH 25677 has 32 tooth rows in the upper and 31 in the lower jaw, and specimen ZMH 25678 has 31 and 30 tooth rows. Last and Stevens [1] specify between 31 and 33 tooth rows for the upper and 30 to 33 for the lower jaw of Chiloscyllium punctatum. Fowler [27] lists 30 tooth rows for the upper and 28 rows for the lower jaw of this species.

4. Conclusion

The results provide several new findings regarding the taxonomy and distribution of the examined species. Additionally, inaccuracies and errors from different references are described and clarified. As 26 to 73 million sharks get caught in commercial fishery each year [39], it is very important to improve our knowledge about these animals. In order to find out which species are particularly used commercially, it is very important to be able to identify the species quickly and accurately. A reliable determination is essential for effective protection and management programs. As mentioned before, detailed morphological information is scarce for several species due to the partially sketchy original descriptions like those by Müller and Henle [14]. Detailed morphological, morphometrical, and meristical descriptions as well as meaningful and detailed drawings are usually missing in their descriptions. Additionally, the margin of variation of a character or ratio in one species is often not fully known, as detected for example in Paragaleus randalli. Furthermore, extensive data about the abundance and the conservation status are not available for almost half of all Elasmobranchii [40]. The disagreement about the exact number of known cartilaginous fish species (1168 according to Fowler et al. [2], 1115 after Camhi et al. [40], over 1200 following Last and Stevens [1]) as well as the many newly described species in recent years [1, 1013] also shows that there is still a huge need for further taxonomic and systematic research in sharks.

The knowledge deficits revealed in this study are, at least partially, based on short and imprecise original descriptions. Additionally, due to the many newly described species, data about similar, earlier described species have to be revalidated because they might include not only the intended, but also the newly described species.

More knowledge deficits become apparent in the not exactly known or patchy distribution areas of some species as well as the fact that the known distribution area for Paragaleus randalli could be extended eastwards significantly due to the examined Thai specimen. A similar extension could be found recently for another elasmobranch species, Rhinobatos formosensis Norman [41], the Taiwan Guitarfish [25].

Important information about distribution areas could eventually be provided by the observations of fishermen, but as mentioned before they are often not able to determine the exact species and simply declare most of their catches as “diverse Elasmobranchii” or “small sharks” [5, 15]. Easy- and fast-to-use identification keys like those by White et al. [3] or Daley et al. [42] could be very helpful for the determination. However, the exact determination of species from genera with many superficially similar species like, for example, most reef shark species (family Carcharhinidae) would still remain very difficult and time-consuming for nonscientists.

Additionally to the comments on literature in the results chapter of this paper, the author suggests to use another distinguishing feature for the differentiation of Carcharhinidae and Hemigaleidae in identification keys: Compagno [18] uses only the folding of the intestinal valve for the differentiation. However, the author suggests using the presence or absence of spiracles instead or additionally as distinctive feature for identification keys because the folding of the intestinal valve is difficult to check. The presence or absence of spiracles, in contrast, can easily be used because all Carcharhinidae with the exception of the unmistakable Tiger Shark Galeocerdo cuvier (Péron & Lesueur) [43] lack spiracles, whereas all Hemigaleidae do have spiracles.

When determining juvenile sharks, caution is advised in matters of possible ontogenetic changes in morphology or morphometrics. In this study the well-known morphological changes in the Hemiscyllidae species Chiloscyllium griseum and C. punctatum were found. However, some deviations from literature that were found in this study might result from ontogenetic changes, also. In an extreme case, ontogenetic changes can even lead to describing a different stage of life of a known species accidentally as a new species. This happened due to strong differences in terms of color in the Zebra Shark Stegostoma fasciatum (Hermann) [44]: Seba [45] described the banded juvenile stage of this species as Squalus varius and Gmelin [46] described the spotted adult form as Squalus longicaudatus.

The results indicate that differences in tooth morphology, which have commonly been used for the distinction of Paragaleus randalli and P. tengi, are probably based on imprecise or inaccurate drawings in Compagno et al. [31] and Chen [32], respectively. Actually, both species have a very similar tooth morphology. Due to these new results, Paragaleus randalli and P. tengi should not be differentiated by means of their teeth only.

In Chiloscyllium griseum, variability in the size of the dorsal ridges between different references and the examined specimens was detected. Unfortunately there is no information about the dorsal ridges in the original description of Chiloscyllium griseum [14], but only a drawing in which no dorsal ridges are shown. This drawing is probably simply inexact or not generally appropriate as Müller and Henle [14] only examined seven individuals. It might be possible that Compagno [19, 24] and Compagno et al. [17] refer to this drawing in their description of the dorsal ridges. However, the drawing in Müller and Henle [14] actually shows a specimen of Chiloscyllium punctatum and not C. griseum, which is evidenced by the pronounced concave posterior margins and elongated free rear tips of the dorsal fins. Dingerkus and DeFino [37] guess that the specimen drawn by Müller and Henle [14] is the Chiloscyllium punctatum specimen RMNH 4178 due to similarities in body proportions and color pattern. In Compagno et al. [17] a similar mistake was made in the black and white drawing of Chiloscyllium griseum because its dorsal fins were erroneously drawn with concave posterior margins and elongated free rear tips like those of C. punctatum. However, the corresponding textual description is correct and describes straight to convex posterior margins as well as not elongated free rear tips. The color painting of Chiloscyllium griseum in Compagno et al. [17] is correct, also.

Altogether, it remains unclear if the size of the dorsal ridges is very variable in this species from not present to prominent or if some sources are imprecise about this character. Generally, Chiloscyllium griseum is considered a taxonomically complex species and the differentiation of several species of Chiloscyllium remains difficult due to strong ontogenetic changes and a high margin of variation in some morphometric ratios [19, 47].

In the future the pit organs might possibly be used in support of the determination of sharks, because the abundance and distribution of these free neuromasts vary widely among species according to Budker [48], Tester and Nelson [49] and Peach [50]. However, further research including the examination of more species is needed to verify if there are species-specific patterns of pit organs and, if so, to characterize the different typal patterns.

Due to the flourishing fin trade, further research is also desirable on the identification of shark species by means of their fins. Although good progress has been made in recent years, for example, by Clarke et al. [51] and Wong et al. [52] related to the genetic and by Deynat [53] regarding the morphological distinguishing, further research is still needed.

Acknowledgments

The author wants to thank Ralf Thiel for his advice during the work and his critical and very useful comments about the paper and Matthias Stehmann, who collected the examined specimens. He also provided information about the expedition and gave instructions for doing the measurements and meristics. Furthermore, the author is grateful to Irina Eidus for her help with the radiography and collection database, to Annelore Kröger for her assistance in taking the photographs with the Nikon-D90, to Anne Préviato and Bernard Séret (Muséum national d’Histoire naturelle, Paris) for providing photographs of the lectotype and paralectotypes of Chiloscyllium griseum, and to Matthias Schneider, Sven Tränkner, and Horst Zetzsche (Senckenberg Naturmuseum Frankfurt) for providing photographs of a paratype of Paragaleus randalli. Many thanks also to William White (CSIRO Marine and Atmospheric Research, and Australia), Alec Moore (RSK Environment Ltd., U.K.), and Vivekanandan Elayaperumal (Central Marine Fisheries Research Institute, India) for their comments about the examined Paragaleus specimen from Thailand and to William White and William N. Eschmeyer (California Academy of Sciences, USA) for their comments about the validity status of Chiloscyllium confusum. Additionally, the author is thankful to the company ESRI for providing an educational edition of ArcGIS 9 and to the Reference Division of Library, Tunghai University, Taiwan. The author confirms to have no conflict of interests by any relation to the commercial identities mentioned in this paper.

References

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