Advertisement

Marine Biodiversity

, Volume 48, Issue 4, pp 2225–2231 | Cite as

A new Sillago species (family Sillaginidae) with descriptions of six sillaginids from the northern Arabian Sea

  • Sher Khan Panhwar
  • Noureen Farooq
  • Nazia Qamar
  • Wajiha Shaikh
  • Mushayida Mairaj
Short Communication

Abstract

This study reviewed the taxonomy of six members of the family Sillaginidae and described a new Sillago species, S. panhwari. The description of the new species was based on 55 specimens sampled from commercial catches and from fishery surveys (24°48’8.31“N, 66°45’28.15″E) on the northern Arabian Sea coast of Pakistan. Taxonomic revisions were based on morphometric, anatomical characteristics, coloration patterns, and meristics of Sillago panhwari sp. nov., S. arabica, S. attenuata, S. indica, S. sihama, Sillaginopodys chondropus, and Sillaginopsis domina. The distinctive characteristics of the new species are (1) X−XII spines in the first dorsal fin; (2) I, 21–22 rays 2nd dorsal fin; (3) 3–4/7-8 gill rakers on 1st gill arch, (4) periorbital length (1.4–2.3), (5) 18.0–23.3 ED/HL, (6) 16.7–21.7 int.OW/HL; (7) 39.5–46.5 snout L/HL, (8) 34.1–38.9 post-OL/HL, (9) swimbladder narrow anterior extensions joined at the origin, diverging to terminate on the both side of the basioccipital above the anditory capsule whereas two posterior extensions penetrating into the caudal region, one usually longer than the other and presence of a duck-like process, (10) the head before the interorbital area is steep and the mouth is contracted relative to the other six species investigated; (11) the upper half of the body is pale brown to dull brown, with a light brown lower half; (12) the presence of a faint mid-lateral streak from the base of the pectoral fin to the base of caudal fin; (13) dusky dorsal fins; (14) a chin covered with adipose tissue; (15) a hyaline to transparent anal fin clear of spots; (16) yellowish posterior head region; and (17) pectoral and pelvic fins yellowish and caudal fin dusky. Sillago panhwari sp. nov. resembled its allopatric congeners in coloration patterns and body structure. This study contributed to the identification of a new species and the description of six sillaginids occurring in the northern Arabian Sea coast of Pakistan.

Keywords

Character displacement Sillago panhwari New species Sillaginids Northern Arabian Sea coast of Pakistan 

Introduction

Thirty-four species of sillaginids (Family Sillaginidae) inhabit estuarine, coastal, and open waters throughout Indo-West Pacific regions (McKay 1985, 1992; Nelson 2006; Kaga et al. 2010). Of these 34 species, Sillago arabica, S. attenuata S. indica, S. sihama and Sillaginopodys chondropus and Sillaginopsis domina have been recorded from the northern Arabian Sea coast of Pakistan (FAO 2015; Panhwar et al. 2017). The Indian sillago, S. indica, comprises over 50% of the catch of sillaginids in Pakistan (Panhwar et al. 2017), followed by S. sihama, which is widely distributed across Indo-West Pacific (McKay 1992). The close resemblance of Sillago species fomented their re-description, resulting in the identification of two sister species (e.g. S. indica and S. sihama). The identification of these species was primarily based on the swimbladder characteristics. To date Sillago, Parasillago and Sillaginopodys subgenera of sillaginids have been identified (Fowler 1933; McKay 1985), also based on the structure of the swimbladder. The genus Sillago (Cuvier 1817) can be differentiated from the subgenera Sillaginopodys and Parasillago by the Sillago swimbladder being divided posteriorly into two tapering extensions and presence of a duct-like process. The subgenus Sillaginopodys has a smaller swimbladder, lacking a duct-like process, and the subgenus Parasillago has a swimbladder with a single posterior extension, with the same duct-like process present. The swimbladders of the two congeneric S. sihama and S. indica are similar, adding to difficulty in their identification. This study reviews the taxonomy of four species belonging to the genus Sillago, co-occurring with one species of Sillaginopodys and one Sillaginopsis from coastal waters of Pakistan were examined. A new species is described, based on morphometric, anatomical characteristics, coloration patterns and meristic counts.

Materials and methods

The description of Sillago panhwari sp. nov. was based on 55 specimens sampled from commercial catches and from fishery surveys (24°48’8.31“N, 66°45’28.15”E) on the northern Arabian Sea coast of Pakistan (Fig. 1). Specimens examined in this study are catalogued and deposited in fish collections of the fishery biology laboratory. Twenty-seven morphometric and 8 meristic characters, as well as information on body and fin coloration, were examined from 55 specimens of S. panhwari and contrasted with eight specimens of Sillago arabica, thirty of S. attenuata, S. indica, S. sihama each, and fourteen of Sillaginopodys chondropus. Comparisons were conducted using a large set of data from earlier accounts by McKay (1985). We did not find Sillaginopsis domina, a co-occurring species, during the fishery surveys and commercial catch sampling. The descriptive abbreviations were defined as: TL total length, SL standard length, HL head length, BW body weight, fin spine, vertebrae and rays counted (Table 1). The counting of gill rakers and swimbladder anatomy observations were made after dissection of paratype specimens. The swimbladder observations followed Shao et al. (1986) and Kaga and Ho (2012). Lengths to the nearest 1 mm and weights to the nearest 0.1 g were taken for all specimens (Table 1). The descriptions of holotype and paratype specimens are consecutive (Table 1).
Fig. 1

Shaded area along the coastal belt indicates the location of commercial fishing grounds and some specimens collected during the surveys made at 24°48’8.31“N, 66°45’28.15”E on the northern Arabian Sea coast of Paksitan

Table 1

Frequency distributions of meristic features for the holotype and 55 paratype specimens of Sillago panhwari sp. nov. (Holotype) = an early sample we collected and preserved in the fish archieves of the fishery biology laboratory; the rest of the individuals of Sillago panhwari will be considered as paratypes

Morphometric measurements (mm)

Holotype 01–1611

Paratypes 02–1612-1641 (n = 55)

Total length

160

140–200

Standard length

137

120–170

Body weight

325

165–5.5

Body depth

24

19–29

Body width

70

55–8

Pre-1st dorsal fin length

50

43–69

Pre-2nd dorsal fin length

80

70–98

Pre-pectoral fin length

44

3.7–5.7

Pre-pelvic fin length

47

39–59

Pre-anal fin length

78

46–102

1st dorsal fin length

26

21–32

Length of base of 1st dorsal fin

29

22–34

2nd dorsal fin length

16

12–19

Length of base of 2nd dorsal fin

5.2

4.5–6

Pectoral fin length

26

21–34

Length of base of pectoral fin

07

5–8

Pelvic fin length

20

16–23

Length of base of pelvic fin

4

2–4

Anal fin length

16

1–15

Length of base of anal fin

55

47–62

Caudal peduncle length

7

4–9

Caudal peduncle depth

9

6–11

Head length

42

35–54

Periorbital length/snout length

17

1.4–2.3

Post-orbital length

16

12–21

Inter-orbital width

0.9

0.6–1

Eye diameter

0.9

0.8–1

Vertebrae

33

33

Meristic count

  1st dorsal fin rays

XI

X−XII

  2nd dorsal fin rays

I,22

I,20–22

  Anal fin rays

II,23

II,18–23

  Caudal fin rays

18

17–21

  Lateral-line scale

78

69–84

  Scale above lateral line with 1st dorsal fin base

3

3–4

  Scale below lateral line

9

7–10

  Gill rakers 1st gill arch

3 + 7

3–4 + 7–9

As % of standard length (SL)

  Head length/SL (%age)

30.6

27.9–35.0

  Body depth/SL (%age)

17.5

14.2–20.0

  Caudal peduncle length/SL (%age)

5.1

3.1–6.4

As % of head length (HL)

  Eye diamter/HL (%age)

21.4

18–23.3

  Inter-orbital width/HL (%age)

21.4

16.7–21.7

  Snout length/HL (%age)

40.5

39.5–46.5

  Post-orbital length/HL (%age)

38.1

34.1–38.9

Results

Systematic accounts.

Order Perciformes.

Family Sillaginidae.

Genus Sillago MacKay, 1985.

Species: Sillago panhwari sp. nov.

Vernacular: Yellow-Brown sillago.

(Tables 1, 2; Figs. 2, 3).
Table 2

Comparisons of selected morphometric and meristic features of Sillago panhwari, S. arabica, S. attenuata, S. indica, S. sihama, Sillaginopodys chondropus, and Sillaginopsis domina, this study (●); McKay 1985 (◘); Kaga and Ho 2012 (■); FishBase (♦); where n is the number of individuals in the present study and dna is data not available

Parameter

Sillago panhwari (n = 55)

S. arabica●,

(n = 8)

S. attenuata●,

(n = 30)

S. indica●,■

(n = 30)

S. sihama●,◘

(n = 30)

Sillaginopodys chondropus●,

(n = 14)

Sillaginopsis domina

Dorsal fins

X-XII, I,20–22

XII, I,21–23

XI-XIII, I, 19–20

X-XI, I,21–22

XI, I,21–22

XI, I,21–22

X,I,25–27

Anal fins

II,18–23

II,20–23

II,17–19

II,21–23

II,21–23

II,20–23

II,24–27

Scales in lateral line

69–84

82–94

71–88

71–78

73–83

75–86

dna

Scales above and below lateral line

3–4,7–10

3–4,7–8

4–5, 7–8

3–4,7–10

4–5,7–9

4–5,8–9

dna

Gill rackers first arch

3–4 + 7–9

2–4 + 7–9

2 + 6–7

2–4 + 6–8

3 + 8–9

2–3 + 6–8

dna

Colour pattern/ Bloches

Present

Absent

Present

Absent/present

Absent

Absent

dna

As % of standard length

  HL/SL (%age)

27.9–35.0

20–26.9

22.5–28.9

31.0-32.1

28.6–31.8

25.2–28

dna

  BD/SL(%age)

14.2–20.0

13.5–19.9

14.7–19.2

14.7–20.8

17.6–19.7

14.6–19.2

dna

  LCP/SL(%age)

3.1–6.4

4.7–7.8

6.0–9.0

4.1–6.5

4.6–5.9

6.5–9.9

dna

As % of head length

  ED/HL(%age)

18.0–23.3

22.2–26.7

21.4–29.4

17.7–25.7

18.2–21.2

18.3–30.4

dna

  Int-OW/HL(%age)

16.7–21.7

17.6–22.9

16.7–22.0

18.5–25.0

19.2–22.7

18.4–25.0

dna

  Snout L/HL(%age)

39.5–46.5

32.3–40.0

36.8–44.4

37.8–43.2

40.4–45.5

36.4–42.3

dna

  Post-OL/HL(%age)

34.1–38.9

38.2–42.4

35.0–44.1

32.7–40.0

34.6–38.6

36.7–43.8

dna

  Swimbladder

Present

Present

Present

Present

Present

Present

Vestigial/absent

HL Head length, SL standard length, BD body depth, LCP caudal peduncle length, ED eye diameter, HL head length, OW orbital width, snout L, snout length, OL orbital length

Fig. 2

Sillago panhwari, new species, holotype (fresh condition) FAMB-01-1611, male, 16 cm TL, northern Arabian Sea coast of Pakistan

Fig. 3

Comparison of swimbladders of six sillaginid species co-occurring in the northern Arabian Sea coast of Pakistan, Sillago panhwari sp. nov. (a), S. arabica (b), S. attenuata (c), S. indica (d), S. sihama (e), Sillaginopodys chondropus (f)

Holotype

FAMB-01–1611, male 16 cm TL, northern Arabian Sea coast of Pakistan, collected by Sher Khan Panhwar, 2014 and deposited in the fish a rchieves of fishery biology laboratory, Center for Excellence in Marine Biology (CEMB), University of Karachi, Sindh.

Paratypes

A total of 55 specimens ranging 14–20 cm TL, weighing 16.5–54.5 g recovered from the northern Arabian Sea at coordinates 24°48’8.31“N 66°45’28.15″E and port landing surveys form 2014–2016. All fresh specimens were deposited in the fish archieves, fishery biology laboratory at the CEMB.

Etymology

The species name “panhwari” was named by the Sher Khan Panhwar, who pioneered work on Pakistani sillaginid fishes.

Description

Sillago panhwari sp. nov. considerably resembles its allopatric sister species, so-called sillago, in coloration and body structure. The present study is the first to examine specimens of S. panhwari sp. nov. from the northern Arabian Sea coast of Pakistan in a comparative context, which has led to the identification of the new species. The specimens were obtained from surveys and frequent visits to port landings at the Karachi fish Harbour from 2014 to 2016. The S. panhwari population differed in the count of dorsal fin spines, in the periorbital length, lateral-line scales, swimbladder anterior and posterior extensions, number of gill rakers, and body coloration compared with the other four Sillago co-occurring species occurring in the area of this study (Figs. 3a, 4). Sillago panhwari sp. nov. was distinct from all other congeneric species according to the following characters: dorsal-fin I, X−XII; II, 20–22 (mostly 22); lateral-line scales 69–84; total gill rakers on 1st arch 3–4; anal fin II, 18–23; periorbital length 1.4–2.3; swimbladder: anterior extensions of the swimbladder joined at the base, diverging to terminate on the both side of the basioccipital above the anditory capsule whereas two posterior extensions penetrating into the caudal region, one usually longer than the other and presence of a duck-like process; the head before the interorbital area is steep and the mouth is contracted relative to the other six species investigated; Lateral-line beginning above gill aperture and anterior portion of pectoral fin, extending along curve of dorsal edge to the caudal fin base (Table 1).

Distribution

Sillago panhwari sp. nov. was presently only found in the northern Arabian Sea coast of Pakistan (Fig. 2).
Fig. 4

Meristic characters for the six Sillaginid species: A) average number of lateral-line scales, B) average number of anal fin rays, C) number of gill rakers on upper limb (Sillago panhwari sp. nov. (a), S. indica (b), S. attenuata (c), S. sihama (d), S. arabica (e), Sillaginopodys chondropus (f)

Colouration pattern

Fresh specimens of S. panhwari comprises of a pale brown to dull brown body dorsally, lighter brown body ventrally, and a faint mid-body line starting from the base of the pectoral fin to the base of caudal fin. The dorsal fins are dusky, the chin is covered with a thick adipose tissues, the lower head region is yellow to brown, the anal fin yellowish to hyaline, the pectoral and pelvic fins yellow to brown, and the caudal fin is dusky.

Comparisons

Arabian sillago, S. arabica McKay and McCarthy, 1989.

Elongated body; snout 32.3-40.0% of head length; opercle with a small sharp spine; anal fin with 2 spines and 22–23 soft rays. Mainly occuring in shallow sandy bottoms of offshore, bay habitats, and estuaries; swimbladder without anterior extensions and with a single posterior extension (Fig. 2a), no blotches on body, distributed in the Western Indian Ocean and Persian Gulf (Figs. 3b, 4).

Slender sillago, S. attenuata McKay, 1985.

Dorsal spine XI–XIII, II,19–21, anal fin rays II,18–20, faint 8–9 spots in two upper rows; 10 spots in a lower lateral row; a row of indistinct spots along the base of the spinous dorsal fin. The first dorsal fin with an anterior interspinous membrane speckled with black spots; 2nd dorsal fin speckled with black spots, with the rest of the fin hyaline; distributed in the Western Indian Ocean and Persian Gulf (Figs. 3c, 4).

Indian sillago, S. indica MaKay, Dutt and Sujatha, 1985.

Dorsal fin X–XI, I,20–22, anal fin II,21–23, lateral-line scales 68–71, scales above and below lateral-line 6–6/10–12, rakers on 1st gill arch 3–4/7–8, vertebrae 33–35, speckles absent, HL/SL (%) 27.5–32.4, swimbladder with two anterior extension and two posterior extensions, distributed in Indian Ocean. This species is generally mistaken in commercial catches with other sillaginids (Figs. 3d, 4).

Silver sillago, Sillago sihama , Forsskål, 1775.

Dorsal fins XI; I, 21-22 (mostly 21) pectoral-fin rays; 22–25; anal-fin rays II, 21-23; gill rackers 2-4/6-8; caudal-peduncle depth 4.6-5.9 SL and maximum head length 28.6-31.8% SL. Large swimbladder with two anterior extensions diverging to terminate on either side of the basioccipital region above the auditory capsule and two posterior tapering extensions of the swimbladder extending into the caudal region, one usually longer than the other. Eight or nine lateral processes extending posteriorly from the lateral surface of the swimbladder; swimbladder with three or four horn-like anterior processes and five or six posterior small triangular processes. The body is yellowish-green dorsally and silver-white ventrally. Darkish brown band on snout, gradually fading posteriorly. Dorsal fins with transparent membranes; first fin darkish anteriorly and the second with 3 or 4 rows of dusky speckles. Pectoral fin pale yellow; pelvic fin white; anal fin membrane transparent with small irregular black spots; caudal fin yellowish with a darkish posterior lobe. A single faint stripe present along middle of body. Distributed in the Indo-West Pacific, Caledonia, and western Indian Ocean (Figs. 3e, 4).

Sillagionpodys chondropus (Bleeker, 1849).

Dorsal fin XI, I, 21–22; anal fin II, 20–23; vertebrae 35; swimbladder small. Ventral surface of urogenital aperture without duct-like process; first ray of the pelvic fin modified into a club-like structure (Figs. 3f, 4). Distributed in Indo-Pacific, northern New Guinea, Thailand, Philippines, and Taiwan. However, it has not been recorded from southern New Guinea or Australia.

Flathead sillago, Sillaginopsis domina (Cuvier, 1816).

Dorsal fin X, I,25–27; anal fin II,24–27, elongated body; head greatly flattened; eyes small, covered by adipose tissue; mouth small, terminal; swimbladder vestigial or absent, body black to light brown, lower half and belly pale brown to white; fins pale brown, with a light black spots. Found in shallow bays and estuaries. This species is distributed in the Western Indian Ocean and rarely to the Indonesian Archipelago (FishBase).

Key to genera and species of family Sillaginidae from the Northern Arabian Sea, coast of Pakistan

  • 1a. Snout and head well depressed; second dorsal fin spine filamentous; eyes small covered with adipose tissue; swimbladder absent or rudimentary Sillaginopsis

  • -First dorsal-fin with X spines; second dorsal fin with I spine, 25–27 rays; anal-fin with II spines, 24–27 rays Sillaginopsis domina

  • 1b. Snout and head not depressed; second dorsal-fin spine not filamentous; eyes large as percentage of head length; swimbladder present 2

  • 2a. First pelvic-fin ray thickened club-like; swimbladder reduced, without anterior and posterior extensions Sillaginopodys chondropus

  • 2b. First pelvic fin ray club-like shaped; swimbladder not reduced, with anterior and posterior extensions Sillago

  • 3a. swimbladder with single posterior extension 4

  • 3b. swimbladder with two posterior extensions 5

  • 4a. Head small, 20–27% of standard length; first dorsal fin spine XII and second dorsal fin-rays I,21–23; anal fin rays II,0–23 S. arabica

  • 4b. Head average in size of standard length, 22.5–29%; first dorsal fin spine XI−XIII and second dorsal fin-rays I,19–20; anal fin rays II,17–19 S. attenuata

  • 5a. Body without black spots, bands 6

  • 5b. Body with black spots, band pattern initiated from gill opening along with lateral-line system ended at the caudal base 7

  • 6. Eye 19.4–21.2% of head length; inter orbital width 19–20% of head length; gill rakers on first gill arch 3/8–9 S. sihama

  • 7a. Anal fin membrane with a clear of black spotted row 8a

  • 7b. Anal fin membrane yellowish 8b

  • 8a. Snout 37–44% of head length; swimbladder with two posterior extension with a gap persist at the origin of both lobes S. indica

  • 8b. Snout ≤64% of head length; anterior extensions of the swimbladder joined at the origin, diverging to terminate on the both side of the basioccipital above the anditory capsule whereas two posterior extensions penetrating into the caudal region, one usually longer than the other and presence of a duck-like process S. panhwari

Discussion

This study resulted in the discovery and description of Sillago panhwari sp. nov. after integrating a large number of phenotypic characters of six congeners from our study area. The swimbladder, first and second dorsal fins, and the anal fin of Sillago panhwari sp. nov. have little resemblance with those from Sillago parvisquamis. Similarly, the lateral line with 79─84 scales and its distribution from Japan and Taiwan (McKay 1985). In comparison with S. parvisquamis which has even great character displacement with S. panhwari characters: for instance, swimbladder structure, spines on the 1st dorsal-fin (XIII-XIV) and second dorsal-fin (II, 20–22), number of vertebrae (39–40), anal-fin (II, 22–24), dorsal fins dusky terminally with five or six rows of dusky spots on second dorsal fin membranes.

The depth distributions of the six sillaginid species indicate a high diversity of vertical habitat preferences. Sillago panhwari sp. nov. occurs from the upper shelf to below the shelf margin, while S. indica and S. sihama occur in more shallow environments and may migrate into shallower water, but remain mostly at less than 100 m depth in coastal waters. According to the FAO (2015) fish catalogue, only four Silago species are listed, namely S. arabica, S. sihama, Sillaginopodys chondropus and Sillaginopsis domina. However, after extensive sampling from port landings and fishery surveys for more than three years for this study, Sillaginopsis domina were not documented. As a possible oversight, S. indica was not listed in the FAO catalogue, even though it comprises over 50% of the total sillaginids catch in Pakistan (Panhwar et al. 2017).

For a better understanding of species-specific and size-/age-specific habitat preferences of sillaginids, more studies on depth distribution and biological characteristics of populations need to be conducted. The description of a new sillago species from the northern Arabian Sea coast of Pakistan highlights the need for further investigations on the ecology, including distribution and abundance patterns, which are now necessary for the effective implementation of management practises and conservation measures of economically and ecologically important sillaginids in the northern Arabian Sea coast of Pakistan.

Notes

Acknowledgments

The Higher Education Commission Paksitan is greatly acknowledg ed for the research grant assistance to SKP under National Research Program for Unive rsities.

References

  1. FAO (2015) Field identification guide to the living marine resources of Pakistan. FAO FishFinder Programme coordinator:2009–2014Google Scholar
  2. Fowler HW (1933) Proc Acad Nat Sci Philadelphia 85Google Scholar
  3. Kaga T, Ho HC (2012) Redescription of Sillago (Parasillago) indica McKay, Dutt & Sujatha, 1985 (Perciformes: Sillaginidae), with a reassignment to the subgenus Sillago. Zootaxa 3513:61–67Google Scholar
  4. Kaga T, Imamura H, Nakaya K (2010) A new sand whiting, Sillago (Sillago) caudicula, from Oman, the Indian Ocean (Perciformes: Sillaginidae). Ichthyol Res 57:367–372CrossRefGoogle Scholar
  5. McKay RJ (1985) A revision of the fishes of the family Sillaginidae. Mem Queensl Mus 22:1–73Google Scholar
  6. McKay RJ (1992) An annotated and illustrated catalogue of the Sillago, smelt or Indo-Pacific whiting species known to date. In: RJ MK (ed) FAO species catalogue vol. 14. Sillaginid fishes of the world (family Sillaginidae). FAO, Rome, pp 1–87Google Scholar
  7. Nelson JS (2006) Fishes of the world. John Wiley & Sons, New Jersey, pp 1–601Google Scholar
  8. Panhwar SK, Qamar N, Mairaj M, Shaikh W, Farooq N, Habib N, Han Z, Gao T (2017) Length weight relationship, sex ratio and growth estimates for five sympatric sillaginids (Pisces), from the northern Arabian Sea coast. J Applied Ichthyol. In pressGoogle Scholar
  9. Shao KT, Shen SC, Chen LW (1986) A newly recorded sandborer, Sillago (Sillaginopodys) chondropus Bleeker, with a synopsis of the fishes of family Sillaginidae of Taiwan. Bull Inst Zool 25:141–150Google Scholar

Copyright information

© Senckenberg Gesellschaft für Naturforschung and Springer-Verlag Berlin Heidelberg 2017

Authors and Affiliations

  • Sher Khan Panhwar
    • 1
  • Noureen Farooq
    • 1
  • Nazia Qamar
    • 1
  • Wajiha Shaikh
    • 1
  • Mushayida Mairaj
    • 1
  1. 1.Center of Excellence in Marine BiologyUniversity of KarachiKarachiPakistan

Personalised recommendations