Introduction
Cardinalfishes are ray-finned fishes belonging to the family Apogonidae Günther, 1859, order Kurtiformes (Fricke et al., Reference Fricke, Eschmeyer and Fong2024), found in the Atlantic, Indian, and Pacific Oceans; they are chiefly marine, but some species are found in brackish water and a few enter freshwater habitats (Johnson and Gill, Reference Johnson, Gill, Paxton and Eschmeyer1998). Cardinalfishes are generally small fish, with most species in the range of 5 to 20 cm in standard length, and often brightly coloured (Johnson and Gill, Reference Johnson, Gill, Paxton and Eschmeyer1998). Among other characters, they are distinguished by their large mouths which are adapted for mouth-breeding of the eggs, and the division of the dorsal fin into two separate fins. Most species live in tropical or subtropical waters, where they inhabit coral or rocky reefs and lagoon habitats (Mabuchi et al., Reference Mabuchi, Fraser, Song, Azuma and Nishida2014).
This family consists of 381 valid species in 40 genera (Fricke et al., Reference Fricke, Eschmeyer and Fong2024). In India, a total of 65 valid species belonging to 17 genera have been reported from various coastal regions and most of them have been reported from the Andaman and Nicobar Islands, Lakshadweep archipelagic, and the eastern and southwestern coasts of India (Saravanan et al., Reference Saravanan, Purushottama and Rohit2017; Kumar et al., Reference Kumar, Dineshbabu, Jaiswar, Shenoy, Kumar, Rahangdale, Vase and Damodaran2019).
The fishes of this family have a high ecological importance owing to their trophic role, especially in reef ecosystems (Marnane, Reference Marnane2001). Despite their ecological significance, only a few studies have been performed to explore the diversity and distribution of apogonids of the northwestern coast of India. Therefore, in the present trawl bycatch study along the coast of Veraval, the presence of two new records of cardinalfishes could be confirmed; these species are reported and described herein.
Materials and methods
In February 2024, regular fishing surveys were conducted at Veraval Fishing Harbour (20°54′27″N 70°23′02″E) off Gujarat, northwestern coast of India, to document the bycatch species assemblage. Specimens of cardinalfishes belonging to the genus Apogon and Apogonichthyoides were collected from the multiday trawler bycatch landed at Veraval Fishing Harbour. The collected specimens were brought to the laboratory, and then photographed. Species-level identification was based on the keys of Gon (Reference Gon2000), Gon et al. (Reference Gon, Bogorodsky, Mal and Alpermann2020), and Fraser et al. (Reference Fraser, Gon, Kraai, Heemstra, Heemstra, Ebert, Holleman and Randall2022). Morphometric measurements were taken using a Mitutoyo 150 mm Vernier caliper (nearest 0.1 mm), following the method of Hubbs and Lagler (Reference Hubbs and Lagler1958). The specimens were preserved in 10% formalin for further studies. The material was deposited in the fish collection at the Department of Fisheries Resource Management, College of Fisheries Science, Kamdhenu University, Veraval (KU/COFS/MUS) for future reference.
Results
Systematic position
Order Kurtiformes
Family Apogonidae Günther, 1859
Subfamily Apogoninae Günther, 1859
Genus Apogon Lacepède, 1801
Apogon fugax Gon et al., Reference Gon, Bogorodsky, Mal and Alpermann2020
Elusive cardinalfish
(Figure 1A, B; Table 1)
Type locality: Off Jizan, Saudi Arabia, southern Red Sea.
Apogon fugax (KU/COFS/MUS/010225) from northwestern India: (A) lateral view and (B) head. Scales (A-B) = 5 mm.
Morphometric and meristic data of Apogon fugax and Apogonichthyoides sialis from Gujarat, India, compared with previous data
Apogon fugax: Gon et al., Reference Gon, Bogorodsky, Mal and Alpermann2020: 485–504, fig 1 & table 3; Moazzam and Osmany, Reference Moazzam and Osmany2023: 50, fig 4.
Material examined. KU/COFS/MUS/010225–7, 3 ex., 46.7–58.0 mm SL (Figure 1A, B), Northwest Indian Ocean, northwestern coast of India, off Gujarat, Veraval Fishing Harbour, 20°54′27″N 70°23′02″E, collected by S. Ragul, 13 February 2024.
Description. First dorsal-fin spines VI; second dorsal-fin elements I,9; anal-fin elements II,8; pelvic-fin elements I,5; pectoral-fin rays 12/12; caudal-fin rays 10/10; lateral-line scales 23–24 + 3; predorsal scales 5–6; gill rakers on 1st arch 4 + 10–11. For detailed comparison of meristic and morphometrics see Table 1.
Body relatively elongate, somewhat deeper anteriorly, laterally compressed; body depth at pelvic-fin base 28.6–33.1% of SL; head length 38.7–42.8% of SL. Body scales ctenoid; a single large scale situated between first dorsal fin and lateral line; distance between snout and origin of first dorsal fin 41.3–42.8% of SL, between snout and origin of anal fin 60.5–62.0% of SL, and between snout and origin of pelvic fins 35.3–38.9% of SL. Caudal peduncle slender, compressed, its length 24.6–27.5% of SL, its width of 6.4–6.8% of SL, its depth 13.7–14.9% of SL.
Head profile between snout and first dorsal fin straight; nape somewhat elevated, width of head at posterior preopercular margin 13.9–14.1% of SL. Opercular margin weakly ossified. Opercle without serrations. Posterior margin of preopercle with serrae (not serrated spines). (Figure 1B). Snout elevated, its length 6.6–7.7% of SL. Eyes large, eye diameter 10.7–12.0% of SL. Mouth terminal, maxilla extending at least to below posterior margin of pupil; upper-jaw length 20.6–22.4% of SL (Figure 1B). Jaws with several rows of small villiform teeth. Tongue with a short prominent lobe.
First dorsal fin triangular, with second spine longest (16.7–17.2% of SL), first spine shortest (8.6–8.7% of SL), and third spine intermediate (14.7–16.8% of SL). Second dorsal-fin base (13.7–13.9% of SL) longer than the first dorsal-fin base (12.2–13.0% of SL). Pectoral fin elongate, pectoral-fin length 29.3–29.9% of SL; pelvic fins short, 22.4–24.6% of SL; pelvic-fin spine length 14.5–14.6% of SL. Anal-fin base similar to second dorsal-fin base, anal-fin base length 13.7–13.9% of SL. Caudal fin narrow, elongate, distally forked, its length 29.4–32.1% of SL (Table 1).
Colouration (fresh specimen) (Figure 1A, B). Body reddish orange. First dorsal-fin membrane with a patch of distinct black dots. Fins otherwise orange; distal part of caudal fin, bases of second dorsal fin, pelvic and anal fins translucent.
Coloration (preserved specimen). Body paler than in fresh condition, black dots more prominent; paired and unpaired fins pale yellowish.
Distribution and habitat. Apogon fugax is known from the southern Red Sea, northern Indian Ocean (Pakistan, India, Myanmar), and the southeastern Indian Ocean (Western Australia). It was collected at depths of 54–166 m (Gon et al., Reference Gon, Bogorodsky, Mal and Alpermann2020). Three adults are here recorded for the first time from the Arabian Sea off Gujarat, northwestern India (Figure 2), at depths of 70–110 m (SR, pers. comm., based on information of the fishing crew).
Geographical distribution of Apogon fugax in the Indian Ocean, showing (A) new record from Gujarat, (B) type locality, and (C) other records.
Systematic position
Order Kurtiformes
Family Apogonidae Günther, 1859
Genus Apogonichthyoides Smith, 1949
Apogonichthyoides sialis (Jordan and Thompson, Reference Jordan and Thompson1914)
Twinbar cardinalfish
(Figure 3; Table 1)
Type locality: Suruga Bay, Pacific coast of Honshu, Japan
Lateral view of Apogonichthyoides sialis (KU/COFS/MUS/010229) from northwestern India. Scale = 10 mm.
Material examined. KU/COFS/MUS/010229, 1 ex, 60.0 mm SL (Figure 3), Northwest Indian Ocean, northwestern coast of India, off Gujarat, Veraval Fishing Harbour, 20°54′27″N 70°23′02″E, collected by S. Ragul, 13 February 2024.
Diagnosis. First dorsal-fin spines VII; second dorsal-fin elements I,9; anal-fin elements II,8, pelvic-fin elements I,5; pectoral-fin rays 15/15; caudal rays 9/10; lateral-line scales 24 + 3; gill rakers on 1st arch 5 + 13. For detailed comparison of meristic and morphometrics see Table 1.
Body relatively deep; depth at first dorsal-fin origin 40.5% of SL. Head with a steep nape, head length 41.3% of SL, head width at posterior preopercular margin 16.1% of SL. Snout relatively short, snout length 9.1% of SL, shorter than eye diameter that equals 11.8% of SL. Mouth large, terminal, maxilla reaching to a vertical through mid-eye. Both jaws with several rows of small villiform teeth. Caudal peduncle length of 25.1% of SL, its depth 16.3% of SL.
Colouration (fresh specimen) (Figure 3). Body greyish black. A distinct black blotch on both lateral sides of the caudal peduncle. Body with two dark vertical bars, the first below first dorsal-fin origin, the second somewhat behind the second dorsal-fin origin. Fins black, except pectoral fins, caudal-fin margin, base of second dorsal fin, tips of pelvic and anal fins translucent.
Coloration (preserved specimen). Body paler than in fresh condition, black blotch and bars more prominent. Fins black to greyish.
Distribution. Apogonichthyoides sialis is distributed in the Indo-West Pacific from Pakistan, India, Bangladesh (Habib et al., Reference Habib, Islam, Nahar, Neogi and Fraser2021) and Myanmar, east to the Philippines, north to Japan (Figure 4); and has also been reported from the United Arab Emirates (Ludt et al., Reference Ludt, Jabado, Al Hameli, Freeman, Teruyama, Chakrabarty and Al Dhaheri2020) as Apogonichthyoides cf. nigripinnis. In India this species has previously been reported from the southeastern coast (Gon, Reference Gon2000); the southwestern coast at Cochin, Kerala (Manjebrayakath et al., Reference Manjebrayakath, Akhilesh and Pillai2012) and the northeastern coast at Visakhapatnam (Silambarasan et al., Reference Silambarasan, Kar, Prasad, Pattnayak and Ramalingam2022); here it is recorded from Gujarat, northwestern coast of India (Figure 4).
Geographical distribution of Apogonichthyoides sialis in the Indo-West Pacific, showing (A) new record from Gujarat, (B) type locality, and (C) other records.
Discussion
A comparison of Apogon fugax with other closely related apogonid species showed that it differs significantly from all of them in many morphometric and meristic characters: smaller size, larger head, preopercle with serrae in one vertical row, numbers of dorsal, anal and pectoral-fin rays. In addition to the above differences, A. fugax differs from Apogon deetsie Randall, 1998 by having a plain colouration without a distinct band on the body (vs a black bar on the caudal peduncle present in A. deetsie). Apogon fugax differs from Apogon rubrifuscus Greenfield and Randall, 2004, Apogon caudicinctus Randall and Smith, 1988 and Apogon dianthus Fraser and Randall, 2002 in having fewer gill rakers on the first arch, 4 + 10–11 (vs 4 + 13 in A. caudicinctus; 4–5 + 14–18 in A. dianthus; 5 + 15 in A. rubrifuscus).
Apogonichthyoides sialis is most similar to Apogonichthyoides pseudotaeniatus (Gon, 1986), but differs in having a lower number of lower gill rakers on the first arch 13 (vs 14 in A. pseudotaeniatus), the length of the second spine of the first dorsal fin 20.1% of SL (vs 15–19% in A. pseudotaeniatus), and the pelvic spine length 18.5% of SL (vs 16–17% in A. pseudotaeniatus).
Conclusion
The present specimens of Apogon fugax and Apogonichthyoides sialis were collected in association with the other apogonid fishes, namely A. pseudotaeniatus (Gon, 1986), Jaydia ellioti (Day, 1875), J. lineata (Temmink and Schlegel, 1843), J. queketti (Gilchrist 1903), J. striata (Smith and Radcliffe, 1912), J. striatodes (Gon, 1997), and Ostorhinchus fasciatus (Shaw, 1790). The present report of A. fugax from off Gujarat confirms the first documentation from Indian waters. Records of A. fugax are sparse, but they seem to indicate an anti-equatorial distribution pattern in the northern and southeastern Indian Ocean, with a wide gap in the equatorial regions.
Acknowledgements
The authors are grateful to the Principal, College of Fisheries Science, Kamdhenu University, for providing facilities enabling this work. The authors wish to extend their sincere gratitude to the anonymous reviewers and the editor, Dr Jim Ellis for their valuable comments and suggestions to improve the manuscript.
Financial support
This research received no specific grant from any funding agency, commercial or not-for- profit sectors.
Data Availability Statement
All relevant dataset supporting the conclusions of this article is included within the article.
Author contributions
S.R. and G.M. wrote the first version of the manuscript. S.R. carried out field sampling and collected the specimens. All authors contributed to the draft, provided critical feedback and helped shape the research. All authors read and approved the final manuscript.
Competing interest
None.
Ethical standards
Not applicable.
