INTRODUCTION
The study of the ichthyofauna of Oman goes back to the end of the second half of the 19th Century when Boulenger (Reference Boulenger1887) reported on a collection of 172 species from the vicinity of Muscat city made by A.S.G. Jayakar (Randall, Reference Randall1995). Since then, several significant works have been published reporting on the presence and taxonomy of different fish species (Steindachner, Reference Steindachner1902; Regan, Reference Regan1905; Norman, Reference Norman1939; White & Barwani, Reference White and Barwani1971; Randall, Reference Randall1994, Reference Randall1995; Al-Abdessalaam, Reference Al-Abdessalaam1995).
No report is on record yet giving the complete check list of fish of Oman, thus further researches and studies are encouraged to take place in the area to record the species as they become available.
The order Lophiformes as currently recognized includes all angler fish and comprises 18 families, 65 genera and more than 300 living species (Shedlock et al., Reference Shedlock, Pietsch, Haygood, Bentzen and Hasegawa2004). Frogfish (family, Antennaridae) are among several representatives of this order. The family Antennaridae comprises 138 nominal species and 16 present allocations belonging to six genera. The genus Antennarius is the largest with 12 species (Froese & Pauly, Reference Froese and Pauly2008). In Oman, there are only five confirmed species of this genus.
In this paper we report the first record of the scarlet frogfish Antennarius coccineus from the southern part of the Gulf of Oman and the second record of the Indian frogfish A. indicus from the Arabian Sea coasts of Oman. The studied specimens are deposited in the fish collection of the Marine Science and Fisheries Centre, Muscat, Sultanate of Oman.
MATERIAL EXAMINED
OMMSFC0241, 233 mm total length (TL), 120 g, November 2007, Wadi Shab, Gulf of Oman, seine net (Figure 1).
Antennarius coccineus.
DESCRIPTION
The last two or three dorsal fin soft rays branched; all anal rays branched; all pectoral rays simple; last pelvic ray branched; esca a small sphere of folded tissue, illicium about as long as second dorsal spine; second dorsal spine curved without membrane linking it to head; colour (in ethanol) mottled dark grey, with small, irregular, dark grey spots; a round dark spot at base of second dorsal fin. This species is unique in having the following set of characters: basidorsal pigment spot present or absent, but it is present only weakly developed; illicium 8.8–13.2% standard length (SL), about as long as second dorsal spine; esca ranging in morphology from a simple, unpigmented sphere of folded tissue to an elongate, pointed appendage; second dorsal spine strongly curved posteriorly, last ray of pelvic fin bifurcate.
REMARKS
Antennarius coccineus is known from the Red Sea and East Africa to the eastern most islands of the Pacific Ocean. Randall (Reference Randall1995) collected a single specimen (62 mm TL) from the coastal area near Mirbat on the Arabian Sea coast in 1993. This species was never reported from the Gulf of Oman area and the present record constitutes an additional north-eastern extension of the previously known distribution of this species. Randall (Reference Randall1995) suggested that this species is a common shallow water dweller in the Indo-Pacific area, but for Oman coasts of the Arabian Sea and Gulf of Oman this species has a rare status. With one large specimen of A. coccineus, it is premature to consider this species has established a sustainable population in its new region. Thus, conservation measures by the Omani Fisheries authority are needed to investigate further the biological characteristics of this species in order to become endangered.
The presence of this species in its new locality can be explained on the basis of rarity of species assumption which prevented its record in the Gulf of Oman until recently.
MATERIAL EXAMINED
OMMSFC 0035,0079, 0207,0212, 0242-0246, (10) 45–148 mm TL, 3.5–70 g, November 2007–August 2008, Al-Ashkarah to Al-Juwayrah, Arabian Sea coast of Oman, midwater and bottom trawler at 26–58 m (Figure 2).
Antennarius indicus.
DESCRIPTION
The posterior two or three dorsal fin soft rays branched; none of the pectoral rays branched; large esca composed of bunch of leaf-like appendages; illicium equal in length to second dorsal spine; colour (in ethanol) light grey; illicium dark; the appendages averaging about 80% of the length of illicium; illicium 12.1–14.9% SL; second dorsal spine straight to slightly curved posteriorly, slightly hooked at tip; ventral portion of membrane behind second dorsal spine terminating well anterior to base of third spine, not extending across depressed naked area between second and third dorsal spines. This species is characterized by yellow colour with dark brown bars or rows of spots on fins; esca large not variable consisting of distinctive shape as cluster of leaf-like appendages; high pectoral-ray count; two to three dark ocelli (one at base of 2nd dorsal fin and the other one or two beneath pectoral fin).
REMARKS
Antennarius indicus is known from the western Indian Ocean, East Africa, Gulf of Aden, and Seychelles to south-east India and Sri Lanka (Froese & Pauly, Reference Froese and Pauly2008). This species is not found in depths less than 25 m. randall (Reference Randall1995) collected one specimen (250 mm TL) from Southern Oman coasts and considered it as rare specimen. For the last 11 years, no specimen of this species has been recovered from Omani waters in general. Therefore, the present report constitutes the second record from the Arabian Sea coasts of Oman and provides evidence that Randall's specimen was not just a sheer accident of a stray event. It also changes the rare status of this species given by Randall (Reference Randall1995) to a common status as it is distributed over large areas both at mid water and bottom.
Except for an unidentified antennarid specimen collected from the waters around Socotra Island (Kemp, Reference Kemp1998), the neighbouring ichthyofauna of Yemen did not show any record of the two species in question (Al-Sakaff & Esseen, Reference Al-Sakaff and Esseen1999; Kemp, Reference Kemp2000; MacAlister-Elliot, 2004). Until further investigations on the Yemen ichthyofauna of the Arabian Sea, it is too early to conclude that the two antennarid species studied in the present work are indigenous to the Omani waters of the Arabian Sea.
ACKNOWLEDGEMENTS
Our thanks to John E. Randall (Bishop Museum) for reading the manuscript and for his valuable advice and suggestions. We would also like to thank the Ministry of Fisheries Wealth and the Directorate of Agriculture and Fisheries Developmental Fund for giving us the opportunity to work on the fish samples within the qualitative and quantitative distribution of marine organisms in the Sultanate of Oman and providing the appropriate financial support. Our thanks also to Raymond Coory (Te Papa Tongarewa, Wellington, New Zealand) for his technical assistance in producing the images.
