Abstract
The paper is the first record of the occurrence of the Pink Lipped Moray Eel, Echidna rhodochilus (Bleeker 1863), from India. The current specimen was caught from the mangrove creeks of Carbyn’s Cove, South Andaman. This species is known so far from Western Pacific and southeastern Indian Ocean up to Australia and Indonesia. The present study indicates that there are more studies to be conducted on the ichthyofauna of these islands for a better understanding of the biodiversity of this area.
1. Introduction
The Andaman and Nicobar Islands have unique ecosystems, mainly contributed by coral reefs, mangroves, seagrass, and seaweed beds as shelters and feeding grounds for many species. The Andaman and Nicobar fish fauna consists of an assemblage of about 1463 species spread over all the diverse habitats representing 586 genera belonging to 175 families. The fish diversity in Andaman and Nicobar Islands is of special interest in terms of marine zoogeography because of the confluence in the fishes of Andaman Sea with those of the Western Pacific and the Indian Ocean [1].
The family Muraenidae belongs to the order Anguilliformes. It contains 15 genera and 300 species [2]. The name of the family comes from the “Latin” word Muraena meaning moray eel [3]. Moray eels are cosmopolitan, most of them exclusively in marine, but several species are regularly seen in brackish water, and a few can sometimes be found in fresh water. They are mainly characterized by a very elongate muscular compressed body with a large mouth. Most have long sharp canine teeth but some such as the species belonging to Echidna have low nodular teeth. The species of Echidna prey principally on crustaceans, especially crabs, for which their blunt crushing teeth are well suited. The dorsal fin extends from just behind the head along the back and joins seamlessly with the caudal and anal fins. All the species lack pectoral and pelvic fins, adding to their serpentine appearance. Their eyes are rather small; morays rely on their highly developed sense of smell, lying in wait to ambush prey. The muraenid eels are often regarded as being nocturnal, but only few species actively forage for food at night [4].
So far, 20 species of muraenids have been reported from Andaman and Nicobar Islands, representing 8 genera (Echidna, Muraena, Gymnomuraena, Gymnothorax, Rhinomuraena, Scuticaria, Strophidon, and Uropterygius). Echidna nebulosa was the only species from the genus Echidna previously reported from Andaman and Nicobar Islands [1].
2. Materials and Methods
During an ichthyofaunal survey in the mangrove creeks of Carbyn’s Cove near Port Blair (Figure 1), fishes were collected by using hook and line. The species was identified following standard identification keys [5, 6]. A detailed literature survey has revealed that the species Echidna rhodochilus was not recorded earlier from Andaman and Nicobar Islands [1, 7–11]. The morphometric and meristic characteristics were analysed and discussed.
3. Results
The newly recorded species was identified as Echidna rhodochilus Bleeker 1863, commonly called Freshwater Moray Eel or Pink Lipped Moray Eel, L. S. Berg, 1940 (Figure 2).
4. Systematics
Kingdom: Animalia Linnaeus, 1758 Phylum: Chordata Haeckel, 1874 Class: Actinopterygii Klein, 1885 Order: Anguilliformes L.S. Berg, 1940 Family: Muraenidae Rafinesque, 1810 Genus: Echidna Forster, 1777 Species: rhodochilus Bleeker 1863
Echidna rhodochilus Bleeker. Ned. Tijdshr.Dierk. I, 1863, p.247.-Atl. Icth, IV, 1864, p79.
New Combination
Muraena rhodochilus, Günther. Cat.Brit.Mus.VIII, 1870, p.132.
Common Name. Freshwater Moray Eel or Pink Lipped Moray Eel.
Two specimens, 326 mm and 324 mm TL, males, were collected by Arun Kumar. M, on February 13, 2010, from the mangrove creek in Carbyn’s Cove, around 5 km from Port Blair, Andaman and Nicobar Islands. The identified specimen was preserved in 5% formalin and deposited in the fishery museum, Department of Ocean Studies and Marine Biology, Pondicherry University, Port Blair (PU/DOSMB/2010/2/1).
4.1. Comparative Material Examined
A specimen of Echidna nebulosa (Ahl, 1789) from the nearby areas of Carbyn’s Cove was compared with E. rhodochilus. E. nebulosa has been the only species in the genus reported from this area so far. The body is moderately elongate and compressed along the tail. The head has a steep profile, and the snout is short and blunt; the eye is relatively small; the anterior nostril is a short tube and the posterior nostril is a simple hole with a raised rim, above and before the eye. The colour is variable, but typically yellowish-brown with 2 or 3 longitudinal series of darker, star-shaped spots along the body, each with a yellow center; the spots variably combined to form vertical bands; smaller spots and mottlings occur between the starry blotches. No pink spot is found on the cheek.
4.2. Diagnosis
E. rhodochilus and E. nebulosa present a marked colour difference, the former being brown in colour and the latter with star-shaped mottled blotches. There is a pink spot on the cheek in E. rhodochilus which is absent in E. nebulosa.
4.3. Key for the Genus Echidna
Genus Echidna Forster, 1777(1a) E. nebulosa: pale body with two rows of star-like blotches with centers.(1b) E. rhodochilus: dorsal fin origin behind gill opening; brown body with darker reticulations; head pores and posterior nostril in small white spots; white blotch on jaws below eye, larger on lower jaw (Figure 3).
5. Description
Characteristically, moray has an elongate, slender, snake-like body, a large mouth, median fins confluent with caudal fin, and no pelvic and pectoral fins. Gill opening is small and round. Head and trunk are equal to or somewhat shorter than the tail. The body is scaleless.
The origin of the dorsal fin is slightly behind gill openings and fleshy. Teeth are obtusely conical, in the maxillaries in 2 series, the outer with 14 and the inner with 9 teeth. In the lower jaw posteriorly a series of about 12 teeth is present and anteriorly two series of 6 pairs of teeth are present, the inner of which are stouter. On the vomer, two complete and one irregular series of strong teeth are found; on the intermaxillary plate a broad, nearly oval group of teeth are found, with the outer series much smaller than the 12 much stouter inner ones. It is brownish black with yellow fins. The specimen preserved in formalin (5%) is dark reddish brown with a whitish pink spot on the upper and lower lips near the corner of the mouth; with this marking, this species can be easily identified.
5.1. Remarks
The morphometric characteristics of the present specimen are similar to specimens reported from Indonesia [12] and significantly differ from those of Echidna nebulosa collected from Port Blair (Table 1). It has a blunt head compared to other well-known morays and is one of the smaller fish of the group. Maximum length is reported up to 33.8 cm [12].
5.2. Habit and Habitat
Adults are benthic, generally in shallow water among rocks and corals; they are mainly nocturnal and hide in holes and crevices during the day. They feed mainly on crustaceans, cephalopods, and small fishes. Primarily, a marine species yet shows a wide range of distribution, also found in brackish and freshwater environments. Some members of this family are used in the aquarium trade [13].
6. Distribution
The species is found in the Indo-West Pacific region: Indonesia and the Philippines [5, 14], Papua New Guinea to New Zealand [15], and Japan to Fiji [16, 17].
7. Conclusion
By comparison with a similar species occurring in the same area and by referring to available literature on the muraenid fishes of Andaman Islands, the specimen was identified and confirmed as Echidna rhodochilus and is reported for the first time from India.
Competing Interests
The authors declare that there is no conflict of interests regarding the publication of this paper.
Acknowledgments
The authors acknowledge sincerely the help rendered by the fisherman Mr. Dhanapal (Babu), who aided the authors in collecting the samples. The authors are indebted to Mr. A. Saravanan, Department of Disaster Management, Pondicherry University, for preparing the map of the study area.