THE RAFFLES BULLETIN OF ZOOLOGY 2003 THE RAFFLES BULLETIN OF ZOOLOGY 2003 51(1): 97-100 © National University of Singapore FIRST RECORD OF THE MUDSKIPPER, PERIOPHTHALMODON SEPTEMRADIATUS (HAMILTON) (TELEOSTEI: GOBIIDAE) FROM PENINSULAR MALAYSIA M. Z. Khaironizam and Y. Norma-Rashid Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia ABSTRACT. – Periophthalmodon septemradiatus (Hamilton) is recorded for the first time from Peninsular Malaysia, from the Selangor and Muar Rivers. Along the Selangor River, the mudskipper occurs on mud banks amongst the mangrove Sonneratia caseolaris and in the small tributaries of the river with Nypa fruticans and village orchard trees, in water that is largely fresh (1 – 3 ppt.). The morphological features of the mudskipper are described and compared with its congeners. INTRODUCTION litt.). Terminology and measurements essentially follow Murdy (1989) and Murdy & Takita (1999). Mudskippers are gobies that have become adapted to an amphibious lifestyle. They occur along the muddy shores of the intertidal areas in estuarine habitats and mangrove swamps of the Indo-Pacific region (Tytler & Vaughan, 1983). Murdy (1989) reported the presence of 10 genera including 34 species found worldwide and 8 species from 6 genera of them can be found in the Peninsular Malaysia. TAXONOMY Periophthalmodon septemradiatus (Hamilton) Material examined. – 20 ex., KMZ-NYR000306KK (2), Malaysia: Selangor, Selangor River at Kampung Kuantan, coll. M. Z. Khaironizam & Y. Norma-Rashid, 6 Mar.2000; 10 ex., ZRC 41648, Malaysia: Johor, Muar, Muar River below Tanjung Selabu, coll. Y. Y. Goh, 8 Sep.1997; 6 ex., ZRC 41172, Malaysia: Johor, Muar, Muar River at Jorak, coll. Y. Y. Goh, 18 Nov.1996. The mudskipper genus Periophthalmodon Bleeker (family Gobiidae, subfamily Oxudercinae) is represented by three species: Pn. schlosseri (Pallas, 1770), Pn. septemradiatus (Hamilton) and Pn. freycineti (Valenciennes, 1837). Until now, only Pn. schlosseri was reported from Peninsular Malaysia (Cantor, 1849; Koumans, 1953; Macnae, 1968; Berry, 1972; Murdy, 1986, 1989; Takita et al., 1999). Diagnosis. – No pelvic frenum, pelvic fins completely separated. Snout scaleless, isthmus completely scaled. Scales on entire body large and cycloid. Teeth of upper jaw in two rows: anterior teeth of outer jaw small caninoid and smaller in the inner row. First dorsal fins (D1) in the female poorly developed possessing 3-5 short spines, and in some specimens are rudimentary. In the male, the first dorsal fin is of moderate height with a concave margin and an elongated first spine with 12 unbranched spines (Figure 2). Second dorsal fin (D2) with 12-14 spines (the first two unbranched). The first and second dorsal fins are contiguous. Pectoral and caudal fin spines are also branched. Table 1 shows the meristic and morphometric data of the specimens under KMZ-NYR000306KK (2). Periophthalmodon septemradiatus was reported by Murdy (1989) from the Bay of Bengal eastwards to the Gulf of Thailand and Sarawak. Koumans (1953) reported the species from India, Andaman Island, Thailand, Sumatera, and Borneo. Takita et al. (1999) reported it from Tebing Tinggi Island, Sumatra, in a small stream under tidal influence. In this paper, Pn. septemradiatus is recorded for the first time in Peninsular Malaysia, from the Selangor and Muar Rivers that drain into the Straits of Malacca. Specimens examined are deposited in the Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur (KMZ-NYR). Additional materials fromPeninsular Malaysia atthe Zoological Reference Collection of the Raffles Museum of Biodiversity Research, Department of Biological Sciences, National University of Singapore (ZRC) were identified by Kelvin K. P. Lim (in Colour description. – Freshly dead specimens have dusky grey heads and, brown on dorsum, white on ventrum and numerous pale red and pale blue spots on snout, opercle and trunk. A dusky longitudinal stripe on the predorsum starts from eye and terminates under the end of D2 or just before 97 Khaironizam & Norma-Rashid: Periophthalmodon septemradiatus from Peninsular Malaysia The separated pelvic fins of Pn. septemradiatus differentiate it from its congeners. Pn. schlosseri and Pn. freycineti have a strong frenum across their pelvic fins which are totally united to form a round disk. Unlike its congeners, Pn. septemradiatus is also sexually dimorphic. In mature males, the dorsal fins are contiguous, and the first dorsal fin is very reduced on females (Figure 2). In addition, adult Pn. septemradiatus is smaller (SL: about 40.0-60.0 mm) compared to Pn. schlosseri (SL: about 100.0-300.0 mm) and Pn. freycineti (SL: about 80.0-200.0 mm) (Murdy, 1989). the D2 in certain specimens. Eight black, saddle-like blotches occur dorsally: first anterior to D1, second across base of D1, third between D1 and D2, fourth, fifth and sixth across base of D2, seventh between D2 and caudal fins and eighth anterior to caudal fin. Dorsal fins: D1 black with reddish margin and D2 dusky with a red margin. Caudal and pectoral fins greyish and numerous red and blue speckles on pectoral fins. Anal and pelvic fins dusky. Preserved specimens are dark brown on body and white on ventrum. Black spots on body and the dusky stripe can only be seen in some specimens. The black blotches on dorsum also can be seen in preserved specimens. D1 black with a transparent margin, D2 dusky with dark brown stripes. Caudal, pectoral, anal and pelvic fin rays dusky. Periophthalmodon septemradiatus was found utilising the habitat that is far from the sea. Although under tidal influence, the water there was almost fresh, with a salinity that ranged between 1 and 3 ppt. In contrast, B. boddarti, Ps. chrysospilos and most other mudskippers live in the littoral zone on the foreshore where the salinity ranges from 30-34 ppt. (Chew & Ip, 1990; Clayton, 1993). Remarks. – Murdy (1989) recognised three species from the genus Periophthalmodon. They are distributed from Ganges Delta eastward to Indonesia, Papua New Guinea and Australia, but only one species, Pn. schlosseri, was recorded from Peninsular Malaysia (Cantor, 1849; Koumans, 1953; Berry, 1972; Murdy, 1986, 1989; Takita et al., 1999). Ecology. – The specimens of Periophthalmodon septemradiatus examined by us were obtained from the banks of the Selangor River at Kampung Kuantan (3° 11’N, 101° 18’E). This study area (Figure 1) is located about 15 km from the river mouth at Kuala Selangor, and about 64 km from northwest Kuala Lumpur. It was largely utilised for fishing, touristic and residential accommodation. A single species of mangrove, Sonneratia caseolaris was dominant. It formed a 10 metre wide belt above the mud banks, and ran parallel to the bund. Mature trees have brownish-grey bark and protruding pneumatophores that grow as high as The genus Periophthalmodon is distinguished from Periophthalmus by having a black stripe coursing posteriorly from the eye to the caudal peduncle, and by having two rows instead of one row of teeth in the upper jaw. These characters differentiate Pn. septemradiatus from the similar looking Periophthalmus weberi, which is known only from Papua New Guinea and Australia (Murdy, 1989). Fig. 1. Map of Selangor River at Kampung Kuantan, Selangor, showing known localities where Periophthalmodon septemradiatus were collected (triangles). Inset: map of Peninsular Malaysia with an additional locality (round spot) in Johor. 98 THE RAFFLES BULLETIN OF ZOOLOGY 2003 Table 1. Meristic and morphometric data from 20 specimens of Periophthalmodon septemradiatus KMZ-NYR000306KK (2). Variable Mean Range Total Length Standard Length First dorsal spines Second dorsal elements Anal fin elements Pectoral fin elements Longitudinal scales Body depth Head length Head width Head depth Length of first dorsal base Length of second dorsal base Length of anal fin base Length of pectoral fin base Length of pelvic fin Wet weight 64.52 mm 55.46 mm 8.50 13.00 10.55 12.00 48.60 14.95 % SL 26.98 % SL 21.59 % SL 19.76 % SL 8.74 % SL 21.92 % SL 16.58 % SL 24.88 % SL 14.89 % SL 3.13 g 57.40-78.50 mm 48.20-68.50 mm 5-12 12-14 10-11 12 48-50 14.31-16.60 % SL 24.44-28.62 % SL 18.90-24.07 % SL 19.09-20.95 % SL 2.36-18.64 % SL 21.29-30.22 % SL 14.34-19.53 % SL 23.32-27.22 % SL 13.70-15.82 % SL 2.10-6.90 g in a small stream at Tebing Tinggi, Sumatra, in a place similar to the present study area, but they did not report on the water salinity or the presence of sympatric mudskipper species there. 10 to 15 cm. The mangrove forest was relatively open with slightly over 15 plants per 6 square metres. There were also some small tributaries draining through stands of Nypa fruticans and village orchard. The mud-banks were gradually sloping and the substrate was extremely soft with high water content. Periophthalmodon septemradiatus was found on the mud banks and in the small tributaries along the upper reaches of the estuary. It was observed living sympatrically with the mudskippers Periophthalmus novemradiatus and Ps. gracilis. Along the upper reaches of the estuary at Kampung Kuantan, the water was fresh (0 ppt) at low tide. During extreme high tides, the salinities recorded in the river ranged from 1 to 3 ppt. Takita et al. (1999) found this species ACKNOWLEDGEMENTS The authors would like to acknowledge Dr. A Sasekumar from Institute of Postgraduate Studies, University of Malaya, Kuala Lumpur; Prof. Dr. M. Zakaria-Ismail from Institute of Biology, University of Malaya, Kuala Lumpur; Dr. Edward O. Murdy from National Science Foundation, Fig. 2. Sexual dimorphism on Periophthalmodon septemradiatus [KMZ-NYR000306KK (2)]. a) Male: the first dorsal fin is of moderate height with an elongated spine and contiguous with the second dorsal fins. b) Female: the first dorsal fin is poorly developed and not contiguous with the second dorsal fins. 99 Khaironizam & Norma-Rashid: Periophthalmodon septemradiatus from Peninsular Malaysia Virginia, USA; and Dr. Helen K. Larson from the Northern Territory Museum, Darwin, Australia for their assistance in taxonomic work. Kelvin K. P. Lim from the Raffles Museum of Biodiversity Research, National University of Singapore for information on the ZRC specimens. Mr. Mohaiyuddin for assistance in the field. This work was funded by PJP SF113/2000A and R&D 09-02-03-0674. Koumans, F. P., 1953. The fishes of the Indo-Australian Archipelago X. Leiden, E.J. Brill. xiii + 423 pp. Macnae, W., 1968. A general account of the fauna and flora of mangrove swamps and forest in the Indo-West-Pacific region. Advance In Marine Biology, 6: 73-270. Murdy, E. O., 1986. The lords of the Mudflats. Freshwater and Marine Aquarium, 9: 20-23. Murdy, E. O., 1989. A taxonomic revision and cladistic analysis of the Oxudercinae gobies (Gobiidae : Oxudercine). Records of the Australian Museum (1988). Supplement 11: 1-93. LITERATURE CITED Berry, A. J., 1972. The natural history of West Malaysian mangrove faunas. Malayan Nature Journal, 25: 135-162. Cantor, T. E., 1849. Catalogue of Malayan fishes. Journal of the Asiatic Society of Bengal, 18(2): 1-1443. Chew, S. F. & Y. K. Ip, 1990. Differences in the responses of two mudskippers. Boleopthalmus boddaerti and Periopthalmus chrysospilos to changes in salinity. The Journal of Experimental Zoology, 256: 227-231. Clayton, D. A., 1993. Mudskippers. Oceanography and Marine Biology Annual Review, 31: 507-577. 100 Murdy, E. O. & T. Takita, 1999. Periophthalmus spilotus, a new species of mudskipper from Sumatra (Gobiidae: Oxudercinae). Ichthyological Research, 46(4): 367-370. Takita, T., Agusnimar & A. B. Ali, 1999. Distribution and habitat requirements of oxudercine gobies (Gobiidae: Oxudercinae) along the Straits of Malacca. Ichthyological Research, 46(2): 131-138. Tytler, P. & T. Vaughan, 1983. Thermal ecology of the mudskippers, Periopthalmus koelreuteri (Pallas) and Boleopthalmus boddarti (Pallas) of Kuwait Bay. Journal of Fish Biology, 23: 327-337.