Journal of Fish Biology (2000) 57, 536–539 doi:10.1006/jfbi.2000.1317, available online at http://www.idealibrary.com on
A new species of Encheloclarias from Sumatra H. H. N* H. H. T Department of Biological Sciences, National University of Singapore, Kent Ridge Crescent, Singapore 119260 (Received 25 January 2000, Accepted 27 March 2000) Encheloclarias velatus sp. nov. is described from central Sumatra. It differs from its congeners in having confluent anal- and caudal-fin bases, number of anal-fin rays, number of caudal vertebrae, length of anal-fin base, body depth at anus, head length, snout length, and 2000 The Fisheries Society of the British Isles interorbital distance. Key words: Encheloclarias; new species; Sumatra.
Encheloclarias Myers in Herre & Myers, 1937, is the only Asian genus of the Old World catfish family Clariidae with an adipose fin and is endemic to South-East Asia. It differs from Heterobranchus Geoffroy-Saint-Hilaire, 1809, and Dinotopterus Boulenger, 1906 (African clariids with an adipose fin) in lacking extensions of the neural spine supporting the adipose fin (Teugels, 1983; Roberts, 1989). The type species, Heterobranchus tapeinopterus Bleeker, 1852, was described from Banka Island, off the east coast of southern Sumatra. Ng & Lim (1993) revised Encheloclarias, in which five species, viz. E. baculum Ng & Lim, 1993 and E. prolatus Ng & Lim, 1993 from western Borneo, E. kelioides Ng & Lim, 1993 from eastern Peninsular Malaysia, and E. curtisoma Ng & Lim, 1993 from western Peninsular Malaysia, were considered valid. During recent collections in central Sumatra, specimens of Encheloclarias were obtained from local markets, which on comparison with other described taxa were found to be specifically different. This species is hereby described in this study as Encheloclarias velatus. Measurements (recorded to the nearest 0·1 mm) were taken from the left side with a pair of dial callipers and follow those of Teugels et al. (1990). Fin ray counts were obtained under transmitted light using a binocular dissecting microscope. Only principal caudal-fin rays were counted, i.e. rays attached to the hypurals. Gill raker counts were made using the method and terminology of Roberts (1992). Vertebral counts were taken from radiographs using the terminology of Roberts (1994). Institutional abbreviations follow those of Eschmeyer (1998). ENCHELOCLARIAS VELATUS SP. NOV. (Fig. 1) Encheloclarias kelioides (non Ng & Lim, 1993): Tan & Tan, 1994, 355. Holotype: MZB 9335, 161·6 mm LS; Sumatra: Jambi, Angso Duo market; purchased by H. H. Tan et al., 26–27 Oct. 1999. Paratypes: ZRC 44113, 3 ex., 142·0–169·2 mm LS; data as for as holotype. Additional (non-type) material: ZRC 32763, 1 ex., 44·4 mm LS; Riau Archipelago: Pulau Bintan north, Tanjung Bintan, swamp forest; P. K. L. Ng et al., 13 May 1993. Diagnosis: Encheloclarias velatus is differentiated from its congeners in having the following unique set of characters: anal and caudal fins confluent only at the base, *Author to whom correspondence should be addressed. Tel.: 065 874 2969; fax: 065 779 2486; email:
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F. 1. Encheloclarias velatus sp. nov., ZRC 44113, paratype, 163·2 mm LS.
54–59 anal-fin rays, 44–45 caudal vertebrae, length of anal-fin base 54·6–61·2% LS, body depth at anus 10·1–11·4% LS, head length 13·1–17·2% LS, snout length 28·9–32·0% LH, and interorbital distance 45·3–50·5% LH. Proportional measurements: In % LS: head length 12·0–14·5, head width 11·2–12·5, head depth 7·5–8·5, predorsal distance 28·9–30·0, preanal length 37·8–42·2, prepelvic length 32·2–35·1, prepectoral length 14·0–15·7, body depth at anus 10·1–11·4, depth of caudal peduncle 5·3–6·1, pectoral-spine length 5·8–7·6, pectoral-fin length 8·6–10·9, length of dorsal-fin base 33·0–34·0, pelvic-fin length 6·4–8·8, length of anal-fin base 57·5–61·2, caudal-fin length 13·0–13·4, length of adipose-fin base 37·8–42·3; in % LH: snout length 28·9–32·0, interorbital distance 45·3–50·5, eye diameter 4·4–6·6, nasal barbel length 112·2–130·7, maxillary barbel length 184·9–213·3, inner mandibular barbel length 121·3–145·7, outer mandibular barbel length 140·4–195·0. Counts: Fin ray counts: dorsal 25 (1), 28 (1) or 29 (2); pectoral I,7,i (2) or I,8,i (2); pelvic i,5 (4); anal 54 (1), 55 (1), 57 (1) or 59 (1); caudal 7/6 (3) or 7/7 (1). Branchiostegal rays 9 (3) or 10 (1). Gill rakers 2+7 (1) or 3+7 (1). Vertebrae 17+45=62 (1), 18+44=62 (1), 18+45=63 (1) or 19+45=64. Colour pattern: Dorsal surface of head and body uniform very dark grey, fading to a paler colour on ventral surfaces; adipose fin very dark grey with hyaline margin; fin rays of all other fins dusky, with hyaline inter-radial membranes. Distribution: Known only from the Batang Hari drainage in central Sumatra, and Binton. Etymology: From the Latin velatus meaning concealed, referring to the fact that this is the first species of Encheloclarias found on Sumatra after 150 years of ichthyological exploration, and the secretive nature of this species. Despite more than 150 years of ichthyological exploration in Sumatra (see Tan & Ng, 2000 for a brief review), our understanding of the Sumatran freshwater fish fauna is still far from complete. One noticeably absent from previous records is the clariid genus Encheloclarias. Tan & Ng (2000) noted this absence, and attributed it to both inadequate sampling and the fact that Encheloclarias is often found deep within the substratum of peat swamps (Ng, 1996), a habitat not easily sampled. The present series of Encheloclarias specimens were all purchased from markets, where they had been found among small specimens of Clarias nieuhofii Valenciennes, in Cuvier & Valenciennes, 1840, a peat swamp species. Bleeker (1862) illustrated E. tapeinopterus as having the anal and caudal fins completely fused, a condition which Ng & Lim (1993) confirmed by examining the radiographs of the (poorly-preserved) holotype. They also postulated E. baculum to have confluent anal and caudal fins based on similar evidence. Our examination of fresh material obtained subsequent to Ng & Lim’s study shows that E. baculum does not have fully confluent anal and caudal fins as supposed, but does have at least confluent analand the caudal-fin bases, a condition shared with E. tapeinopterus and E. velatus but not with other species of Encheloclarias. Encheloclarias velatus differs from E. tapeinopterus in having anal and caudal fins confluent only at the base (v. fully confluent anal and caudal fins), more anal-fin rays (54–59 v. 47–50) and caudal vertebrae (44–45 v. 34–37), and from E. baculum in having fewer caudal vertebrae (44–45 v. 48), and a shorter anal-fin base (54·6–61·2% LS v. 61·3–63·6) and head (13·1–17·2% LS v. 15·7–16·0). Encheloclarias velatus differs from E. curtisoma, E. kelioides and E. prolatus in having the confluent (v. separate) anal- and caudal-fin bases. It further differs from E. curtisoma in having a deeper body (10·1–11·4% LS v. 11·3–13·5), longer snout (28·9–32·0% LH v. 28·1–28·8), and eyes set further apart (interorbital distance 45·3–50·5% LH v. 39·8–41·9),
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F. 2. Map showing distribution of Encheloclarias baculum (), E. curtisoma (), E. kelioides (), E. prolatus (), E. tapeinopterus ( ) and E. velatus ().
from E. kelioides in having more caudal vertebrae (44–45 v. 41–43), and from E. prolatus in having fewer anal-fin rays (54–59 v. 65) and caudal vertebrae (44–45 v. 50). A specimen of a second Encheloclarias species was purchased along with the types of E. velatus. This specimen differs noticeably from E. velatus in having a longer, rounded head (17·2% LS v. 12·0–14·5) without expanded maxillary muscles (v. with expanded maxillary muscles causing the cheeks to appear inflated), separate anal and caudal fins (v. anal-and caudal-fin bases confluent), fewer caudal vertebrae (38 v. 44–45), and shorter barbels (nasal barbel length 84·7% LH v. 112·2–130·7; maxillary barbel length 107·5% LH v. 184·9–213·3). In most respects except for having fewer caudal vertebrae (38 v. 41–43), it closely resembles E. kelioides. Since the holotype and paratype of E. kelioides are much smaller than the Sumatran specimen, and no further material of E. kelioides has been obtained (especially from Peninsular Malaysia) since the original description, it is difficult to make meaningful comparisons between the large Sumatran specimen and the much smaller types and determine the limits of intraspecific variation. We therefore identify the Sumatran material as E. cf. kelioides. Comparative material: Encheloclarias baculum Ng & Lim, 1993: ZRC 39748, 1 ex., 50·1 mm LS; Borneo: Sarawak, c. 200 m into peat swamp forest from left side of road towards Gedong, c. 11·0 km after turnoff towards Gedong from Serian-Sri Aman road (112 08·7 N 11039 52·2 E); H. H. Tan & S. H. Tan, 16 Jan. 1996. ZRC 44215, 2 ex., 105·5–109·7 mm LS; Borneo: Sarawak, Sibu, Sungai Kemayan; donated by D. Yong, 1998. Encheloclarias curtisoma Ng & Lim, 1993: ZRC 14886, holotype, 79·4 mm LS; ZRC 14887–14888, 2 ex., paratypes, 61·3–61·7 mm LS; Peninsular Malaysia: Selangor, north Selangor peat swamp forest, blackwater stream at 39 km milestone on road to Tanjung Malim from Sungei Besar; P. K. L. Ng, T. Tan & K. K. P. Lim, 19 Jun. 1991. ZRC 17356, 1 ex., paratype, 45·1 mm LS; Peninsular Malaysia: Selangor, north Selangor peat swamp forest, blackwater stream at 50 km milestone on road to Tanjung Malim from Sungei Besar; P. K. L. Ng, 14 Sep. 1991. ZRC 29368–29369, 2 ex., paratypes, 19·9–23·0 mm LS; Peninsular Malaysia: Selangor, north Selangor peat swamp forest, shallow blackwater stream, between 43 and 33 km milestone; P. K. L. Ng & D. G. B. Chia, Jun. 1992. ZRC 29367, 1 ex., paratype, 57·9 mm LS; Peninsular Malaysia: Selangor, north Selangor peat swamp forest, blackwater stream at 39 km milestone on road to Tanjung Malim from Sungei Besar; P. K. L. Ng et al., Sep. 1992. ZRC 38259, 1 ex., 121·6 mm LS; Peninsular Malaysia: Selangor, Sabak Bernam; P. K. L. Ng, Sep. 1993.
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ZRC 34553, 1 ex., 33·4 mm LS; Peninsular Malaysia: Selangor, Sabak Bernam; P. K. L. Ng, Apr. 1993. ZRC 45671, 2 ex., 109·6–124·9 mm LS; Peninsular Malaysia: Selangor, Sabak Bernam; P. K. L. Ng, 1993. Encheloclarias kelioides Ng & Lim, 1993: ZRC 29401, holotype, 60·5 mm LS; Peninsular Malaysia: Pahang, south of Pekan, blackwater stream across road, 69 km stone on road from Mersing to Pekan, near Kuantan; M. Kottelat & P. K. L. Ng, 9 Mar. 1992. Encheloclarias cf. kelioides: ZRC 44213, 1 ex., 147·9 mm LS; Sumatra: Jambi, Angso Duo market; H. H. Tan et al., 26–27 Oct. 1999. Encheloclarias prolatus Ng & Lim, 1993: SMK 5686, holotype, 85·0 mm LS; Borneo: Sarawak, Kuching; collector unknown, Jun. 1892 (radiograph examined); additional data from Ng & Lim (1993). Encheloclarias tapeinopterus (Bleeker, 1852): RMNH 6806, holotype, 111·0 mm LS; Sumatra: Banka, Toboali; H. L. van Bloemen Waanders, 1852 (radiograph examined); additional data from Ng & Lim (1993). We thank P. K. L. Ng, for his support and mentorship; Gunawan ‘Thomas’ and Verawaty Kasim, for their hospitality and patience; K. K. P. Lim and M. C. C. de Pinna, for helping out on the trip that unveiled this species. This work is funded partly by research grant 3982327 to P. K. L. Ng from the National University of Singapore. References Bleeker, P. (1852). Nieuwe bijdrage tot de kennis der ichthyologische fauna van het eiland Banka. Natuurkundig Tijdschrift voor Nederlandsch Indie¨ 3, 715–738. Bleeker, P. (1862). Atlas. Ichthyologique des Indes Orientales Ne´ eˆ rlandaises. Vol. 2. Siluroı¨des. Chacoı¨des et He´ te´ robranchoı¨des. Amsterdam: Muller. Eschmeyer (1998). Catalog of Fishes. San Francisco: California Academy of Sciences. Ng, P. K. L. (1996). The rediscovery of the rare bladefin catfish, Encheloclarias. Nature Malaysiana 21, 52–58. Ng, P. K. L. & Lim, K. K. P. (1993). The Southeast Asian catfish genus Encheloclarias (Teleostei: Clariidae), with descriptions of four new species. Ichthyological Exploration of Freshwaters 4, 21–37. Roberts, T. R. (1989). The freshwater fishes of western Borneo (Kalimantan Barat, Indonesia). Memoirs of the California Academy of Sciences 14, 1–210. Roberts, T. R. (1992). Revision of the striped catfishes of Thailand misidentified as Mystus vittatus, with descriptions of two new species (Pisces: Bagridae). Ichthyological Exploration of Freshwaters 3, 77–88. Roberts, T. R. (1994). Systematic revision of Asian bagrid catfishes of the genus Mystus sensu stricto, with a new species from Thailand and Cambodia. Ichthyological Exploration of Freshwaters 5, 241–256. Tan, H. H. & Ng, H. H. (2000). The catfishes (Teleostei: Siluriformes) of central Sumatra. Journal of Natural History 34, 267–303. Tan, S. H. & Tan, H. H. (1994). The freshwater fishes of Pulau Bintan, Riau Archipelago, Sumatera, Indonesia. Tropical Biodiversity 2, 351–367. Teugels, G. G. (1983). La structure de la nageoire adipeuse dans les genres Dinotopterus, Heterobranchus et Clarias (Pisces: Siluriformes: Clariidae). Cybium 7, 11–14. Teugels, G. G., Denayer, B. & Legendre, M. (1990). A systematic revision of the African catfish genus Heterobranchus Geoffroy-Saint-Hilaire, 1809 (Pisces: Clariidae). Zoological Journal of the Linnean Society 98, 237–257.
