Heteroconger mercyae, a new species of garden eel (Congridae: Heterocongrinae) from West Papua, Indonesia.

INTRODUCTION

Heterocongrine garden eels are common inhabitants of sand-rubble areas, frequently in the vicinity of coral reefs. The group contains 32 species worldwide in two genera (Eschmeyer & Fricke 2009), Gorgasia Meek & Hildebrand, 1923 and Heteroconger Bleeker, 1868. The majority, with the exception of eight species from the eastern Pacific and Atlantic, are restricted to the Indo-Pacific region. They were reviewed by Castle & Randall (1999), who also provided descriptions of five new species. An additional species, Gorgasia thamani Greenfield & Niesz, 2004 was later described from Fiji. Earlier publications treating this group include those of Bohlke & Randall (1981) and Castle & Randall (1995).

Garden eels occur at depths between about 2-55 m. The eels construct permanent burrows in the sand, which they never leave. Mating occurs between members of the opposite sex that occupy adjacent burrows by intertwining their bodies while the tail tips remain in their respective burrows (personal observations). Zooplankton is the primary dietary item and the eels rise nearly to full extent out of their burrows when feeding in the passing current. When disturbed the eels retreat backward down their burrows. When a diver swims through an extensive colony a "wave effect" is often created--the eels directly ahead gradually disappear into the sand, while those in the divers wake slowly reappear. Randall & Castle (1999) provided further details of the biology and systematics of the group.

The present paper describes a strikingly-marked species of Heteroconger that was discovered at Papisol Bay (Fig. 1), on the southern Bird's Head Peninsula of West Papua, Indonesia during March 2009. This general region has proved to be particularly rich for garden eels during our investigations over the past three years having previously collected and/or observed Heteroconger enigmaticus Castle & Randall, 1999, H. hassi (Klausewitz & Eibl-Eibesfeldt, 1959), H. perissodon Bohlke & Randall, 1981, H. taylori Castle & Randall, 1995, Gorgasia barnesi Robison & Lancraft, 1984, G. maculata Klausewitz & Eibl-Eibesfeldt, 1959, G. naeocepaea (Bohlke, 1951), and G. preclara Bohlke & Randall, 1981.

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MATERIALS AND METHODS

Terminology and methods follow Castle and Randall (1999). Head pore terminology is from McCosker et al. (1989) and the following abbreviations are used: SO (supraorbital series), IO (infraorbital series), POM (preopercular-mandibular series), ST (supratemporal series). Total length and head length are abbreviated as TL and HL respectively. Vertebral counts were made from radiographs and include the hypural. Type specimens are deposited at Pusat Penelitian dan Pengembangan Oseanologi, Jakarta, Indonesia (NCIP), National Museum of Natural History, Washington, D.C. (USNM), and the Western Australian Museum, Perth (WAM).

Heteroconger mercyae n. sp. (Figs 2-4)

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Holotype: NCIP 6352, male, 641.5 mm SL, Papisol Bay, 4[degrees]4.601'S 133[degrees]2.576'E, Papua Barat Province, Indonesia, 5-6 m depth, clove oil and hand net, M. Paine, M. Erdmann & G. Allen, 20 March 2009.

Paratypes (collected with holotype): NCIP 6353, 3 specimens, 560.7-653.9 mm TL; USNM 391795, 4 specimens, 385.1-678.1 mm TL; WAM 33088-001, 5 specimens, 106.3-677.4 mm TL.

Diagnosis: A relatively slender species of Heteroconger (Congridae) with dorsal-fin origin anterior to gill opening, pterygoid teeth present, body depth at gill opening 28.8-35.2 percent of HL, 62-71 (mean = 65) preanal vertebrae, 204-213 (mean =207.4) total vertebrae, 63-69 preanal lateral-line pores, and body colouration consisting of zebra-like black and white barring on head grading to complex black and white maze pattern on body.

Description: Counts and proportions of holo-type, followed by range and mean value for 9 paratypes (in parentheses). Vertebral formulae 6/67/205 (4-9/62-71/204-213); average total vertebrae for holotype and nine paratypes 207.4; lateral-line pores before pectoral fin 6 (6-7); lateral-line pores before anus 66 (63-69, mean = 65.7); total lateral-line pores 201 (198-210; mean = 205.8); pectoral-fin rays 10 (9-11; mean = 10.3); dorsal-fin rays before anus 190 (173-215; mean = 193.8); total dorsal rays 588 (578-629; mean = 591.6); anal rays 395 (390-432; mean = 412.5); head pores on left side, holotype (and 9 paratypes): SO 1+2, IO 2+2, POM 5+2, ST 1+1. As percent of total length: snout-anus length 29.7 (27.0-31.3; mean = 29.4); as percent of snout-anus length: HL 11.8 (10.9-14.7; mean = 11.9); predorsal length 11.0 (10.1-13.8; mean = 11.4); as percent of HL: snout 14.9 (13.5-15.7; mean = 14.7); eye 19.7 (20.0-23.9; mean = 21.2); fleshy interorbital 11.4 (10.2-14.1; mean = 10.9); mouth 21.9 (18.1-23.6; mean = 21.3); gill opening 9.2 (6.6-10.1; mean = 8.6); branchial interspace 21.5 (18.9-24.7; mean = 21.6); pectoral-fin length 10.1 (7.3-10.6; mean = 9.0); depth at gill opening 32.9 (28.8-35.2; mean = 32.0); depth at anus 24.1 (23.5-28.4; mean = 25.7).

Body relatively elongate, slightly compressed along head, progressively more so to tail tip; greatest depth at pectoral fins; anus at about 30% TL; head little depressed, flexed downward at pectoral fins; lower jaw slightly protruding; snout short and rounded; upper and lower lips well developed, the upper confluent medially, enclosing anterior nostrils, and turned back on anterolateral face of snout; lower lip similarly turned back on lower jaw; anterior nostril a minute tube close to midline of snout; posterior nostril a simple opening near anterodorsal corner of eye; mouth oblique, reaching to below anterior rim of eye; eye relatively large, oval, scarcely intruding into dorsal profile; throat with moderately developed folds extending to branchial aperture.

Gill opening before pectoral fins, slightly oblique with its ventral end more posterior than dorsal end; pectoral fins small rounded flaps; dorsal-fin origin about one-half eye diameter anterior to gill opening and low in preserved specimens; anal fin similarly low; caudal fin much reduced, tip of tail pointed.

Head pores inconspicuous, with very slightly raised rims; lateral-line pores minute and difficult to distinguish, especially on posterior one-fourth of body, approximately matching number of vertebrae.

Teeth small, although those of pterygoid and rear portion of vomer slightly enlarged; teeth in three rows on maxilla, tapering to two rows posteriorly; teeth in about five irregular rows on dentary, tapering to a single row posteriorly; intermaxillary-vomerine patch with 3-4 rows of teeth anteriorly, the tooth patch tapering posteriorly and nearly as long as maxillary row; pterygoid teeth in single row.

Colour in life (Figs 2, 3): conspicuous black and white zebra-like bars, spots, and oblique bands on head, grading to bold maze of black and white vermiculations on body; dorsal fin translucent with occasional rays marked with alternating black and white bands, and alternating black and white spots along outer margin; a yellow-orange iris ring on eye; lips white.

Colour in alcohol (Fig. 4): Generally dark brown, but close inspection reveals dark markings as described in live colouration above; about posterior one-fifth of total length light brown with dense pattern of melanophores.

Remarks: The new species has one of the highest average number of vertebrae (207.4) for the genus. Other species with relatively high average counts include H. cobra Bohlke & Randall 1981 from the Solomon Islands (199.8), H. tomberua Castle & Randall, 1999 from Fiji (195.1), and H. tricia Castle & Randall, 1999 from Flores, Indonesia (210, based on a single specimen). However, these three species have very different colour patterns consisting of either numerous small round spots and trio of large u-shaped black saddles (with white cental portion) on head and anterior body (H. cobra), 2-3 irregular rows of small dark spots above and below lateral-line (H. tomberua), or widely scattered large dark tan (possibly orange in life) spots, becoming more numerous on posterior half of body (H. tricia). The only species that has a colour pattern similar to H. mercyae is H. taylori, which ranges from Papua New Guinea westward to Bali, Indonesia. Although the usual pattern consists of numerous, relatively large black spots with white interspaces (Fig. 5), some individuals (Fig. 6) exhibit a pattern that approaches that of H. mercyae. However, the head is marked with irregular spots and bands rather than zebra-like bars and the vermicular pattern of the body is less complex. Moreover, H. taylori has relatively large black spots on the dorsal fin and lacks the pattern of alternating black and white spots along the dorsal-fin margin. The two species also show significant differences in vertebral counts (204-213 for H. mercyae and 169-172 for H. taylori). The new species also appears to attain a larger size than most members of the genus, at least based on museum specimens. Castle & Randall (1999) reported maximum total lengths ranging from 331-537 mm TL, with most species under 450 mm.

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Etymology: The new species is named mercyae in honour of Mercy Paine, who discovered the eel colony and helped us collect the type specimens.

Key to the Indo-west Pacific species of Heteroconger (adapted from Castle & Randall 1999)

1a. Body white with numerous narrow black bars on head and trunk, some on trunk meeting opposite neighbour ventrally; no pectoral fins; total vertebrae 153-159 (central Indonesia to Japan and Vanuatu) .. H. polyzona Bleeker, 1868

1b. Colour not as in 1a; pectoral fins present .. 2

2a. Body plain brown, with or without light head markings .. 3

2b. Body colour not as in 2a, variously spotted or mottled and/or with more prominent additional black blotches or marks .. 5

3a. Body plain medium brown with a white-yellow patch on postorbital and white margins on median fins; pterygoid teeth present; lateral-line pores before anus 54-59; total vertebrae 173-176 (Philippines and Indonesia) .. H. perissodon

3b. Body dark brown without light head markings or white margins on median fins; pterygoid teeth present or absent; lateral-line pores before anus 47-55 .. 4

4a. Pterygoid teeth present on most specimens; total vertebrae 154-163 (eastern Indonesia) .. H. enigmaticus

4b. No pterygoid teeth; total vertebrae 144 (Nicobar Islands) .. H. obscurus (Klausewitz & Eibl-Eibesfeldt, 1959)

5a. Body with relatively large, evenly spaced, round dark tan spots (orange in life in H. balteatus), with or without other markings .. 6

5b. Body markings as small closely packed dark spots or freckles on a pale background; the spots may link together to form irregular mottling or a maze-like network, with or without several other prominent dark and/or light bars or patches .. 7

6a. A wide oblique white bar on trunk and a less prominent white patch on postorbital head; lateral-line pores before anus 52-56; HL 15.0-18.0% of snout-anus length; total vertebrae 158-161 (Red Sea) .. H. balteatus Castle & Randall, 1999

6b. No white bar on trunk and no white patch on head; lateral-line pores before anus 64-68; HL 13.5-14.5% of snout-anus length; total vertebrae 210 (central Indonesia) .. H. tricia Castle & Randall, 1999

7a. Body markings as evenly distributed, rounded, small, discrete dark spots on a light background, but with no other markings; total vertebrae 186-208 (Fiji) .. H. tomberua Castle & Randall, 1999

7b. Body markings more intense, either consisting of closely packed dark spots or spots more closely packed and/or joining to form conspicuous mottling, or maze-like network, with or without additional, prominent and distinctive bars, bands or blotches; total vertebrae 164-213 .. 8

8a. Dorsal-fin origin more or less over gill opening or a little behind it .. 11

8b. Dorsal-fin origin clearly anterior of gill opening .. 9

9a. Body colouration consisting of zebra-like black and white bars on head grading to complex black and white maze pattern on body; total vertebrae 204-213 .. H. mercyae n. sp.

9b. Body colouration not as in 9a, usually spotted, although sometimes consisting of maze-like pattern on body without zebra-like bars on head; total vertebrae 169-176 .. 10

10a. Body evenly spotted to mottled or occasionally with maze-like pattern, without other markings; total lateral-line pores 157-160; mouth 24-30% of HL; pterygoid teeth present; total vertebrae 169-172 (Indonesia and Papua New Guinea) .. H. taylori

10b. Body evenly and closely spotted, with a blackish anterior head and light throat; total lateral-line pores 161-168; mouth 18.4-21.3% of HL; no pterygoid teeth; total vertebrae 173-176 (Marshall Islands and French Polynesia) .. H. lentiginosus Bohlke & Randall, 1981

11a. Three prominent black patches, one encompassing gill opening and pectoral fin, a second halfway along midlateral portion of trunk, and the third encompassing anus; total vertebrae 164-175 (Indo-Pacific) .. H. hassi

11b. Three prominent dark and light (combined), u-shaped saddles, one on postorbital and two spaced along anterior trunk; vertebrae 198-204 (Solomon Islands) .. H. cobra Bohlke & Randall, 1981

Zoogeography and habitat: The new species is currently known for certain only from the type locality (Fig. 1), which is situated about 95 km southwest of the town of Kaimana, West Papua, Indonesia. However, it likely ranges at least as far east as Rabaul, New Britain, based on an underwater photograph by R. Steene, showing a close-up view of the head of a garden eel that appears to be H. mercyae.

The type specimens were obtained from a single colony, occupying about 100 [m.sup.2] and containing approximately 50 eels in 5-6 m depth. The bottom consisted of fine, silty sand and was no doubt influenced by a freshwater stream along the adjacent shoreline, about 100 m distance. The nearest reef formation was about 50 m from the site.

ACKNOWLEDGEMENTS

We are especially grateful to Dexter and Susan Paine and their three children, Mercy, Sam, and Honor, for inviting us to participate on the Silolona cruise to Banda and West Papua during March 2009. Special thanks are also due Mercy Paine for her diving and collecting assistance, including her discovery and capture of the first specimen of H. mercyae. We anticipate a bright future for her in ichthyology. We also express sincere thanks to Patti Seery, owner of the live-aboard dive vessel Silolona, and her wonderfully efficient and hospitable crew. We thank the local governments of Kaimana and Raja Ampat for continued support of Conservation International's marine conservation initiatives in the Bird's Head, and Dr. Suharsono and Rianta Pratiwi of the Indonesian Institute of Sciences for support and assistance with curation of specimens. Sue Morrison of WAM prepared radiographs and offered curatorial assistance.

REFERENCES

BOHLKE, J. E. & RANDALL, J. E. 1981. Four new garden eels (Congridae, Heterocongrinae) from the Pacific and Indian Oceans. Bulletin of Marine Science 31(2): 366-382.

CASTLE, P. H. J & RANDALL, J. E. 1995. A new garden eel (Congridae, Heterocongrinae) from Papua New Guinea and Indonesia. Revue francaise d'Aquariologie 22 (1-2): 3-6.

CASTLE, P. H. J & RANDALL, J. E. 1999. Revision of the Indo-Pacific garden eels (Congridae: Heterocongrinae), with descriptions of five new species. Indo-Pacific Fishes 30: 1-52.

ESCHMEYER, W. N. & FRICKE, R. (eds.) Catalog of Fishes electronic version (updated 13 Mar. 2009). http://research.calacademy.org/ichthyology/catalog/fishcatsearch.html

MCCOSKER, J. E., BOHLKE, E. B. & BOHLKE, J. E. 1989. Family Ophichthidae. In: Fishes of the Western North Atlantic. Part Nine. Volume 1: Orders Anguilliformes and Saccopharyngiformes. (Ed. E. B. Bohlke): 254-412. Sears Foundation for Marine Research, New Haven.

Gerald R. Allen (1) and Mark V. Erdmann (2)

(1) Department of Aquatic Zoology, Western Australian Museum, Locked Bag 49, Welshpool DC, Perth, Western Australia 6986. E-mail: [e-mail]

(2) Conservation International Indonesia Marine Program, Jl. Dr. Muwardi No. 17, Renon, Denpasar 80235 Indonesia

Received: 23 April 2009-Accepted: 03 July 2009