Aulopidae: Sgt. Bakers, Aulopus

J.M. Leis

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Aulopids are marine, demersal fishes of shallow to great depths. They are found world-wide in tropical to temperate waters. There are two genera and about 12 species world-wide (Nelson, 1994). In temperate waters off eastern Australia, there are three species in one genus, but one (Hime japonicus) is know only from seamounts and ridges of the Tasman Sea, and not the mainland shelf (Parin and Kotalyar, 1989). A possibly undescribed Hime species occurs off Western Australia, and may penetrate into temperate waters (Bruce Thompson, personal communication). Adults are of moderate size (up to 60 cm) with no fin-spines, but possess a dorsal adipose fin. The body is cylindrical, and the head triangular with large mouth and pointed teeth. These reddish ambush predators rest on the bottom on the pelvic and caudal fins. Larvae are poorly known, but relatively consistent in morphology (Okiyama, 1984, 1988; Ambrose, 1996; Chiu, 1999). In addition to the main characters of Aulopid larvae, the fins are late to form, in the sequence: C, A, P1, P2, D. Notochord flexion occurs at 7-9 mm, and all rays are present in the dorsal fin by about 15 mm. The anteriorly located dorsal fin forms in an unusual manner in the fin fold before becoming directly attached to the myomere blocks. The large, dorsal adipose fin is distinctive and located opposite the anal fin. The pelvic fins are initially present as a thickening ventrolaterally at about midgut. As the pelvic-fin bud forms, it moves anteriorly and ventrally to just behind the level of the pectoral-fin base. Small melanophores may form along the ventral midline of the tail, and on the base of the caudal fin. Specialisations to pelagic life are the short to moderate, striated gut, and the distinctive saddle of pigment on the gut.

Meristic characters of aulopid genera of temperate Australia

	Anal	Dorsal	Pectoral	Pelvic	Caudal	Vertebrae
Hime	15-22	9-14	11-12	8-9	19	42-48

Note: although frequently placed in the Atlantic genus Aulopus, all Australian species are correctly allocated to Hime unless Whitley’s Latropiscis is applied to purpurissatus (Bruce Thompson, personal communication).

Main characters of aulopid larvae

42-48 myomeres
Slender body with PAL < 66% BL
Hindgut swollen and striated
Large VAFL
Moderate, pointed head, with large, round eye
No head spination
Early-forming canine teeth
Fins late to form; no spines in fins; dorsal adipose fin present
Prominent, dense pigment saddle over hindgut. Otherwise, lightly pigmented

References to Aulopid larvae

Okiyama (1984), Okiyama (1988), Ambrose (1996), Chiu (1999).

Families with similar larvae

The larvae most likely to be confused with aulopids are those of other aulopiform families, in particular, scopelarchids, synodontids, paralepidids, anotopterids and evermanellids. All of these other aulopiform groups have slender larvae with pigment saddles over the gut. All can readily be distinguished from aulopids because all have either multiple pigment saddles; narrow eyes; a long gut, with PAL > 66%BL (some have two or three of these).
Chlorophthalmidae have a much shorter gut than aulopids.
Pseudotrichonotidae and Paraulopidae - larvae are unknown, but may be similar to aulopids. Pseudotrichonotids - 30 dorsal-fin rays; juveniles have 12 pigment saddles on the gut.
Paraulopids - 48-51 myomeres; 10-12 dorsal-fin rays; 13-20 pectoral-fin rays.

References:

Okiyama, M. (1984). Myctophiformes: development. –In: Moser, H.G.; Richards, W.J.; Cohen, D.M.; Fahay, M.P.; Kendall, Jr, A.W. and Richardson, S.L. (Eds.). Ontogeny and Systematics of Fishes. American Society of Ichthyologists and Herpetologists, Special Publication 1, Lawrence, Kansas: 206-218.
Okiyama, M. (Ed.) (1988). An Atlas of the Early Stage Fishes in Japan. Tokai University Press, Tokyo: 1154 pages.
Ambrose, D.A.(1996). Aulopidae: Aulopids. –In: Moser, H.G. (Ed.), The Early Stages of Fishes in the California Current Region. CalCOFI Atlas No.33 Ed. Allen Press Inc, Lawrence, Kansas: 329-331.
Chiu, T.S. (1999). Larval and juvenile fishes of Taiwan. Preparatory Office, National Marine Biology Museum and Aquarium, Kenting. 296 pages.
Nelson, J.S. (1994). Fishes of the world (third edition). John Wiley and sons, New York: 600 pages.

Acknowledgments

We would like to thank Dr Muneo Okiyama for critical comments on our descriptions of Hime curtirostris and H. purpurissatus.

Correct citation of this description:

Leis, J.M. (2004). Aulopidae: Sergeant Bakers, Aulopus. Australian Museum Larval Fishes Website, viewed 1 July 2004 (i.e. date viewed), http://amonline.net.au/larval_fishes/descriptions/aulopidae.htm.