Key to the Leptocephali of Southwest Pacific Species of the Genus Anguilla

This key has been prepared from the 16 known Anguilla larvae from this area; the number of myomeres in each species (one more than the number of vertebrae) has been taken from the observed range of variation in the vertebral count of the adult. The key is simple to use. Where there is agreement at one number, proceed to the consecutive number; where there is no agreement, proceed to the alternative indicated in parentheses.

Body elongate to elongate-oval, not filamentous, reaching about 50mm just before metamorphosis begins, depth about one-fifth of total length. Pectoral fin present; upper jaw reaching to below middle of pupil; gut straight, not swollen or festooned; major vertical intestinal vessels usually lying at segments 17, 40, 45; vent never closer to tip of tail than by about 30 segments, before metamorphosis the myomeres numbering about 70 + 40 with a page 14 total in all species between 100 and 120. Pigment restricted to the chorioid of the eye but very young specimens have a few small black spots on the caudal tip	Anguilla Shaw.
1 (4) Number of complete myomeres between verticals through the dorsal and anal origins less than six (short-finned species)
2 (3) Myomeres 102–108, anterior margin of gall-bladder at the level of the 27 th myomere, a–d = 5–6, major vertical blood-vessels at 15–17, 35–37, 42–44	A. obscura Günther, known from Tahiti, south of Fiji and New Hebrides.
3 (2) Myomeres 109–117, anterior margin of gallbladder at the level of the 27th myomere, a–d = 1–4	A. australis Richardson.
Major vessels at 16–17, 39, 45–46	A. australis ?australis Richardson, known from south-east of New Caledonia and North Queensland.
Major vessels at 17, 41, 48	A. australis ? schmidti Phillipps, known from east of New Caledonia and north-east of New Hebrides.
4 (1) Number of complete myomeres between verticals through the dorsal and anal origins more than six (long-finned species).
5 (8) Myomeres 101–111, a–d = 8–10.
6 (7) Anterior margin of gall-bladder at level of 25th myomere, major vessels at 15–17, 36–37, 42–43	A. marmorata Quoy & Gaimard, known in the south-west Pacific from near Samoa and between Solomon Is. and New Caledonia.
7 (6) Anterior margin of gall-bladder at level of 31st myomere, major vessels at 16–17, 38–39, 44	A. reinhardti Steindachner, known from north-west of New Caledonia.
8 (7) Myomeres 109–117, a–d = 7, major vessels at 17–19, 41–42, 47–48, anterior margin of gall-bladder at 29–31	A. megastoma Kaup, known from northeast of New Hebrides. A. dieffenbachi Gray is unknown as a leptocephalus but would probably fall close to A. megastoma in its larval characters.