Leptoderma

Angulo, Arturo, Baldwin, Carole C. & Robertson, D. Ross, 2016, A new species of Leptoderma Vaillant, 1886 (Osmeriformes: Alepocephalidae) from the Pacific coast of Central America, Zootaxa 4066 (4), pp. 493-500 : 498

Key to species of Leptoderma

1 Both dorsal and anal fins confluent with caudal fin; procurrent caudal-fin rays few (dorsal 7–9; ventral 6–8) not extending far forward on caudal peduncle; dorsal procurrent caudal-fin section about 3.2–4.2% of SL; ventral procurrent caudal-fin section about 3.4–5.3% of SL................................................................................. 2

- Both dorsal and anal fins separated from caudal fin; procurrent caudal-fin rays numerous (dorsal 21–29; ventral 19–26) extending far forward on caudal peduncle; dorsal procurrent caudal-fin section 14.1–16.6% of SL; ventral procurrent caudalfin section 14.0–16.9% of SL........................................................................... 4

2 Dermal papillae absent along lateral line (Indo-West Pacific Ocean)................................... L. retropinna

- Dermal papillae present along lateral line.................................................................. 3

3 Dorsal-fin rays about 66; anal-fin rays about 85 (Indo-West Pacific)...................................... L. affinis

- Dorsal-fin rays 57–67, usually less than 64; anal-fin rays 74–85, usually less than 82 (Atlantic)............... L. macrops

4 Dermal papillae present along lateral line; lateral line pores 55–66; pectoral fin inserted high on body, central fin ray level with dorsal corner of gill opening, slightly above midline of body; length of anal-fin base 36.6–41.0% of SL (Western Pacific).............................................................................................. L. lubricum

- Dermal papillae absent along lateral line; lateral line pores, if conspicuous, about 48; pectoral fin inserted low on body, uppermost fin ray level with dorsal corner of gill opening, slightly below midline of body; length of anal-fin base 40.7–42.2% of SL.................................................................................................... 5

5 Pre-dorsal region short, length about 49.3% SL; pectoral-fin rays 8; pelvic-fin rays 8; dorsal- and anal-fin rays short, longer rays less than half body depth at anus; pre-ural vertebrae about 66 (North Atlantic).................. L. macrophthalmum

- Pre-dorsal region long, length about 54.9% SL; pectoral-fin rays 6; pelvic-fin rays 5; dorsal- and anal-fin rays long, longer rays greater than half body depth at anus; pre-ural vertebrae about 60 (Eastern Pacific).......................... L. ospesca