Lampriformes

Angulo, Arturo & López-Sánchez, Myrna I., 2017, New records of lampriform fishes (Teleostei: Lampriformes) from the Pacific coast of lower Central America, with comments on the diversity, taxonomy and distribution of the Lampriformes in the eastern Pacific Ocean, Zootaxa 4236 (3), pp. 573-591 : 586-587

Key to eastern Pacific species of the order Lampriformes

The following key is based on our research and data available in the literature ( Fitch 1964, Miller & Lea 1972, Hart 1973, Rosenblatt & Butler 1977, Heemstra 1986a, b, c, Heemstra & Kannemeyer 1984, 1986a, b, Hulley 1986, Nakamura et al 1986, Paulin et al. 1989, Pequeño 1991, 2011, Collette 2003, Olney 2003a, b, c, d, e, Craig et al. 2004, Nelson 2006, Ruiz & Gosztonyi 2010, Savinykh & Baitalyuk 2011, Roberts 2012)

1 Body oval; all fins well developed, the caudal fin forked ( LAMPRIDAE ); body blue (dorsally), purple or pink (ventrally), with prominent pale spots in irregular rows (off California, USA, and Baja California Sur, Mexico; Gulf of California, Mexico; off Peru and Chile)............................................................ Lampris guttatus (Brünnich 1788)

- Body elongate, ribbonlike; pelvic and anal fins usually absent or reduced, caudal fin not forked; body color not as described above...............................................................................................2

2 Eyes tubular, directed forward; jaws highly protrusible; lower jaw length about equals to head length ( STYLEPHORIDAE ) (off California, USA, Baja California and Baja California Sur, Mexico; Gulf of California, Mexico; off Colombia, Ecuador, Peru and Chile)............................................................ Stylephorus chordatus Shaw 1791

- Eyes not tubular; jaws more or less protrusible; lower jaw shorter than head length................................. 3

3 Upper jaw slightly protrusible; maxilla slender, its width less than 50% the eye diameter; anus located at the posterior end of body; anal fin present ( LOPHOTIDAE ).................................................................. 4

- Upper jaw very protrusible; maxilla width more than 50% the eye diameter; anus located at or near middle of body; anal fin present, rudimentary, or absent.......................................................................... 5

4 Crest on top of head protrudes far forward of the upper jaw; dorsal fin with more than 300 rays (usually 310–392); anal-fin rays 5–9 (off California, USA; Gulf of California , Revillagigedo Islands and central coast of Mexico)............................................................................................. Eumecichthys fiski (Günther 1890)

- Crest on top of head extends forward to the tip of the upper jaw; dorsal fin with fewer than 300 rays (usually 210–229); analfin rays 19–21 (off California, USA, and Baja California, Mexico)......... Lophotus capellei Temminck & Schlegel, 1845

5 Anal fin present, rudimentary, with 6–7 rays; caudal fin highly modified and divided in two lobes, upper lobe with four or five short rays, lower lobe with six or seven elongate rays forming a caudal projection that may equal the body length in undamaged specimens ( RADIICEPHALIDAE ) (off California, USA, and Baja California, Mexico)................................................................................................ Radiicephalus elongatus Osório, 1917

- Anal fin absent; caudal fin absent (in large specimens of REGALECIDAE ) or, if present (in members of TRACHIPTERIDAE and small specimens of REGALECIDAE ), not as described above.............................................. 6

6 Body greatly elongated, its depth usually 1–8% SL; dorsal fin with more than 250 rays (usually 320–450), the rays smooth (without minute spines or prickles along their lateral edges); pelvic fin with a single elongate ray ( REGALECIDAE )..... 7

- Body less elongated, its depth usually 10–40% SL; dorsal fin with less than 250 rays (usually 130–215), the rays with minute spines or prickles along their lateral edges; pelvic fins usually with 5–10 rays, often elongate in juveniles, sometimes lost at metamorphosis ( TRACHIPTERIDAE )................................................................... 9

7 Premaxilla extending forward along dorsal profile of head; axis of maxilla oblique; dorsal-fin origin usually located behind middle of eye; first 1–3 dorsal-fin rays elongated, not forming a single or double crest but membranously joined to each other as well as to the other dorsal-fin rays; total gill rakers on first gill arch 6–10 (off Chile)...................................................................................................... Agrostichthys parkeri (Benham 1904)

- Premaxilla usually not extending forward along dorsal profile of head; axis of maxilla not oblique; dorsal-fin origin usually located ahead middle of eye; first 4–19 dorsal-fin rays elongated, forming a double crest, the first crest with 3–8 rays membranously joined to each other and the second crest with 1 or 5–11 rays not membranously joined to each other as well as to the other dorsal-fin rays; total gill rakers on first gill arch 33–60................................................... 8

8 Dorsal fin with more than 390 rays (usually 400–450); dorsal-fin rays until the end of the abdomen usually 90–120; first dorsal fin crest with 6–8 rays; second dorsal fin crest with 5–11 rays; total gill rakers on first gill arch usually 33–47, in large fish (off California, USA, and Baja California Sur, Mexico; off Ecuador, Peru and Chile).......... Regalecus glesne Ascanius 1772

- Dorsal fin with less than 390 rays (usually 320–370); dorsal-fin rays until end of abdomen usually less than 85; first dorsal fin crest with 3–6 rays; second dorsal fin crest with a single ray; total gill rakers on first gill arch usually 47–60 (from California, USA, to central Mexico)...................................................... Regalecus russelii (Cuvier 1816)

9 Ventral portion of tail smooth, not covered by spiny plates or bony tubercles; caudal fin not divided in two lobes and on the horizontal axis of the body, with 4–10 total rays........................................................... 10

- Ventral portion of tail covered by spiny plates or bony tubercles; caudal fin divided in two lobes, upper lobe upturned and usually fan-like, usually with 6–12 rays, lower lobe on the horizontal axis of the body or slightly upturned, usually with 1–6 rays (rudimentary spiny nubbins in some Trachipterus and large specimens of Zu)................................... 11

10 Snout length greater than eye diameter; scales present in prejuveniles and small juveniles, absent in adults; precaudal vertebrae 21–25, preanal vertebrae 46–51, total vertebrae 106–110; caudal-fin rays 4–7 (usually 6) (off Oregon and California, USA, Baja California, Baja California Sur and the mouth of the Gulf of California, Mexico; off Peru)......................................................................................... Desmodema lorum Rosenblatt & Butler 1977

- Snout length shorter than eye diameter; scales usually absent; precaudal vertebrae 18–20, preanal vertebrae 37–42, total vertebrae 71–74; caudal-fin rays 7–10 (usually 8) (from California, USA, to Chile)...... Desmodema polystictum (Ogilby 1898)

11 Dorsal-fin rays 115–150 (usually less than 145); scales usually present, deciduous, imbricated and cycloids; lateral line runs along ventral edge of tail as a zigzag series of elongate spiny plates; ventral edge of body usually scalloped and without bony tubercles (from California USA, to Chile)............................................ Zu cristatus (Bonelli, 1820)

- Dorsal-fin rays 145–185 (usually more than 155); scales usually absent or, if present, modified ctenoids; lateral line usually straight, as a series of oval plates each with a central and well-defined spine (usually in juveniles) or as an almost continuous tube (formed by the fusion of plates) with rudimentary blunt spines (usually in adults), usually well above ventral edge of tail; ventral edge of body usually straight and with bony tubercles................................................. 12

12 Ventral and dorsal body contours converge behind the anus (to within about an eye’s diameter of each other) and continue posteriorly nearly parallel to each other, forming an elongate strap-like tail; precaudal vertebrae usually 25–28, preanal vertebrae usually 39–42, total vertebrae usually 69–72 (from Oregon, USA, to Chile)............. Trachipterus fukuzakii Fitch, 1964

- Ventral body contour straight for entire length, dorsal contour descending in a straight line from nuchal crest to caudal fin origin; precaudal vertebrae usually 35–45, preanal vertebrae usually 50–55, total vertebrae usually 90–94 (from Alaska, USA, to Chile).............................................................. Trachipterus trachypterus (Gmelin, 1789)