Osteichthyes
Actinopterygii

Famiglia Myctophidae

Benthosema Goode & Bean, 1896
Benthosema glaciale  Reinhardt, 1837

Ceratoscopelus
Ceratoscopelus maderensis  Lowe, 1839

Diaphus Eigenmann & Eigenmann, 1890
Diaphus holti   Tċning, 1918
Diaphus metopoclampus   Cocco, 1829
Diaphus rafinesquii   Cocco, 1838

Electrona Goode & Bean, 1896
Electrona risso   Cocco, 1829

Gonichthys
Gonichthys cocco  Cocco, 1829

Hygophum Bolin, 1939
Hygophum benoiti   Cocco, 1838
Hygophum hygomii   Lütken, 1892

Lampanyctus
Lampanyctus crocodilus Risso, 1810
Lampanyctus pusillus Johnson, 1890

Lobianchia Gatti, 1903
Lobianchia dofleini  Zugmayer, 1911
Lobianchia gemellarii   Cocco, 1838

Notoscopelus Günther, 1864
Notoscopelus bolini   Nafpaktitis, 1975
Notoscopelus elongatus   Costa, 1844

Myctophum
Myctophum punctatum  Rafinesque, 1810

Symbolophorus Bolin & Wisner, 1959
Symbolophorus veranyi   Moreau, 1888

Dn: Dorso-nasale

PO: Pettorali

AOp: Anali posteriori

Vn: Ventro-nasale

VLO: Sopraventrali

Prc: Precodali

So: Suborbitale

POL: Posterolaterale

Gs: Ghiandola luminosa sopracodale

Br: Branchiostegi

AOa: Anali anteriori

Gi: Ghiandola luminosa infracodale

PLO: Soprapettorale

SAO: Sopranali

PVO: Subpettorali

VO: Ventrali

1a. Two Prc photophores > 2

1b. Three or more Prc (1 may be at or above lateral midline at base of caudal peduncle) or none in Taaningichthys paurolychnus > 12

2a. Four photophores (VLO, SAO3, Pol,Prc2) well above the midlateral line; specimens usually skinned and photophores often lost; small species, never over 2.5 cm - Notolychnus valdiviae

2b.  No photophores above lateral line  > 3

3a.  AO in a single uninterrupted series; Pol absent  > 4

3b.  AO divided into 2 groups, AOa and  AOp; Pol present  > 5

4a.  PVO1-2 inclined, in line with PO1; interorbital wide; eye normal, pointing laterally  Electrona risso

4b.  PVO1-2 in an almost horizontal line, a line through them markedly above PO1; interorbital very narrow; eyes pointed upward, almost telescopic   Protomyctophum arcticum

5a. Mouth terminal, snout not projecting; jaws short, extending less than 1/2 eye diameter behind orbit.  > 6

5b. Mouth subterminal, snout projecting; jaws moderate, extending 1/2 eye diameter behind orbit >10

6a.  PVO1-2 in a horizontal line; VO2 elevated  >7

6b.  PVO1-2 in an inclined line, with PVO2 usually more than 1 photophore diameter above PVO1; all VO level > 8

7a.  Prc2 high, from 1 to 2 photophore diameters below, or on, midlateral line; teeth simple, never hooked   Benthosema

7b.  Prc2 low, level with Prc1; outer dentary teeth flattened and hooked forward   Diogenichthys atlanticus

8a.  Two Pol  Hygophum

8b.  One Pol > 9

9a.  SAO forming an almost right angle with SAO1 over or in advance of VO3  Symbolophorus

9b.   SAO in an almost straight or slightly angled line with SAO1 well behind VO3  Myctophum

10a. Gill rakers absent  Centrobranchus nigroocellatus

10b. Gill rakers present  >11

11a. AOp 7 or fewer, at most 1 over anal base; anal-fin origin about under middle of dorsal-fin base  Loweina

11b. AOp 10 or more, with 5 to 7 over anal-fin base; anal-fin origin under end of dorsal-fin base   Gonichthys cocco

12a. Dn absent; VO and Pol never arranged as in 12b   >13

12b. Dn present; either 2 horizontal Pol near lateral line or VO1-3 on a straight ascending line with VO4-5 level > 19

14a. A large white crescent on posterior half of eye; dorsal-fin origin behind base of pelvic fin; only 1 SAO (at midbody) or none in T. paurolychnus Taaningichthys

14b. No large white crescent on posterior half of eye; dorsal-fin origin over or slightly in front of pelvic fin; 3 SAO  Lampadena

15a. Luminous tissue restricted to caudal luminous glands and occasionally at base of adipose fin >16

15b. Luminous tissue over base of anal or dorsal fins and on other portions of body > 17

16a. Pectoral fin long, at least reaching SAO photophores, often to anterior anal fin.  Lampanyctus

16b. Pectoral fin rudimentary or short, seldom reaching PO4 (note that L. macdonaldi is the only Atlantic Lampanyctus with a short pectoral fin but it has 21 or more gill rakers vs. fewer than21 in all Nannobrachium)  Nannobrachium

17a. Three (2+1) Prc; a whitish crescent on posterior half of eye; luminous tissue above eyes in some species  Bolinichthys

17b. Four (3+1) Prc; eye without whitish crescent; no luminous tissue above eyes >18

18a. PO4 elevated; VO2 elevated; no medial luminous tissue either at bases of pelvic fins or between pelvic fins and anal-fin origin; pectoral fin long, reaching adipose origin   Lepidophanes

18b. PO4 not elevated; VO only slightly arched; medial luminous tissue present at bases of pelvic fins or between pelvic fins and anal-fin origin; pectoral fins moderate, not reaching adipose fin  Ceratoscopelus

19a. VO1-5 level; both supra- and infracaudal glands present in both sexes; 2 horizontal Pol near lateral line  Notoscopelus

19b. VO1-3 on a straight, inclined, ascending line with VO4-5 level; no caudal glands (Diaphus) or only 1 caudal gland (Lobianchia); 1 Pol >20

20a. Caudal glands absent; more than 1 pair of luminous glands on head (Ant, Dn, Vn, or So); usually a luminous scale at PLO  Diaphus

20b. Supracaudal (males) and infracaudal (females) well developed; 1 pair (Dn) of luminous organs on head; luminous scale at PLO absent   Lobianchia