Fig 1.
Phylogenetic relationships of lanternfishes and illustration of common light organs and primary photophores.
(A) Lanternfish genus-level cladogram from Martin et al. (2018) illustrating genera with previous research investigating cellular structure of primary photophores. A list of associated studies can be found in text. (B) Rendering of a generalized lanternfish depicting primary photophore series and additional common light organs. Abbreviations are as follows: Ant, antorbital organ; AOa, anterior anal organs; AOp, posterior anal organs; Br, branchiostegal organs; Bu, buccal organ; Ce, cervical; CP, cheek photophore; Dn, dorsonasal organ; INGL, infracaudal luminous gland; Op, opercular organs; PLO, suprapectoral organ; PO, pectoral organs; Pol, postero-lateral organ; Prc, precaudal organs; PVO, subpectoral luminous glands; SAO, supraanal organs; So, suborbital organ; Suo, supraorbital organ; SUGL, supracaudal luminous gland; VLO, supraventral organ; Vn, ventronasal organ; VO, ventral organs.
Fig 2.
Generalized illustration of the lateral section through a lanternfish VO primary photophore.
Main elements colored similar to tissues stained via Masson’s trichrome stain. Arrow V points ventrally.
Table 1.
Lanternfish specimens dissected for histological analysis in this study.
Table 2.
All lanternfish species assessed in this study including newly dissected (see additional Table 1) and those described and analyzed in previous publications.
Fig 3.
Stained sections of lanternfish primary VO photophores from species in the subfamily Gymnoscopelinae.
Organized alphabetically by genus. Masson’s trichrome: (A) Gymnoscopelus braueri MCZ 148790. (B) Hintonia candens LACM 11329–3. (C) Lampanyctodes hectoris LACM 10969–6. (D) Lampichthys procerus MCZ 102795. (Ei, Eii) Scopelopsis multipunctatus MCZ 102573. (Eiii) Scopelopsis multipunctatus LACM 31380–7. Toluidine blue: (Eiv) Scopelopsis multipunctatus LACM 31380–7. Abbreviations are as follows: C, scale cup; CT, connective tissue; DP, distal pigmentation; E, epidermis; LR, lens reflector; P, photocytes; PL, pigmented layer; R, reflector; SL, scale lens. Scale bars represent 200 μm.
Fig 4.
Stained sections of lanternfish primary VO photophores from species in the subfamily Lampanyctinae.
Masson’s trichrome: (A) Bolinichthys longipes AMNH 266513. (B) Ceratoscopelus townsendi AMNH 277131. (C) Lepidophanes guentheri AMNH 258059. (D) Lampadena urophaos AMNH 261300. (E) Parvilux ingens LACM 9559–12. (F) Taaningichthys minimus AMNH 270079. (G) Triphoturus mexicanus AMNH 252051. Abbreviations are as follows: C, cup; CPL, coelom pigment layer; CT, connective tissue; DP, distal pigmentation; E, epidermis; LR, lens reflector; P, photocytes; PL, pigmented layer; R, reflector; SL, scale lens; SPL, secondary pigment layer. Scale bars represent 200 μm.
Fig 5.
Stained sections of lanternfish primary VO photophores from species in the subfamily Diaphinae.
Organized alphabetically by genus. Masson’s trichrome: (A) Diaphus regani AMNH 270350. (B) Idiolychnus urolampus LACM 37002–1. Abbreviations are as follows: C, cup; CT, connective tissue; P, photocytes; PL, pigmented layer; R, reflector. Scale bars represent 200 μm.
Fig 6.
Stained sections of lanternfish primary VO photophores from species in the subfamily Myctophinae.
Organized alphabetically by genus. Masson’s trichrome: (Ai, ii) Benthosema suborbitale AMNH 270136. (B) Ctenoscopelus phengodes LACM 31317–7. (C) Dasyscopelus obtusirostris AMNH 30537. (D) Diogenichthys atlanticus MCZ 117647. (E) Hygophum proximum AMNH 270116. Toluidine blue: (Aiii) Benthosema suborbitale AMNH 270136. Abbreviations are as follows: C, cup; CT, connective tissue; DP, distal pigmentation; E, epidermis; L?, unknown layer; LR, lens reflector; P, photocytes; PL, pigmented layer; R, reflector; SL, scale lens; SPL, secondary pigment layer; SR, secondary reflector. Scale bars represent 200 μm.
Fig 7.
Stained sections of lanternfish primary VO photophores from species in the subfamily Myctophinae.
Organized alphabetically by genus. Masson’s trichrome: (A) Krefftichthys anderssoni LACM 11494–12. (B) Loweina rara LACM 38251–3. (C) Metelectrona ventralis LACM 11077–13. (D) Protomyctophum arcticum AMNH 215743. (Ei) Symbolophorus evermanni AMNH 270083. Toluidine blue: (Eii) Symbolophorus evermanni AMNH 270083. Abbreviations are as follows: C, cup; CPL, coelom pigment layer; CT, connective tissue; E, epidermis; LR, lens reflector; P, photocytes; PL, pigmented layer; R, reflector; SL, scale lens; SPL, secondary pigment layer; SR, secondary reflector. Scale bars represent 200 μm.
Fig 8.
Illustrations of the morphology of lanternfish primary photophores from early previously published works.
Brauer [40] Tafel XXX, Fig (8) Hygophum benoiti; (10) Lampanyctus macropterus; (12) Diaphus dumerilii; (13) Bolinichthys longipes. Abbreviations for Brauer [40] are as follows: bl, blood vessel; dr, glandular cells; e, epidermis; g, gelatinous body; m, membrane; p, pigment; r, reflector; s, scale. Lendenfeld [39], Plate 5, Fig 23) Myctophum aurolaternatum. Abbreviations for Lendenfeld [39] are as follows: b, blood vessels; c, connective tissue of the interior of the organ; p, section through the outer horseshoe-shaped pigment cell band; pc, radiating cells; pp, internal pigment cell layer; si, scale underlying the radiating organ; ss, scale covering the radiating organ; t, section through the H-shaped thickening of the covering scale. Emery [36], Tafel 27, Fig 1) Notoscopelus elongatus. Abbreviations for Emery [36] are as follows: a, specific mass of flattened cells; l, lenticular swelling of the scale; m, mucous connective tissue; s, superficial scale; sp, deep scale; t, silver carpet; v, blood vessels.
Fig 9.
Examples of primary photophore pigment variation in formalin-fixed ethanol preserved lanternfish specimens.
(A) Benthosema suborbitale AMNH 270136. (B) Ctenoscopelus phengodes LACM 31317–7. (C) Diaphus regani AMNH 270350. (D) Hygophum proximum AMNH 270116. (E) Loweina rara LACM 38251–3. (F) Scopelopsis multipunctatus LACM 31380–7. (G) Variation in photophore color in formalin-fixed ethanol preserved lanternfish specimen Triphoturus mexicanus (AMNH 252051) with scale lens present (starred photophores) and without the scale lens (remaining photophores). Scale bars represent 1,000 μm.