Gigantactis Brauer, 1902

Gigantactis Brauer, 1902 View in CoL View at ENA

Diagnosis. Metamorphosed females of Gigantactis are distinguished from those of Rhynchactis , the other genus of the family, by the absence of pelvic bones and by having 5–9 dorsal-fin rays (rarely 4–10) and 4–7 anal-fin rays (rarely 8) ( vs. 3–4 dorsal-fin rays, rarely 5, and 3–4 anal-fin rays). They further differ from those of Rhynchactis by the following characters: frontal and parietal bones present ( vs. absent), premaxilla well developed, with teeth present throughout their length ( vs. premaxilla represented by a remnant bearing 0–2 teeth), maxilla reduced to threadlike remnants ( vs. maxillae absent), dentary with several rows of strong recurved teeth ( vs. dentary toothless or with only minute teeth), a single hypohyal ( vs. two hypohyals), all caudal-fin rays unbranched ( vs. 9 caudal-fins rays, 2 simple + 4 branched + 3 simple), skin spinulose ( vs. skin covered with minute spinules in larger specimens, but juveniles naked), snout produced in front of mouth, illicium originating at its tip ( vs. snout truncated, illicium origin slightly behind its tip), and esca consisting of an expanded luminous bulb ( vs. absence of bulbous, terminal, escal light organs) (Bertelsen et al., 1981; Pietsch, 2009).