View data on Catalog of Fishes here.
Escal appendage pattern B; esca with an anterior appendage bearing several filaments, two or three of which are stouter than others and darkly pigmented on distal one-third of length in specimens approximately 65 mm and larger; anterior appendage internally pigmented in 91-mm specimen; a pair of medial escal appendages each consisting of three primary branches, giving rise to numerous unpigmented tapering filaments some of which may be six times length of escal bulb; a truncated terminal escal papilla, with a distal streak of pigment in specimens 44 mm and larger; a stout posterior escal appendage bearing from four to nine tapering filaments, the distal tips of which are lightly pigmented in some specimens; lateral escal appendages absent; on each side, a filamentous anterolateral escal appendage usually consisting of two bifurcated unpigmented filaments.
Subopercle without indentation on posterodorsal margin; length of ventral fork of opercle 27.9–33.0% SL; ratio of lengths of dorsal and ventral forks of opercle 0.57–0.62.
Epibranchial teeth absent; teeth present on pharyngobranchial II, total number of teeth in upper jaw 30–48, in lower jaw 30–56; number of teeth on vomer 4–7; dorsal-fin rays 5 or 6; anal-fin rays 4 (the posterior-most anal-fin ray of the 91-mm specimen is divided at its base); pectoral-fin rays 15 or 16.
Measurements in percent of standard length: head length 34.6–45.4; head depth 40.0–51.1; premaxilla length 29.5–35.2; lower jaw length 44.2–52.3; illicium length 18.7–21.6.Sexual maturity: The right ovary of the 370-mm specimen of O. heteronema, the largest known oneirodid, is approximately 70 mm long (18.9% SL), 30 mm wide (8.1% SL), and filled with numerous eggs approximately 0.2–0.3 mm in diameter; that of the 91-mm specimen is 22 mm long (24.2% SL), with eggs measuring approximately 0.15–0.20 mm in diameter. The 65-mm specimen has small, undeveloped ovaries, as do all other individuals examined.
Except for the relatively short illicium and high ratio between the lengths of the upper and lower forks of the opercle, the escal characters of O. heteronema are the only satisfactory means of separating this species from most other members of the genus.
Oneirodes heteronema is known only from the Gulf of Panama and Peru-Chile Trench as far south as 20°S. The holotype is from 7°15'N, 78°54'W. Little information concerning vertical distribution is available. The 65-mm specimen was taken between the surface and 500 m; the 14-mm specimen was captured in a closing net between 1000 and 1250 m.
Mesopelagic.
Pietsch TW. 2009. Oceanic Anglerfishes: Extraordinary Diversity in the Deep Sea. Berkley: University of California Press. 638 p.
Although unknown, males of O. macronema are certainly free living and non-parasitic, as is the case with most oneirodid taxa.
Known from 10 metamorphosed females (13.5–370 mm).
DANA station 1209(4), 7°15'N, 78°54'W, 2000 m wire, 1845 hr, 17 January 1922.
Holotype of Oneirodes heteronema: ZMUC P92150, 13.5 mm.
