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Escal appendage pattern B; esca with a stout, internally pigmented, anterior appendage, greater than length of escal bulb, bearing along posterior margin a single branched filament proximally and a series of unbranched filaments distally; medial escal appendages in three groups, a highly filamentous pair lying between a similar but unpaired appendage, and a series of three stout papillae situated at base of terminal escal papilla; terminal papilla unusually long, directed posterodorsally; posterior escal appendage as long as anterior appendage, highly compressed, bearing one or two short lateral filaments, and a considerably longer branched filamentous anterolateral escal appendage on each side; distal tip of internal tube of anterior escal appendage, and dorsal pigment patch of escal bulb, with a paired circular translucent "eye spot."
Subopercle short and broad, upper end rounded without indentation on posterior margin; length of ventral fork of opercle 27.7–30.2% SL; ratio of lengths of dorsal and ventral forks of opercle 0.48–0.50.
Epibranchial teeth absent; teeth present on pharyngobranchial II; total number of teeth in upper jaw 32, in lower jaw 30; number of teeth on vomer 4–6; dorsal-fin rays 6; anal-fin rays 4; pectoral-fin rays 17.
Measurements in percent of standard length: head length 45.3; head depth 43.4; premaxilla length 30.2; lower jaw length 47.2; illicium length 26.4.
A species of Oneirodes differing from all previously described species in escal morphology: anterior appendage with a series of filaments along posterior margin; medial appendages in three groups; terminal papilla elongate; posterior appendage compressed and branched.
The two known specimen of Oneirodes thysanema were collected from widely separated localities, the holotype from off Bermuda in the Western North Atlantic, with gear fished open between the surface and 1500 m; and the second from the Banda Sea in the Philippine Archipelago, with a closing net between 650 and 1000 m.
Pietsch TW. 2009. Oceanic Anglerfishes: Extraordinary Diversity in the Deep Sea. Berkley: University of California Press. 638 p.
Although unknown, males of O. thysanema are certainly free-living and presumed non-parasitic, as is the case with most taxa of the family Oneirodidae.
Known from two metamorphosed females (13–26.5 mm).
Ocean Acre cruise 7, station 13N, Bermuda, 32°18'N, 63°30'W, 3-m Isaacs-Kidd Mid-water Trawl, 0–1500 m, 1430–1730 hr, 8 September 1969.
Holotype of Oneirodes thysanema: USNM 207931, 26.5 mm.
