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Esca with a bulbous posteriorly oriented terminal papilla, rounded in smaller specimens, becoming pointed by 100 mm, often capped with a small pointed terminal appendage; escal pore at postero-basal margin of terminal papilla; number of teeth in lower jaw 25–65, in upper jaw 27–82; vomerine teeth 4–14.
Metamorphosed females of Diceratias pileatus differ from those of all other species of the genus in having a relative small esca, width about equal to length; a conspicuous bulbous terminal escal papilla; anterior and posterior escal appendages absent.
Except for a single 275-mm female found floating on the surface off Kona, Hawaii, the known material of D. pileatus is restricted to the Atlantic Ocean. In the Western Atlantic, all specimens, including the holotype, were collected from off Surinam, except for a single 235-mm specimen from the Bahamas. On the eastern side of the Atlantic, it is known from a number of localities along the West African coast, ranging from off Guinea Bissau to Gabon at about 2ºS, 8ºE.
Meso- to bathypelagic. All known specimens were taken in open trawls, one individual (USNM 217527, 41 mm) in a net fished at a maximum depth of only 400 m, the remaining in nets fished at maximum depths of 640 to 1430 m.
Pietsch TW. 2009. Oceanic Anglerfishes: Extraordinary Diversity in the Deep Sea. Berkley: University of California Press. 638 p.
The body plan and basic morphology of the family Diceratiidae varies little between genera and species. The following descripiton of all species of the family was taken from Pietsch (2009).
The body of metamorphosed females is short, globular, its depth approximately 50% SL. The mouth is large, the cleft extending past the eye, the opening oblique. The oral valve is well developed, lining the inside of both the upper and lower jaws. There are two nostrils on each side of the snout at the end of a single short tube. The jaw teeth are slender, recurved, and depressible, arranged in overlapping sets. There are 14–65 teeth in the lower jaw and 12–99 in the upper jaw. There are 4–15 teeth on the vomer. The first epibranchial is free from the wall of the pharynx. All four epibranchials are closely bound together by connective tissue. The fourth epibranchial and ceratobranchial are bound to the wall of the pharynx, leaving no opening behind the fourth arch. The proximal two-thirds of the first ceratobranchial are bound to the wall of the pharynx, but the distal one-third is free. The distal end of the first ceratobranchial is free, not bound by connective tissue to the adjacent second ceratobranchial. The proximal one-quarter to one-half of ceratobranchials II–IV are free, not bound together by connective tissue. Gill filaments are absent on the epibranchials, but present on the proximal tip of the first ceratobranchial, the full length of the second and third ceratobranchials, and the distal three-quarters of the fourth ceratobranchial. A pseudobranch is absent. The length of the illicium of females is highly variable, 26–47% SL in Diceratias, 83–225% SL in Bufoceratias. The anterior end of the pterygiophore of the illicium is exposed, emerging on the snout (Diceratias), or concealed beneath the skin of the head, the illicium emerging on the back at the rear of the skull (Bufoceratias). The posterior end of the pterygiophore of the illicium is concealed beneath the skin of the head. There is a second cephalic spine (second dorsal-fin spine), with a distal light organ, emerging from the dorsal surface of the head just behind the base of the illicium. The second cephalic spine tends to sink beneath the skin of the head with age, but remains connected to the surface through a small pore. The lumen of the escal bulb is connected to outside by a pore located on the posterior margin of the base of the terminal escal papilla. The internal pigment of the escal lumen is visible in lateral view, while the basal half of the escal bulb is usually covered with dark pigment. There are numerous, small, rounded, darkly pigmented papillae on the head and body associated with the acoustico-lateralis system, each with an unpigmented distal tip; the pattern of placement is as described for other ceratioids.
The single known metamorphosed male (a juvenile specimen from the Halmahera Sea, 14 mm, LACM 36091-4; see Bertelsen, 1983:312, fig. 1) has relatively large eyes, about 1.2 mm (8.6% SL) in diameter, with a narrow aphakic space surrounding the lens. The olfactory organs are well separated from the eye, the vertical diameter of the posterior nostrils about 0.5 mm, slightly larger than the anterior nostrils. The number of olfactory lamellae is less than 10 (no exact count possible). The frontals are broad, meeting on the midline. Crescent shaped parietals are present, but they are relatively small, their anterior tips just touching the posterior margin of the frontals. The opercle is bifurcate, the dorsal fork nearly as long (95%) as the ventral fork. The dorsal part of the subopercle is slender and tapering to a fine point; the ventral part is elongate and rounded, with a well-developed spine on the anterior margin. There are 6 dorsal-fin-rays, 4 anal-, and 15 pectoral-fin rays. The caudal fin contains 9 rays, the ninth well developed and nearly one-half the length of the longest medial rays. All the caudal-fin rays are simple (Table 0). The testes are oval in shape, about 2.0 mm in length and 0.9 mm in greatest width.
The premaxillae and dentaries of the male have irregularly resorbed edges. There are few larval teeth, only 2–4 on each premaxilla and 1 or 2 on each dentary. There is a pair of recurved denticular teeth on the snout lying slightly posterior to the symphysis of the upper jaw, each about 0.25 mm in length. There are 9 similar denticular teeth lying slightly behind the tip of the lower jaw, 8 of which are arranged in a regular symmetrical pattern consisting of an anterior and posterior transverse series of 4 teeth in each series. The ninth lower denticular tooth is the smallest, placed asymmetrically to the right of the lower series. The slender distal part of each of the four largest denticular teeth are about 0.25–0.30 mm in length (lying medial to the anterior series and lateral to the posterior series), emerging in an obtuse angle from a stout, nearly cylindrical base. All the denticular teeth are mutually free, without expanded connecting bases.
The pterygiophore of the illicium of the male is subdermal, its length 2.5 mm or 18% SL. The anterior end of the pterygiophore lies near the tip of the snout, the posterior end is connected to the anterior edge of the frontals by relatively strong extrinsic muscles. An irregularly shaped rudiment of the second cephalic spine lies slightly posterior to the middle of the pterygiophore, connected to the anterior edge of the parietals by retractor muscles (posterior inclinatores dorsalis).
The skin of the male is everywhere covered with tiny conical dermal spinules, those on the tip of the snout and chin slightly larger, more sharply pointed, and more closely spaced. The rounded basal plates of the largest spinules are about 0.15–0.2 mm in diameter.
The larvae (two known specimens, both females, 7–10.5 mm; ZMUC P922538, P92676) are extremely similar despite the large difference in size. The eye diameter is about 1.1–1.2 mm, relatively larger in the smaller specimen. The skin is inflated, forming an almost perfect sphere. The head is very large, its length more than 50% SL, but the mouth is relatively small. Both specimens are females, with relatively large rudiments of two cephalic spines: the illicium arising just in front of the eyes, its length almost equal to the diameter of the eye; and the second cephalic spine, arising just behind the first, about one-half as large. The overall color of the head and body is light gray-brown. There are tiny melanophores of almost uniform density over the entire body. Only the illicium and distal part of the fins are unpigmented. The second cephalic spine is pigmented with same density as the rest of the skin. Inner pigmentation of the body is visible through the skin, consisting of very small branched melanophores, arranged without distinct groups. The dorsal surface is slightly darker than the belly. The melanophores are grouped slightly more densely along the margins between the myomeres. There are 5–6 dorsal-fin rays, 4 anal-fin rays, 14–15 pectoral-fin rays, and 9 caudal-fin rays.
The color of metamorphosed specimens is dark brown to black over the entire surface of the head, body, and oral cavity, except for the distal portion of the escal bulb. The dorsal, anal, and caudal fins are unpigmented in females less than about 50 mm. The skin of the male is brownish black, except for that associated with the olfactory organs and tip of the snout. The subdermal pigmentation is light, without distinct concentrations of melanophores.
The largest known specimen of the family is a 275-mm female of Diceratias pileatus (BPBM 30655) found floating on the surface off Kona, Hawaii. The only known metamorphosed male measures 14 mm.
No sexually parasitized female of the family has ever been found. The largest known female of the family, a solitary and apparently mature female Diceratias pileatus, with large ovaries containing numerous eggs 0.3–0.7 mm in diameter, is good evidence that sexual parasitism does not occur in this family. The assumption that diceratiid males do not become parasitically attached to females seems supported further by the general morphology and spinulose skin of the single male described here, being remarkably similar to the males of the Himantolophidae and Melanocetidae, which undoubtedly are non-parasitic.
To 235 mm SL.
OREGON II station 10616, Western North Atlantic, off Surinam, 7º37'N, 53º32'W, 0–722 m, 13 May 1969.
Holotype of Diceratias pileatus: UF 23774, 82 mm.
Diceratias pileatus is a species of double angler, a type of anglerfish. The fish is bathypelagic and has been found at depths ranging from 640 to 1,430 metres (2,100 to 4,690 ft). It is endemic to the Atlantic Ocean.[1]
Diceratias pileatus is a species of double angler, a type of anglerfish. The fish is bathypelagic and has been found at depths ranging from 640 to 1,430 metres (2,100 to 4,690 ft). It is endemic to the Atlantic Ocean.
