Himantolophids are among the most easily recognized taxa of the suborder: with their globose spiny bodies, short stout illicia, elaborately decorated escae, and protruding chins covered with numerous wart-like swellings, they can hardly be confused with anything else.
Five species groups are recognized based on females and three based on males, following the revision of Bertelsen and Krefft (1988). Females may be placed in the H. cornifer-group, H. albinares-group, H. nigricornis-group, H. appelii-group, or the H. groelandicus-group; males in the H. rostratus-group, H. appelii-group, and the H. brevirostris-group.
Metamorphosed females are characterized by having a short stout body, best described as globose, the depth (in the best preserved specimens) 60–70% SL. The head is about 60% SL. The mouth is large, the opening oblique to almost vertical, the cleft extending below or slightly behind the eye. The snout and chin are unusually blunt, padded with thick skin, and covered with wart-like papillae, forming thick fleshy lips. The lower jaw is unusually thick and heavy, protruding slightly in front of the upper jaw, with a well-developed symphysial spine. The oral valve is weakly developed. The nostrils are set on low rounded papillae. The jaw teeth are relatively short, arranged in several oblique, longitudinal series, with 10 to more than 20 such series in the lower jaw. There are about 35–150 teeth on each side of the upper jaw, about 40–210 on each side of the lower jaw. The longest teeth in lower jaw are 3–8% SL, those of the upper jaw somewhat shorter. Vomerine teeth are absent. Epibranchial and ceratobranchial teeth are present: one or more tooth plates on the proximal tips of all four epibranchials and 8–20 tooth plates along the full length of all four ceratobranchials (see Bertelsen and Krefft, 1988:16, fig. 4C). The first epibranchial is free from the wall of the pharynx, but closely bound to the second epibranchial. The fourth epibranchial and ceratobranchial are bound to the wall of the pharynx, leaving no opening behind the fourth arch. The proximal one-half to two-thirds of the first ceratobranchial is bound to the wall of the pharynx, but the distal one-half to one-third is free. The distal end of the first ceratobranchial is also 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 present on epibranchials II–IV, the proximal one-half to two-thirds of ceratobranchial I, and the full length of ceratobranchials II–IV. A pseudobranch is absent. The illicium is unusually stout and thick, its length 26–86% SL, The pterygiophore of the illicium is short, its anterior end nearly completely covered by skin of the head and not reaching beyond the anterior-most margin of the snout when protruded. The escal bulb is short, oval in shape, with well-developed distal light-guiding appendages. The neuromasts of the acoustico-lateralis system are set on low rounded papillae, the pattern of placement as described for other ceratioids.
Recently metamorphosed females, measuring 30 to about 34 mm, differ from larger specimens in having a shorter illicium and shorter escal appendages, in lacking dermal spines and papillae on snout and chin, and in having fewer jaw teeth.
Metamorphosed males have relatively well-developed eyes, their diameter 5.5–8.7% SL. The olfactory organs are large, the nostrils directed laterally. The posterior nostril is slightly larger than the anterior, its greatest diameter 3.3–7.6% SL, and well separated from the eye and from the anterior nostril by pigmented skin. The nasal area is pigmented, but not inflated. There are 10–17 olfactory lamellae. The maxillae and premaxillae are not reduced, but jaw teeth are absent. The upper denticular bone bears 16–31 recurved teeth arranged in a semicircular, fan-shaped series, with some shorter denticles within. The upper denticular is fused dorsally with a number of large dermal spinules of the snout forming a conspicuous median ridge between the large olfactory organs, and attached to anterior end of the illicial pterygiophore. The lower denticular bone bears 20–50 recurved teeth, more-or-less distinctly separated into a median and a pair of lateral groups.
The skin of the head and body of the larvae is greatly inflated, giving a nearly spherical appearance. A conspicuous, pigmented dorsal hump is sometimes present just in front of the dorsal fin (Bertelsen and Krefft, 1988:74, fig. 34). The subdermal pigmentation consists of a dorsal group of melanophores well separated from the peritoneal pigmentation and a group of melanophores on the caudal peduncle.
The color in preservation is black to dark brown over the entire surface of the head and body. The females of some species have whitish or lightly pigmented areas on the chin, snout, and upper surface of the head or body. One or more shiny white patches are sometimes present on the ventral and/or dorsal midline of the body, situated at or on the bases of one or more of the median fins. The pigmentation of the illicium and fin rays increases with the size of specimens and is highly variable among species.
The largest known female is the holotype of H. groenlandicus from southwest Greenland (not preserved, except for the illicium; ZMUC 65), which measured about 465 mm. There are several additional individuals in the range of 250–400 mm. Metamorphosed males measure between 23–39 mm, and the largest larvae range from 17–22.5 mm.
Metamorphosed females and males of the family Himantolophidae are distinguished from those of all other ceratioid families by lacking parietal bones throughout life (lost during metamorphosis in females of the gigantactinid genus Rhynchactis) and in having a broad toothless vomer and triradiate pelvic bones (triradiate pelvic bones are also found in some specimens of the oneirodid genus Chaenophryne).
Metamorphosed females and males are further unique in having the following combination of character states: The supraethmoid, pterosphenoid, metapterygoid, and mesopterygoid are all present. The hyomandibular has a double head. There are two hypohyals and six (2 + 4) branchiostegal rays. The opercle is bifurcate. The subopercle has a slender tapering dorsal prolongation, but the ventral end is rounded, without an anterior spine or projection. Quadrate, articular, angular, and preopercular spines are absent. A postmaxillary process of the premaxilla is absent. The first pharyngobranchial is reduced in females, but rudimentary in males. The second and third pharyngobranchials are present, well toothed in females, but toothless in males. The fourth pharyngobranchial is absent, the first epibranchial is present, the third hypobranchial is absent, and there is only a single ossified basibranchial. Epibranchial and ceratobranchial teeth are present in females, but there are only minute remnants of ceratobranchial teeth present in males; see below. Epurals are absent. The hypural plate is entire, without a posterior notch. The posteroventral process of the coracoid is absent. There are three pectoral radials. Fin-ray counts are as follows: dorsal-fin rays 5 or 6; anal-fin rays 4; pectoral-fin rays 14–18; pelvic fins absent; caudal-fin rays 9 (1 simple + 6 bifurcated + 2 simple), the ninth or ventral-most caudal ray is well developed, more than half the length of the eighth (Table 0). The skin is everywhere covered with dermal spines or spinules, the spines hypertrophied in females (see below).
Metamorphosed females are further differentiated by having low rounded wart-like papillae covering the snout and chin; and large conical dermal spines, with extremely broad rounded bases, widely spaced and scattered over the head and body. Metamorphosed females are also unique in having the following combination of character states: The frontal bones are widely separated, but without ventromedial extensions. Sphenotic spines are present. The jaws are sub-equal, the lower jaw extending anteriorly beyond the upper. The lower jaw has a well-developed symphysial spine. The anterior-maxillomandibular ligament is present. The pterygiophore of the illicium bears a small ossified rudiment of the second cephalic spine. The escal bulb has a central lumen, with a pore leading to the outside. The esca is without tooth-like denticles. The ovaries are paired. Pyloric caecae are absent.
Metamorphosed males are further differentiated by having a series of enlarged dermal spines above and posterior to the upper denticular bone. They are also unique in having the following combination of character states: the eyes are positioned laterally and are slightly oval in shape, with a narrow aphakic space in front of the lens. The olfactory organs are large, the nostrils directed laterally. There are 16–31 denticular teeth on the snout and 20–50 on the chin, each cluster of teeth fused at the base to form upper and lower denticular bones, respectively. Fin-ray counts are as given for metamorphosed females. The skin is densely covered with close-set dermal spinules. They are free-living, never becoming parasitic on females, but temporarily attached males are so far unknown.
Himantolophid larvae differ from those of other ceratioids in having the following combination of character states: The body is short, almost spherical. The skin is highly inflated. The pectoral fins are of normal size, not reaching posteriorly beyond the dorsal and anal fins. Pelvic fins are absent. Sexual dimorphism is evident, the females bearing a small, club-shaped illicial rudiment protruding from the head. Fin-ray counts are as given for metamorphosed females. Unlike most other ceratioids, metamorphosis is delayed, the larvae attaining lengths of 17–22.5 mm, and metamorphosis taking place at lengths between about 20 and 33 mm.
Pietsch TW. 2009. Oceanic Anglerfishes: Extraordinary Diversity in the Deep Sea. Berkley: University of California Press. 638 p.
Bertelsen E, Krefft G. 1988. The ceratioid family Himantolophidae (Pisces, Lophiiformes). Steenstrupia 14(2):9–89.
Except for the presence of white circular scars found on the bodies of five females, which Maul (1961:115, fig. 15) argued might be “the result of an injury caused by a male that had grown fast there and has for some reason become suddenly detached”—but which Bertelsen and Krefft (1988) suggested might be caused by parasitic copepods—there is no evidence of sexual parasitism in this family.
