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Proximal one-half to two-thirds of escal bulb darkly pigmented, distal portion oval in shape, proximal portion tapering into stem of illicium; a single slender escal appendage arising just anterior to escal pore, usually simple but occasionally with as many as three short filaments on each side; escal pore situated at apex of bulb, nearly always raised on a pigmented papilla; at least 1, but usually 2–6, vomerine teeth present in all known material less than 80 mm (except for a single 57.5-mm specimen, ISH 2007/71), and in five of 19 examined specimens larger than 80 mm.
A species of Ceratias, the metamorphosed females of which are distinguished from those of all other described species of the genus in having a single distal escal appendage; illicium length 14.5–37.8% SL; vomerine teeth (2–6) nearly always present in metamorphosed specimens less than approximately 80 mm, but rarely present in larger specimens.
Ceratias holboelli has a broad distribution in all three major oceans of the world, but is excluded from the Southern Ocean by its congener C. tentaculatus. It is known from throughout the North Atlantic, ranging as far north as the Strait of Denmark and extending south to approximately 8°S in the Central Atlantic. In the Pacific, C. holboelli has been collected from off New South Wales, in the Coral and Celebes Seas, the Bismarck Archipelago and Solomon Islands, from off Hokkaido, Japan, the Bering Sea, off central California, and from off Oahu, Hawaiian Islands. Two records are known from the Indian Ocean, one from off Durban, South Africa, and the other from the Arabian Sea.
Meso- to bathypelagic. Juveniles and adults of C. holboelli may be captured anywhere between approximately 150 and 3400 m, but the majority of specimens were captured between 400 and 2000 m. Of the material for which depth of capture is known (123 of 155 known specimens), 84% of was taken by trawls that reached a maximum depth of 2000 m or less; 76% was taken by trawls that reached a maximum depth of 1100 m or less. At the upper end of its vertical range, 80% of the known material was taken in 400 m or more. A number of large adult specimens have been found in relatively shallow water in high latitudes of the North Atlantic and in the Bering Sea, some of them from unknown depths, others in as little as 120 to 680 m. The 770-mm holotype of Reganichthys giganteus (MCZ 36042) was captured by otter trawl somewhere between the surface and 230 m. The average maximum depth for all known captures was 1143 m.
Pietsch TW. 2009. Oceanic Anglerfishes: Extraordinary Diversity in the Deep Sea. Berkley: University of California Press. 638 p.
The genus Ceratias differs from Cryptopsaras, the only other recognized genus of the family, in having nine caudal-fin rays, the ninth or ventral-most ray reduced to a small remnant; and in lacking a spine on the anterodorsal margin of the subopercle. Metamorphosed females of the genus are further distinguished from those of Cryptopsaras in having a long illicium (19.0–28.2% SL) and only two club-shaped caruncles (minute in specimens greater than approximately 400 mm) on the dorsal midline of the trunk just anterior to the origin of the soft-dorsal fin. Metamorphosed males of the genus are further distinguished from those of Cryptopsaras in having the two pairs of lower denticular teeth nearly equal in size. Larvae, males, and juvenile females lack subdermal pigment.
The esca of metamorphosed females is somewhat variable, with or without one or two distal appendages. If present, the escal appendages are simple or bear one to eight lateral filaments. The number of teeth in the lower jaw ranges from 44 to 102. Vomerine teeth are sometimes absent, but there may be as many as eight. Fin-ray counts are as follows: dorsal-fin rays 4 (excluding those embedded within the caruncles), very rarely 3 (only one of 196 specimens counted); anal-fin rays 4; pectoral-fin rays 15–19, usually 17 or 18 (Table 0). The skin of juvenile females is covered with minute, close-set spinules, that of large adults with large, conical dermal spines, each with a broad rounded base.
The skin of metamorphosed, free-living males is naked. The denticles are faintly barbed. There are two pairs of lower denticulars nearly equal in size, one pair situated immediately behind the other. Caruncles are absent. Adult males are parasitic, the skin spinulose, the denticles, eyes, and gut degenerated.
Larval females are distinguished in having two dorsal caruncles.
Females are dark red-brown to black over the entire surface of the body (except for the distal portion of the escal bulb) and oral cavity. The skin is unpigmented in juvenile males, but darkly pigmented in parasitic stages. Subdermal pigment is absent. The larvae are unpigmented.
Females are the largest known ceratioids, attaining a standard length of at least 855 mm (BMNH 1953.2.25.1). All known free-living males are small, less than 12 mm. Parasitically attached males become considerably larger, ranging from 9.2 to about 140 mm, and having a weight several times greater than that of the largest known free-living males.
Ceratias, with three species, is one of the most common and best-known ceratioids, now represented by well over 300 metamorphosed females, about 75 free-living males, 37 parasitic males (attached to 35 females), and about 160 larvae. All free-living Ceratias males are small, less than 20 mm, whereas the vast majority of attached males are considerably larger, greater than 25 mm. Most weigh several times that of the largest known free-living male and a few have attained quite remarkable sizes, exceeding 140 mm.
No free-living ceratiid male with large testes has ever been found, yet large ripe testes have been described in several attached males: those of three previously unreported UW specimens range from 7.3 mm to about 30 mm long (32.4–37.5% SL). Histological examination of the testes of two of these specimens (UW 21774, UW 21775; 20 and 34 mm, respectively), showed evidence of resorption, this indicating a recent spawning event. All known gravid females have a parasitic male attached. These data taken from both males and females reaffirm the idea that sexual maturity is never attained in members of this family unless stimulated by the attachment of a male.
The eyes of metamorphosed free-living males are unusually large in ceratiids, each having a prominent crescent-shaped aphakic space, but they quickly degenerate upon attachment to a female. The nostrils of ceratiid males, however, are minute, in marked contrast to those of all other ceratioids. The general assumption that pair formation in ceratioids is mediated by a species-specific pheromone emitted by the female and tracked by the male does not appear to apply to this family.
The denticular jaw apparatus of metamorphosed ceratiid males is well developed, consisting of a pair of upper and two pairs of lower teeth, each elongate and slightly hooked distally, appearing quite capable of nipping onto a female, but not especially well suited for prey capture. The alimentary canal is rather poorly developed. The few millimeters that the males increase in length during and after metamorphosis seem to result from a stretching of the body rather than any increase in body weight, and the liver decreases somewhat in size during this period. Thus, it appears that free-living metamorphosed males of this family do not eat.
Femle ceratiidas may become sexually parasitized at almost any size once past metamorphosis. Examples of small parasitized individuals include a 15.5-mm female, with a 9.8-mm male (USNM 234867); a 45-mm female, with a 10-mm male (ARC 8707665); and a 77-mm female, with a 15-mm male (BMNH 2004.6.29.4-5). In these three couples, the ovaries are as small as those found in non-parasitized females of a similar size, whereas the testes of the males are well developed, occupying more than half the volume of the coelomic cavity (1.7 mm long or 17% SL in ARC 8707665). Histological examination of the testes of the 10-mm male shows moderate resorption, thus indicating a recent spawning event. The members of the smallest attached pair appeared to be quite young, perhaps six months and certainly less than 12-months old.
The parasitic males of Ceratias are invariably attached to the belly of the female somewhat anterior to the anus. Although it is difficult to say in all cases, males more often than not attach themselves upside down with respect to the surface of the female and they are almost invariably directed anteriorly as if they approached their mate from behind.
Females to 855 mm and parasitic males to 140 mm.
680 mm, South Greenland, 0–340 m.
Holotype of Ceratias holboelli: ZMUC 61.
