Stephanoberyciformes

(Whalefishes and relatives)

Class Actinopterygii

Order Stephanoberyciformes

Number of families 9

Evolution and systematics

The order Stephanoberyciformes comprises deepwater, bathypelagic fishes that are for the most part poorly known anatomically. The order has a checkered systematic history; some of the families currently assigned to this order were treated as part of the formerly larger order Beryciformes (sometimes called Trachichthyiformes), others were previously included in the Lampridiformes. Stephanoberyciforms, as presently constituted, were given the status of an order by G. D. Johnson and C. Patterson in a phylogenetic survey of acanthomorph teleosts in 1993 (which is followed here); parts of the group were previously recognized as separate orders by earlier authors, including the whalefishes (Cetomimiformes) and pricklefishes and allies (Xenoberyces in part, or Stephanoberyciformes sensu stricto).

The 9 families that form the Stephanoberyciformes are divided into 28 genera and about 92 species. The families are:

• Stephanoberycidae (pricklefishes; 3 monotypic genera)
• Melamphaidae (bigscales or ridgeheads; 5 genera, about 38 species)
• Gibberichthyidae (gibberfishes, Gibberichthys; 2 species)
• Hispidoberycidae (Hispidoberyx ambagiosus)
• Cetomimidae (flabby whalefishes; 9 genera, about 35 species)
• Barbourisiidae (Barbourisia rufa)
• Rondeletiidae (redmouth whalefishes, Rondeletia; 2 species)
• Mirapinnidae (3 genera, 5 species)
• Megalomycteridae (largenoses; 4 genera, 5 species)

The first four families form the superfamily Stephanoberycoidea; the remaining families are united in the Cetomimoidea. Stephanoberyciforms share a specialization of the posterior dermal skull roof, in which the enlarged extrascapular bones cover the parietal bones. They are closely related to the bony fish groups Zeiformes, Beryciformes (sensu stricto), and Percomorpha, sharing with them the presence of pelvic fin spines (lost in certain stephanoberyciforms), as well as specialized features of their pelvic fin anatomy.

The fossil history of the Stephanoberyciformes is almost negligible in contrast to the more extensive fossil history of the Beryciformes. No fossil stephanoberyciform taxon has been erected to date, even though fossil otoliths (paired ear stones of the membranous inner ear labyrinth present in many fishes that can aid in detecting motion) and scant skeletal remains have been mentioned. Otoliths are difficult to identify because they lack features that are diagnostic of taxa of fishes; nonetheless, two unnamed species referred to the living genus Melamphaes have been recorded from the Tertiary period (some 50 million years ago) of France.

Physical characteristics

Stephanoberyciforms are a morphologically diverse lineage, ranging from the large-headed whalefishes to the small-headed megalomycterids and mirapinnids. In stephanoberyciforms generally, the head is somewhat large, with numerous bony ridges in the stephanoberycoids (giving them a highly armored look), usually with small eyes, the dorsal and anal fins end in opposition posteriorly on the body, the pectoral fins are of moderate size, and the caudal fin is truncated and not very large. All families have a single dorsal fin, either with very few spines (stephanoberycoids) or lacking them completely. Pelvic fins can be well developed (as in melamphaids), reduced (as in stephanoberycids), absent (as in cetomimids), and even winglike and aberrant (as in the hairyfish, Mirapinna esau). The caudal fin may have procurrent spines (as in stephanoberycoids), and is uniquely subdivided in Mirapinna. The jaw bones are rather weak and easily bent.

Many stephanoberyciform species appear velvety due to small protrusions from the epidermis (as in Mirapinna), or even from numerous spines on the scales (as in stephanoberycids) that are usually deciduous. Many species, such as the cetomimids, lack scales, others, such as the melamphaids, have large cycloid scales (their scales are rarely seen as they are easily lost on capture). The teeth are very small; numerous pores are usually visible on the head and lateral line, and some species may have luminous tissues and highly distensible stomachs, and are soft and flabby (as in whalefishes). One family, the Megalomycteridae, has extremely well-developed olfactory organs and nostrils. Species of the mirapinnid genera Eutaeniophorus and Parataeniophorus, and those in the family Megalomycteridae are morphologically quite distinct from other stephanoberyciforms.

The fishes of this order are usually small, rarely surpassing 9.8 in (25 cm) in length, and usually below 4.7 in (12 cm); only a few specimens above 13.8 in (35 mm) are known. Coloration is drab, brown, grayish black, or reddish (as in whale-fishes). Many stephanoberyciform species are known from very few specimens, and sometimes these represent only a single sex or a juvenile stage; no adult mirapinnid has been collected to date.

Distribution

The fishes of this order are widely distributed throughout all major oceans, but are yet to be recorded from the Mediterranean Sea or from Arctic waters.

Habitat

Stephanoberyciforms are deepsea fishes, generally inhabiting bathypelagic depths down to about 13,123 ft (4,000 m). A few species, especially juvenile forms, have been captured closer to the surface in waters as shallow as 164 ft (50 m), probably an indication of vertical migrations. The only specimen of the hairyfish was captured near the surface. Stephanoberyciforms, especially whalefishes and melamphaids, form an important and very large proportion of fishes in the bathypelagic realm.

Behavior

Stephanoberyciforms undertake vertical migrations from deeper waters into shallower regions.

Feeding ecology and diet

Very little is known concerning the food preferences of stephanoberyciforms, as the stomachs of relatively few individuals have been found to contain food. Copepods and other small crustaceans have been found in the stomachs of a few specimens of different species, but many, including, stephanoberycoids and whalefishes, are probably capable of ingesting larger prey items because of their relatively wide gape. Stephanoberyciforms are probably eaten by larger fishes.

Reproductive biology

The reproductive biology of stephanoberyciforms is largely unknown, but both eggs and larvae are pelagic. Eggs are unknown in many species. One highly modified larval form was originally described as a separate genus, Kasidoron, and even given familial status, but it is now well established that it represents the larval form of the gibberfish (Gibberichthys pumilus). This larval form is remarkable, presenting a very long pelvic appendage that superficially resembles algae (such as Sargassum) or siphonophores. The appendage is lost by about 1.2 in (3 cm) standard length. The larvae of Eutaeniophorus and Parataeniophorus are remarkable in presenting very elongated caudal "streamers," long tape-like projections that may reach several times body length (somewhat smaller in Parataeniophorus); the streamer is lost in adults. Larvae also have been described for Melamphaes, Poromitra, Scopeloberyx, and Scopelogadus. These begin to display their generic characteristics from between 0.2 and 0.8 in (0.5 and 2 cm) standard length. As a general rule, larvae and juveniles appear to occur in more shallow water compared to adults of the same species, which tend to be more bathypelagic.

Conservation status

No species in Stephanoberyciformes are listed by the IUCN.

Significance to humans

Stephanoberyciforms are not eaten and are therefore of little direct importance economically. Whalefishes are very numerous, and believed to form the most numerous fish species in terms of biomass in the bathypelagic zone 3,281–13,123 ft (1,000–4,000 m) in depth; therefore they are probably important food items of other commercial species, such as the orange roughy (Hoplostethus atlanticus).

Species accounts

List of Species

Red whalefish

Barbourisia rufa

family

Barbourisiidae

taxonomy

Barbourisia rufa Parr, 1945, Gulf of Mexico.

other common names

English: Velvet whalefish; Japanese: Aka-kujira-uo-damashi.

physical characteristics

Length about 15.8 in (40 cm). Unusual, with very large mouth (maxillae extend posteriorly well beyond level of eyes); teeth present on entire length of jaws; single dorsal fin located far posteriorly on back, close to caudal fin, with 20–23 rays; anal fin terminating at same level of dorsal fin, with 14–18 rays; pelvics (with 6 rays) and pectorals (with 12–14 rays) very small; skin covered in minute protuberances (velvety to the touch); lateral line very clearly demarcated by large-pored scales; coloration a uniform bright red.

distribution

Widespread but uncommon, occur in every major ocean usually at low latitudes, but reported to reach as far north as Greenland.

habitat

Captured usually near the bottom or in midwater over continental slopes and seamounts in depths of 394–6,562 ft (120–2,000 m).

behavior

Benthopelagic, believed to be capable of vertical midwater migrations for feeding.

feeding ecology and diet

Nothing known.

reproductive biology

Presumably lays pelagic eggs.

conservation status

Not threatened.

significance to humans

None known.

Longjaw bigscale

Scopeloberyx robustus

family

Melamphaidae

taxonomy

Melamphaes robustus Günther, 1887, Eastern Atlantic.

other common names

English: Ridgehead; Japanese: Tate-kabuto-uo.

physical characteristics

Length 2.8–3.9 in (7.3–10 cm). Head large (from 36 to 45% of standard length), with many bony ridges and deep sensory canals; elongate mouth reaching posteriorly well beyond relatively small eyes; large cycloid scales; 19–25 gill rakers; single dorsal fin originating at midlength, with 2–3 spines and 9–13 rays; anal fin posterior to dorsal, with a single spine and 7–9 rays; pelvic fins well posterior to head and with a single spine and 6–8 rays; pectoral fins elongate, reaching to level of middorsal fin, with 11–14 rays; caudal fin with some 20 rays; small teeth in 2–4 rows in upper and lower jaws. Coloration dark brown (at least in preservative).

distribution

Cosmopolitan in all major oceans except the Mediterranean Sea and Arctic Ocean. Reported to be common around the Commander Islands.

habitat

Meso- and bathypelagic; adults usually at depths of 1,640– 11,102 ft (500–3,384 m), juveniles in slightly shallower waters.

behavior

Nothing known.

feeding ecology and diet

Unknown, but because of its relatively wide gape it may consume fishes.

reproductive biology

Probably lays pelagic eggs.

conservation status

Not threatened.

significance to humans

None known.

Hairyfish

Mirapinna esau

family

Mirapinnidae

taxonomy

Mirapinna esau Bertelsen and Marshall, 1956, Eastern Atlantic.

other common names

None known.

physical characteristics

Size of only specimen 0.16 in (4 cm). Unusual appearance, head region proportionally small; mouth upturned; pelvic fins huge, projecting dorsally and located at throat, with 8 rays; small pectoral fins located more dorsally, with 13 rays; caudal fin divided into 2 distinct lobes that overlap; single dorsal fin posteriorly located, with 16 rays; anal fin opposite dorsal fin, with 14 rays; skin covered in hairlike protuberances; coloration dark brown.

distribution

Known from a single specimen, caught north of the Azores in the Eastern Atlantic.

habitat

Only known specimen was caught at the surface.

behavior

Nothing known.

feeding ecology and diet

Copepods were the only food item in the stomach.

reproductive biology

Unknown; only known specimen is a juvenile female.

conservation status

Not listed by IUCN.

significance to humans

None known.

Pricklefish

Stephanoberyx monae

family

Stephanoberycidae

taxonomy

Stephanoberyx monae Gill, 1883, Western North Atlantic.

other common names

None known.

physical characteristics

Length 3.9 in (10 cm). Head region proportionally large with many ridges; round eyes; mouth large extending posteriorly beyond level of eyes; single dorsal fin located posteriorly, with 1–3 poorly developed spines and 11–13 rays; anal fin terminating at level of dorsal fin, with 1–3 spines and 11–12 rays; pectoral fins with 12–13 rays; pelvic fins rudimentary and abdominal, with 5 rays; caudal fin with supports over and under caudal peduncle, with 8–11 spines on upper and lower aspects; body covered in scales that have small spines; coloration dark brown.

distribution

Western North Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico.

habitat

Presumably bathypelagic or demersal in relatively deep waters 1,115–15,673 ft (340–4,777 m).

behavior

Nothing known.

feeding ecology and diet

Unknown, but its large gape suggests it may feed on fishes and invertebrates.

reproductive biology

Essentially unknown; two specimens measuring 3 in (8 cm) were sexually mature.

conservation status

Not threatened.

significance to humans

None known.

Resources

Books

Bertelsen, E. "Families Mirapinnidae, Eutaeniophoridae." In Fishes of the North-Eastern Atlantic and the Mediterranean. Vol. II, edited by P. J. P. Whitehead, M.-L. Bauchot, J.-C. Hureau, J. Nielsen, and E. Tortonese. Paris: UNESCO, 1986.

Bertelsen, E., and N. B. Marshall. "Mirapinnatoidei: Development and Relationships." In Ontogeny and Systematics of Fishes, edited by H. G. Moser, W. J. Richards, D. M. Cohen, M. P. Fahay, A. W. Kendall, Jr., and S. L. Richardson. Special Publication No. 1. Lawrence, KS: American Society of Ichthyologists and Herpetologists, 1984.

Ebeling, A. W. "Family Melamphaidae." In Smiths' Sea Fishes, edited by M. M. Smith and P. C. Heemstra. Grahamstown, South Africa: J. L. B. Smith Inst. of Ichthyology, 1986.

Ebeling, A. W., and W. H. Weed. "Order Xenoberyces (Stephanoberyciformes)." In Fishes of the Western North Atlantic, edited by D. M. Cohen. Sears Foundation for Marine Research. Mem. No. 1, Part 6. New Haven: Yale University, 1973.

Gon, O. "Melamphaidae." In Fishes of the Southern Ocean, edited by O. Gon and P. C. Heemstra. Grahamstown, South Africa: J. L. B. Smith Inst. of Ichthyology, 1990.

Heemstra, P. C. "Family Stephanoberycidae." In Smiths' Sea Fishes, edited by M. M. Smith and P. C. Heemstra. Grahamstown, South Africa: J. L. B. Smith Inst. of Ichthyology, 1986.

Keene, M. J., and K. A. Tighe. Beryciformes: Development and Relationships. In Ontogeny and Systematics of Fishes, edited by H. G. Moser, W. J. Richards, D. M. Cohen, M. P. Fahay, A. W. Kendall, Jr., and S. L. Richardson. Special Publication no. 1. Lawrence, KS: American Society of Ichthyologists and Herpetologists, 1984.

Masuda, H., K. Amaoka, C. Araga, T. Uyeno, and T. Yoshino. The Fishes of the Japanese Archipelago, Vol. 1. Tokyo: Tokai University Press, Japan, 1984.

Maul, G. E. "Families Melamphaidae, Stephanoberycidae." In Fishes of the North-Eastern Atlantic and the Mediterranean. Vol. II, edited by P. J. P. Whitehead, M.-L. Bauchot, J.-C. Hureau, J. Nielsen, and E. Tortonese. Paris: UNESCO, 1986.

Mecklenberg, C. W., T. A. Mecklenberg, and L. K. Thorsteinson. Fishes of Alaska. Bethesda, MD: American Fisheries Society, 2002.

Moore, J., and J. R. Paxton. "Melamphaidae. Bigscales, Ridgeheads." In FAO Species Identification Guide for Fishery Purposes: The Living Marine Resources of the WCP. Vol. 4, Bony Fishes. Part 2 (Mugilidae to Carangidae), edited by K. E. Carpenter and V. H. Niem. Rome: FAO, 1999.

Patterson, C. "Osteichthyes: Teleostei." In The Fossil Record 2, edited by M. J. Benton. London: Chapman & Hall, 1993.

Paxton, J. R. "Families Cetomimidae, Rondeletiidae." In Fishes of the North-Eastern Atlantic and the Mediterranean. Vol. II, edited by P. J. P. Whitehead, M. -L. Bauchot, J. -C. Hureau, J. Nielsen, and E. Tortonese. Paris: UNESCO, Paris, 1986.

——. "Gibberichthyidae (Gibberfishes), Megalomycteridae (Bignose Fishes)." In FAO Species Identification Guide for Fishery Purposes: The Living Marine Resources of the WCP. Vol. 4, Bony fishes. Part 2 (Mugilidae to Carangidae), edited by K. E. Carpenter and V. H. Niem. Rome: FAO, 1999.

Paxton, J. R., and D. J. Bray. "Order Cetomimiformes." In Smiths' Sea Fishes, edited by M. M. Smith and P. C. Heemstra. Grahamstown, South Africa: J. L. B. Smith Inst. of Ichthyology, 1986.

Paxton, J. R., and O. Gon. "Cetomimidae." In Fishes of the Southern Ocean, edited by O. Gon and P. C. Heemstra. Grahamstown, South Africa: J. L. B. Smith Inst. of Ichthyology, 1990.

Periodicals

Bertelsen, E., and N. B. Marshall. "Mirapinnati, a New Order of Teleost Fishes." Dana Report 42 (1956): 1–34.

De Sylva, D. P., and W. N. Eschmeyer. "Systematics and Biology of the Deep Sea Fish Family Gibberichthyidae, a Senior Synonym of the Family Kasidoridae." Proceedings of the California Academy of Sciences. Series 4, 41 (1977): 215–231.

Ebeling, A. W. "Melamphaidae I. Systematics and Zoogeography of the Species in the Bathypelagic Fish Genus Melamphaes Günther." Dana Report 58 (1962): 1–164.

Ebeling, A. W., and W. H. Weed. "Melamphaidae III. Systematics and Distribution of the Species in the Bathypelagic Fish Genus Scopelagadus Vaillant." Dana Report 60 (1963): 1–58.

Kotlyar, A. N., and D. P. Andrianov. "Systematics and Biology of Acanthochaenus luetkenii (Stephanoberycidae)." Journal of Ichthyology 33, no. 6 (1993): 85–95.

Paxton, J. R. "Synopsis of the Whalefishes (Family Cetomimidae) with Descriptions of Four New Genera." Records of the Australian Museum 41 (1989): 135–206.

Paxton, J. R., G. D. Johnson, and T. Trnski. "Larvae and Juveniles of the Deepsea Whalefishes, Barbourisia and Rondeletia (Stephanoberyciformes: Barbourisiidae, Rondeletiidae) with Comments on Family Relationships." Records of the Australian Museum 53 (2001): 407–425.

Yang, Y.-R., B.-G. Zeng, and J. R. Paxton. "Additional Specimens of the Deepsea Fish Hispidoberyx ambagiosus (Hispidoberycidae, Berciformes [sic]) from the South China Sea, with Comments on the Family Relationships." Jap. Soc. Ichthyol. 38 (1988): 3–8.

Marcelo Carvalho, PhD