Argentiniformes - AccessScience from McGraw-Hill Education http://accessscience.com/content/802830

Article by: Boschung, Herbert Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama. Publication year: 2012 DOI: http://dx.doi.org/10.1036/1097-8542.802830 (http://dx.doi.org/10.1036/1097-8542.802830)

Content

Argentinoidei Opisthoproctidae specializations Bibliography Alepocephaloidei

An order of teleost fishes in the superorder Protacanthopterygii. These fishes, collectively called the argentines or herring smelts, were elevated from Osmeriformes (which are treated herein as a superfamily of the Salmoniformes) to ordinal rank.

Argentiniforms are identifiable by the following combination of characters: body variable, elongate and cylindrical in some to short and compressed in others; jaw mechanism and dentition greatly reduced; premaxillary absent in some species, if present lacks teeth; maxillary usually toothless; eyes variously directed, some species with tubular eyes; some species with specialized light organs, which may be associated with tubular eyes; no serial photophores; adipose fin present or absent; caudal fin forked; swim bladder, when present, physoclistous (not attached to gut). In addition, the argentines have a crumenal organ (paired branchial pouches in which food particles are trapped by large interlocking toothed gill rakers).

Two distinct groups (suborders in this classification), Argentinoidei and Alepocephaloidei, are identified by the characters listed in the table.

Table - Argentiniformes features

Argentinoidei (families Argentinidae, Opisthoproctidae, and Alepocephaloidei (families Platytrocidae, Bathylaconidae, Microstomatidae) and Alepocephalidae)

Eyes tubular or not tubular Adipose fin usually present Dorsal fin Eyes not tubular Adipose fin absent Dorsal fin inserted well back inserted near center of body on body

Maxillary and premaxillary, when present, toothless Upper jaw usually with teeth

Mouth usually small Mouth usually large

Swim bladder present or absent Swim bladder absent

Eggs small, development gradual Eggs large, development direct

12 genera, 61 species 37 genera, >100 species

Argentinoidei

This suborder consists of the families Argentinidae, Opisthoproctidae, and Microstomatidae.

The Argentinidae (argentines or herring smelts) is found in the Atlantic, Indian, and Pacific oceans, and consists of two

1 of 3 8/31/2015 10:17 AM Argentiniformes - AccessScience from McGraw-Hill Education http://accessscience.com/content/802830 genera, with about 19 species.

The Opisthoproctidae (barreleyes or spookfishes) is found in tropical to temperate Atlantic, Indian, and Pacific oceans, and consists of six genera with about 10 species.

The Microstomatidae (includes Bathylagidae, deep-sea smelts) is found in all seas, mostly ranging from subarctic to Antarctic waters, and consists of four genera, with about 32 species. Bathylagus, the largest genus, contains about 15 species.

Alepocephaloidei

This suborder consists of the families Platytrocidae, Bathylaconidae, and Alepocephalidae.

The Platytrocidae (searsides) is found in all oceans, but is absent from the Mediterranean Sea. It consists of 13 genera, with 37 species.

The Bathylaconidae (no common name) is found in circumtropical waters, and consists of two genera, with three species.

The Alepocephalidae (slickheads) is found in all oceans, and consists of 22 genera, and no less than 60 species.

Opisthoproctidae specializations

Some of the most bizarre fishes in all the seas of the world are the family Opisthoproctidae. As a family, most of the species have tubular eyes; pectoral fins on the lower side of the body; pelvic fins posteriorly placed; and parietal bones that do not meet on the midline of the skull. Most lack a swim bladder. Most species are long and subcylindrical, but one genus, Opisthoproctus, has a foreshortened, deep and compressed body and sole (an elongate forward projection on the underside of the abdomen that may act as a reflector for the light organ inside the body near the anus) covered with large deciduous cycloid scales. The tubular eyes are directed dorsally and topped with a gelatinous transparent tissue. The interorbital bones are reduced to a mere sliver, exposing the brain through the transparent roof of the skull; the premaxillary is absent; and the maxillary is reduced to a thin scalelike bone which is easily lost, leaving the toothless dentary to occupy almost half the length of the snout. Some of these bathypelagic fishes have never been seen alive and are known from only a few specimens. See also: Aulopiformes (/content/aulopiformes/802820); Salmoniformes (/content/salmoniformes/599300)

Herbert Boschung

Bibliography

D. P. Begle, Monophyly and relationships of the argentinoid fishes, Copeia, 1992(2):350–366, 1992 DOI: 10.2307/1446196 (http://dx.doi.org/10.2307/1446196)

D. M. Cohen, Argentinoidea, pp. 1–70, in FWNA Fishes of the Western North Atlantic, pt. 4, 1964

D. M. Cohen, Argentinidae, pp. 215–216 in M. M. Smith and P. C. Heemstra (eds.), Smiths' Sea Fishes, Springer-Verlag, Berlin, 1986

J. S. Nelson, Fishes of the World, 4th ed., Wiley, 2006

J. R. Paxton and D. M. Cohen, Argentinidae, p. 1884, in K. E. Carpenter and V. H. Niem (eds.), FAO Species Identification Guide for Fishery Purposes: The Living Marine Resources of the WCP, vol. 3: Batoid Fishes, Chimaeras and Bony Fishes, Part 1 (Elopidae to Linophrynidae), FAO, Rome, 1999

M. Schneider, Argentinidae: Argentinas, pp. 858–859 in W. Fischer et al. (eds.), Guia FAO para Identification de Especies para lo Fines de la Pesca, Pacifico Centro-Oriental, 3 vols., FAO, Rome, 1995 2 of 3 8/31/2015 10:17 AM