Aulopiformes

Aulopiformes
Variegated Lizardfish, Synodus variegatus
(Synodontoidei: Synodontidae)
Scientific classification
Kingdom: Animalia
Subkingdom: Eumetazoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclass: Osteichthyes
Class: Actinopterygii
Subclass: Neopterygii
Infraclass: Teleostei
Superorder: Cyclosquamata (disputed)
Order: Aulopiformes
Suborders

Alepisauroidei
Chlorophthalmoidei
†Enchodontoidei
Giganturoidei
Synodontoidei
Synonyms

Macristiidae (see text)

Aulopiformes is an order of marine ray-finned fish consisting of some 15 extant and several prehistoric families with about 45 genera and over 230 species. The common names grinners, lizardfishes and allies or aulopiforms are sometimes used for this group. The scientific name means "Aulopus-shaped", from Aulopus (the type genus) + the standard fish order suffix "-formes". It ultimately derives from Ancient Greek aulós (αὐλός, "flute" or "pipe") + Latin forma ("external form"), the former in reference to the elongated shape of many Aulopiformes.[1]

They are grouped together because of common features in the structure of their gill arches. Indeed, many authors have considered them so distinct as to warrant separation in a monotypic superorder of the Teleostei, under the name Cyclosquamata. However, monotypic taxa are generally avoided by modern taxonomists if not necessary, and in this case a distinct superorder seems indeed unwarranted: together with the equally dubious superorder "Stenopterygii", the grinners appear to be so closely related to some Protacanthopterygii to be included in that superorder. In particular, this group might be the sister taxon of the Salmoniformes (salmon, trouts and relatives). As an alternative, the superorders are sometimes united as an unranked clade named Euteleostei, but in that case the Protacanthopterygii would need to be split further to account for the phylogenetic uncertainty. This would result in a highly cumbersome and taxonomically redundant group of 2 very small and no less than 4 monotypic superorders.[2]

Contents

Description

Many of the aulopiforms are deep-sea fishes, and many species are hermaphrodites, some with the ability to self-fertilise. Some are benthic, but most are pelagic. In general, aulopiform fish have a mixture of advanced and primitive characteristics relative to other teleost fish.[3]

They have no or just a vestigial gas bladder, a hypaxialis muscle that is unusually extended to forward at its upper end and attaches to the neurocranium below the spine (perhaps to snap the upper part of the skull down when catching prey) and the position of the maxillary bone. Their second pharyngobranchial is greatly elongated posterolaterally away from third pharyngobranchial, which lacks a cartilaginous condyle to articulate with the preceding, but is contacted by the elongated uncinate process of the second epibranchial. Other features include the position of the pelvic fins far back on the body, the fused medial processes of pelvic girdle and the presence of an adipose fin (which is also typical for the Protacanthopterygii).[4]

The larvae of some Aulopiformes are extremely bizarre-looking, with elongated fins, and do not resemble the adult animals. They were not only described as distinct species, but even separated as genera and finally in a family "Macristiidae" which was allied with various Protacanthopterygii (sensu lato). But the initial assessment – which found "Macristium" to resemble the deepwater lizardfishes (Bathysauridae) in some details – was not far off the mark: "Macristium" are larvae of Bathysaurus, while the supposed other "macristiid" genus "Macristiella" are larvae of the deepsea tripodfish Bathytyphlops.[5]

Classification

Timeline of genera


Footnotes

  1. ^ Woodhouse (1910), Glare (1968-1982), FishBase (2000)
  2. ^ Nelson (2006): p.214, Diogo (2008)
  3. ^ Johnson & Eschmeyer (1998), Nelson (2006): p.214
  4. ^ FishBase (2000), Johnson & Eschmeyer (1998), Nelson (2006): p.214
  5. ^ Taylor (2009)

References

Extant Actinopterygii orders by subclass
Chondrostei
Neopterygii