Neogastropoda
| Neogastropoda Fossil range: Early Cretaceous–Recent |
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| The shell of a neogastropod, the muricid species Chicoreus palmarosae | |
| Scientific classification | |
| Kingdom: | Animalia |
| Subkingdom: | Eumetazoa |
| Superphylum: | Protostomia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| (unranked): | clade Caenogastropoda clade Hypsogastropoda clade Neogastropoda |
| Superfamilies | |
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See text |
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The Neogastropoda was, for many years, an order of sea snails, marine gastropod mollusks. In the current version of gastropod taxonomy however, Neogastropoda is an unranked clade of sea snails.
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Description
The available fossil record of Neogastropoda is quite thorough, and supports a widely accepted evolutionary scenario of an Early Cretaceous origin of the group followed by two rapid diversification rounds in the late Cretaceous and the Paleocene.[1]
They only have one auricle, one kidney and one monopectinate gill, i.e. the gill filaments develop on only one side of the central axis.[2]
The shell has a well-developed siphonal canal. The elongated trunk-like siphon is an extensible tube, formed from a fold in the mantle. It is used to suck water into the mantle cavity. At the base of the siphon is the bipectinate (branching from a central axis) osphradium, a sensory receptacle and olfactory organ, that is more developed than the one in the Mesogastropoda. They achived important morphological changes including e.g., the elongation of the siphonal canal, a shift in the mouth opening to a terminal position on the head, and the formation of a well-developed proboscis.[1]
The nervous system is very concentrated. Many species have the ganglia in a compact space.
The rachiglossate (rasp-like) radula, a layer of serially arranged teeth within the mouth, has only three denticles (small teeth) in each transverse row.[2]
The Neogastropoda have separate sexes.
There are about 16,000 species. Neogastropoda includes many well-known gastropods including the cone snails, conchs, mud snails, olive snails, oyster drills, tulip shells, and whelks. The Neogastropoda all live in the sea, except Clea, a rare freshwater genus. They are most diversified in tropical seas.[1] They are mostly predators, but some are saprophagous (scavengers).
Taxonomy
When Neogastropoda was an order, it was placed within the prosobranch gastropods according to the taxonomy developed by Thiele (1921). The families which used to form the order Neogastropoda are now included in the clade Neogastropoda Cox, 1960.
Ever since Thiele (1929),[3] Neogastropoda have been considered a natural group, clearly differentiated from other Caenogastropoda.[1] The monophyly of the group is widely accepted among morphologists, and it is based on several synapomorphies mostly related with the anatomy of the digestive system.[1] Current classifications of Neogastropoda generally recognize up to six superfamilies: Buccinoidea, Muricoidea, Olivoidea, Pseudolivoidea, Conoidea, and Cancellarioidea. Phylogenetic relationships among neogastropod superfamilies based on morphological characters are rather unstable, and for instance, Cancellarioidea[4] or Buccinoidea[5] have been alternatively proposed as the sister group of the remaining Neogastropoda.[1]
According to the taxonomy of the Gastropoda by Bouchet & Rocroi (2005) the clade Neogastropoda consists of these superfamilies:
- Buccinoidea Rafinesque, 1815
- Muricoidea Rafinesque, 1815
- Olivoidea Latreille, 1825
- Pseudolivoidea (de Gregorio, 1880)
- Conoidea Fleming, 1822
- Cancellarioidea Forbes & Hanley, 1851
Families
According to the taxonomy of the Gastropoda by Bouchet & Rocroi (2005) the taxonomy of clade Neogastropoda is like this:
- Unassigned to a superfamily
- † Family Johnwyattiidae
- † Family Perissityidae
- † Family Sarganidae
- † Family Speightiidae
- † Family Taiomidae
- † Family Weeksiidae
- Superfamily Buccinoidea
- Family Buccinidae
- Family Colubrariidae
- Family Columbellidae
- Family Fasciolariidae
- Family Nassariidae
- Family Melongenidae
- Superfamily Muricoidea
- Family Muricidae
- Family Babyloniidae
- Family Costellariidae
- Family Cystiscidae
- Family Harpidae
- Family Marginellidae
- Family Mitridae
- † Family Pholidotomidae
- Family Pleioptygmatidae
- Family Strepsiduridae
- Family Turbinellidae
- Family Volutidae
- Family Volutomitridae
- Superfamily Olivoidea
- Family Olividae
- Family Olivellidae
- Superfamily Pseudolivoidea
- Family Pseudolividae
- Family Ptychatractidae
- Superfamily Conoidea
- Family Conidae
- Family Clavatulidae
- Family Drilliidae
- Family Pseudomelatomidae
- Family Strictispiridae
- Family Terebridae
- Family Turridae
- Superfamily Cancellarioidea
- Family Cancellariidae
References
This article incorporates CC-BY-2.0 text from the reference [1].
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Cunha R. L., Grande C. & Zardoya R. (23 August 2009). "Neogastropod phylogenetic relationships based on entire mitochondrial genomes". BMC Evolutionary Biology 2009, 9: 210. 10.1186/1471-2148-9-210
- ↑ 2.0 2.1 Barnes, Robert D. (1982). Invertebrate Zoology. Philadelphia, PA: Holt-Saunders International. p. 376. ISBN 0-03-056747-5.
- ↑ Thiele J. (1929). Handbuch der Systematischen Weichtierkunde Volume 1 (1) (Loricata; Gastropoda: Prosobranchia). Jena, 376 pp. In: (23 October 1929). Reprint, Asher & Co., Amsterdam, 1963; translation by J.S. Bhatti Edited by: R. Bieler & P. Mikkelsen, Smithsonian Libraries, 1993.
- ↑ Kantor YI. (1996). Phylogeny and Relationships of Neogastropoda. In: Taylor J. D. (ed.) Origin and Evolutionary Radiation of the Mollusca. Oxford, Oxford University Press, 221-230.
- ↑ Ponder W. F., Colgan D. J., Healy J. M., Nützel A., Simone L. R. L. & Strong E. (2008). Caenogastropoda. In: Ponder W. F., Lindberg D. R. Phylogeny and evolution of the Mollusca. Berkeley, University of California Press, 331-383.