Akera

Akera; Temporal range: Callovian–recent PreꞒ Ꞓ O S D C P T J K Pg N
	shells of Akera bullata
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Order:	Aplysiida
Superfamily:	Akeroidea
Family:	Akeridae
Genus:	Akera; O. F. Müller, 1776
Species
	See text
Synonyms
	Acera Jeffreys, 1867 (unjustified emendation of Akera Müller, 1776); Aceras Locard, 1886 (unjustified emendation of Akera); Bulla (Akera) O. F. Müller, 1776; Eucampe Leach, 1847; Vitrella Swainson, 1840;

Akera is a marine genus of sea hare in the family Akeridae, known from the late Callovian (Jurassic) to the recent periods.^[2]^[3]

Akera is the sole genus within the family Akeridae.

Description

Akera is a primitive genus. Their soft and elongated body does not fit completely in their external shell; it just covers their visceral hump which is positioned at the posterior end of their bodies. Their streamlined bodies are adapted for burrowing.

The shell is large and glossy, globosely cylindrical with a paper-thin, translucent, and flexible texture that provides minimal protection. The spire is truncated, and the whorls are deeply channeled. The protoconch is partially embedded. The upper whorls are blunt. The aperture spans the length of the body whorl or is slightly shorter. It is expanded and deeply sinuated in front, with the outer margin disunited at the suture. The columella is exposed, revealing the inner whorls. The color of the shell is muted, ranging from pale brown to greenish hues.

The head-disc is greatly elongated, wide, and bifid anteriorly, tapering towards the rear. The mantle's hind edge is fimbriated and extends through the fissured shell suture. The foot is expanded and narrow with a rounded anterior end, becoming broad and truncated posteriorly. Using its extended lateral parapodia, the animal swims with considerable agility. ^[4]

Distribution

Species of this marine genus have a global distribution including temperate and tropical seas, inhabiting soft muddy bottoms, sea grass beds and coral sand. They are herbivorous, feeding on algae and detritus.

Species

Akera bayeri (Marcus & Marcus, 1967) - It can be found along the coast of Colombia and Brazil.
Akera bullata (O. F. Müller, 1776) - type species
Akera constricta Kuroda, 1947
Akera julieae Valdes & Barwick, 2005
Akera silbo Ortea & Moro, 2009
Akera soluta (Gmelin, 1791) - Also called the Solute akera, this species can be found in the Indo-West Pacific. Little is known about this species. Its shell can grow as large as 45 mm in length.
† Akera spirata Staadt, 1913
† Akera striatella Lamarck, 1804 - fossil from the Eocene and Oligocene.

Synonyms

Akera aperta Hedley, 1899: synonym of Oxynoe aperta (Hedley, 1899) (original combination)
† Akera eliai Shalem, 1928 : synonym of † Hamlinia eliai (Shalem, 1928) (original combination)
Akera flexilis T. Brown, 1844: synonym of Akera bullata O. F. Müller, 1776
Akera tasmanica Beddome, 1883 ^[5] synonym of Diaphana tasmanica (Beddome, 1883)
Akera thompsoni Olsson & T. L. McGinty, 1951: synonym of Akera bayeri Ev. Marcus & Er. Marcus, 1967 (unavailable name, no description)

References

^ Müller O. F. (1776). Zoologiæ Danicæ prodromus, seu animalium Daniæ et Norvegiæ indigenarum characteres, nomina, et synonyma imprimis popularium. pp. I-XXXII [= 1-32], 1-274. Havniæ. (Hallager). page 242.
^ ^a ^b Gofas, S. (2012). Akera O.F. Müller, 1776. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=137641 on 2012-03-31
^ Sepkoski's Online Genus Database. Downloaded 14 October 2008.
^ Tryon, G.W. (1882). Structural and systematic conchology (vol. 1 ed.).
^ Schiøtte T. (1998). "A taxonomic revision of the genus Diaphana Brown, 1827, including a discussion of the phylogeny and zoogeography of the genus (Mollusca: Opisthobranchia)". Steenstrupia. 24: 77–140.

External links

Leach, W.E. (1852). Molluscorum Britanniae Synopsis. A synopsis of the Mollusca of Great Britain arranged according to their natural affinities and anatomical structure (VIII ed.). London: Van Voorst. pp. 1–376.
Locard, A. (1886). Prodrome de malacologie française. Catalogue général des mollusques vivants de France. Mollusques marins. Lyon: H. Georg & Paris: Baillière. pp. 1–778.
Jeffreys, J.G. (1862–1869). British conchology vol. 1-5. London: van Voorst. pp. 1–429.
Gofas, S.; Le Renard, J.; Bouchet, P (2001). "Mollusca. in: Costello, M.J. et al. (eds), European Register of Marine Species: a check-list of the marine species in Europe and a bibliography of guides to their identification" (PDF). Patrimoines Naturels. 50: 180–213.{{cite journal}}: CS1 maint: multiple names: authors list (link)
Valdés Á. & Barwick K. (2005). "First record of Akera Müller, 1776, from the Eastern Pacific, with the description of a new species". The Nautilus. 119 (1): 43–49.
Akeroidea at Sea Slug Forum showing Akera soluta
Akera soluta at Sea Slug Forum
Akera bullata

[1] Müller O. F. (1776). Zoologiæ Danicæ prodromus, seu animalium Daniæ et Norvegiæ indigenarum characteres, nomina, et synonyma imprimis popularium. pp. I-XXXII [= 1-32], 1-274. Havniæ. (Hallager). page 242.

[WoRMS-2] Gofas, S. (2012). Akera O.F. Müller, 1776. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=137641 on 2012-03-31

[3] Sepkoski's Online Genus Database. Downloaded 14 October 2008.

[4] Tryon, G.W. (1882). Structural and systematic conchology (vol. 1 ed.).

[Akera_tasmanica-5] Schiøtte T. (1998). "A taxonomic revision of the genus Diaphana Brown, 1827, including a discussion of the phylogeny and zoogeography of the genus (Mollusca: Opisthobranchia)". Steenstrupia. 24: 77–140.

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