{{Short description|Species of sea snail}} {{Speciesbox | name = Needle pyram | image = Longchaeus acus 01.jpg | image_caption = A shell of ''Longchaeus acus'' from Samoa | taxon = Longchaeus acus | authority = (Gmelin, 1791) | synonyms_ref = <ref name="WoRMS" /> | synonyms = * ''Lonchaeus acus'' [sic]<small>Gmelin, 1791</small> * ''Longchaeus punctatus'' <small>(Férussac, 1821)</small> * ''Pyramidella (Longchaeus) acus'' <small>(Gmelin, J.F., 1791)</small> * ''Pyramidella acus'' <small>(Gmelin, 1791)</small> * ''Pyramidella maculosa'' <small>Lamarck, J.B.P.A. de, 1822</small> * ''Pyramidella musculosa'' <small>Lamarck, J.B.P.A. de, 1816</small> * ''Pyramidella punctata'' <small>Schubert, H.G. & A.J. Wagner, 1829</small> (invalid: homonym and synonym of ''Pyramidella punctata'' <small>Férussac, 1821</small>) * ''Pyramidella punctata'' <small>Férussac, 1821</small> * ''Voluta acus'' <small>Gmelin, 1791</small> (original combination) * ''Voluta guttata'' <small>Link, H.F., 1807</small> }}

'''''Longchaeus acus''''', common name the '''needle pyram''', is a species of sea snail, a marine gastropod mollusk in the family Pyramidellidae, the pyrams and their allies.<ref name="WoRMS">Rosenberg, G. (2010). ''Pyramidella acus'' (Gmelin, 1791). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=208425 on 2012-01-12</ref><ref>Drivas, J. & M. Jay (1988). Coquillages de La Réunion et de l'île Maurice</ref><ref>Dautzenberg, P. (1923). Liste preliminaire des mollusques marins de Madagascar et description de deux especes nouvelles. Journal de Conchyliologie 68: 21-74.</ref>

==Description== thumb|200px|left| Drawing of ''Pyramidella acus'' from Manual of conchology, structural and systematic (1881) The shell is polished. Its color is white, with dark chestnut or chocolate spots, usually arranged in three revolving series on the whorls of the teleoconch and five series on the body whorl. The columella is three-plaited with the upper plait largest. The lip is sometimes lirate within. The peripheral groove becomes in this species either obsolete or indicated by a slight angle.<ref>[https://archive.org/stream/manualconch08tryorich#page/n5/mode/2up G.W. Tryon, Manual of Conchology vol. VIII p. 301; 1889]</ref> The length of the shell varies between 19&nbsp;mm and 67&nbsp;mm.

==Distribution== This marine species occurs in the Indo-W Pacific (Red Sea, Tanzania, Madagascar, Mauritius, Mascarene Basin<ref name="WoRMS" /> and in South East Asia, in Vietnam and Philippines).

==References== {{Reflist}} * Okutani T., ed. (2000) Marine mollusks in Japan. Tokai University Press. 1173 pp. page(s): 703

==External links== {{Commons category|Longchaeus acus}} * [https://www.biodiversitylibrary.org/name/Pyramidella+acus Biodiversity Heritage Library (12 publications)] * [http://www.eol.org/pages/4812631 Encyclopedia of Life] * [http://collections.mnh.si.edu/search/iz/?qn=Pyramidella+acus USNM Invertebrate Zoology Mollusca Collection] * [http://www.marinespecies.org/aphia.php?p=taxdetails&id=208425 World Register of Marine Species] * {{Gastropods.com|key=0|id=4020|title=''Pyramidella (Longchaeus) acus''|access-date=7 February 2012}}

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Category:Pyramidellidae Category:Gastropods described in 1791 Category:Taxa named by Johann Friedrich Gmelin

{{Pyramidellidae-stub}}