Alpheus formosus Gibbes, 1850

Alpheus formosus
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Original DescriptionAlpheus formosus Gibbes, 1850: 196. 
ClassificationArthropoda: Crustacea: Malacostraca: Decapoda: Alpheidae. 
SynonymyAlpheus poeyi Guérin-Méneville, 1857. 
Type LocalityKey West, Florida (symbol on the map). 
Type MaterialNeotype: USNM 1100697, in ethanol, in excellent condition. 
Common NameLarger blue-legged snapping shrimp. 
Taxonomic StatusValid, taxonomy revised by Anker, Hurt and Knowlton, 2008b
Geographic DistributionTropical western Atlantic [WA]: North Carolina and Bermuda throughout Caribbean to Brazil (Chace, 1972; Christoffersen, 1998) (see map). 
FrequencyCommon throughout its range, for instance, in the Florida Keys; Isla Grande and Bocas del Toro, Panama; along the southern coast of the Dominican Republic; and in Morrocoy, Venezuela. 
HabitatCoral reefs and coral rubble fields close to seagrass beds; seagrass and Halimeda clumps. 
Depth RangeIntertidal to about 15 m. 
Life History and BehaviorLives in pairs under coral rubble and rocks, in crevices of corals and coral rocks, in clumps of Halimeda etc. 
Related SpeciesAlpheus panamensis Kingsley, 1878 [EP]; A. paraformosus Anker, Hurt and Knowlton, 2008b [WA]. Alpheus formosus differs from A. panamensis, its transisthmian sister species, by the narrower rostrum and shorter adrostral furrows, and from A. paraformosus by the presence of balaeniceps setae on the minor cheliped and longer adrostral furrows. The color patterns of the three species, especially A. formosus and A. panamensis, are very similar (see comparison photos). 
SizeMaximum body length at least 30 mm. 
Color PatternSee photo
Molecular BarcodeGenBank number EF532605, EF532608, AF309903, AF309904
RemarksAlpheus formosus is one of the most commonly encountered snapping shrimps in the Caribbean. 
Major ReferencesGibbes, 1850 [original description]; Guérin-Méneville, 1857 [description of A. poeyi]; Hendrix, 1971 [illustrations]; Chace, 1972 [records in W Atlantic]; Christoffersen, 1979 [records in Brazil, premature synonymy]; Williams, 1984 [figures, notes on ecology]; Sterrer, 1986 [illustration of color pattern]; Kim and Abele, 1988 [comparison with A. panamensis]; Knowlton and Mills, 1992 [recognition of two cryptic species in W Atlantic based on color patterns]; Knowlton et al., 1993 [recognition of two cryptic species based on reproductive incompatibility and genetic analyses]; Williams et al., 2001 [molecular phylogeny of A. formosus clade]; Anker, Hurt and Knowlton, 2008b [revision of A. formosus complex, figures, color photos]. 

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