Alpheus christofferseni is a snapping shrimp associated with innkeeper worms (echiurans) such as Ochetostoma cf. edax (Anker et al. 2007). A. christofferseni occurs in the Western Atlantic (Brazil and the Caribbean coast of Panama), and is morphologically and genetically most similar to two eastern Pacific species of alpheid, Alpheus naos and A. aequus, that are also found in echiuran burrows, (Anker et al. 2007).
Systematics and Identification
|Alpheus christofferseni is a member of the Brevirostris species group within the genus Alpheus. This species is named after Dr. Martin L. Christoffersen, in recognition of his contributions to the knowledge of Brazilian shrimps. Type locality: Brazil, Atol das Rocas, Ilha do Cemitério (Anker, Hurt, and Knowlton 2007b), types stored at the Museu Nacional, Rio de Janeiro, Brazil. Holotype: MNRJ 17905, allotype: none.|
|Western Atlantic: Known from the type locality, Atol das Rocas (off northeastern Brazil) and Bocas del Toro, Caribbean coast of Panama (Anker et al. 2007) |
|Like other members of the 'Alpheus barbatus' species complex (within the larger 'A. brevirostris' species group), Alpheus christofferseni have a short rostrum and a short and stout major chela (claw) (Anker et al. 2007). Maximum body size (carapace length, or CL) of males is 6.75 mm (holotype); females, 7.0 mm (Anker et al. 2007). Color: Body semitransparent, with reddish chromatophores forming several bands; tail fan, anterior rostral region, walking legs semitransparent, with red chromatophores; palm of major chela distally pale orange..|
Habitat and Host Associations
|Associate of thalassematid echiurans (inkeeper worms) such as Ochetostoma cf. edax; found in intertidal sand and seagrass sand flats (Anker et al. 2007).|
Evolution and Systematics
|Snapping shrimp in the genus Alpheus have been a model system for studying molecular divergence in "transisthmian" taxa that diverged following the closure of the Isthmus of Panama. Alpheus christofferseni occurs in the Western Atlantic (Brazil and the Caribbean coast of Panama), and is morphologically and genetically most similar to two eastern Pacific species of alpheid, Alpheus naos and A. aequus (Anker et al. 2007). Estimates of divergence based on genetic sequence variation (mitochondrial cytochrome oxidase I) suggest that A. christofferseni was isolated from its closest transisthmian relative (the eastern Pacific clade A. naos-A. aequus) ~11-12 million years ago (Anker et al. 2007).|
|Sequenced in Anker, Hurt, and Knowlton 2007; sequences available in GenBank for COI mtDNA (HCO/LCO, EF092273) and 16S mtDNA (EF092274).|
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