Alpheus cylindricus is a highly derived member of the Macrocheles species group within the genus Alpheus (Anker et al. 2008), and occurs in the eastern Pacific. Common name: Pacific cylinder-clawed snapping shrimp. For additional descriptions, see Kim and Abele (1988), Anker et al. (2008), Knowlton et al. (2008): http://biogeodb.stri.si.edu/bioinformatics/alpheus/Alpheus_Template.php?....

Alpheus cylindricus is a highly derived member of the Macrocheles species group within the genus Alpheus; this species complex was recently revised, with this species limited to the eastern Pacific (Anker et al. 2008). Type locality of Alpheus cylindricus: Las Perlas, Panama (neotype) (Anker et al. 2008), types stored at the National Museum of Natural History, Smithsonian Institution (USNM). Neotype, USNM 1109158. Common name: Pacific cylinder-clawed snapping shrimp. For additional descriptions, see Kim and Abele (1988), Anker et al. (2008), Knowlton et al. (2008).

Crangon cylindricus (Chace 1937, Schmitt 1939); not Alpheus cylindricus (sensu Crosnier and Forest 1965, 1966; Coelho and Ramos 1972; Chace 1972; Pequenat and Ray 1974; Christoffersen 1979; Abele and Kim 1986; Martinez-Iglesias et al. 1993; Knowlton et al. 1993, part; Williams et al. 2001, part); for full list of synonomies, see Anker et al. (2008).

FAO fishing area 34, FAO fishing area 47

Eastern Pacific: central Gulf of California south to Colombia and the Galapagos; for specific localities, see Kim and Abele (1988), Anker et al. (2008).

Maximum body size (carapace length, or CL) of males is 9.5 mm; females, 11.3 (Kim and Abele 1988, Anker et al. 2008c). Color: body pale grey, carapace with x-shaped patch of red chromatophores on gastric region; legs colorless, palm of major chela (claw) pale orange to orange-brown distially; ovigerous females with bright yellow eggs (Anker et al. 2008). Closely related to A. vanderbilti; can be distinguished from the latter by the absence of red chromatophores on the dorsal half of the body (and with DNA sequencing; Anker et al. 2008).

Neotype for Alpheus cylindricus Kingsley, 1878
Collection: Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology
Sex/Stage: Male;
Preparation: Alcohol (Ethanol)
Collector(s): J. Jara, C. Hurt, A. Anker, E. Tóth & E. Gómez
Year Collected: 2006
Locality: Las Perlas Islands, off Contadora Island, Panama, Gulf of Panama, North Pacific Ocean

Depth range based on 1 specimen in 1 taxon.
Water temperature and chemistry ranges based on 1 sample.

Environmental ranges
  Depth range (m): 18 - 18
  Temperature range (°C): 27.345 - 27.345
  Nitrate (umol/L): 0.583 - 0.583
  Salinity (PPS): 36.311 - 36.311
  Oxygen (ml/l): 4.545 - 4.545
  Phosphate (umol/l): 0.099 - 0.099
  Silicate (umol/l): 2.370 - 2.370
 
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Lives in intertidal to shallow subtidal (to 37 m), on mud or rock-mud bottoms or in rocky intertidal; occasional associate of sponges, often living in pairs in unidentified greyish-purple sponges lining rock crevices (Anker et al. 2008).

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 cylindricus occurs in the eastern Pacific, and is morphologically and genetically similar to Alpheus vanderbilti from the Atlantic (Anker et al. 2008). Estimates of divergence based on genetic sequence variation (mitochondrial cytochrome oxidase I) suggest that A. cylindricus was isolated from its closest transisthmian relative ~7 million years ago (Anker et al. 2008).

Sequenced in Knowlton et al. 1993;; Williams et al. 2001; Morrison et al. 2004; Anker et al. 2008; sequences available in GenBank for 16S mtDNA (AF230272), COI (EU652331-3), elongation-factor 1 alpha (AF310838, AF310795, AF310835), glucose-6-phosphate isomerase (AF310740-1).