Arenaeus

Dana, 1851

speckled crabs

Species Guides

1

Arenaeus is a of swimming crabs in the Portunidae containing two : Arenaeus cribrarius (Atlantic coasts of the Americas) and Arenaeus mexicanus (Pacific coasts). These crabs inhabit shallow marine waters, particularly sandy beach surf zones. The genus has been subject to taxonomic confusion due to imprecise historical descriptions, but recent morphological and molecular revision clarified diagnostic features separating the species.

Arenaeus by (c) James Kindt, some rights reserved (CC BY), uploaded by James Kindt. Used under a CC-BY license.Arenaeus cribrarius I1020 (22404658792) by Smithsonian Environmental Research Center. Used under a CC BY 2.0 license.Arenaeus cribrarius by Mural Nativo. Used under a CC BY-SA 4.0 license.

Pronunciation

How to pronounce Arenaeus: //ˈæɹəˌniːəs//

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Identification

of Arenaeus can be distinguished by: number of rostral teeth on the front; number of carpal spines on the chelipeds; and presence or absence of a spine on the epistome region (the latter feature being particularly diagnostic and previously overlooked in literature). Males are generally larger than females. Carapace and structure of the first male provide additional distinguishing characteristics from other portunid .

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Habitat

Shallow marine coastal waters, particularly surf zones of sandy beaches; tropical arid beaches; hyperbenthic zone. Juveniles and show distinct temporal and bathymetric distribution patterns.

Distribution

Mirrored trans-American distribution: Arenaeus cribrarius occurs along Atlantic coasts from North to South America with extensive range and high across ; Arenaeus mexicanus occurs along Pacific coasts of the Americas.

Life Cycle

Long-lived pelagic larval stage facilitates extensive across . and size classes overlap (males approximately 40–70 mm width; females 45–75 mm), with size-based zonation in use.

Behavior

Activity patterns and zonation documented in A. cribrarius, with local distribution and abundance varying by transect and season. Sex ratio varies by size class and location: near 1:1 in smaller size classes, female-biased in intermediate classes, male-biased in larger classes. Approximately 73% of specimens are right-handed (right cheliped larger).

Ecological Role

Component of surf zone hyperbenthic fauna; part of macrobenthic in tropical Pacific continental shelf .

Similar Taxa

  • Other Portunidae generaArenaeus can be distinguished by and first male structure, which suggest closer relationships with particular portunid groups than previously recognized.

Sources and further reading