Description ⁷

The invasive and suspected non-native (to Florida) green porcelain crab Petrolisthes armatus is a small, flat crab that is usually orange-brown to dark brown as an adult, with a speckled and somewhat lighter appearance as juveniles. Individuals may also be olive green to dark green in color, giving rise to the common name. Mature specimens of both sexes have portions of their mouthparts pigmented brilliant blue. The chelae (pincers) are long and each possesses a distinct orange spot that is visible when they are open.As is characteristic for all porcelain crabs, the antennae are inserted external to the eyes, not between them as is observed in most other crab families (Knott and King undated, IRL Field Guide).

Distribution ⁸

Petrolisthes armatus is believed native to Brazil and occurs in shallow subtidal and low intertidal habitats such as oyster reefs and rock rubble (Hartman and Stancyk 2001, Knott and King undated). Other investigators differ in their opinion, suggesting P. armatus is native to the Gulf of Mexico and Florida's Gulf Coast.Modern distribution of P. armatus is broad. In the Atlantic, it includes tropical western Africa, Ascension Island, Bermuda, the Bahamas, West Indies and Caribbean, the Gulf of Mexico and South America to southern Brazil. In the eastern Pacific, this crab occurs from the Gulf of California south to Peru. The current range of P. armatus in the southeastern U.S. includes the South Atlantic Bight from South Carolina down to the southern tip of Florida, and the species has also been reported from Mississippi (Knott et al. 1999, Hartman and Stancyk 2001). India River Lagoon distribution records are poor, but the species is presumed to occur throughout the entire length of the estuary.

Size ⁹

Petrolisthes armatus is a diminutive crab. Boudreaux et al. (2006) report a size range of 6-8 mm body width and a weight range of 0.3-0.6 g for the specimens they collected in the Mosquito Lagoon. Knott and King (undated) indicate P. armatus from South Carolina can attain a somewhat larger maximum body width of 12 to 14 mm. The authors report collecting female specimens that are sexually mature at just 3-4 mm body width.

Look alikes ¹⁰

The body plan and the position of the antennae relative to the eyes (see above) can be used to differentiate porcellanids from other crab species. Petrolisthes armatus can be distinguished from co-occurring porcellanids by means of its characteristic blue mouthparts and orange spot on the chelae.

Reproduction ¹¹

Details of reproduction in Petrolisthes armatus are similar to those of other crabs. After mating, females can store sperm-containing spermatophores until eggs are ready for release and fertilization. Fertilized eggs are then held in a mass between the abdominal flap and body and the eggs are aerated by continuous beating of the pleopods until they hatch.P. armatus sex ratios observed in their putative native range in Brazil remain close to 1:1 throughout the year (Oliveira and Masunari 1995). Investigations in Georgia have also revealed ratios that are essentially 1:1 (Hollebone 2006), whereas ratios reported from South Carolina were male-biased at a ratio of 1.5:1 (Hartman and Stancyk 2001).

Link to Access Genomic Data ¹²

http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=84662&lvl=0

Sources and Credits

1. (c) Bernadette, some rights reserved (CC BY-NC), uploaded by Bernadette
2. (c) 2010 Moorea Biocode, some rights reserved (CC BY-NC-SA), http://calphotos.berkeley.edu/cgi/img_query?seq_num=91168&one=T
3. (c) 2010 Moorea Biocode, some rights reserved (CC BY-NC-SA), http://calphotos.berkeley.edu/cgi/img_query?seq_num=91397&one=T
4. (c) 2010 Moorea Biocode, some rights reserved (CC BY-NC-SA), http://calphotos.berkeley.edu/cgi/img_query?seq_num=91065&one=T
5. (c) stevenw12339, some rights reserved (CC BY-NC), https://www.flickr.com/photos/100620478@N03/14080384438/
6. (c) stevenw12339, some rights reserved (CC BY-NC), https://www.flickr.com/photos/100620478@N03/14080388028/
7. Adapted by matbio from a work by (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11526641
8. (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11526642
9. (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11526647
10. (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11526644
11. Adapted by matbio from a work by (c) Smithsonian Marine Station at Fort Pierce, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/11526646
12. (c) Emily Rose Sharkey, all rights reserved

More Info

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