Geosesarma

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Geosesarma
Geosesarma sp. in the terrarium

Geosesarma sp. in the terrarium

Systematics
Order : Decapods (decapoda)
Subordination : Pleocyemata
Partial order : Crab (Brachyura)
Superfamily : Grapsoidea
Family : Sesarmidae
Genre : Geosesarma
Scientific name
Geosesarma
De Man , 1892

Geosesarma is a genus of crabs from the family of Sesarmidae . In Southeast Asia, they mostlylivenear rivers and lakes, but mostly live on land. Some species are exported all over the world because of their color and the ability to keep them with plants. Because of their small size, they can also be kept in smaller aquaterrariums . Because of the conspicuously colored eyes of the first imported forms and species, they are known as so-called vampire crabs .

features

The Geosesarma species differ from other genera of freshwater crabs in that they are relatively large eggs with a diameter of at least 1 mm. The larval development is shortened in this genus, in most species late Zoea larvae or fully developed juveniles hatch from the eggs . As a result, it is no longer necessary to return to the water to lay eggs, as is the case with other genera. The members of the genus therefore live semiterrestrially .

These are very small crabs, which, even as sexually mature animals, rarely exceed a shell width of 10 to 30 millimeters. They are usually strikingly purple or orange to orange-red in color.

Their carapace is somewhat wider than it is long, and when viewed from above, these crabs appear almost square. The carapace is well calcified and has a rough surface. You have seven abdominal segments. The eyes are large and their stalks reach the edge of the carapace. The carapace is hairy below the eyes. The basal antenna segment is thickened. The third, outer pair of maxillipedas does not completely cover the mouth; even when closed, a clear gap remains between these maxillipedas. The merus of the third maxillipedas shows a clear, narrow bar that runs diagonally across the surface and is absent in other genera. The striding legs are not flattened and have no fringes like the related genus Varuna .

Gender differences

As is the case with all crabs, males have a narrow ventral flap and females have a wide one.

Distribution and systematics

Their main distribution area of ​​the genus is East Asia , where there are their own endemic species on many islands . Their northern distribution extends to Taiwan and the Philippines . Since larval development in this genus no longer takes place in rivers or in the sea, the young are not spread by the currents. The individual species are therefore restricted to small areas of distribution. The researchers are constantly finding and describing new species. The group, however, is likely not monophyletic .

Types (selection)

Red silam crab Geosesarma aurantium

Geosesarma was previously placed in the Grapsidae (square crabs ) family, but later placed in the Sesarmidae family with other genera. In 1970 23 species were known, by 2009 a total of 43 species had been described. According to Peter Ng from the "National University of Singapore", 53 species of the genus Geosesarma were known to science in 2015 .

Some types:

attitude

Geosesarma notophorum , one of the species on the market.

Since 2006 the species Geosesarma dennerle from the island of Java has been exported as a "vampire crab" for keeping in terrariums. The purple drawings on the carapace and the orange eyes of the initially only imported taxon of the species are striking .

Other Geosesarma species later came on the market, including the mandarin crab ( Geosesarma notophorum ), Geosesarma hagen and a form previously classified by Geosesarma as Geosesarma sp. "Blue" as well as the form now described by Geosesarma dennerle as nominate form , then imported as Geosesarma bicolor , the "two-colored vampire crab", dark purple with a light yellow spot on the back and yellow eyes. In addition, Geosesarma krathing , called "orange vampire crab" or "orange head", is also available in stores.

Another species that is quite common in terrariums is the so-called disco vampire crab. The animals are now called Geosesarma cf. tiomanicum .

A breeding in the aquarium with a large land area or in the terrarium without any problems. The crabs are mostly on land. Vampire crabs are carnivorous . It behaves peacefully towards conspecifics and young animals, but not towards other species of the genus.

literature

  • Warren W. Burggren, Brian Robert McMahon (Eds.): Biology of the land crabs. Cambridge University Press, 1988, pp. 35-38 ISBN 0-52130-690-6
  • KL Ng, Danièle Guinot & Peter JF Davie: Systema Brachyurorum: Part I. An annotated checklist of extant Brachyuran crabs of the world. Raffles Bulletin of Zoology, 17, pp. 1–286, 2008 Online (PDF, English; 8.2 MB)

Web links

Individual evidence

  1. ↑ After the revision of Sèrene and Soh in 1970, 23 species were added to Geosesarma . Quoting: Warren W. Burggren, Brian Robert McMahon (Eds.): Biology of the land crabs. Cambridge University Press, 1988, pp. 35-36 ISBN 0-52130-690-6
  2. ↑ a b c https://www.livescience.com/50183-vampire-crabs-origins-java.html
  3. ↑ https://www.researchgate.net/publication/237524723_Geosesarma_aedituens_a_new_terrestrial_crab_Crustacea_Decapoda_Brachyura_Sesarmidae_from_Bali_Indonesia
  4. ↑ Darren CJ Yeo and Peter K. L Ng: A new species of Geosesarma (Crustacea: Decapoda: Brachyura: Sesarmidae) from Pulau Tioman, peninsular Malaysia. The Raffles Bulletin of Zoology Supplement No. 6, pp. 189–196, 1999 First description of the species Geosesarma albomita ( Memento of the original from June 17, 2007 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (English, PDF file, 257 kB) @1@ 2Template: Webachiv / IABot / rmbr.nus.edu.sg
  5. ↑ a b https://decapoda.nhm.org/pdfs/31155/31155.pdf
  6. ↑ PK L Ng, H.-C. Liu and CD Schubart: Geosesarma hednon, a new species of terrestrial crab (Crustacea: Decapoda: Brachyura: Sesarmidae) from Taiwan and Philippines. The Raffles Bulletin of Zoology, 52 (1), pp. 239–249, 2004 [1] First description of the species Geosesarma hednon ] (English, PDF file, 849 kB)
  7. ↑ https://www.wirbellose.de/artdatenbank/krabben/1739-geosesarma-dennerle-vampirkrabbe
  8. ↑ a b c http://www.iflscience.com/plants-and-animals/two-new-vampire-crabs-traced-back-java-indonesia/
  9. ↑ https://www.wirbellose.de/artdatenbank/krabben/1740-geosesarma-hagen-ng-schubart-lukhaup-2015-rote-vampirkrabbe
  10. ↑ http://www.panzerwelten.de/forum/showthread.php?tid=8363
  11. ↑ Peter KL Ng and P. Naiyanetr: On a new species of Geosesarma de Man, 1892 (Crustacea: Decapoda: Brachyura: Grapsidae) from Chanthaburi Province, eastern Thailand. Zool. Med. Leiden, 66 (34), pp. 449–452, 1992 first description of Geosesarma krathing (PDF, engl.)
  12. ↑ Archive link ( Memento of the original from March 30, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. @1@ 2Template: Webachiv / IABot / www.datz.de