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Geosesarma hagen:
Geosesarma hagen:
Geosesarma hagen Ng, Schubart & Lukhaup, 2015 is a small species of terrestrial freshwater Brachyuran crab endemic to Java, Indonesia. It is commonly known as the Red Devil Vampire Crab and the specific epithet gets its name from the Rolf C. Hagen Group whose support was appreciated by the describers of this species, Peter K. L. Ng, Christoph D. Schubart & Christian - Lukhaup, in 2018 in the paper “New species of “vampire crabs” (Geosesarma De Man, 1892) from central Java, Indonesia, and the identity of Sesarma (Geosesarma) nodulifera De Man, 1892 (Crustacea, Brachyura, Thoracotremata, Sesarmidae)”.
The carapace of Geosesarma hagen is dark brown on the anterior ½ or ⅓ with the ambulatory legs matching this coloration and the posterior ½ or ⅔ of carapace being orange to yellow. The amount of bright orange on the carapace varies significantly with some individuals being almost entirely orange. The chelae of G. hagen are bright orange and the eyes are bright yellow. The thoracic sternum is a grayish-white to gray with numerous gray specks and the abdomen is dark-gray with small white specks.
Size of Geosesarma hagen
Size of Geosesarma hagen
Adult males of this species were described as ranging from 12.6mmx11.6mm L to 13.9mmx13.3mm L and females ranging from 11.3x10.7mm to 14.5x13.4mm. Given the carapace dimensions it is seen that the carapace is squarish in appearance although slightly wider than they are long. The anterior dorsal surface of the carapace is densely covered with small round granules.
Habitat of Geosesarma hagen
Habitat of Geosesarma hagen
In the wild Geosesarma hagen was described by Ng, Schubart, & Lukhaup (2015) hiding under dense forest floor vegetation on a banana and rubber plant plantation. This location was about 300 meters from a road on a small hill with a stream and small trickles of water in the same general area. Most individuals were found under and in between rocks but were also occasionally found at the edge of the body of water in excavated burrows.
Breeding Report of Geosesarma hagen, Courtesy of Heath Gariss
Breeding Report of Geosesarma hagen, Courtesy of Heath Gariss
A group of adult Geosesarma hagen consisting of two males and four females was acquired in 2022 and placed in a 25 gallon ZooMed front opening enclosure that is heavily planted and with a large bottom heated water feature approximately 12”x8.5” and around 2.5-3” deep. No physical courting or breeding behavior was noticed but offspring were noticed after around 2 months, and new offspring have been continuing to be born seemingly so breeding seems continuous. The offspring of G. hagen appear to develop and grow quickly, growing from freshly born to about ½-¾” in only two months. Mortality rates of the offspring do not appear from any inborn weaknesses and have been attributed to cannibalism. Environmental cues for breeding behavior have not been able to be documented yet as not enough time has elapsed. Brood size also has not been documented as the initial brood was not noticed until some time had elapsed, by then more fresh offspring had been born and potentially cannibalized.
Geosesarma hagen adult in a burrow, Courtesy of Heath Gariss
A fully planted paludarium vivarium for Geosesrama hagen, Courtesy of Heath Gariss
Geosesarma hagen freshly hatched crablets underwater, Courtesy of Health Gariss
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References:
WoRMS (2022). Geosesarma hagen Ng, Schubart & Lukhaup, 2015. Accessed at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=881928 on 2022-10-08
iNaturalist. (2022). Geosesarma hagen. Geosesarma Red Devil. https://www.inaturalist.org/taxa/639107-Geosesarma-hagen
Wikipedia. (2022). Rolf C. Hagen Group. https://en.wikipedia.org/wiki/Rolf_C._Hagen_Group
Ng, P, K, L., Sschubart, C, D., & Lukhaup, C. (2018). New species of “vampire crabs” (Geosesarma De Man, 1892) from central Java, Indonesia, and the identity of Sesarma (Geosesarma) nodulifera De Man, 1892 (Crustacea, Brachyura, Thoracotremata, Sesarmidae). Raffles Bulletin of Zoology, 63, 3-13. http://zoobank.org/urn:lsid:zoobank.org:pub:9F76CF88-A3DD-4F0E-B348-EEB9558DBBC4
Gariss, H. (2022). Geosesarma hagen, Species Banner. Photograph. Permission granted soley to TGD.
Gariss, H. (2022). Geosesarma hagen adult in a burrow. Photograph. Permission granted soley to TGD.
Gariss, H. (2022). Geosesarma hagen freshly hatched crablets underwater. Permission granted soley to TGD.
Gariss, H. (2022). A fully planted paludarium vivarium for Geosesrama hagen. Permission granted soley to TGD.
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