Perisesarma guttatum

Along with the other species within the genus Perisesarma, the red-claw mangrove crab has a relatively square-shaped carapace and a “tooth” protruding off the sides of it.{{cite journal | vauthors = Shahdadi A, Schubart CD | date = January 2015 |title=Evaluating the consistency and taxonomic importance of cheliped and other morphological characters that potentially allow identification of species of the genus Perisesarma De Man, 1895 (Brachyura, Sesarmidae) |journal=Crustaceana |language=en |volume=88 |issue=10–11 |pages=1079–1095 |doi=10.1163/15685403-00003473 |issn=1568-5403}} The claw of the crab consists of a palm and dactylus. At the end of the dactylus are oval or circular shaped bumps called tubercles. The part leading up to the claws, the chelar carpus, also has pectinate crests on males within the genus. A pectinate crest is a ridge-like projection on the crab; these ridges line the chelar carpus side-by-side.{{cite web | title = Crustacean Glossary. | date= 2012 | vauthors = Bowling B | work = Texas Parks and Wildlife Department | access-date = 24 April 2022 | url = https://txmarspecies.tamug.edu/crustglossary.cfm }} Different species of Perisesarma vary in the amount of their tubercles in addition to the number of pectinate crests.

P. guttatum have 20 pectinate crests and 11 to 13 oval-shaped tubercles on top of their claws.{{cite web |title=Perisesarma guttatum (A. Milne Edwards, 1869) |url=http://www.madeinnys.com/mangrove/s_guttatum.htm |publisher=A field guide to Kenyan mangroves |access-date=1 November 2016}} Their claws are reddish in color with bright orange internal palms. The carapace is about 3 cm in length and between 1.5 and 2.2 cm in width on average in adults.{{cite journal | vauthors = Amaral V, Penha-Lopes G, Paula J |date= July 2009 |title=RNA/DNA ratio of crabs as an indicator of mangrove habitat quality |journal=Aquatic Conservation: Marine and Freshwater Ecosystems |language=en |volume=19 |issue=S1 |pages=S56–S62 |doi=10.1002/aqc.1039|s2cid= 84150126 }} At maturity, males display larger claws than females, showing sexual dimorphism.

P. samawati, a sympatric species, was confused for P. guttatum until more recently, though their morphologies are distinctly different.{{cite journal | vauthors = Gillikin DP, Schubart CD |title=Ecology and systematics of mangrove crabs of the genus Perisesarma (Crustacea: Brachyura: Sesarmidae) from East Africa | journal = Zoological Journal of the Linnean Society | date = July 2004 | volume = 141 | issue = 3 | pages = 435–445 |doi=10.1111/j.1096-3642.2004.00125.x|url=https://zenodo.org/record/5430727 | doi-access = free }} Unlike P. guttatum, P. Samawati only has 7 to 9 tubercles on the upper surface of their claws. The sizes of their bodies differs as well.

P. guttatum are mangrove inhabitants mostly located by Avicennia marina. The species inhabit these mangroves in east African coasts and Madagascar.{{cite journal | vauthors = Fratini S, Ragionieri L, Cannicci S | title = Correction: Demographic History and Reproductive Output Correlates with Intraspecific Genetic Variation in Seven Species of Indo-Pacific Mangrove Crabs | journal = PLOS ONE | volume = 12 | issue = 12 | pages = e0189550 | date = December 2017 | pmid = 29228041 | pmc = 5724817 | doi = 10.1371/journal.pone.0189550 | bibcode = 2017PLoSO..1289550F | doi-access = free }} Despite increases in pollution from sewage in these areas, the crabs tolerate and are even capable of using the excess nutrients, making them less helpful in measuring mangrove health.{{cite journal | vauthors = Cannicci S, Bartolini F, Dahdouh-Guebas F, Fratini S, Litulo C, Macia A, Mrabu EJ, Penha-Lopes G, Paula J | display-authors = 6 | date = September 2009 |title=Effects of urban wastewater on crab and mollusc assemblages in equatorial and subtropical mangroves of East Africa |journal=Estuarine, Coastal and Shelf Science |series=Marine Science in the Western Indian Ocean Responds to Population Pressures and Climate Change |language=en |volume=84 |issue=3 |pages=305–317 |doi=10.1016/j.ecss.2009.04.021 | bibcode = 2009ECSS...84..305C |issn=0272-7714| url = https://dipot.ulb.ac.be/dspace/bitstream/2013/46671/1/Canniccietal_2009_ECSS.pdf }}

The species use burrows and natural crevices made by Neosarmatium smithi to hide from predators and also for survival. P. guttatum are mainly herbivorous, eating dead plant material and other organic matter foraged from the estuarine or forest floor during low tides. Their diets therefore contribute to leaf turnover and the general removal of matter from the substratum.{{cite journal | vauthors = Silva IC, Mesquita N, Paula J | title = Genetic and morphological differentiation of the mangrove crab Perisesarma guttatum (Brachyura: Sesarmidae) along an East African latitudinal gradient. | journal = Biological Journal of the Linnean Society | date = January 2010 | volume = 99 | issue = 1 | pages = 28–46 | doi = 10.1111/j.1095-8312.2009.01338.x | doi-access = free }}

Females begin to reach sexual maturity around 2 years old; adults then mate throughout the year, but a study suggests that breeding correlates with lunar phases. Females tend to release their larvae before spring tides, which occur during new and full moons. However, females cannot breed for two consecutive spring tides, which suggests this pattern is seen due to two breeding groups within one population.

During the early stages of life, planktonic larvae move offshore and are distributed with the help of ocean currents. They later return as megalopa larvae – the step in their development that comes after 5 planktonic life stages – and settle in the nearshore environments around where they were once born.

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Category:Sesarmidae

Category:Crustaceans described in 1869