Sesarmops Indicus

''Sesarmops'' is a genus of crabs in the family Sesarmidae. Its members are distributed through the Indo–West-Pacific oceanic region. They live in freshwater forest streams near the coast, and in mangroves.

Taxonomy

''Sesarmops'' was defined in 1970 when Serène and Soh re-organised the existing genus ''Sesarma''. They included five species: ''S. atrorubens'', ''S. impressus'', ''S. intermedius'', ''S. mindanaoensis'', ''S. sinensis''.

Ng et al. provisionally added ''Sesarma weberi'' in 2008, Paulay and Starmer (2011) transferred ''Sesarma angustifrons'' to the genus in 2011.

Culminating work through the 2000s and 2010s, the genus was revised in January and December 2020. Species were split and redefined, and two species were transferred to a new genus.

The type species ''Sesarmops impressum'' (formerly ''Sesarma impressa'') and related species were reviewed by Ng et al. in 2020. ''S. impressa'' ''sensu lato'' from the West Pacific have different colouration and gonopods to those of the Indian Ocean. Ng, Li, & Shih restricted ''S. impressesus'' to the west Indian Ocean populations, defining ''S. indicus'' in the East Indian and ''S. imperator'' in the West Pacific oceans. The type locality for ''S. indicus'' is the Andaman Islands, records from northern Sumatra, Mentawei Islands and Engano Islands are provisionally referred to the same species.

Hess's original types, from "Sydney", for ''S. atrorubens'' and ''S. similis'' are lost. Scholars believe that he received the specimens via Sydney, and that they were collected elsewhere. Ng et al. designated neotypes from Fiji and Samoa, respectively.

Comparisons of mitochondrial DNA found that ''S. impressus'' and ''S. imperator'' form a clade sister to ''Bresedium eurypleon'' and ''B. brevipes'', indicating that ''Sesarmops'' is paraphyletic to '' Bresedium''. ''S. mora'' is sister to the impressum–Bresidium clade, whilst the ''Sesarmops intermedius'' complex, ''Pseudosesarma patshuni'', and the ''Chiromantes dehaani'' complex form another grouping. ''S. mindanaoensis'' was found to be more distantly related than the other ''Pseudosesarma'' species (''edwardsii, boucourtii, crassimarum''). The latter group (''intermedius–patshuni–dehaani'') was re-classified into a new genus '' Orisarma'' by Schubart & Ng (2020), having five species.

Species

As at 2023, the World Register of Marine Species recognises 9 species of ''Sesarmops'', with two former species moved to ''Orisarma''.

* '' Sesarmops angustifrons'' ( A. Milne-Edwards, 1869)
* '' Sesarmops atrorubens'' (, 1865) – Fiji.
* '' Sesarmops imperator'' Ng, Li & Shih, 2020 – East Asia to Taiwan and Ryukyus.
* ''Sesarmops impressus'' (H. Milne Edwards, 1837) – Madagascar, Comoros, Mayotte.
* '' Sesarmops indicus'' Ng, Li & Shih, 2020 – Andaman Islands. Possibly north Sumatra and nearby islands.
* ''Sesarmops intermedius'' = '' Orisarma intermedium'' ( De Haan, 1835)
* ''Sesarmops mindanaoensis'' ( Rathbun, 1914) – Taiwan ( Pingtung) and Philippines (Cebu and Bohol)
* ''Sesarmops mora'' Li, Shih & Ng, 2020 – Taiwan (Pingtung), Philippines (Cebu and Bohol), Indonesia ( Sulawesi and Manado)
* ''Sesarmops similis'' (Hess, 1865) – Samoa.
* ''Sesarmops sinensis'' = '' Orisarma sinense'' (H. Milne Edwards, 1853)
* ''Sesarmops weberi'' (De Man, 1892)

References

External links

Sesarmidae
Decapod genera
Terrestrial crustaceans

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