Menaethius monoceros   (Latreille,  1825) (Crab)
Organism information awaits expert curation
Class: Malacostraca

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Length of carapace: 22 mm.
Breadth of carapace: 21 mm.
Length of rostrum: 8 mm.

Color: Pale lemon yellow.

The crab is distinguished by its elongate-triangular carapace, and the acute, styliform, horizontally compressed rostrum, flanked on either side by the forwardly directed supraocular spine.
The carapace is usually encrusted with weeds, and is very variable as regards the number, position, and size of the spines. The tubercles on the carapace are arranged in a regular manner, viz. three in a triangle on the gastric region, three others forming a triangle on the cardiac region (three to four lateral spines on the antero-lateral borders), two on the branchial region, and a medium intestinal one at the posterior end.
The carapace is finely granular under the microscope. The rostrum, which is as long as the carapace in some, varies greatly. It is hairy, the hairs being of two types: (1) simple, (2) clubbed
There are two to three hairy knobs on the anterior border of the meropodites of the legs, and one in the middle of the posterior border of the propodites. There is a spine-like tubercle near the base of the arm of the chelipeds.
The anterior male abdominal appendage is peculiar, its tip being at right angles to the body and shaped like a bird's head. The distal half of the appendage is abruptly narrowed. The phenomenon referred to as 'facultative dimorphism' i.e alternate phases in the life-history of the same individual co-related with the breeding male with pronounced secondary sexual characters changed by a moult to the non-breeding form with much resemblance to the young.

Synonym (s)
Pisa monoceros Latreille, 1825
Menaethius tuberculatus Adams & White, 1848
Menaethius subserratus Adams & White, 1848
Menaethius rugosus A. Milne-Edwards, 1862
Menaethius porcellus White, 1848
Menaethius inornatus Dana, 1852
Menaethius depressus Dana, 1852
Menaethius dentatus Stimpson, 1857
Menaethius areolatus Dana, 1852
Menaethius angustus Dana, 1852
Inachus arabicus Ruppell, 1830

Common Name (s)
Economic Importance and Threats

Habitat:  Reef Associated, Estuarine, Rocky, Coastal


• Gujarat, Okha INDIA
• West Coast INDIA
• Andaman and Nicobar Islands INDIA
• Lakshadweep INDIA
• Tamil Nadu, Gulf of Mannar INDIA
• Red Sea
• Tamil Nadu, Vedalai INDIA
• Karnataka INDIA (Record: 2001-2007)
• Andaman and Nicobar Islands, Car Nicobar INDIA
• Andaman and Nicobar Islands, South Andaman, Aberdeen Bay INDIA
• Lakshadweep, Minicoy INDIA
• Tamil Nadu INDIA

Literature Source(s)
  • Simoes, N; Apel, M and David, AJ (2001) Intertidal habitats and decapod faunal assemblages (Crustacea: Decapoda) of Socotra Island, Republic of Yemen Hydrobiologia Kluwer Academic Publishers 449 81-97
  • Chhapgar, BF (1957) Marine crabs of Bombay state Contribution No. 1 of the Taraporevala Marine Biological Station Marine Biological Station, Department of fisheries, Bombay 89 pp Available at - NIO, Goa
  • Society for the Management of European Biodiversity Data (2009) World Register of Marine Species (WoRMS) Available at -
  • Jeyabaskaran, R; Wafar, S and Wafar, M (2002) CD on Brachyuran Crabs of West Coast, India Available at -
  • Sankarankutty, C (1966) On Decapoda Brachyura from the Gulf of Mannar and Palk Bay Proceedings of the Symposium on Crustacea Marine Biological Association of India, Mandapam Camp Part I 347-362 Available at -
  • Roy, MKD and Nandi, NC (2005) Brachyuran diversity of coral reef ecosystems in India Proceedings of the National Seminar on Reef Ecosystem Remediation SDMRI Special Research Publication No.9 220-231 Available at -
  • Dineshbabu, AP; Durgekar, RN and Zacharia, PU (2011) Estuarine and marine decapods of Karnataka inventory Fishing Chimes Mr.J.V.H. Dixitulu 30 (10-11) 20-24 Available at -
  • James, PSBR ; Thomas, PA ; Pillai, CSG and Achari Kumaraswamy, GP (1969) ´╗┐Catalogue of types and of sponges, corals, polychaetes, crabs and echinoderms in the reference collections of the Central Marine Fisheries Research Institute Bulletin of Central Marine Research Institute CMFRI, Cochin 7 1-66 Available at -
  • Sankarankutty, C (1962) On decapoda brachyura from the Andaman and Nicobar islands 3. Families: Calappidae. Leucosiidae, Parthenopidae, Maiidae, and Gecarcinidae Journal of the marine biological association of India. The marine biological association of India 4(1) 151-164 Available at - NIO, Goa
  • Roy, MKD and Nandi NC (2007) Brachyuran diversity in coastal ecosystems of Tamil Nadu Journal of Environment and Sociobiology Social Environmental and Biological Association, Kolkata, India 4(2) 169-192 Available at - NIO,Goa

Page last updated on:2011-10-03

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