genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
crab
Crabs are decapod crustaceans of the infraorder Brachyura (meaning "short tailed" in Greek language, Greek), which typically have a very short projecting tail-like abdomen#Arthropoda, abdomen, usually hidden entirely under the Thorax (arthropo ...
s in the family
Hexapodidae
Hexapodidae is a family of crabs, the only family in the superfamily Hexapodoidea. It has traditionally been treated as a subfamily of the family Goneplacidae, and was originally described as a subfamily of Pinnotheridae. Its members can be d ...
. It contains only three
extant
Extant or Least-concern species, least concern is the opposite of the word extinct. It may refer to:
* Extant hereditary titles
* Extant literature, surviving literature, such as ''Beowulf'', the oldest extant manuscript written in English
* Exta ...
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
found in the
Indo-West Pacific
The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the s ...
. They inhabit the
intertidal
The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various sp ...
and
subtidal
The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth.
From the point of view of marine biology it forms a relatively stable and well-illuminate ...
areas of shorelines.
Description
Like other members of the family, these crabs are easily recognizable due to the complete absence of the last pair of walking legs (
pereiopod
The anatomy of a decapod consists of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment – often called a somite – may possess one pair of appendages, although in various groups these m ...
s). They thus only have six walking legs (excluding the
claw
A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or Arthro ...
s), unlike the usual eight. Their
carapace
A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...
is subquadrate, wider than it is long, with a rounded anterior.
Species
The following are the species classified under ''Hexapus''.
:Species marked with are
extinct
Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...
Extant species
*''
Hexapus bidentatus
''Hexapus'' is a genus of crabs in the family Hexapodidae. It contains only three extant species found in the Indo-West Pacific. They inhabit the intertidal and subtidal areas of shorelines.
Description
Like other members of the family, these ...
'' Velip & Rivonker, 2014
::Found in
Goa
Goa (; ; ) is a state on the southwestern coast of India within the Konkan region, geographically separated from the Deccan highlands by the Western Ghats. It is bound by the Indian states of Maharashtra to the north, and Karnataka to the ...
,
India
India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
Cochin
Kochi ( , ), formerly known as Cochin ( ), is a major port city along the Malabar Coast of India bordering the Laccadive Sea. It is part of the district of Ernakulam in the state of Kerala. The city is also commonly referred to as Ernaku ...
, southwest India to
Phuket
Phuket (; , , or ''Tongkah'') is one of the Southern Thailand, southern Provinces of Thailand, provinces (''changwat'') of Thailand. It consists of the island of Phuket, List of islands of Thailand, the country's largest island, and another 3 ...
,
Thailand
Thailand, officially the Kingdom of Thailand and historically known as Siam (the official name until 1939), is a country in Southeast Asia on the Mainland Southeast Asia, Indochinese Peninsula. With a population of almost 66 million, it spa ...
and the
Penang Strait
The Penang Strait is an 11 kilometre-wide strait that separates Penang Island from mainland Malay Peninsula. Penang Island is to the west of the channel, while Seberang Perai, the mainland half of the State of Penang, is to the east. The northe ...
of
Malaysia
Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...
*''
Hexapus timika
''Hexapus'' is a genus of crabs in the family Hexapodidae. It contains only three extant species found in the Indo-West Pacific. They inhabit the intertidal and subtidal areas of shorelines.
Description
Like other members of the family, these ...
'' Rahayu & Ng, 2014
::Found in
Timika
Timika is a chartered city (''kota''), and the capital of Mimika Regency on the southern coast of Central Papua, Indonesia. At the 2020 Census, the district which includes the town (it remains administratively within the Regency, rather than havin ...
Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania, between the Indian Ocean, Indian and Pacific Ocean, Pacific oceans. Comprising over List of islands of Indonesia, 17,000 islands, including Sumatra, ...
Fossil species
*''
Hexapus decapoda
''Hexapus'' is a genus of crabs in the family Hexapodidae. It contains only three extant species found in the Indo-West Pacific. They inhabit the intertidal and subtidal areas of shorelines.
Description
Like other members of the family, these ...
'' (Morris & Collins, 1991)
::Originally described as ''Prepaeduma decapoda''. From
Sarawak
Sarawak ( , ) is a States and federal territories of Malaysia, state of Malaysia. It is the largest among the 13 states, with an area almost equal to that of Peninsular Malaysia. Sarawak is located in East Malaysia in northwest Borneo, and is ...
,
Borneo
Borneo () is the List of islands by area, third-largest island in the world, with an area of , and population of 23,053,723 (2020 national censuses). Situated at the geographic centre of Maritime Southeast Asia, it is one of the Greater Sunda ...
,
Malaysia
Malaysia is a country in Southeast Asia. Featuring the Tanjung Piai, southernmost point of continental Eurasia, it is a federation, federal constitutional monarchy consisting of States and federal territories of Malaysia, 13 states and thre ...
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58
*'' Hexapus granuliformis'' Karasawa & Kato, 2008
::From Bolbe,
Davao City
Davao City, officially the City of Davao, is a City of the Philippines#Legal classification, highly urbanized city in the Davao Region, Philippines. The city has a total land area of , making it the List of Philippine cities and municipalities ...
,
Philippines
The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...
Pleistocene
The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
)
*''
Hexapus nakajimai
''Hexapus'' is a genus of crabs in the family Hexapodidae
Hexapodidae is a family of crabs, the only family in the superfamily Hexapodoidea. It has traditionally been treated as a subfamily of the family Goneplacidae, and was originally de ...
'' Imaizumi, 1959
::From the Jōban Coal Field of
Iwaki, Fukushima
is a Cities of Japan, city located in Fukushima Prefecture, Japan. , Iwaki had a population of 322,019 in 143,500 households, and population density of 261 persons per km². The total area of the city is , making it the largest city in the prefec ...
,
Japan
Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...
Miocene
The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...
Khyber Pakhtunkhwa
Khyber Pakhtunkhwa (; ; , ; abbr. KP or KPK), formerly known as the North West Frontier Province (NWFP), is a Administrative units of Pakistan, province of Pakistan. Located in the Northern Pakistan, northwestern region of the country, Khyber ...
of
Pakistan
Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...
Lutetian
The Lutetian is, in the geologic timescale, a stage (stratigraphy), stage or age (geology), age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it ...
)
Excluded species
''Hexapus estuarinus'' is now regarded as a
junior synonym
In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently.
...
of ''Hexapus sexpes''. In addition, the following the species has been transferred to other genera:
*''Hexapus anfractus'' (Rathbun, 1909) - Originally described as ''Lambdophallus anfractus'', now accepted as '' Mariaplax anfracta''
*''Hexapus buchanani'' Monod, 1956 - Now accepted as '' Theoxapus buchanani''
*''Hexapus edwardsii'' Serène & Soh, 1976 - Now accepted as '' Hexapinus edwardsii''
*''Hexapus granuliferus'' Campbell & Stephenson, 1970 - Now accepted as '' Mariaplax granuliferus''
*''Hexapus latipes'' De Haan, 1835 - Now accepted as '' Hexapinus latipes''
*''Hexapus stebbingi'' Barnard, 1947 - Now accepted as '' Tritoplax stebbingi''
*''Hexapus stephenseni'' Serène & Soh, 1976 - Now accepted as '' Mariaplax stephenseni''
*''Hexapus williamsi'' Glassell, 1938 - Now accepted as '' Stevea williamsi''