genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
crab
Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (abdomen) ( el, βραχύς , translit=brachys = short, / = tail), usually hidden entirely under the thorax. They live in all the ...
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 di ...
. It contains only three
extant
Extant 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
* Extant taxon, a taxon which is not extinct, ...
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
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 ...
. They inhabit the
intertidal
The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of Marine habitat, habitats with var ...
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-illuminated ...
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 decapod (crustaceans such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment may possess one pair of appendages, although in various g ...
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 tarsus ...
s), unlike the usual eight. Their
carapace
A carapace is a Dorsum (biology), 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 tor ...
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 a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
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 located between the Indian states of Maharashtra to the north and Karnataka to the ...
,
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
*''
Hexapus sexpes
''Hexapus'' is a genus of crabs in the family Hexapodidae. It contains only three Extant taxon, extant species found in the Indo-West Pacific. They inhabit the intertidal and subtidal areas of shorelines.
Description
Like other members of the ...
'' (Fabricius, 1798)
::Found from
Cochin
Kochi (), also known as Cochin ( ) ( the official name until 1996) is a major port city on the Malabar Coast of India bordering the Laccadive Sea, which is a part of the Arabian Sea. It is part of the district of Ernakulam in the state of K ...
, southwest India to
Phuket
Phuket (; th, ภูเก็ต, , ms, Bukit or ''Tongkah''; Hokkien:普吉; ) is one of the southern provinces (''changwat'') of Thailand. It consists of the island of Phuket, the country's largest island, and another 32 smaller islands of ...
,
Thailand
Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...
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 northern ...
of
Malaysia
Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...
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 having ...
Indonesia
Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
Fossil species
*'' Hexapus decapoda'' (Morris & Collins, 1991)
::Originally described as ''Prepaeduma decapoda''. From
Sarawak
Sarawak (; ) is a States and federal territories of Malaysia, state of Malaysia. The largest among the 13 states, with an area almost equal to that of Peninsular Malaysia, Sarawak is located in northwest Borneo Island, and is bordered by the M ...
,
Borneo
Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and eas ...
,
Malaysia
Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ...
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58
*'' Hexapus granuliformis'' Karasawa & Kato, 2008
::From Bolbe,
Davao City
Davao City, officially the City of Davao ( ceb, Dakbayan sa Dabaw; ), is a first class highly urbanized city in the Davao Region, Philippines. The city has a total land area of , making it the largest city in the Philippines in terms of lan ...
,
Philippines
The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no),
* bik, Republika kan Filipinas
* ceb, Republika sa Pilipinas
* cbk, República de Filipinas
* hil, Republ ...
Pleistocene
The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...
)
*'' Hexapus nakajimai'' Imaizumi, 1959
::From the Jōban Coal Field of
Iwaki, Fukushima
is a city located in Fukushima Prefecture, Japan. , Iwaki had a population of 337,765 in 143,500 households, and population density of 270 persons per km2. The total area of the city is , making it the largest city in the prefecture and the 10th ...
,
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
Miocene
The Miocene ( ) is the first 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 means "less recen ...
Khyber Pakhtunkhwa
Khyber Pakhtunkhwa (; ps, خېبر پښتونخوا; Urdu, Hindko: خیبر پختونخوا) commonly abbreviated as KP or KPK, is one of the Administrative units of Pakistan, four provinces of Pakistan. Located in the Geography of Pakistan, ...
of
Pakistan
Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
Lutetian
The Lutetian is, in the geologic timescale, a stage or 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 is sometimes referred to as the Midd ...
)
Excluded species
''Hexapus estuarinus'' is now regarded as a
junior synonym
The Botanical and Zoological Codes of nomenclature treat the concept of synonymy differently.
* In botanical nomenclature, a synonym is a scientific name that applies to a taxon that (now) goes by a different scientific name. For example, Linna ...
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''