''Hemigrapsus estellinensis'' is an
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 ...
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 ...
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 ...
, formerly endemic to the
Texas Panhandle
The Texas Panhandle is a region of the U.S. state of Texas consisting of the northernmost 26 counties in the state. The panhandle is a square-shaped area bordered by New Mexico to the west and Oklahoma to the north and east. It is adjacent to ...
. It was discovered by Gordon C. Creel in 1962 and was probably already extinct before his description was published in 1964, after the Estelline Salt Springs where it lived were contained by the
. ''H. estellinensis'' is closely related to species from the
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
such as ''
Hemigrapsus oregonensis'', but lived inland in a hypersaline spring. It differed from its relatives by the pattern of spots on its back, and by the relative sizes of its limbs.
Description
![Hemigrapsus on Orcas Island 07](https://upload.wikimedia.org/wikipedia/commons/a/a1/Hemigrapsus_on_Orcas_Island_07.JPG)
''Hemigrapsus estellinensis'' has a rectangular carapace with almost parallel sides. Males have a carapace length of up to and a carapace width of up to , while females have a carapace up to long and wide. The front corners of the carapace are developed into three strong teeth on each side.
The chief difference between ''H. estellinensis'' and other species in the genus is the extensive pattern of rust-red spots on the animal's "drab green"
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 ...
.
''H. estellinensis'' also has a pair of conspicuous white spots near the ends of the H–shaped indentation on the animal's back, and another spot between each of those spots and the lateral margin of the carapace.
The legs are marked with larger spots than the carapace, and both the
cheliped
A chela ()also called a claw, nipper, or pinceris a pincer-like organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through New Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds. ...
s and the walking legs are shorter than in other species. There are no spots on the animal's underside, including the
abdomen
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
.
In males, the chelipeds bear a hairy patch containing
chemoreceptor
A chemoreceptor, also known as chemosensor, is a specialized sensory receptor which transduces a chemical substance (endogenous or induced) to generate a biological signal. This signal may be in the form of an action potential, if the chemorecept ...
s on the ventral side of 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 ...
.
Creel collected 6 males and ten females; one of the males is the
holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
and all the others are
paratype
In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). Of ...
s. All sixteen are held in the
National Museum of Natural History
The National Museum of Natural History is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. In 2021, with 7 ...
as specimens USNM 107855 and USNM 107856.
A few living specimens were taken to Wayland College (now
Wayland Baptist University
Wayland Baptist University (WBU) is a private Baptist university based in Plainview, Texas. It is affiliated with the Baptist General Convention of Texas (Southern Baptist Convention). Wayland Baptist has 11 campuses in five Texas cities, six ...
), but died within 17 hours for unknown reasons. Two of the females laid eggs before dying, one laying 3,000 and the other 8,000.
Distribution and ecology
''H. estellinensis'' lived in Estelline Salt Springs east of the town of
Estelline in
Hall County, Texas
Hall County is a county located in the U.S. state of Texas. As of the 2020 census, the population is 2,825. Its county seat is Memphis. The county was created in 1876 and later organized in 1890. It is named for Warren D. C. Hall, a secretary ...
, from the nearest ocean.
Before its extinction, it was the only
troglobitic
A troglobite (or, formally, troglobiont) is an animal species, or population of a species, strictly bound to underground habitats, such as caves. These are separate from species that mainly live in above-ground habitats but are also able to live u ...
crab in the
contiguous United States
The contiguous United States (officially the conterminous United States) consists of the 48 adjoining U.S. states and the Federal District of the United States of America. The term excludes the only two non-contiguous states, Alaska and Hawaii ...
. Its occurrence so far from the ocean has been described as "curious", and the species was "probably a
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 ...
relic
In religion, a relic is an object or article of religious significance from the past. It usually consists of the physical remains of a saint or the personal effects of the saint or venerated person preserved for purposes of veneration as a tangi ...
".
The springs originally produced water with a
salinity
Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...
of 43
‰
Per mille (from Latin , "in each thousand") is an expression that means parts per thousand. Other recognised spellings include per mil, per mill, permil, permill, or permille.
The associated sign is written , which looks like a percent sig ...
that fed the
Prairie Dog Town Fork of the
Red River.
[Proofs]
of the entire chapter are also available. The salinity derives from
Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
red beds
Red beds (or redbeds) are sedimentary rocks, typically consisting of sandstone, siltstone, and shale, that are predominantly red in color due to the presence of ferric oxides. Frequently, these red-colored sedimentary strata locally contain ...
, and has a strong structuring effect on the Red River's biota.
It had a flow of approximately per minute, and the pool was wide at the surface, which was at an altitude of
above sea level
Height above mean sea level is a measure of the vertical distance (height, elevation or altitude) of a location in reference to a historic mean sea level taken as a vertical datum. In geodesy, it is formalized as ''orthometric heights''.
The comb ...
.
At a depth of , it was only wide, and then widened slightly down to a depth of .
Below that, an opening wide led into a cavern completely filled with water.
The
built a dike around the Estelline Salt Springs in January 1964,
which has reduced the
chloride
The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride salts ...
load on the Red River by per day.
Before it was contained, the spring had a rich biota, comprising the
cyanobacteria
Cyanobacteria (), also known as Cyanophyta, are a phylum of gram-negative bacteria that obtain energy via photosynthesis. The name ''cyanobacteria'' refers to their color (), which similarly forms the basis of cyanobacteria's common name, blu ...
''
Oscillatoria
''Oscillatoria'' is a genus of filamentous cyanobacterium which is often found in freshwater environments, such as hot springs, and appears blue-green. Its name refers to the oscillating motion of its filaments as they slide against each other ...
'' and ''
Lyngbya
''Lyngbya'' is a genus of cyanobacteria, unicellular autotrophs that form the basis of the oceanic food chain.
As a result of recent genetic analyses, several new genera were erected from this genus: ''e.g.'', ''Moorea'', '' Limnoraphis'', '' Ok ...
'', the
green algae
The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...
''
Ulva clathrata'' and ''
U. intestinalis'', twenty species of
diatom
A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...
, many
invertebrate
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...
s – including a species of
barnacle
A barnacle is a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in eros ...
– and a single fish species, ''
Cyprinodon rubrofluviatilis
''Cyprinodon rubrofluviatilis'', known as the Red River pupfish, is a species of pupfish from the United States. It is found only in the Red River of the South and Brazos River drainages of Texas and Oklahoma.
It grows to a total length of and f ...
''.
The springs have since increased in salinity, and many species have been driven to
extinction
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 ...
, including ''H. estellinensis'' and the
undescribed barnacle.
As early as December 1962, attempts to find further living individuals of ''H. estellinensis'' were unsuccessful, and it was probably extinct before Creel's description was published in 1964.
The closest relative of ''H. estellinensis'' is the shore crab ''
Hemigrapsus oregonensis'', which lives along the coast of the
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
. The entire genus is restricted to the Pacific Ocean, except for ''
Hemigrapsus affinis
''Hemigrapsus'' is a genus of varunid crabs comprising thirteen species native almost exclusively in the Pacific Ocean, but two have been introduced to the North Atlantic region.
Biogeography
The natural range of the genus is restricted to th ...
'' which lives along the Atlantic coasts of South America, from
Cape San Roque (
Rio Grande do Norte
Rio Grande do Norte (, , ) is one of the states of Brazil. It is located in the northeastern region of the country, forming the northeasternmost tip of the South American continent. The name literally translates as "Great Northern River", ref ...
state,
Brazil
Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...
) to the
Gulf of San Matías (
Patagonia
Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...
,
Argentina
Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
), and population of ''
Hemigrapsus sanguineus
''Hemigrapsus sanguineus'', the Japanese shore crab or Asian shore crab, is a species of crab from East Asia. It has been introduced to several other regions, and is now an invasive species in North America and Europe. It was introduced to thes ...
'' which have been introduced from the species' native range in
East Asia
East Asia is the eastern region of Asia, which is defined in both geographical and ethno-cultural terms. The modern states of East Asia include China, Japan, Mongolia, North Korea, South Korea, and Taiwan. China, North Korea, South Korea and ...
to the Atlantic coast of the United States from
Portland, Maine
Portland is the largest city in the U.S. state of Maine and the seat of Cumberland County. Portland's population was 68,408 in April 2020. The Greater Portland metropolitan area is home to over half a million people, the 104th-largest metropol ...
to
North Carolina
North Carolina () is a state in the Southeastern region of the United States. The state is the 28th largest and 9th-most populous of the United States. It is bordered by Virginia to the north, the Atlantic Ocean to the east, Georgia and So ...
, and to the
English Channel
The English Channel, "The Sleeve"; nrf, la Maunche, "The Sleeve" (Cotentinais) or ( Jèrriais), (Guernésiais), "The Channel"; br, Mor Breizh, "Sea of Brittany"; cy, Môr Udd, "Lord's Sea"; kw, Mor Bretannek, "British Sea"; nl, Het Kana ...
and
North Sea
The North Sea lies between Great Britain, Norway, Denmark, Germany, the Netherlands and Belgium. An epeiric sea on the European continental shelf, it connects to the Atlantic Ocean through the English Channel in the south and the Norwegian S ...
.
References
External links
*
*Estelline Salt Springs:
{{Taxonbar, from=Q5711611
Grapsoidea
Extinct crustaceans
Endemic fauna of Texas
Crustaceans of the United States
Freshwater crustaceans of North America
Extinct animals of the United States
Extinct invertebrates since 1500
Species made extinct by human activities
Crustaceans described in 1964
Pleistocene animals of North America
Pleistocene first appearances