''Plato'' is a genus of

ray spider Theridiosomatidae, commonly known as ray spiders, are a family of araneomorph spiders first described by Eugène Simon in 1881. The family includes 137 species divided between 20 genera. They are most recognizable for their construction of cone-sha ...

(family Theridiosomatidae). The American biologist

Jonathan A. Coddington Jonathan A. Coddington is an American museum scientist and biologist. From 2009 to 2014, he was the Associate Director for Science at the Smithsonian National Museum of Natural History (NMNH), located in Washington, D.C., United States. , he is th ...

named and

circumscribed In geometry, a circumscribed circle for a set of points is a circle passing through each of them. Such a circle is said to ''circumscribe'' the points or a polygon formed from them; such a polygon is said to be ''inscribed'' in the circle. * Circum ...

the genus in 1986. It is a

Neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeogra ...

genus and it is limited to South America. , nine species were recognized. They are found in caves and have a distinctive cubic

egg sac Spiders (order (biology), order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude spider silk, silk. They are the largest order of arachnids and ran ...

. The generic name comes from the ancient Greek philosopher

Plato Plato ( ; Greek language, Greek: , ; born BC, died 348/347 BC) was an ancient Greek philosopher of the Classical Greece, Classical period who is considered a foundational thinker in Western philosophy and an innovator of the writte ...

Description

The head region of the carapace is tan, and not especially elevated. The sternum is also tan, sometimes darker, as wide as long, convex, and rounds towards the rear. The abdomen is light grey or tan, with no clear markings, and bears sparse setae. The legs are long and slender, pale tan in colour without annulations. Although the genus is

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 ...

, they have no specific modifications for living in caves or other dark places. The clypeal height is 3x the diameter of the AME. All of the eyes are roughly the same size, although the lateral eyes may be slightly smaller. The AME are separated by half their diameter, and the PME are separated by at least their diameter. Diagnostic features include: the base of the epigynum in female ''Plato'' species having a median projection; the cymbium having distal or mesal groves; and the underside of the male

conductor Conductor or conduction may refer to: Biology and medicine * Bone conduction, the conduction of sound to the inner ear * Conduction aphasia, a language disorder Mathematics * Conductor (ring theory) * Conductor of an abelian variety * Cond ...

having a curved apophysis.

Habitat and distribution

''Plato'' is found in the

Neotropical realm The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropics, tropical Ecoregion#Terrestrial, terrestrial ecoregions of the Americas and the entire South American temperat ...

. Its range is limited to South America (including the island of

Trinidad Trinidad is the larger, more populous island of the Republic of Trinidad and Tobago, the country. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is the southernmost island in ...

), within the countries Brazil, Ecuador, Trinidad & Tobago, and Venezuela, as well as in the French overseas region

French Guiana French Guiana, or Guyane in French, is an Overseas departments and regions of France, overseas department and region of France located on the northern coast of South America in the Guianas and the West Indies. Bordered by Suriname to the west ...

. Their

orb web A spider web, spiderweb, spider's web, or cobweb (from the archaic word '' coppe'', meaning 'spider') is a structure created by a spider out of proteinaceous spider silk extruded from its spinnerets, generally meant to catch its prey. Spider w ...

s hang from the ceilings and walls near the entrance of caves. They are typically found in humid environments, near streams or other bodies of water.

Behaviour

As with other ray spiders, ''Plato'' constructs an orb web, although their webs lack a tension line. Their

s are cubical, and are suspended in long threads from their vertices. Each egg sac can contain between eight and seventeen eggs. The diet of ''Plato'' species consists of small flying insects such as

chironomids Chironomidae , commonly known as non-biting midges or chironomids , are a family of Nematoceran flies with a global distribution. They are closely related to the families Ceratopogonidae, Simuliidae, and Thaumaleidae. Although many chironomid s ...

and other flies, tineid moths, and

caddisflies The caddisflies (order Trichoptera) are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the basis ...

Species

, the

World Spider Catalog The World Spider Catalog (WSC) is an online searchable database concerned with spider taxonomy. It aims to list all accepted families, genera and species, as well as provide access to the related taxonomic literature. The WSC began as a series of ...

recognizes the following nine species: * '' P. bicolor'' — Brazil * '' P. bruneti'' — Trinidad * '' P. ferriferus'' — Brazil * '' P. guacharo'' — Venezuela * '' P. juberthiei'' — French Guiana * '' P. miranda'' — Venezuela * '' P. novalima'' — Brazil * '' P. striatus'' — Brazil * '' P. troglodita'' — Ecuador

Taxonomic history

, a biologist at the

National Museum of Natural History The National Museum of Natural History (NMNH) 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. With 4.4 ...

the genus ''Plato'' in a 1986 revision of the family

Theridiosomatidae Theridiosomatidae, commonly known as ray spiders, are a family of araneomorph spiders first described by Eugène Simon in 1881. The family includes 137 species divided between 20 genera. They are most recognizable for their construction of cone-sha ...

. He designated ''P. troglodita'', which he described in the same work, to be the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of the genus. The other species he included in his initial circumscription had been initially described in the genera ''

Maymena ''Maymena'' is a genus of spiders in the family Mysmenidae. It was first described in 1960 by Gertsch. , it contains 13 species. Species ''Maymena'' comprises the following species: *''Maymena ambita'' (Barrows, 1940) *'' Maymena calcarata'' (Si ...

'' (''P. bruneti'') and ''

Wendilgarda ''Wendilgarda'' is a genus of ray spiders that was first described by Eugen von Keyserling in 1886. Species it contains fourteen species and one subspecies, found in Asia, the Caribbean, Central America, São Tomé and Príncipe, Brazil, and Me ...

'' (''P. miranda'', ''P. guacharo'', and ''P. bicolor''). André Lopez at the

Centre national de la recherche scientifique The French National Centre for Scientific Research (, , CNRS) is the French state research organisation and is the largest fundamental science agency in Europe. In 2016, it employed 31,637 staff, including 11,137 tenured researchers, 13,415 eng ...

described ''P. juberthiei'' in 1996, and Pedro H. Prete and colleagues at the

Instituto Butantan The Instituto Butantan () is a Brazilian biologic research center located in Butantã, in the western part of the city of São Paulo, Brazil. Instituto Butantan is a public institution affiliated with the São Paulo State Secretariat of Health ...

described the three species ''P. novalima'', ''P. ferriferus'', and ''P. striatus'' in 2018. Coddington named the genus after the ancient Greek philosopher

. Coddington's reasoning were their "strikingly cubical egg sacs" and their "partiality for caves." These relate to the philosopher by way of the

Platonic solid In geometry, a Platonic solid is a Convex polytope, convex, regular polyhedron in three-dimensional space, three-dimensional Euclidean space. Being a regular polyhedron means that the face (geometry), faces are congruence (geometry), congruent (id ...

s and the Allegory of the Cave, respectively. The generic name is masculine in

gender Gender is the range of social, psychological, cultural, and behavioral aspects of being a man (or boy), woman (or girl), or third gender. Although gender often corresponds to sex, a transgender person may identify with a gender other tha ...

. Coddington placed ''Plato'' in a new subfamily Platoninae, alongside the genus '' Chthonos''. In 2011, the German arachnologist changed the status of Platoninae to be the tribe Platonini in the subfamily Theridiosomatinae instead, although Prete and colleagues followed Coddington in having ''Plato'' in the subfamily ''Platoninae''.

References