Cosmetidae, with around 700 species, is the second most diverse family of the Suborder Laniatores

Laniatores

Laniatores is the largest suborder of the arachnid order Opiliones with over 4,000 described species worldwide. The majority of the species are highly dependent on humid environments and usually correlated with tropical and temperate forest habitats....

. They are distributed from Argentina to southern USA, most diverse in northern South America, Central America and Mexico. This Nearctic

Nearctic

The Nearctic is one of the eight terrestrial ecozones dividing the Earth's land surface.The Nearctic ecozone covers most of North America, including Greenland and the highlands of Mexico...

-Neotropical family comprises Opiliones with elaborate white/yellow/green/orange/red stripes and spots on the dorsal scutum and peculiar pedipalps strongly compressed and applied on the chelicerae.

Name

The family name is derived from the type genus

Type genus

In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...

 Cosmetus, which is from Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 kosmetós = ornate.

Diagnosis

• Eye mound is very low, saddle shaped, placed on middle of cephalothorax, each ocular globe bears a crest of small pointed tubercles or is smooth. Ozopores slit-like, one opening partially covered by tubercle of coxa II. Scutal areas are often indistinct; sometimes the sulci can be distinguished by color pattern or absence of tubercles; scutum and tergites are typically weakly armed.
• Genitalia. Penis are standard gonyleptoid and very conservative, with rectangular ventral plate, puffed sac-glans, well-developed thumb-like dorsal process.

See more details in Kury & Pinto-da-Rocha (2007).

Distribution

The Cosmetidae are endemic of the New World

New World

The New World is one of the names used for the Western Hemisphere, specifically America and sometimes Oceania . The term originated in the late 15th century, when America had been recently discovered by European explorers, expanding the geographical horizon of the people of the European middle...

. The peak of their diversity is in northern South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

, Central America

Central America

Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...

, and Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

, where maybe one third to half of species of Opiliones are represented by this single family; they are numerous in Amazonian and Andean realms and also in the Caribbean

Caribbean

The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

. They are absent in Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

. They also reach southwards as far as Argentina

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 and even southern Brazil

Brazil

Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...

 (genus Metalibitia). There are a few species in the Brazilian Atlantic Forest, mostly belonging to the genus Metavononoides. A few species now in Vonones

Vonones

Vonones was the name of three kings of the ancient Middle East:*Vonones was king of the Indo-Scythians c. 75–65 BC.*Vonones I was king of Parthia c. AD 8–12*Vonones II was king of Parthia c. 51...

reach far northwards into the USA, were they occur in many of the southern states.

Subtaxa

As of 2006, there are 125 genera and 712 species described. Most species belong to Cynorta (153 spp), Paecilaema (102 spp), Flirtea and Erginulus (30 spp each). However, there is no reason to believe most of genera of cosmetids are natural groups, except for a few like Metavononoides and Cosmetus (Kury, 2003). Attempts to organize the family in supra-specific units are hindered by the poorly resolved basic taxonomy.

Relationships

Cosmetidae is the sister-group of Gonyleptidae

Gonyleptidae

Gonyleptidae is a Neotropical family of harvestmen with more than 800 species, the largest in the Suborder Laniatores and the second largest of the Opiiones as a whole...

 and both are related to the Stygnidae

Stygnidae

The Stygnidae are a family of neotropical harvestmen within the suborder Laniatores.-Description:Body length ranges from about one to six millimeters. The color ranges from light brown to reddish...

 and Cranaidae

Cranaidae

The Cranaidae are a family of neotropical harvestmen within the suborder Laniatores.-Name:The name of the type genus is derived from Cranaus, the successor of Cecrops I as king of Attica in Greek mythology.-Description:...

(Kury, 1992).