Ricinulei


Also found in: Wikipedia.

Ricinulei

 

an order of the class Arachnida. The body, which reaches 1 cm in length, is divided into a cephalothorax and a wide, segmented abdomen. The abdomen ends in a small, tightly constricted section known as the postabdomen. The movable hood of the cephalothorax folds over small two-jointed chelicerae. A six-legged larva hatches from the egg (as in ticks). There are about 15 species, distributed in western Africa and South America.

Mentioned in ?
References in periodicals archive ?
Only three of the ten Ricinulei specimens were dried because of their rarity in museum collections.
A few species of the first true spiders, the Ricinulei, survive today as ``living fossils'' in tropical forests.
Several arachnid orders have pore-like chemosensory organs on the tarsus, including Amblypygi (Weygoldt 2000), Araneae (Foelix 1996), and Ricinulei (Talarico et al.
On Two Orders of Arachnida: Opiliones, Especially the Suborder Cyphophthalmi, and Ricinulei, Namely the Family Cryptostemmatoidae.
Group Paleozoic Mesozoic Cenozoic Total Pycnogonida 6 3 -- 9 "Euchelicerata" 5 -- -- 5 Xiphosura 75 20 1 96 Chasmataspidida 8 -- -- 8 Eurypterida 241 -- -- 241 Scorpiones 79 16 16 111 Opiliones 7 1 17 25 Phalangiotarbida 30 -- -- 30 Pseudoscorpiones 1 2 35 38 Solifugae 2 1 2 5 Acari: Anactinotrichida -- 1 10 11 Acari: Actinotrichida 15 15 253 283 Palpigradi -- -- 1 1 Ricinulei 15 -- -- 15 "Pantetrapulmonata" 3 -- -- 3 Trigonotarbida 71 -- -- 71 Araneae 18 31 930 979 Haptopoda 1 -- -- 1 Amblypygi 5 1 3 9 Uropygi 6 1 -- 7 Schizomida -- -- 4 4 all Chelicerata 588 92 1272 1952 Arachnida only 253 69 1271 1593 Table 2.
The extant Ricinulei are usually considered to lack eyes although they bear more or less distinct light spots on the cuticle that may be associated with light reception.
Ricinulei is one of the rarest arachnid orders, comprising 63 living species known to date.
Arachnids of the order Ricinulei can be locally abundant, inside caves and in epigean habitats such as Amazonian forests, where densities as high as 36 individuals per square meter have been reported (Adis et al.
Catalogue of the Smaller Arachnid Orders of the World: Amblypygi, Uropygi, Schizomida, Palpigradi, Ricinulei and Solifugae.
AF005445 Uropygi Mastigoproctus giganteus AF005446 (Lucas 1835) Schizomida Stenochrus portoricensis AF005444 Chamberlin 1922 Ricinulei Pseudocellus pearsei U91489 (Chamberlin & Ivie 1938) Palpigradi Eukoenenia sp.
Some of the smaller arachnid groups, such as the 78 species of Palpigradi and 55 Ricinulei species, are so poorly known that no conclusions can be made about their social tendencies.