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99THE ORDER RICINULEI IN MEXICAN CAVESby James ReddellAustin, TexasThe Order Ricinulei is an unusual order of arachnids, regardedby most authorities to be the rarest of all arthropods. Althoughsuperficially resembling ticks and moving in much the same way asticks do, they possess a number of characteristics which set themapart from all other living arachnids. They also represent a groupfar more abundant in the Carboniferous than today. All species lacktrue eyes and possess a hood, the cucullus, which fits down tightlyover the chelicerae. A complicated copUlatory apparatus on the thirdleg of the male is believed to aid in the transfer of the spermatophoreto the female during mating. This has not, however, ever beenobserved.Although described in 1838 by Guerin-Meneville from specimenstaken in Africa, the order, in 1939, was represented in publishedaccounts by only thirty-five specimens. The order is divided intotwo genera, Ricinoides in Africa and Cryptocellus in the Americas.H. W. Bater in a ramed trip to the Amazon in 1861 collected the firstAmerican species, described as Cryptocellus foedus. Since that timeadditional species have been taken in other parts of South and CentralAmerica. One species, C. dorotheae Gertsch and Mulaik, has beendescribed from the United States. It was found beneath sheet ironand other permanent cover at Edinburgh, Texas, in 1939.Chamberlin and Ivie (1938) described C. aearsei on the basis oftwo specimens in Balaam Canche Cave and Oxolo t Cave, Yucatan. Thiswas the first species to be reported from a cave and the firstMexican species to be described. In 1941 C. BolIvar y Pieltaindescribed C. boneti from Grutas de Cacahuamilpa, Guerrero (seefigure, page 101). His description was based on two males taken inthe end room of the cave. Yet a third species, C. osorioi, wasdescribed from a cave in 1946 (Bolivar y Pieltain, 1946). Thisspecies was described from Cueva de los Sabinos and was representedby eight specimens. One other Mexican species has been described.This is Cryptocellus spinotibialis described from a surface localityat Finca Guatimoc, ChIapas (Goodnight and Goodnight, 1952).Despite the discovery of several hundred specimens of anAfrican species of ricinulid the order in America has remained quiterare and probably less than one hundred specimens have ever beenreported in the literature on the order. When compared with otherorders, such as the mites and spiders, this is qUite amazing.Several arachnologists have stated that the discovery of a singlespecimen of this order is an "event". It was with great shock thatDavid McKenzie and I discovered that the "ticks" collected fromCueva de Taninul n. 1, Ciudad Valles, San Luis Potosi, were in thisphenomenally rare group of animals. Even more exciting was the newsthat not only were specimens of crtptocellus osorioi found but alsospecimens belonging to an undescrl ed species. Collected on June 7,1964, only about ten individuals were taken. On January 24, 1965,Terry Raines collected a few specimens of C. osorioi in Sotano delVenadito, Tamaulipas, making this the only-known species to bereported from more than two localities. In August 1964 Bill Russellfound several specimens in a moist area near the end of Cueva de losRiscos, Durango. The appearance of this order in Durango, a desert