Thelocactus lausseri is a species of cactus in the genus Thelocactus, family Cactaceae, endemic to Mexico.
Description
The plant grows as a single, spherical to short-elongated stem. The grey-green body reaches 7 to 10 cm in height and 5 to 8.5 cm in diameter. It has 8 ribs arranged in a slight spiral. The areoles, which lack glands, are about 5 to 6 mm in diameter. The rounded tubercles (warts) are 7 to 9 mm in diameter and 8 to 12 mm high. The cactus bears 20 to 25 radial spines, 18 to 25 mm long, silvery-white to yellowish in color. There are 4 central spines (occasionally up to 6) that are 6 to 10 cm long, yellow to greyish, straight or slightly curved, and needle-shaped. The flowers are 2.5 to 4.4 cm in both length and width, ranging from whitish to light pink with a darker central stripe. The flowers are noted as the smallest in the genus Thelocactus (25–45 mm). The fruits are scaly and burst open when dry. The seeds are approximately 2 mm long and thick.
Distribution and habitat
The species is endemic to the Sierra de las Ovejas in the state of Coahuila, Mexico. It grows in shrubland on limestone and calcareous soils at elevations between 800 and 1,500 meters above sea level. Its range lies within the Central Chihuahuan subregion of the Chihuahuan Desert ecoregion.
Taxonomy
The species was first described in 1986 by Czech botanists Jan Říha and Josef Busek, published in Kakteen und Andere Sukkulenten (volume 37, page 164). The specific epithet lausseri honors the German cactus collector and nursery owner Alfons Lausser, who discovered the species. The holotype specimen (PR 377518) is held at the herbarium of the National Museum in Prague.
Conservation status
Thelocactus lausseri is listed in Appendix II of CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora), which includes all species of the family Cactaceae not already listed in Appendix I.
